Wednesday, March 9, 2011

FTL Part II: Just Plain Cheating


In our last exciting episode we considered the possibility that the dictum Causality, Relativity, FTL travel: chose any two may not be strictly true. Consult the comment thread for discussion, particularly some thought experiments offered by commenter Luke.

I cannot vouch for the validity of these arguments, only that they are either a) valid, or b) extremely high quality bullshit, and I choose a as my working hypothesis.

Einsteinian street-legal FTL is, as the discussion takes note, subject to certain constraints. Its use in a story is, in turn, subject to some meta-level contraints. So far as I can tell, it is consistent only with the 'jump' style of FTL, in which you pre-select your destination before hitting the big red button. FTL in which you navigate freely seems ruled out. And you are taking your chances with drawing (or narratively describing) a 'subway map' of FTL jump routes, unless you can ensure that your map meets the requirements for a directed acyclic graph.

You have been warned.


Having said that, the whole subject is pretty much moot unless you are a physicist, or can credibly impersonate one. Nearly all your readers will ignore your validation, and assume either that you are jiving them as part of the story, or else that you are simply a crank. (Which will not help them buy into the story.) Within the SF world, FTL is more or less universally understood to be a pure dodge, dumping physics for the sake of story. And it is just as universally accepted on that basis.

A point made in comments to last post was that there are also STL workarounds, even for such tropes as interstellar empires. Said commenter Horselover Fat: "For FTL, you need to dump Einstein. For STL empires, you need to dump your cultural assumptions. And you choose to dump Einstein?"

Very good question. My answer would be that cultural assumptions tie in closely to characterization, right at the heart of fiction. Change them greatly and your story pretty much has to be about those changes. Dumping Einstein, not so much. (Note: I am not saying that you need to ignore the laws of physics, only that - in space opera - you can.)

You do still have to fake it convincingly. As I suggested last post, the less you say about your specific handwaves the better off you will probably be. You also have to adhere to some internal consistency. If FTL jumps require generating Stupendous Energy on demand, you need to deal with the implications of a technology that can do this. Similarly, if you need to travel 100 AU in normal space to reach jump points, you need a normal-space drive capable of doing so in convenient time. (And if you stick with relativistic STL, you need a beaucoup powerful drive.)

All of which produces, or can produce, its own awkward complications. If your interstellar tramp freighter has a drive engine capable of slagging a continent, the movement of such ships anywhere near an inhabited planet will be very strictly regulated. This may spoil some otherwise charming tropes. (Think Firefly.)

There are a host of other possible complications to bear in mind. If FTL jumps can be made by small spacecraft just above planetary atmospheres, you've opened the door to bomber-mission nuclear strikes, or even interstellar ICBM strikes. But if it takes too long to reach jump points in normal space you could end up at least partly defeating the purpose of FTL.

Another criticism I have seen is mildly meta: settings in which there is FTL for convenient star travel, while the rest of the technology pretty much resembles the Plausible Midfuture [TM]. The problem here is that you have supposedly had a fundamental revolution in physics, yet with no technological consequence other than FTL itself. How remarkably convenient ....

A reasonable counter-argument might be that relativity itself gave us the atomic bomb and nuclear subs to deliver it, but no atomic motorcycles or force-field steak knives. Nuclear power plants put out the same kind of juice as coal-fired plants, and for most story purposes are pretty much invisible. I imagine that modern physics is implicated in a host of everyday gadgets, but not in dramatic ways.

So, the presumed future physics that gives us FTL might also give us antigravity drive and other Cool Stuff, or - for different desired values of coolness - might have few other obvious effects besides fast interstellar travel.

For that matter, a Pretty Strong argument could be made that all of this is tech geek navel gazing, irrelevant to the practical problems of SF world building. Heinlein's Starman Jones remains a favorite of mine in spite of an FTL that requires you to violate relativity in normal space, before you even get to make the FTL jump.

And to take a more modern example, I thoroughly enjoyed Elizabeth Moon's Heris Serrano books, though the stuff that reads like hard SF is really almost pure bluff. The fact of the matter is that if onboard instruments indicate the approach of an enemy ship, and the characters respond to this situation in a persuasive way, we as readers do not insist that they stop to calibrate their instruments for us.

On the other hand, this blog is more or less dedicated to the art of faking details convincingly.



Discuss. (As if you needed an invitation.)


The subway-esque hyperspace image comes, via Google Images, from a screensaver website.

328 comments:

1 – 200 of 328   Newer›   Newest»
Raymond said...

The problem with cheating, of course, is when your plot suddenly hinges on the precise weight of handwavium, and you just don't know...

Thucydides said...

Which is where the SF rubber hits the road; if you are just handwaving for dramatic effect and don't think about the implications of FTL/STL/massive energy sources or mind bending effects like "The Way" in Greg Bear's EON, then you are really writing space opera on the level of Hornblower in Space or maybe the Sacketts homesteading on Tau Ceti 4.

Now there is nothing wrong with that, and a large portion of what passes for Science Fiction is precisely this sort of story telling, so there is a market for writers to exploit.

The really good and smart writers will be able to write true SF by incorporating the concepts and their effects as the driving elements of the story rather than window dressing. This is a bit like the idea that the automobile was predicted hundreds of years before the actual invention (first order), but no one ever predicted drive throughs, strip malls or any of the other second or third order effects of the automobile.

Francesco said...

A possible solution (one that, if I remember well, was used by Philip Jose Farmer in a novel wich name I don't remember), is to bypass FTL space travel at all, and introduce parallel universe wormhole travels that still require spaceships to make the jump.
If you make the creation of the wormhole route sufficiently-but-not-too much random, you obtain a bag of desiderable space-opera consequences: plenty of habitable worlds, with the occasional weird one for variety, variant rubber-forehead aliens, earthanimal-like aliens, the occasional civilization strangely similar to our one, etc. etc....

ElAntonius said...

I've said it before and I'll say it again: a brilliant use of FTL "cheating" is present in the in-game codex for the Mass Effect series of video games.

Everything in that game hinges on, essentially, one technology:

"Element Zero", a specific species of handwavium that has the titular "Mass Effect"...in application, it can reduce or increase an object's mass via some sort of field.

Element Zero is used for:
-FTL.
-Artificial gravity on ships (IIRC, by making parts of the ship relatively massive).
-Hypervelocity railguns.
-Shields.
-Hover vehicles.
-Space fighters (although I've never actually seen one shown in game)
-"Psychic" powers via manipulation of said mass effect.

Everything in the game is shown to be a result of this one bit of phlebotinum.

Plus, it's a game where this is said by a character: "Sir Isaac Newton is the Deadliest Son-of-a-Bitch in Space!"

Citizen Joe said...

The bottled demon drive (or the Great Old One drive, if you don't mind plagiarism) might be an obvious cheat, but it solves many of the problems associated with a purely science based FTL drive. In setting, it would probably be called a 'Fold Drive' or 'Compression Drive' and the actual bottled demon part would probably be kept secret to the general population.

1. Using a demon in a drive implies the existence of demons which could also imply that they may be rampaging across Earth. This justifies the leap to space and space colonies. Literally a Hell on Earth has driven us to space.

2. It doesn't require humans to figure out how to manipulate space time, only how to enslave a creature (which we are pretty good at).

3. Since it is a demon, it really won't stick around with strictly robotic crews, it needs a human presence. Thus you have justification for crews.

4. Since it is hard enough just keeping the demon bottled, you don't get much abuse of the system. Attempting to do so invariably results in you dying or going insane or both.

5. The demon manipulates space time in order to compress/fold it. Technology just expands that power to useful levels. This allows FTL via crossing folded space at sublight (orbital) speeds. This also allows space combat via compression of the space between distant vessels. No longer is it an eyeball frying match since you can simply reduce the distance for a broadside salvo. Likewise you could warp space such that light would just bend around your ship, essentially shielding.

6. For flavor, you can literally have the Welsh chanting as a means of restraining the demon while in use. This could also be the presence of pure Hestian virgins aboard ship compared to the gruff and dirty space fighters. And there could be that conflict between true love and dooming the ship by deflowering one of its shield maidens.

7. Since planets warp space (gravity) around them, it is very difficult to warp it further with the bottled demon. This prevents those sneak attacks. Also, since it requires the demon and a whole crew, you don't get those FTL missiles. And since nothing is actually traveling beyond orbital speeds, you don't get into relativistic weapons (although it doesn't disallow them either).

8. The bottled demon doesn't require a massive power source, or rather a power source usable for other things.

9. Since nobody wants a demon released, space combat would move towards boarding actions.

So, it is an obvious cheat, but once accepted, it solves many problems.

jollyreaper said...

Power to slag continents and yet you're a space courier delivering pizzas: Yeah, that's a really hard one to get around. The question is "what's space economics like?" The only comparison I can think of is post-communism Russia where they have enough nukes to end human civilization and this giant, crumbling military machine but seemingly nothing to offer the international market. How could they fall to such irrelevance? And they're getting their butts kicked by Chechnya. How did this happen?

FTL but nothing's different: And this is just a variant of that complaint above, we think everything would be different. But how much will likely change? Will doors look any different in the future? You might get automatic doors in the supermarket but for the most part we're going to have doors with hinges and knobs. There's not really much you can do to change the mechanics of that! Same reason why it's pretty safe to assume that the dominant weapon for the mid-future will be the gun using gunpowder. The only plausible tweak to that I can imagine is a smart bullet that can track and kill a target and possibly selectively change its characteristics on the fly so it can act as armor-piercing or human-squishing-without-passing-through-walls all at a flick of thought from the user. That would involve crazy-advanced interfaces between the operator and the gun and could even potentially be post-midfuture tech. But we'd see that before we see laser pistols, I think. Point-defense lasers on tanks rated for use against people and anti-tank missiles would be more likely but that's expressly NOT man-portable.

Overall, I still say you win points with rigorous self-consistency in the setting and thinking through the implications of the technology.

Case in point, there's an urban-fantasy series that is by turns engaging and frustrating. Black magic is supposed to smut up your soul. Black magic requires killing things, animals or humans. Any witch who kills with black magic puts a huge smut on her soul. But there's no smut for killing with normal weapons. That with could shoot someone with a gun and they're dead with no penalty other than legal but shooting with a deadly curse will smut her soul. So why ever kill with magic unless you really have to? And the heroine refuses to kill with guns. She uses a paint-ball gun that fires balls filled with a charmed potion she makes that puts anyone it hits to sleep. It's basically a magic stun gun. The implications of which are astounding. Every single police department should carry both kinds of weapons. It's he ultimate taser because it can't possibly kill unless as a secondary effect, i.e. stun someone on a ledge and they fall to their deaths, stun someone in the water and they drown. You'd still need a bullet gun for whatever targets don't succumb to the paint-ball gun but seriously, this would change everything. But it doesn't, not within that setting. It's just a quirk of the heroine that she uses such a gimmick. Same goes with magic lie detectors. It should change EVERYTHING. For that matter the existence of any kind of effective magic disguise like polyjuice potion. Just consider the implications handguns have in this day and age. Metal detectors everywhere, politicians tightly screened from the public, bullet-proof vehicles everywhere.

Then again, the existence of the International Space Station doesn't mean much on Earth. We're retiring the shuttle fleet with no NASA-based successor in sight. We'll get the Falcon/Dragon setup if we're lucky. We've got fast computers, jetliners, no flying cars, no robot butlers but wheeled hockey puck robot vacuums, and most of our power generation still comes from burning dead plants and animals. But there are very good explanations for why we don't have the future we'd always imagined. It's not just author oversight.

Anonymous said...

I having been playing around with a story involving an STL Jump Drive. Or more properly a LS Jump Drive. Perfect time dilatation during Jump. No time from here to Alpha Centauri, from the pilots perspective.

But it comes with the following limitations: Your exit point is uncertain. Like 6 light-seconds worth of uncertainty for an in-system Jump. For near interstellar Jumps the uncertainty falls more in the AU range. Time has to pass before you can Jump again, say a couple of days, to allow the drive to cycle, or for the virtual particles to decay, or some such nonsense.

Could an interstellar empire function with cheap, abundant LS travel? How screwy would society get if Chris Colomubus of Space pops by every few centuries or so to say hello in Neo-Italian? Or if every wealthy tycoon can just skip a few decades to come back and see how his business it doing?

I am sure it has been done more than once. But I can't recall any stories where Light Speed travel was as cheap as FTL normally is in Light Space Opera.



-Free Hatani

jollyreaper said...

An example of a Bottled Demon universe--

Charlie Stross' A Colder War.

"It’s the Oliver North/Guns for Hostages scandal, seen from the viewpoint of a CIA bureaucrat, in a universe in which the entire Cthulhu Mythos is real."

The Soviet Union has developed a superweapon called Project Koschei[6] for use against NATO. Located at Chernobyl, Koschei is based on captured Nazi Germany research into an underwater city in the Baltic Sea. The Soviets have also deployed smaller weapons called servitors, as found in the Kitab Al-Azif, in their occupation of Afghanistan.

Doing so violates the Dresden Agreement, a secret multinational treaty signed in 1931 after an expedition to a strange Antarctic plateau that appears on no maps. Even Adolf Hitler adhered to the treaty, which hides the existence of the supernatural entities from the public and prohibits their use in war.

The United States' countermeasures for Koschei include 300 megatons of nuclear weapons and a continuity of government base hundreds of light years from Earth. American research also indicates that all intelligent species that experiment with the entities exterminate themselves. Other nations emulate the superpowers; Iran and Israel plan a nuclear defense against Iraq's attempts to open a gate to the stars.

As a Congressional committee examines American cooperation with Iran's plans, the Soviets and their leader Yegor Ligachev unexpectedly overreact to a joke by President Reagan, with dire results.


So perhaps Earth was not overrun when the bottled demon research began but was a result of fighting with cthulhutech weapons. That drives your diaspora. And all of your high technology in this setting would derive from cthulhutech, the same way Mass Effect does with their handwavium.

KraKon said...

following

KraKon said...

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Tony said...

jollyreaper:

"But there are very good explanations for why we don't have the future we'd always imagined. It's not just author oversight."

If it works, don't fix it.

+10

I take the same attitude about the whole FTL "authenticity" question -- don't waste your time or aggravate your readers by showing how much of a smart boy you are. It generally pisses readers off, unless you want your readership to be a bunch of pimply-faced physics grad students. But since your readership is actually computer programmers, legal secretaries, bankers, cabinet makers, electronic salesmen, tool designers, animators, soldiers, sailors, airmen, Marines, doctors, lawyers, retirees, etc., etc., ad infinitum, you should consider the "this guy's a pedantic ass" factor.

Tony said...

Re: Free Hatani

Poul Anderson beat you to it, by better than 50 years: The Long Way Home.

jollyreaper said...


"But there are very good explanations for why we don't have the future we'd always imagined. It's not just author oversight."

If it works, don't fix it.

+10


Yup. Sometimes it's "good enough" like the QWERTY keyboard. Is it perfect? No. Will you ever get people to change over? No. We're stuck with it. Sometimes it's "good as we're able to think of." The bicycle is a case in point. It's one of the best human transport solutions ever invented. You can refine it some with better materials, refinement on gears, but you're not replacing it. Segway? Neat idea, neat exercise in tech, completely impractical. It would not surprise me in the least if the history of the far future shows us that we have to wait five thousand years for personal wormholes to finally beat the bike and another thousand for them to actually become affordable. :)

Anonymous said...

Rick wrote: "My answer would be that cultural assumptions tie in closely to characterization, right at the heart of fiction. Change them greatly and your story pretty much has to be about those changes."

I thought that was kind of the point of SF. A trivial example: drive-thrus are not product of the automobile as such. Once the concept blossomed in a particular culture, it must have been tried in many places but it didn't take hold everywhere. You need a culture that matches the technology (and vice-versa) to have a coherent setting.
Your cultural assumptions are not valid even now. Not dumping them for a story which happens in a very different environment far in the future (or perhaps not so far in the future after aliens gave humanity a ticket to the stars) is not likely to result in something believable or (in my opinion) interesting. Certainly it would be very limiting.
Excuse me for coming up with an extreme example but the reimagined Battlestar Galactica purposefully transposed the writers' culture into a SF setting for instance. I'm sure it made the writing easier and it certainly cut down on the exposition but it also made it very hard to take anything seriously. In a setting that's basically a joke to begin with, I suppose that's OK. But then it looked like they wanted to try to do something more serious with the concept and it was a chronic trainwreck.
I guess there's no accounting for taste but I think there are plenty of good characters in settings which have very different cultures than ours. A lot of contemporary fiction deals with cultural issues and uses them for characterization. Historical fiction and especially SF should have more of that. And SF simply has to be more creative. Recycling historical cultural elements is fine but space has got to bring about something new and different.


Some of the old timers here do not seem to realize that relativity in taught in some schools and in several college curricula, not only to physics students. Since you've been to school, a whole new generation of physics teachers (or two) has been at work. Some of them seem to relish in holding little talks about the double slit experiments, relativity, QM and stuff. They should be banned from sharing theit idiosyncratic views about QM if it's not on the curriculum if you ask me. That aside, my point is that a whole lot more than 0.001% of people who read sci-fi nowadays understand that FTL is verboten and have a vague idea as to why. Galilean relativity is something kids are asked to do math about and which has applications in real life so people tend to understand what a frame of reference is.
Some commenters here seem to be appyling a good deal of wishful thinking to the plausibility of wormholes and other theorized means of FTL. And why not? I'm not one to take offense at a little fantasy as long as it's not taken too seriously. But please don't judge the thinking public intelligence by what you see on the telly. And please don't assume your ignorance is shared by >99% of the population without some solid evidence.

-Horselover Fat

Anonymous said...

@Tony

Ha! Can't wait to read it! So it does cheap LS Jump drive?

Thanks for the recommendation.

-Free Hatani

Tony said...

Free Hatani:

"Ha! Can't wait to read it! So it does cheap LS Jump drive?"

It has LS jump technology affordable by anything from a medium sized corporation on up. IIRC, LS courier vessels are cheaper -- or at least more convenient -- than interstellar radio traffic. (Talk about a solution to the Fermi Paradox, BTW...)

Stevo Darkly said...

Free Hatani --

A lightspeed drive similar to what you describe (except for your second paragraph*) appears in Ken MacLeod's "Engines of Light" trilogy:

- Cosmonaut Keep
- Dark Light
- Engine City

The series also features uncaring but sometimes meddling "elder gods," super-intelligent starfaring tentacled creatures, ETs resembling Alien Grays, and flying saucers -- and a hard SFnal explanation for each.

It also features an abundance of habitable worlds with Earthlike life, exotic human cultures, and interstellar trade -- likewise with a hard SFnal approach. It's an unusual and interesting worldbuilding set-up.

Oh, and alien invaders of a sort. Great line: "Resistance is futile. You will assimilate us."

The limits of lightspeed do place some interesting limits on interstellar society, which complicates plans to fight the invaders.

* Light jumps can be made anywhere, with accuracy apparently dependent on the quality of your sensors, computers and drive. Late in the trilogy, some aliens are able to jump their spacecraft inside of a building on a planet's surface -- but such precision is difficult, and only one very advances race is able to do it.

Tony said...

Horselover Fat:

"Recycling historical cultural elements is fine but space has got to bring about something new and different."

Why? Human nature hasn't changed in the last 5000 years. There's no reason to think it will change in the next 5000. Only hubris would suggest that we live in a special time, or that we are on the thresshold of a sea change in human history.

"Some of the old timers here do not seem to realize that relativity in taught in some schools and in several college curricula, not only to physics students...But please don't judge the thinking public intelligence by what you see on the telly. And please don't assume your ignorance is shared by >99% of the population without some solid evidence."

"[O]ld timers"? "[T]hinking public"? Heh...

Here's a shocker -- people were exposed to relativity in high school back in the Seventies as well. And nobody that I know deprecates the intelligence of the people in general, nor does anybody divide them into "thinking" and (presumably) unthinking castes.

It's just that the average SF reader, regardless of education, simply doesn't care to be bothered with theoretical esoterica. Newtonian movement in space? Okay. The implications of ubiquitous computing? Okay. Advanced bioltechnology? Okay? Realistic military (or legal or business or whatever) action? Okay. Those all apply to the human and gross mechanical verisimilitude of the story. Wank about FTL and causality? Great conversation for people who care about that stuff, bad for storytelling. Most SF readers interpret it as the author showing off, because most SF readers, even those with a reasonably strong scientific education, just don't GAS.

Anonymous said...

@Stevo Darkly

Another series for the reading list then. Thanks!

The idea is obviously much more common that I believed. My Sci-Fi education continues...

-Free Hatani

Jnani said...

@Horselover Fat:

You make some good, valid points, and I suppose the only thing that I could say is that it really depends what you are looking for in Sci-Fi. It's become pretty clear that not everyone is looking for the same thing. Myself, I love seeing Sci-Fi as a thought experiment where we take a political or sociological idea that is meaningful in today's world and use the extremities of the future world to fully examine it. For instance, and you will disagree with me on this obviously, I loved the revamped Battlestar Galactica for this reason. Much of the internal domestic debate in America had been asking the question "How far should we go to protect our society from external threats? How much is liberty worth, weighed against the extermination of our way of life?" The show took that to an extreme: there are little more than 40,000 people left in the universe. They are being hunted down by a robotic species that will never stop trying to kill them, and which has sleeper cell agents in their ranks. How far are they willing to go to keep humanity alive?

By taking a serious real world question, a philosophical difference that at least splits America neatly in half, and presenting it in its most extreme form, it created a very dramatic and stark place for debate. Not to mention that there was lots of sweet explosions in space, interesting and meaningful characters, and a really killer soundtrack.

But obviously not everyone wants that in their sci-fi (I wouldn't be surprised if I'm the only person who actually appreciated that show who reads this blog, from the looks of it). Obviously, you want a fiction that explores social changes, and the impact that technology has on society, which can be smart and dramatic in and of itself. Others want to see a good analysis of future tech, and the ramifications of that technology on other aspects of life. And some just want a good opportunity to see space battles, hot green alien chicks, and gruff smugglers giving rouge-ish grins to said aliens chicks.

Like I said, it all depends what you want. Theres an audience for all of it.

Anonymous said...

Your "human nature" is a cultural fiction, Tony. Not only has it changed a lot over 5K years, it's not that widely shared around the world here and now.
I will not comment further on this topic.

Tim said...

One way of dealing with the huge can of worms opened by gravitational/spacetime manipulation is to restrict it to a large scale. A space-bending drive housed in an ocean-liner sized vessel seems reasonable, one housed in ship the size of fighter jet seems less so, and if it can fit on a wrist watch it stretches my credulity past the breaking point. As Rick pointed out: we currently have nuclear submarines, warheads and municipal power plants, but not atomic cars or jetpacks.

Personally, when reading a story in an interstellar setting, I don't have any problem with FTL drives. I don't need a physics lecture, but it's nice to know what the specs are (maximum speed, distance, time to reset between jumps, what happens if you screw up a calculation, etc.) especially if they figure into the plot later on. But when we have cheap ubiquitous gravity control, like giving the ship's floors a constant gravity under all conditions, the effect softens a bit (TV and movies get a pass, due to production constraints). Or if you can "jump" between points by stepping into a booth, I'm really starting to have my doubts about this setting...

One possible solution is that your spacetime-bending FTL (or STL or LS, for that matter) mechanism emits gravitational waves as a byproduct that are harmful to the wellbeing of the passengers. Maybe it's about as bad as a chest X-ray, where you don't notice a few, but there could be a potential problem after several hundred exposures. So you definitely don't use the artificial gravity machine for mundane uses like simulating earth gravity, or to make a flying car, etc. Also, your astronauts will have a maximum number of safe jumps they can make in a lifetime. There's no workaround, because nothing can shield against gravitational waves.

Anonymous said...

Jnani: I just can't relate to that. Maybe one of my problems with BSG is that it's provincially yankee. It's by no means the only one however.
Maybe this show frustrated me because I thought it had some great episodes and there was much to like about it (the colors, some of the actors, the set and so on). But the writing...

I'm not looking for any one thing in SF. Ludicrous heroic space fantasy does not have to be culturally inept. Since we're talking about TV, just look at B5. It was partly Gringolandia in space... but only in part. And that part was mostly justified considering the (implausible) mid-future setting.

Tony said...

"Your "human nature" is a cultural fiction, Tony. Not only has it changed a lot over 5K years, it's not that widely shared around the world here and now.
I will not comment further on this topic."


Of course it's your right to withhold further comment, but here's your chance to support you assertion...

Who said this, and what impact do you think it has on your case?:

"The strong do what they can, while the weak suffer what they must."

Tim said...

@ Stevo Darkly

I've read Cosmonaut Keep, and enjoyed many of the concepts, (especially the lightdrive, squid-piloted ships, and recreational dinosaur hunting) but couldn't get into the characters so much. Also the jumping back and forth between the near future and far future bugged me. How are the second two books in the trilogy? I've heard mixed reviews. Do they stick with one time period?

Tony said...

"Maybe one of my problems with BSG is that it's provincially yankee."

Gee, it was made for American television. But provincial? I think the British, Canadian, and even South African actors might have a problem with that, dontcha think?

Jim Baerg said...

Jollyreaper: "and most of our power generation still comes from burning dead plants and animals. But there are very good explanations for why we don't have the future we'd always imagined. It's not just author oversight."

I'm getting more & more convinced by a blogger who says the reason for our power generation mostly coming from burning dead plants & animals is that the people who get rich from that situation put all the road blocks they can in the way of nuclear power.

Free Hatani: About stories with a Light Speed drive - I see Tony beat me to mentioning _The Long Way Home_ & Stevo Darkly mentioned a series I haven't read, but will have to find.

There was also a series of short stories published in Analog in the 80's or 90's IIRC which centered on a LS drive & your wealthy tycoon idea. The villains of the stories were a family that jump between colonies & have manipulated the governments of those colonies to avoid having their compound interest taxed away.

Rick said...

Welcome to a new commenter!

I'd guess that there's been little exploration of LS travel for the same reason there's been not all that much exploration of STL (compared to FTL): Too many of our favorite tropes require fast interstellar round trips, including from the stay at home perspective.

Riffing on Thucydides' point about what was not predicted about cars, think of how completely the Internet was not predicted, either in SF or 'nonfiction' futurism. There are a handful of limited exceptions, but in general hardly anyone though of the implications of enhanced communications between/among people.

Tony said...

Jim Baerg:

"I'm getting more & more convinced by a blogger who says the reason for our power generation mostly coming from burning dead plants & animals is that the people who get rich from that situation put all the road blocks they can in the way of nuclear power."

Funny how the dark and mysterious forces of petro-capitalism don't seem to be able to help themsleves one bit in France and Japan. And while they don't like nuclear power, they seem to think it's okay to burn food for energy.

Or maybe it's just the American public being stupid about energy all the way around.

Rick said...

I ask 'anonymous' commenters to sign a name, as Free Hatani did and some longtime regulars do. No big deal if someone forgets now and then, but it helps in following conversations.

Regarding BSG, I never watched it, for essentially shallow reasons. First, because I remembered the 70s version, which was pretty lame, and second, because 'USN carrier ops in SPAAACE !!!' has no particular appeal to me. That said, the 'new' BSG got a lot of high regard from people whose opinions I respect.

More broadly this touches on principles of SF criticism; follow the link for an early post here with my biases on the subject.

Anonymous said...

The spinoff series Caprica and other published materials do flesh out the BSG universe to a degree. They imply that it is the colony of Caprica itself that is culturally similar to today's USA, so the American feel of BSG may be the result of the dominance of Caprica as the capital of the Colonies, and also due to the Caprican origin of several of the main characters. Even in the series itself, cultural differences between the Colonies are mentioned, such as Sagittarons being distrustful of modern medicine, and Gemenese being religious fundamentalists.

R.C.

ElAntonius said...

Rick: The new BSG wasn't all that "Carriers in SPAAAAACE" focused, actually. Sure, it had a fair share of battles, but surprisingly less than you would expect given the premise...which actually helps stretch the premise a bit. (After all, it's hard to hold faith in a series where the titular ship gets blown half to hell every week, or you start asking questions like "where do they get more supplies, pilots, ammo?")

It was more a political examination with strong overtones of The War on Terror.



I think part of the problem with trying to be too realistic about FTL (and trying to show your work) is that, in reality, known science doesn't really support FTL. So authors that try to focus on it too much just look like they're burying the ever-present handwave.

Even intelligent readers don't want to read a textbook on something that isn't real, for the most part...so as has been echoed a million times on this blog, I think the best solution is to start from the effects and then work in a "how it works."

I don't know why FTL gets so much attention anyway...it's not like most sci-fi goes into the mechanics of STL rockets, or how the air purifiers work, or how missiles guide in on their target.

I think it's because in our world FTL is the unknown quantity, and we can accept the rest easily because we know they work in the real world.

But imagine reading a modern-setting book where the author spends 150 pages discussing the history of the ICE, how it all works, who invented it, and the physics behind it...

At some point...isn't: "Max Steel planted the gas pedal in his Corvette, 7 liters of V8 engine howling as the tires desperately grabbed the pavement. Ebil Jurk was getting away...but not for long." enough to denote our hero has a sports car, a powerful one?

Why is it so different for FTL? We accept that it works for the story, we accept the rules, no need to wank on about it.

Raymond said...

ElAntonius:

"At some point...isn't: "Max Steel planted the gas pedal in his Corvette, 7 liters of V8 engine howling as the tires desperately grabbed the pavement. Ebil Jurk was getting away...but not for long." enough to denote our hero has a sports car, a powerful one?"

The difference is, we have a sense of what a Corvette is (a sports car) and how big a 7L V8 is (nice and big), not to mention a visual reference for a powerful sports car looks and sounds like when taking off (well, the Hollywood version, anyways - the racers in the audience will have very different tastes). Most of the audience will be well-acquainted with at least the existence of the ICE, as well as basic operational principles (needs gas, makes noise, gets hot, is attached to a transmission with different gears). It's a wonderful shorthand - but it's only possible because it's so common.

The larger implications of common ICE-powered vehicles are more subtle: highways, suburbs, dependence on foreign oil, others. They're already part of the landscape, so to speak, so authors don't have to spend time explaining them. It's the age-old problem with SF - how to describe a world which doesn't work the same way as the present one without confusing or boring the reader.

Anonymous said...

ElAntonius, that's a fair question. I agree with you actually: there's generally no need to lecture about how the FTL works. That's not the issue. The issue is that FTL breaks the universe. What we need to understand if the story is going to happen at least partly in space is how the story's universe works. You've changed physics to have FTL. Fine. But if you don't tell what you changed we won't know how to make sense of the stuff going on in space.
You could change the speed of light for instance or say that light is not the fastest thing in the universe after all. Or you could say that causality only works in a priviledged frame of reference and so on. These choices affect the goings-on in space.
I'll use an example I discussed with a Rocketpunk commenter over email: if the speed of light we are familar with was maintained but FTL was nevertheless allowed, the tactics of warships equipped with lasers must change. Ships going faster than light on the right vector would be able to shoot at a target before they are seen without fear of retaliation. In order to prevent that, you would need FTL scanners, not something relying on electro-magnetism. FTL scanners in turn would have consequences such as FTL communication. And so on.
In other words, you don't need to explain your engines but if you want your universe to make sense, you must explain how it works and think about the consequences.
FTL implies fundmental changes to our understanding of the universe. It's possible to sweep them away in a mostly theorectical realm where they will not affect your story but how are your we to guess you have done so if you don't tell?

-Horseolver Fat (apologies Rick: I thought I only needed to sign once as long as there was continuity between by comments)

Milo said...

Citizen Joe:

"2. It doesn't require humans to figure out how to manipulate space time, only how to enslave a creature (which we are pretty good at).

3. Since it is a demon, it really won't stick around with strictly robotic crews, it needs a human presence. Thus you have justification for crews."


It's perfectly possible to create an automated torture device. Electric fences are an obvious example, and scientists use more elaborate setups for animal behavior experiments (do X, you inevitably get an electric shock).


"This could also be the presence of pure Hestian virgins aboard ship compared to the gruff and dirty space fighters. And there could be that conflict between true love and dooming the ship by deflowering one of its shield maidens."

Of course, this could be a temporary vocation. Once you, umm, stop being a virgin, you get pulled out of active combat duty, and perhaps start training the next generation of maidens. (Like the practice of ace fighter pilots being pulled out of combat, in part to avoid the morale loss if a celebrated hero were actually shot down.) Or just producing the next generation of maidens.

Unless, of course, the purpose of those virgins is to get eaten by the demon.



Tim:

"There's no workaround, because nothing can shield against gravitational waves."

If nothing can shield against it, then it's harmless.

Radiation deals damage by dumping energy into stuff it hits. Shielding works by ensuring the energy gets dumped into unimportant stuff before it reaches any important stuff.

If the radiation can pass through shielding without losing much energy, then it can also pass through people without doing much damage to them.

Raymond said...

Citizen Joe, Milo:

The Demon Drive sounds fun - you'd have to work to keep it from too closely resembling Lovecraft or 40K, though.

Tim:

"One way of dealing with the huge can of worms opened by gravitational/spacetime manipulation is to restrict it to a large scale."

A point that Luke mentioned in an older thread in which wormholes came up (the Torchship one, or Rapid Transit - I forget) is that the wormhole itself can function as a rocket (and, in fact, it can be microscopic during transit and expanded later using local mass). I think it's a cool idea to run with, frankly, and it means that the origin of the wormhole can be a massive base station (which would limit the pace of and access to spacetime trickery quite nicely).

Tony said...

Re: Horselover Fat

Whatever is broken or changed for FTL to exist need only be explained if it affects the story. If people just hop in the ship and jump off to another star to move the plot along, why wank?

Teleros said...

ElAntonius: ""Element Zero", a specific species of handwavium that has the titular "Mass Effect"...in application, it can reduce or increase an object's mass via some sort of field.

Element Zero is used for:
-FTL.
-Artificial gravity on ships (IIRC, by making parts of the ship relatively massive).
-Hypervelocity railguns.
-Shields.
-Hover vehicles.
-Space fighters (although I've never actually seen one shown in game)
-"Psychic" powers via manipulation of said mass effect.

Everything in the game is shown to be a result of this one bit of phlebotinum."


Whilst it's good to see them thinking through the various uses for it, how the hell do they get the railguns to work? If you reduce the mass, the KE & inertia goes down (less damage). If you increase it, you've got to fire a more massive shell, and keep it in the field (I assume) to gain the benefit of the additional KE / inertia.

Moving on before we get too sidetracked by RPG mechanics...

"Plus, it's a game where this is said by a character: "Sir Isaac Newton is the Deadliest Son-of-a-Bitch in Space!" "

By / to someone called Winchell I believe, after the guy who maintains Atomic Rockets.



jollyreaper: "Power to slag continents and yet you're a space courier delivering pizzas: Yeah, that's a really hard one to get around."

Planetary shields are your friend :P . That or a region around each planet / colony that's covered by very powerful guns: enter it under your own power and kiss your starship goodbye.



Tony: "Why? Human nature hasn't changed in the last 5000 years. There's no reason to think it will change in the next 5000. Only hubris would suggest that we live in a special time, or that we are on the thresshold of a sea change in human history."

One possibility is good old genetic engineering. Suppose all colonists have to have a whole suite of engineered genes, that are all dominant - that is, always passed on to the next generation. That would allow for them to rapidly spread through the growing population, and if you're changing the way people think (even accidentally) then that will have a potentially huge knock-on effect. Or imagine that, as a side-effect of another gene mod, alcohol no longer affects people (maybe its metabolised instead). That would be a HUGE impact on social life.

Teleros said...

Jnani: (I wouldn't be surprised if I'm the only person who actually appreciated that show who reads this blog, from the looks of it)"

Probably :P . Not going to go further than this though: there are better places for discussing nBSG IMHO.

In terms of what I want from my sci-fi though... I want to enjoy it and I want to be inspired (be it "cool I've painted that WH40K cruiser from the book now" or "that's a nice idea for my own stuff"). Some of the stuff I also read for how it explores concepts and ideas, but the above two are my main reasons. Or put it this way: I don't read Warhammer 40,000 because it explores serious social issues, but nor do I read Stephen Baxter because he writes interstellar war (or characters :P ) particularly well.



Anonymous: "Your "human nature" is a cultural fiction, Tony. Not only has it changed a lot over 5K years, it's not that widely shared around the world here and now."

I'm with Tony on this actually. Cultures & technology have changed tremendously over the last few thousand years, but human nature... not so much. A human today is basically identical to a human being 10,000 years ago. Better educated and probably healthier, and with lots of gizmos, fancy toys and cultural baggage, but that's all.



Tim: "As Rick pointed out: we currently have nuclear submarines, warheads and municipal power plants, but not atomic cars or jetpacks."

How much of that is down to the fact that a small atomic-powered object would be pointless and dangerous, rather than impossible? I mean, if your FTL wristwatch is possible (but just very expensive), is it not possible that the super-rich have them - just because it's a status symbol? Or that the 25th Century's James Bond types use them, even though they're not cost-effective for widespread use?



Jim Baerg: "I'm getting more & more convinced by a blogger who says the reason for our power generation mostly coming from burning dead plants & animals is that the people who get rich from that situation put all the road blocks they can in the way of nuclear power."

I think it's more a case of simple inertia. Fossil fuels work and they're cheap, relative to most alternatives. In the case of nuclear power, it also doesn't have vocal loonies poo-pooing it every time it's mentioned. Certainly the fossil fuel industry has a vested interest, but I wouldn't say it's their fault we're not all using nuclear power yet.



ElAntonius: "Why is it so different for FTL? We accept that it works for the story, we accept the rules, no need to wank on about it."

People know what cars are though, and how they work. The same isn't true for FTL - ALTHOUGH, that said, I also agree that too much detail really isn't necessary. Best IMHO to spread the exposition out & just give the bare bones IMHO. After all, in most cases an FTL drive in a setting is no more unusual than a car with an engine in it: it's there, it works, now let's get to Tau Ceti pronto!



Horselover Fat: "What we need to understand if the story is going to happen at least partly in space is how the story's universe works. You've changed physics to have FTL. Fine. But if you don't tell what you changed we won't know how to make sense of the stuff going on in space."

Further to this, I'd say that the person this stuff REALLY matters to is not the reader but the author. If hyperspace is a special frame of reference, then you can all-but bury that fact in a sentence or two somewhere in the story (if you need to at all). Most readers will be more interested in the top speed / accel of your FTL drive anyway, whether hyperspace is pretty, and how you protect yourself from the demons outside the ship.

David said...

Several thoughts:

1. I still keep thinking that just having a jump drive, where the ship was at point a, then jumps across to point b, with energy expended might just be enough to get the readers to by in to FTL.

2. One of the things I liked about BSG was that the FTL drives required "spinning up", and some precision navigational setup to jump safely. I even liked the idea of being able to combat jump into a planetary atmosphere, provided accurate enough jump co-ordinates were available.

3. Since we are really discussing what amounts to Elven underwear, how realistic do we have to be? Should we have a primer, giving a more detailed description of our drive and physical principals, so that the reader can, if they choose, get a better idea of what we were talking about in our story. I have read several stories where the author decided to include such a primer, so as to more accurately describe the color of their particular handwavium. I am not sure that is always appropriate, but it might alleviate any anxiety on both the author and reader's parts.

4. I still like Drocher and Hauser's interpretation of Heim theory. It gives you FTL, anti-grav, and unifed physics. Is it real, I don't know. I'm a pilot/teacher of english/tech nerd...not a quantum physicist. Does it make sense, again...I don't know, but it allows me to take a ship about the size of a A380, jump 10ly in about 90 days, and it gives me the ability to have interesting adventures in space.

Which is what we're after, isn't it?

Teleros said...

From a 8.6k word story I wrote a while back on Stardestroyer.net, re how much you need to describe the FTL method. Just 320 words, but it's enough I think to get the important information across:


"Aye sir," replied the navigation officer a moment later. "Course set. Rotating... now."

The swarming environs of Athens Station vanished. So too did space itself - replaced by the swirling blue, white and purple lights of hyperspace. Held inside this strange realm by their hyperspace fields, the five destroyers under Hart's command adopted a delta formation, with her ship in the centre, engaged their plasma drives, and shot away. Leaning back in her chair, Hart took in the view. After nearly a century in the Alliance Navy, hyperspace still managed to look new and fresh every time she gazed into it. Ever-shifting patterns of light glittered just beyond the bubble of normal space that enclosed her ship, and she knew she could spend hours just watching the universe's most magnificent natural light show.


...


"Commander Hart, how good to see you again." Admiral Alfredo Caldera smiled with genuine warmth on the main viewing screen as Hart's squadron entered the inner sensor envelope of the Free Madrid system, some seven parsecs beyond the system itself. "I trust that the Harpies have had good hunting?" he added, referring to the unofficial name of Hart's squadron.

...

"Three point zero two minutes until arrival," interrupted Stevenson.


...


The minutes ticked by, until the five-ship squadron arrived, several lightseconds from the Free Madrid capital world. Or rather, from the co-ordinates in hyperspace that corresponded to the capital world, for without precise maps, computers and scanners, hyperspace was essentially the same wherever you were in it. One moment, the ships were surrounded by the twisting lights of hyperspace and the various civilian ships travelling to and from the tiny one-system kingdom, the next they had rotated out of that alien realm and back into ordinary space.


...


"Master-Commodore! The destroyers have rotated out!"

"Is the hyperwall generator functioning?"

"No my lord, the government on David is refusing to activate it. We've just activated our own, but they still managed to coast half the distance in hyperspace. They'll escape its radius in... four point nine neffa, assuming we chase them immediately."


...


Racing forwards at a fraction under the speed of light, the Harpies crept towards the edge of the Core Empire's hyperwall, and Hart let out the breath she'd been unconsciously holding as Stevenson rotated the [i]Strophades[/i] into hyperspace the moment it was possible to.



1. Ships "rotate" into / out of hyperspace

2. It's pretty (is the transition?).

3. It seems safe (unless you get lost?).

4. 7 parsecs in 3.02 mins gets you the speed.

5. No causality screw-ups mentioned (it's actually a special frame of reference, but that's not specifically mentioned).

6. You can block access to hyperspace with a "hyperwall" generator".

Anonymous said...

David wrote: "I still keep thinking that just having a jump drive, where the ship was at point a, then jumps across to point b, with energy expended might just be enough to get the readers to by in to FTL."

In a universe where the speed of light is essentially infinite, that could work well.
But with our speed of light, for one thing you're going to have a hairball of counter-intuitive combat tactics with lots of room for "why didn't they simply do X instead?" moments. If that's what you're shooting for and you're prepared to put in the work to make the stuff intelligible and plausible, fine. If not, why not drop the speed of light instead?

Frankly the people who want simple FTL puzzle me. If you're not going with real-world physics, why not get rid of the speed of light entierly? It makes things so much more intuitive in space and you can do it with a couple of sentences.

"how realistic do we have to be? Should we have a primer, giving a more detailed description of our drive and physical principals, so that the reader can, if they choose, get a better idea of what we were talking about in our story."

I'd say that depends on how much of the story involves space not just as a backdrop but as something the characters are going to interact with.
Any conflictual situation where people are trying to get an edge over the others by moving around in space (or time) is going to require particular attention is you want it to be plausible (even if it doesn't involve actual combat).
If you're going to have anything but the most intuitive shortcuts like getting rid of the speed of light, my opinion is that the physical and/or supernatural ways in which your universe is different than the one we believe we live in should be integrated into the story and not just tacked on. But that's just me.

-Horselover Fat

Tim said...

Teleros:

"How much of that is down to the fact that a small atomic-powered object would be pointless and dangerous, rather than impossible? I mean, if your FTL wristwatch is possible (but just very expensive), is it not possible that the super-rich have them - just because it's a status symbol? Or that the 25th Century's James Bond types use them, even though they're not cost-effective for widespread use?"

One reason I would want to avoid FTL wristwatches and the like is that it's a plot killer: "why don't they just use their FTL wristwatch to get out of this situation?" You have to come up with more and more convoluted reasons why the protagonist can't just call in for back-up or be whisked to safety.

If FTL is limited to devices that take up a city block and only work outside of gravity wells, then once your secret agent is dropped onto the planet, he's only got a few simple pieces of equipment and his own wits to get the mission done and return to the ship. That would tend to make for a more exciting story, don't you think?

That's a literary justification. If you need a physics/engineering justification to back it up, just remember that any proposed method of FTL communication or travel involves some serious bending of spacetime (and likely the laws of physics) that I'm having a hard time believing can be accomplished by a wristwatch, no matter how expensive.

Anonymous said...

Ok, several things, so in no paticular order;

As far as I know, the railgun rounds in Mass Effect are mass-reduced when fired, but are mass-ehanced once they leave the gun.

In stories with FTL, I like the ones that show the effects of the stardrive with maybe a little background being inserted into character building conversations ("Ok, Cadet Newbee, why do we Jump from the poles of stars? Limit your answer to 100 words or less. Perferably less. 30 seconds, go!")

If you need huge amounts of power for your stardrive, then you should have huge amounts of power for your sub-light drive; if it needs the equivelent of a car battery you might not have a very powerful sub-light drive...

As far as new tech giving rise to new cultural norms; I say stretch your imagination! well thought out consequences, no matter how far-out, should be formost for those stories which are based on this premiss.

Having a group of people that plod along, living their lives on a single world vs. a group of people that skip generations as they flit from world to world...which one would you belong too?

All in all, I personnally tend to keep the FTL tech in the background, with only a few sentences of explination worked into the story as seamlessly as possible. I don't always succeed in the level of smoothness that I aim for, but I try.

Still, for satire, go with outragious; the Zoom-a-tron(tm) or the biofeedback hyperdrive. The Demon-in-a-Bottle Drive is also a good one...

Ferrell

Citizen Joe said...

RE: Milo's automated torture devices.
Torturing a demon requires emotional impact, such as singing Celene Dionne songs, or pop princess renditions of the National Anthem. Thus you need the human presence. They also need the emotional back up singers chanting to keep the demon hedged in.

Raymond said...

ElAntonius:

I do love me some Mass Effect. It's also a good example of logically consistent and demi-plausible FTL considerations, but tucked out of the way so people who don't care don't trip over it. Appendices are great for that.

And the mass relays remind me of Luke's tramlines.

Ferrell:

"As far as I know, the railgun rounds in Mass Effect are mass-reduced when fired, but are mass-ehanced once they leave the gun."

That was my impression as well. I suspect the mass reduction was to improve the muzzle velocity, and the energy cost of returning the mass to normal is what prevents the guns from becoming hand-held battleship cannons. Or something like that. '

Teleros:

"By / to someone called Winchell I believe, after the guy who maintains Atomic Rockets."

Given the general approach of ME, I'm fairly certain several of the writers (of the codex, anyways) had the site in a tab at all times.

David:

Extended Heim theory is definitely fun. I'm pretty sure the current(ish) 12-D version elminated the neutral electrons which banish it to never-never-land, and the antigrav just barely escapes the normal reactionless drive problems. It's useful in its potential to kickstart the kind of space opera setting we're used to, without requiring the kind of general techlevel advance that would totally reshape society.

Raymond said...

Teleros (again):

"After all, in most cases an FTL drive in a setting is no more unusual than a car with an engine in it: it's there, it works, now let's get to Tau Ceti pronto!"

"Further to this, I'd say that the person this stuff REALLY matters to is not the reader but the author. If hyperspace is a special frame of reference, then you can all-but bury that fact in a sentence or two somewhere in the story (if you need to at all). Most readers will be more interested in the top speed / accel of your FTL drive anyway, whether hyperspace is pretty, and how you protect yourself from the demons outside the ship."

Probably true, as far as it goes. Where it too often leads, though, is the Standard Sci-Fi History (Evil Website warning!) which frankly bores the fsck out of me as a setting.

Not to say that everything has to be diamond-hard and read like a technical manual. To transplant a couple comments from the previous thread (so I can sync up the reference frames - tabs make nice wormholes, but the spacelike separation is bugging me):

Tony: "Basically, I think it's offensive (yes, I really do mean offensive) to bore the reader with any more technical detail that is absolutely required to justif a technical artifact's effect on the action. That's a big reason, aside from the Mary Suisms, that I could never get into the Honorverse. Half of the text was techno-wank."

Honorverse excepted, that reaction is a complete blackbox to me. I know it exists, but I don't (and likely never will) understand it. I like technical things. I don't mind learning something new in a novel instead of a textbook. If the infodump is boring, I'll skip or skim, but it won't ever offend me. I'd much rather have a technical infodump than purple prose, lurid emotional handwringing, or my personal bugaboo, intricate descriptions of appearance.

Most of that, though, is just bad writing.

Milo: "Personally, I think both "any space opera story that doesn't mention relativity at least in passing is utter garbage and cannot be taken seriously" and "mentioning any hard science that doesn't outright form the basis of the plot is a pretentious distraction that ruins your pacing" are a little extreme. If you can work it in smoothly, then do. Otherwise don't."

So I'm clear, I'm not in favor of including a hundred pages of GR calculations and spacetime maps anywhere but a completely optional appendix (online or built-in). Dune stuffed all sorts of information in the appendix, and almost none of it directly influenced the plot without being mentioned in a minimum-cost way in the main text. But it gave flavor and consistency and history, and made the overall context more comprehensible.

Stevo Darkly said...

@Tim:

@ Stevo Darkly

I've read Cosmonaut Keep, and enjoyed many of the concepts, (especially the lightdrive, squid-piloted ships, and recreational dinosaur hunting) but couldn't get into the characters so much. Also the jumping back and forth between the near future and far future bugged me. How are the second two books in the trilogy? I've heard mixed reviews. Do they stick with one time period?


The two sequels are all set in the Second Sphere in the era of Elizabeth and Gregor -- there are no flashbacks to the 21st century like in the first book.

Couldn't get into the characters in the first book? Hmmm. Well, you may be glad to know, then, that the central characters of the first book, Gregor and Elizabeth, become increasing less important in the sequels, going mostly off-stage (and seemingly more cold and distant to the other characters as well).

The central characters in book 2 are plenty interesting -- a female mechanic on the planet Croatan, plus a member of a fairly sophisticated but Stone Age tribe from the same planet. The tribe has some rather weird, but mostly internally logically consistent definitions of "man" vs. "woman" (hint: it's based on division of labor). The industrialized society to which the woman mechanic belongs is interesting too; at least it's politics are.
I found these two to be very engaging characters. We also learn a little more about Salasso the saur and his people -- and also about the DeTenebre interstellar trading family, mostly through the eyes of the daughter Lydia. I liked the 2nd book, Dark Light a lot. It's my favorite of the set.

The 3rd book is set mostly on Nova Babylonia (which undergoes a political revolution), but we also learn more about some of the other exotic planets and creatures that humans share the galaxy with. The main viewpoint characters in this book are Lydia DeTenebre and a man who is (IIRC) a defense contractor and part-time spy on Nova Babylonia. I liked this book a lot too. The ending was a little weird and abrupt, and I don't think I understood it at all the first time I read it. When I reread the book, I understood the ending better, but I'm still not sure I understand it entirely. Still, I found it an enjoyable and thought-provoking read.

Milo said...

Regarding the cultural effects of space travel, it depends on how accessible it is.

If space travel is expensive and mostly limited to professional spacers who spend months at a time in space, then the most noticeable effect would be in "port cities", and their set of associated stereotypes. Social norms onboard a spaceship may be entirely different from what landlubbers are familiar with, but most people won't notice.

If individual spaceships are too large and expensive for most people to own, but chartered commercial space liners provide cheap interstellar travel, then the social effects will be about the consequences of a very large civilization with easy travel. (But we already have that today, so what will change?) You still won't get space drive-throughs. And most people still won't think of the spaceships as anything more than "something that gets me from point A to point B".

If an average family can own a five-seater spacecraft, then the effects of space travel are going to be much more immediate and visible to laymen - this is where the really wacky effects like drive-throughs start to come into play.



Teleros:

"After all, in most cases an FTL drive in a setting is no more unusual than a car with an engine in it: it's there, it works, now let's get to Tau Ceti pronto!"

In this case, it makes a big difference whether the main action happens on planets, and ships are just there to get from one Adventure Planet to another, or whether there is a major focus on ship-to-ship combat (or other spaceship maneuvers). In the latter case, you need to know with reasonable detail how ships move, to keep every battle from being complete author fiat.



David:

"3. Since we are really discussing what amounts to Elven underwear, how realistic do we have to be?"

To mangle your metaphor: elves are humanoid. Since underwear doesn't normally cover ears, their underwear is going to be fairly similar to ours by necessity. If you have bipedal elves wearing clothes that look like they were designed for a quadrupedal creature, I'm going to complain.

Of course, you could make the underwear out of magical elfweave or whatever, but adding magical properties does not take away expectation of logic.



Horselover Fat:

"Frankly the people who want simple FTL puzzle me. If you're not going with real-world physics, why not get rid of the speed of light entirely?"

That works fine if you have a "long ago in a galaxy far far away" type setting. It doesn't work, however, for any story that is allegedly set in our own future.

There is also the issue that even with Newtonian mechanics, it still takes nearly a year of acceleration at one Earth gravity to reach the speed of light, let alone surpass it. (This also requires so much energy that you need a staged antimatter rocket.) Of course you could throw Newtonian mechanics out too and invent reactionless drives...

Tony said...

Horselover Fat:

"Frankly the people who want simple FTL puzzle me. If you're not going with real-world physics, why not get rid of the speed of light entierly? It makes things so much more intuitive in space and you can do it with a couple of sentences."

Because nobody would by it. Everybody knows light has a speed, and if you try to go faster than light in normal space, Einstein will pull you over and write a ticket. Having a "jump" drive, or "hyperspace" drive, or "warp" drive means you respect the law, but have a waiver for certain circumstances. Everybody in the readership understands that. They don't need to be told how you got the waiver, or how it works.

ElAntonius said...

While normally I'd try to respond post for post, this thread be moving fast for me! :)

RE "The Corvette Example":
Well, while we have a good idea of what our car culture looks like, I disagree that people have any clue how cars work.

Given that most people know a Corvette is a sports car (probably the most popular, or at least most famous one, in America), and most people know that a 7.0L engine is very powerful for a car, the reality is most people have no idea how an ICE works, how the transmission works, or how the rear differential works.

So for story telling purposes, the fact of "there's an engine, a big one, and this is a sports car" is really what most non-car-nerds would process out of my example.

So for an FTL example...sure, we can expand the culture and how it's changed...and we can explore the limitations of FTL, and what it means, and how the hero ship is special (or not).

But do we really need to get nuts and bolts? My point is, you don't need to explain how a jet engine works to write a fighter jet story, and you shouldn't have to get into fictional FTL physics to explain "this is how it works, a general handwave of why, and how it's affected my setting".



RE Mass Effect:
Yeah, the way almost every weapon in the Mass Effect universe works is as follows:

A sand-grain sized particle of metal is shaved off a block in the weapon, and its mass is further reduced by a "Mass Effect" field generated by the weapon. A coilgun-like arrangement hyper-accelerates the micro-mass shot, which gains mass again after it exits the field.

Because of this, ammo is not a practical concern for combat...instead, rate of fire is governed by recoil and the weapon's capacity to dissipate the enormous heat generated by firing.

In the first game that meant "no clips", instead you had to manage heat in your weapon by stopping firing while it cooled down.

In the second game, "clips" are simulated via ejectable/swappable heat sinks (which are disposable, and as such pretty much emulate clips, apart form being universal...a bit of a wallbanger for various reasons but in gameplay it is more fun than the cooldown base of the first). This is justified in universe as "science marches on".

Powered armor is ubiquitous, and even the most basic powered armor has mass effect shields (I believe these work by being massive at point of impact, but I'm not sure.)

Amusingly, they even mention the effects on time dilation that mass effect has (negative mass is possible).

Also:
Gunnery Chief: "Damn straight! I dare to assume you ignorant jackasses know that space is empty. Once you fire this hunk of metal, it keeps going til it hits something. That can be a ship. Or the planet behind that ship. It might go off into deep space and hit somebody else in ten thousand years. If you pull the trigger on this, you are ruining someones day, somewhere and sometime. That is why you check your targets. That is why you wait for the computer to give you a damn firing solution. That is why, Serviceman Chung, we do not "eyeball it". This is a weapon of mass destruction. You are not a cowboy shooting from the hip!"

(The next line is Sir Isaac Newton being the deadliest sumbitch in space)

The TVTropes page for Mass Effect is fascinating reading. I won't link it.

Teleros said...

Milo: "In this case, it makes a big difference whether the main action happens on planets, and ships are just there to get from one Adventure Planet to another, or whether there is a major focus on ship-to-ship combat (or other spaceship maneuvers). In the latter case, you need to know with reasonable detail how ships move, to keep every battle from being complete author fiat."

True, although I still don't think you need particularly much. The main thing to get across in ship-to-ship combat are the limitations of the FTL drive.

"Of course you could throw Newtonian mechanics out too and invent reactionless drives..."

Anyone seen my basin? I had some copper coated in some platinum residues, applied an electric current by accident and it disappeared out the window...



ElAntonius: "A coilgun-like arrangement hyper-accelerates the micro-mass shot, which gains mass again after it exits the field."

See, this I don't get. The projectile's velocity is a function of the force applied to it & its own mass. So low mass + force of X = high velocity. But if that mass suddenly gets an order of magnitude more massive, surely you'd expect to see a corresponding decrease to its velocity? And if it keeps its velocity when the mass goes up, doesn't that mean energy has been imparted to it from... somewhere?

Tony said...

ElAntonius:

"But do we really need to get nuts and bolts? My point is, you don't need to explain how a jet engine works to write a fighter jet story, and you shouldn't have to get into fictional FTL physics to explain 'this is how it works, a general handwave of why, and how it's affected my setting'."

Y'know, I can't count the number of times I've been reading a western and wondered why the author didn't explain how photosynthesis caused grass to grow and how horses ate grass for energy. And what's the idea behind having a train robbery without a thermodynamic explanation of how a steam engine works? And how in the heck did readers let Forester get away with the entire Hornblower series without a single mention of Archimedes Principle? WTF!?

Raymond said...

ElAntonius:

"I disagree that people have any clue how cars work."

Oh, I know all too well how little most people know about the workings of the cars they drive (I work at a Porsche dealer). But if you're an author writing a car chase, you should probably know why a Corvette could take a turn a '69 Camaro couldn't.

"...you don't need to explain how a jet engine works to write a fighter jet story..."

Same as above, but more so. If you're writing about air combat, you should be passingly familiar with the principles of air combat. You don't need to insert a lecture on the difference between airspeed and ground speed, or go through all the numbers on fuel loadouts, or give a history of air-to-air missile design. You should, however, know at least something about these things yourself.

"The TVTropes page for Mass Effect is fascinating reading."

One of the things I like about Mass Effect is how much effort they put into consistency and (semi-)plausible explanations for the myriad tropes of space opera they reference, deconstruct, subvert, and reconstruct. They don't always put the explanation front and center (very rarely, in fact), but they make a herculean effort to have everything make sense in the writers' room.

Teleros:

"See, this I don't get. The projectile's velocity is a function of the force applied to it & its own mass. So low mass + force of X = high velocity. But if that mass suddenly gets an order of magnitude more massive, surely you'd expect to see a corresponding decrease to its velocity? And if it keeps its velocity when the mass goes up, doesn't that mean energy has been imparted to it from... somewhere?"

One of the problems with mass manipulation - fundamentally the same conservation problems as some forms of FTL. I'm pretty sure ME handwaves it as the additional energy and momentum being stored in the mass effect field of the weapon.

Tony:

"Y'know, I can't count the number of times I've been reading a western and wondered why the author didn't explain how photosynthesis caused grass to grow and how horses ate grass for energy. And what's the idea behind having a train robbery without a thermodynamic explanation of how a steam engine works? And how in the heck did readers let Forester get away with the entire Hornblower series without a single mention of Archimedes Principle? WTF!?"

Yeah, and we've never been treated to a long dissertation on the care, feeding and lifecycle of horses in a western, nor do we ever have lengthy descriptions of rigging in age-of-sail historical novels. And if ever someone wrote a novel about whaling, he'd better make sure not to put in too much superfluous detail about the industry or its tools, else nobody will take his novel seriously.

ElAntonius said...

Teleros: I don't have access to the Mass Effect codex right now (being at work), but IIRC it's handwaved as being an effect of the mass effect field.

One interesting and related bit, however, is how fighters are handwaved:

-Mass effect fields can be used to create, essentially, hyper-massive torpedos.

-Kinetic barriers repel fast moving objects but allow slow moving objects to pass.

-Point defense lasers exist (and are very good), but as the lasers overheat they correspondingly lose performance, so sheer numbers can overwhelm them.

-As such, fighters are used to deliver (slow, massive) torpedoes in close to overwhelm the point defenses and get under shields.

-Due to mass modification, fighters are less subject to the normal performance problems in space.

-Even with all that, the main reason they exist is because there's treaties in place that limit the numbers of battleships. Carriers circumvent this (so in the setting, battleships are still superior fighting platforms, but massed fighters are just viable enough to require dedicated defenses)

-Additionally, due to one race building AI servants and then nearly wiping themselves out trying to destroy them, AI is utterly outlawed, putting human pilots back in the fore.

In the second game, a plot point is made that the player ship is MUCH more capable than normal precisely because an (illegal) AI and a human work in concert to pilot it, whereas most ships only have the meat.

Anonymous said...

Milo: "There is also the issue that even with Newtonian mechanics, it still takes nearly a year of acceleration at one Earth gravity to reach the speed of light, let alone surpass it."
I was answering someone who wanted some form of teleportation (jump drives). If you have teleportation, increasing the speed of light or getting rid of it means your universe isn't broken by the teleportation. You stay clear of fun causality violations but also of a number of more practical exploits like laser strikes you can't defend against. It's the difference between:
"Jump point forming Captain!"
"Charge lasers! Evasive manoevers!"
and
"Jump point forming Captain!"
"It was a honor serving with you Lieutenant."

Sure, you need an alternate history to get our future without the speed of light. But, wishful thinking aside, our future is sooner going to have reactionless drives than FTL.

-Horselover Fat

Tim said...

@ Stevo Darkly:

Thanks for the recommendation! I'll give the second book a try.

Apparently, I need to check out Mass Effect 2 as well. Does anyone have an opinion on the plausibility of Dead Space? I haven't played it, but it looks pretty "gritty" from what I've seen.

jollyreaper said...


Y'know, I can't count the number of times I've been reading a western and wondered why the author didn't explain how photosynthesis caused grass to grow and how horses ate grass for energy. And what's the idea behind having a train robbery without a thermodynamic explanation of how a steam engine works? And how in the heck did readers let Forester get away with the entire Hornblower series without a single mention of Archimedes Principle? WTF!?


And at the same time, there are other examples of historical novels that are part story and part travelogue and the readers love them for that.

There's also stories that are so terse and dialog-driven that they could be occurring virtually anywhere. All you know about the room is that someone opened a door and there were people seated inside. You don't really know what they look like, just who they are and what they're saying. The plot moves like a burning carriage careening downhill.

There's room for different approaches. Some people want erotica, some people don't want it to go any further than lingering gazes. Erotica readers shouldn't go read modern Christian romance complaining about the lack of action and people who don't like explicit sex shouldn't read erotica and act indignant about what they find in there.

I reiterate -- if a fan of the genre tells you you're doing it wrong, then you need to worry. If you're writing a techno-thriller and a fan tells you he likes the story just fine but you're getting the details wrong, listen to him. If he tells you the plot has holes in it, listen to him.

As a personal preference, I LIKE when novels will give me background information about the setting that I might not have gone into the story knowing about. The trick for the author is to skillfully weave that stuff in so it doesn't feel like a book report, doesn't feel like an infodump, it feels like an organic part of the story.

If you don't want to read that sort of thing, that's perfectly fine. But it's not a universal sin.

jollyreaper said...


One of the things I like about Mass Effect is how much effort they put into consistency and (semi-)plausible explanations for the myriad tropes of space opera they reference, deconstruct, subvert, and reconstruct. They don't always put the explanation front and center (very rarely, in fact), but they make a herculean effort to have everything make sense in the writers' room.


Exactly. You have to have all this stuff figured out to your own satisfaction before you start writing. It may not make it into the book but the parts you do bring in will fit the overall shape. It will feel planned. And what's perfectly acceptable is for the author to include his background history in an appendix. Read if you're interested, otherwise you can skip doing no harm to the story you read.

I forget if I've gone into my cannonball analogy here. If not, here it is.

My driving standard is that a story should flow logically from internal motivations. Everything you need to know should be within the story and should make sense. If the answer to why someone did something or something happened a given way is “because we wouldn’t have a story otherwise” then the author has failed.

Imagine you have a sheet of graph paper in front of you. You draw several cannon along the bottom with varying powder charges but they all are aimed at a square of empty space further up the page. We can also assume the weight of the balls is inconsistent since they were sourced from China. You simultaneously fire every cannon and plot out the course their cannonballs will take. This is physics. There’s a reason the balls are moving as they are. If you only focus on that square you will see the cannonballs enter, each on its own trajectory. Some trajectories grow close, others apart. Some balls may collide and the parabola will be redefined. Air pressure and gravity remain constant and have the same effect on every ball but some balls had greater charges, some have more mass, and so each trajectory varies. While it may seem random to the person looking at the square, if you work things back to the beginning everything will make sense.

Characters should move like those arcs. Their lives are those parabolas. The story is that little square where we see them all coming together. No cannonball materialized out of thin air, nor do we see one ball behaving as if gravity is a half-G while another acts like its 3 G’s.

Now remember that I said this analogy is sketched out on graph paper. This is important because this was never a real physics experiment. You could have drawn the cannonballs flying in corkscrews if you wanted to. Your adherence to realism and rationality prevented you from doing so. And let us say that you decide another cannonball must be added inside that square. You may do so, assuming that it would not violate any of the other trajectories so sketched out. You can plunk that cannonball down and sketch a trajectory back to an empty space on the bottom and place your cannon there. To anyone looking at your graph, there would be no way to tell that your extra line was a late addition. Everything appears logical and orderly, as if you documented the flight of real cannonballs instead of imaginary ones.

Raymond said...

Tim:

Definitely play ME2. It was tied with Minecraft for my GotY last year.

Dead Space's plausibility problem isn't in the physics, so much as the biology - but don't let that stop you. Also note that they acknowledge the pervasiveness of gravity control in more places than FTL (kinesis and stasis tools, singularities used as power supplies, not to mention gravity-based planet cracking).

Tony said...

Raymond:

"Yeah, and we've never been treated to a long dissertation on the care, feeding and lifecycle of horses in a western, nor do we ever have lengthy descriptions of rigging in age-of-sail historical novels. And if ever someone wrote a novel about whaling, he'd better make sure not to put in too much superfluous detail about the industry or its tools, else nobody will take his novel seriously."

Of course we have. And when the exposition dosen't support the plot, but just serves to show what a pedant the author is, the suckage is almost palpable. Ya see, there's a difference between what editors let authors get away with and what makes entertainment.

Tony said...

Re: jollyreaper

Hmmm...I don't recall anybody suggesting that scene setting and justifed exposition were wrong. It's showing off your irrelevant research or catering to a miniscule portion of readers that is the offense.

WRT readers telling you what you're doing wrong, well, all of the professions I listed earlier weren't just off the top of my head. They're the professions of some regular -- often voracious -- hard SF readers that I know. None of them GAS about justifying how an FTL drive skirts around relativity without breaking it. I've never actually had a discussion with a live person who cared, just guys on the interwebs...and not too many of those.

Tony said...

Raymond:

"Honorverse excepted, that reaction is a complete blackbox to me. I know it exists, but I don't (and likely never will) understand it. I like technical things. I don't mind learning something new in a novel instead of a textbook. If the infodump is boring, I'll skip or skim, but it won't ever offend me. I'd much rather have a technical infodump than purple prose, lurid emotional handwringing, or my personal bugaboo, intricate descriptions of appearance."

If I want to read about 20th Century battleship design, I'll pull out my copy of Friedman. If I want to read a story about battleships in action, I don't want a treatise on design. In an SF setting, where there aren't any technical references, of course there has to be more -- and more detailed -- exposition about the features of given technologies, so that the reader will understand how they affect the story. But endless guff thrown in just to tickle the fancy of technoweenies? No thanks.

Thucydides said...

We're drifting into issues about writing stories (should be the start of a new post; hint, hint).

The writer needs to know and understand the topic enough to avoid real clangers, and the intricate details are only required insofar as they actually affect the plot.

From the movies, consider "Top Gun"

The female love interest is a consultant for the school, but is introduced as an "Astrophysicist". This might be good if she consulted for "Rocketpunk's FTL war division", but in the context of the movie simply makes informed people cringe. (Since the school is about air combat, they should have spent the money on an expert in Aerodynamics, which may be what they wanted to say).

We do get some discussion on real aerodynamics when the pilots are being debriefed after an air combat scenario, where it is appropriate in both context and story terms, but not enough detail to overwhelm the audience.

Movies and TV also have the opportunity to do exposition by showing a scene on screen. In a Civil War movie like "Glory", there is no need to explain how and why the regiment is going to assume a certain formation, you just see them form a firing line or a column for the attack and then watch what happens. Authors of books need to dig in the weeds a bit in order to set the scene for the reader, but not to block the flow of the narrative.

In narrative terms, if FTL provides weird effects like time travel or requires the use of deamons chanting in Welsh, the author needs to know and understand how this will affect the plot and find a way to slide it in smoothly as not to disrupt the flow of the story.

jollyreaper said...

Apollo 13 was great at that. You had all this flavoring of what was going on and to people who didn't care it would just be authentic-sounding technobabble and to the people who did care, they'd be able to follow along.

What you said about background authenticity is film is exactly right. It costs time in a story to do that but it costs no time at all in a movie. If it's not going to hurt or hinder, why not just do it right? You have to design a costume to begin with, right? Why not do the research and get it right instead of just slapping something inauthentic together?

One thing I really hate is if they're going to the trouble of making a movie based on real history and then making everything up. No, this is important! This is what people are likely to remember, not what they learned in school.

Raymond said...

Tony:

"If I want to read about 20th Century battleship design, I'll pull out my copy of Friedman. If I want to read a story about battleships in action, I don't want a treatise on design."

If your story is a series of rollicking action scenes and little else, sure.

Not all stories are like that. Not everything is focused so completely on plot and/or character at the expense of setting, history, or (gasp) ideas in general. If I don't have a copy of Friedman, or if I don't already know battleship design, then I have no sense of why things are, how they got to be that way, or what to expect. You can get by with just the plot-relevant stuff, sure - but then as a reader I have only the bare minimum. I don't get as much of a sense that the universe extends off-panel, that larger systems and interactions are in play. And if we're speaking of SF in particular, that includes a history of not just action and plot, but consideration and examination of speculative ideas. Why cut off that rich legacy?

"...endless guff thrown in just to tickle the fancy of technoweenies..."

"...a bunch of pimply-faced physics grad students..."

"...why wank?"


I can't tell if you're hostile to the ideas themselves or the people who are interested in them, but may I respectfully suggest that whichever the case, it would serve your case better to present it in a less hostile manner.

jollyreaper said...


I can't tell if you're hostile to the ideas themselves or the people who are interested in them, but may I respectfully suggest that whichever the case, it would serve your case better to present it in a less hostile manner.


He's projecting personal preference onto the entire scene. Like I said, there's a difference between "I don't like the genre" and "I like the genre and you're not doing it right" and even in the latter it's a question of whether the objection is fundamental or stylistic.

I had my stylistic objections to BSG, for example, but I think the fundamental problems were serious enough to sink the entire series. But I've spoken with seemingly intelligent people who thought the series was perfect. I also know people who loved Voyager.

The Lost Fleet gets a lot of bashing around here but I think the criticism is legitimate since we're squarely in the target audience and are objecting for critical, fundamental failings in world-crafting and proper storytelling.

I'm a firm believer in judging a piece not just by what it is but by what it's trying to be. A novel meant to be a silly lark will be judged by how enjoyable a lark it is. Something trying for serious drama should be judged as a drama. And something trying to be a masterfully detailed and realized space opera setting complete with flushed out applied handwavium should be judged as such.

By way of comparison to video games you have your light and fluffy Mario Kart racers and you have your Gran Turisimo ridiculously detailed simulations. You don't criticize Mario Kart for lacking in rigor and detail and you don't criticize Gran Turisimo for being sadistically over-detailed with too steep a learning curve. That's what the fans are paying for! You criticize Turisimo for getting the physics wrong and you criticize Mario Kart for not getting the fun right.

Anonymous said...

Thucydides wrote: "if FTL provides weird effects like time travel"
In the universe we know and love, FTL has such effects. That's the thing.
Make it so that it doesn't have such effects if it pleases you but do tell what you changed in order to get your plot device. There are any number ways to do it and we can't guess.


In order to not reinforce a pathological values, perhaps we should reaffirm that wanking is a good, that calling someone a wanker is therefore not a hostile act and only reflects poorly on you if you inappropriately do it in a hostile fashion and that "why wank?" has a very, very obvious answer.

-Horselover Fat

ElAntonius said...

I think, however, that discussing th effects and implications of a technology is different than discussing in detail all the physics involved in making it work.

Going back to cars, most people understand the societal impact of cars, the understand that some cars are faster than others, others are more efficient, others carry more people, etc. A story rarely needs to do more than describe "truck" or "sports car" and people will get the idea.

Of course, when we're talking about fictional physics things are a bit different...but I hold that the implications of the nature of FTL are far more important than the mechanics, especially since the mechanics are bound to be...gently...make-believe anyway.

FTL with rules, that shapes battles and empires, that changes civilization and exploration, and dictates a map of who can go where, and when? Fantastic.

A treatise on how technology could never work, however, is little more than an author showing his work on imaginary doctorates.

ElAntonius said...

jollyreaper: Actually, your GT5 example proves the opposite.

Well, I'll go with Forza Motorsport since that's the one I'm familiar with (equivalent game on rival system, for the non-gamers).

The goal of both games are to be realistic racing simulators with accurately modeled cars and physics engines, on real world courses. We're talking about series where the graffiti on the Nurburgring is properly modeled.

That being said: in Forza, it's perfectly possible to buy a car, hit a button saying "upgrade it to this class", and get in and race it.

For us car nerds, you can actively inflate or deflate tires, adjust suspensions, change gear ratios, and hand pick upgrades to fine tune different desired parameters for each race...but in reality, you DON'T need to sit through that to enjoy the game.

Forza 3, at least, was critically lauded for having that level of detail in terms of physics, but still remaining accessible enough for people more casual in their approach. It's literally the Mass Effect Codex approach again...it's there if you want to take advantage, but you're not bombarded with it.

I haven't played GT5, but if GT3 was any indication, I'd imagine it's much the same.

Raymond said...

ElAntonius:

"...but I hold that the implications of the nature of FTL are far more important than the mechanics, especially since the mechanics are bound to be...gently...make-believe anyway."

Fair - but the implications are derived from the mechanics, whether completely made-up or painstakingly derived from modern research. If the implications matter, the mechanics will come up somewhere (especially if the plot involves trying to push the implications to their limits).

"Forza 3, at least, was critically lauded for having that level of detail in terms of physics, but still remaining accessible enough for people more casual in their approach. It's literally the Mass Effect Codex approach again...it's there if you want to take advantage, but you're not bombarded with it."

And I'm on record as saying that's probably the best generalized approach (unless your main characters are trying to invent a new FTL drive while on the run, or something).

Side note RE: GT5 - based on the opinions of the racing fans I know, you may find GT5 disappointing, especially if you're a Forza 3 fan.

Tony said...

Raymond:

"If your story is a series of rollicking action scenes and little else, sure.

Not all stories are like that. Not everything is focused so completely on plot and/or character at the expense of setting, history, or (gasp) ideas in general. If I don't have a copy of Friedman, or if I don't already know battleship design, then I have no sense of why things are, how they got to be that way, or what to expect. You can get by with just the plot-relevant stuff, sure - but then as a reader I have only the bare minimum. I don't get as much of a sense that the universe extends off-panel, that larger systems and interactions are in play. And if we're speaking of SF in particular, that includes a history of not just action and plot, but consideration and examination of speculative ideas. Why cut off that rich legacy?"


Even the people who operated the battleships didn't know the technical history of the vessels. They were too busy dealing with the work they had in front of them to sail and fight the ships effectively. All they needed to know was how their ship operated, what was going on around them, and how to respond to the situation. Why does the reader need to know more?

"I can't tell if you're hostile to the ideas themselves or the people who are interested in them, but may I respectfully suggest that whichever the case, it would serve your case better to present it in a less hostile manner."

The hostility is towards the synergy of readers who demand ridiculous and boring detail with authors who can't help catering to them.

jollyreaper said...

Maybe I got the name of the game wrong -- I don't play the racers -- but there was one that was realistic enough that the top player was taken by Top Gear out to a real track and given a spin in the real vehicle. He wasn't physically prepared for it -- the cars are brutal on the body -- but mentally and reflex-wise, he was a bloody champ.

Raymond said...

Tony:

"Why does the reader need to know more?"

Since when is the reader on a need-to-know basis?

"The hostility is towards the synergy of readers who demand ridiculous and boring detail with authors who can't help catering to them."

Ridiculous and boring to you. Plenty of room for all kinds. You have a problem with authors catering to an audience, just because you're not part of it? It's easy to skip infodumps in novels, really.

ElAntonius said...

jollyreaper: That was indeed Gran Turismo 4 (the fifth installment was just released in the last few months).

Generally though, the better reviewed installments in those types of games feature a lot of hand-holding for beginners, intrinsic in the sense that you almost always are exposed to slower cars at first, and explicit in the sense that they feature auto upgrading of cars and things like a recommended line to follow with braking points highlighted on the track.

Raymond: Yes, we're in agreement then :). Well "researched" phlebotinum is important enough to be cohesive, as long as the dissertation is safely tucked into an appendix that we the geek can enjoy at our leisure.

Tony said...

Raymond:

"Since when is the reader on a need-to-know basis?"

Oh...about ever since tight prose and good flow have been appreciated by readers more than irrelevant trivia.

"Ridiculous and boring to you. Plenty of room for all kinds. You have a problem with authors catering to an audience, just because you're not part of it? It's easy to skip infodumps in novels, really."

Incorrect. Ridiculous and boring to the vast majority of readers. The issue, I think, is that a certain type of SF reader has a mental model of other SF readers that looks pretty much like themselves. But the readership is much wider and deeper than that model recognizes. There's no excuse on the part of the author for making the majority of the readers skip infodumps, no matter how easy that may seem to some people.*

*Not that it really is all that easy, because the infodump is rarely so modular that it doesn't contain important information. So the reader finds himself constantly going back to the infodump to dig up what he missed.

ElAntonius said...

*Not that it really is all that easy, because the infodump is rarely so modular that it doesn't contain important information. So the reader finds himself constantly going back to the infodump to dig up what he missed.

I disagree there. If a universe is well grounded by an author constructing logical rules, then the infodump really does become miscellaneous.

I mean, for your average reader...things like weapons, shields, and propulsion are all accepted as "working" as part of their suspension of disbelief. As long as it's all consistent and logical (and truth be told, you do need to do some homework for that to work) then an infodump becomes a nerd* bonus.

Keeping in mind the primary audience of SF, having that sort of layer becomes part of the fun. How many random Star Wars technical manuals exist? And THAT universe might as well run on crystallized unicorn poop.

*-I'm using the words nerd and geek affectionately in my posts, BTW.

jollyreaper said...


I disagree there. If a universe is well grounded by an author constructing logical rules, then the infodump really does become miscellaneous.


I would slightly amend this by saying infodumps, if done properly, don't appear like infodumps. They'll look like artful exposition. Inartful infodumps are characterized by "As you already know" while stating the obvious.

I think the painfulness of this sort of storytelling has become more obvious sine we've moved from working on the stage which has its own artificialities and conventions to working with film which "feels" more real. Soliloquies and narrators and expositionary speechifying feels a little more natural in the unnatural environs of a stage than when the camera is just another person in a room and it feels like you're watching something already going on.

"Emperor Napoleon! As you know, you've foolishly started a war with Russia and are now retreating from Moscow."

"Of course I know this. I was there for everything!"

"I know. This is for those of us joining the story already in progress."

About the only way around this with any grace is inserting the n00b aka reader stand-in to whom everything is explained.

I did a variant on this in a comic I wrote for where the exposition character was a 19th century street arab with the freckles and rosy cheeks. He'd make a polite inquiry about what was just mentioned and someone would explain it to him. The running gag, of course, is that he would a) be in all sorts of places he'd have no right to be to ask the question and b) nobody would think it odd.

Tony said...

ElAntonius:

"Keeping in mind the primary audience of SF, having that sort of layer becomes part of the fun. How many random Star Wars technical manuals exist? And THAT universe might as well run on crystallized unicorn poop."

A couple of things here...

1. There's a definite difference between science fantasy and hard SF. The audiences overlap somewhat, but the technical manuals are aimed at the sci-fan chort, not the SF.

2. They do have technical manuals. They don't stop in the middle of the movie and present a mini-documentary on TIE fighters, turbo-lasers, and hyperspace motors. They sell that supplementary information in Barnes & Noble, to the denizens of the last row in the SciFi section.

Anonymous said...

jollyreaper: "About the only way around this with any grace is inserting the n00b aka reader stand-in to whom everything is explained."
I think irrationality can often be used as an excuse for exposition: someone comes in with a casualty report. Someone makes a disparaging quip about who is to blame for this mess. Argument follows. Depending on the characters and how formal their relationships are, this might or might not feel right.
Or people could discuss the irrationality of a third party who just did something irrational and possibly dangerous. Like "What the hell is wrong with Major Untel?" "They say he's been like this since the crossing of the Berezina." and so on.
People do argue about things. And they disagree about whether one should say it like it is in the report. And so on. As long as the exposition is relevant to a conflictual situation, I believe one can usually find a way to mix the exposition with character stuff.
Amnesia or diaries as an excuse for exposition are a bit overused if you ask me...

Anonymous said...

I forgot to sign again. -Fat

jollyreaper said...

I'm utterly sick of amnesia and prophecies as major plot devices. There's a difference between beloved tropes and cliché but the damnable thing is which is which is completely subjective to the observer!

Raymond said...

Tony:

"Oh...about ever since tight prose and good flow have been appreciated by readers more than irrelevant trivia."

What, everyone has to write like Cormac McCarthy? Don't get me wrong, I like Cormac, but I don't want everything to be written like that.

You've mentioned the Culture series before, and indicated you were a fan. Are Banks' digressions about his fiction's physics a major stumbling block? How about Dune? Starship Troopers? Hitchhiker's Guide to the Galaxy?

"Ridiculous and boring to the vast majority of readers. The issue, I think, is that a certain type of SF reader has a mental model of other SF readers that looks pretty much like themselves. But the readership is much wider and deeper than that model recognizes."

I'd recommend taking your own statement at face value and stop assuming the "vast majority" of SF fans are like yourself.

"They don't stop in the middle of the movie and present a mini-documentary on TIE fighters, turbo-lasers, and hyperspace motors."

Nobody here is suggesting they do.

ElAntonius: " disagree there. If a universe is well grounded by an author constructing logical rules, then the infodump really does become miscellaneous."

jollyreaper: "I would slightly amend this by saying infodumps, if done properly, don't appear like infodumps. They'll look like artful exposition. Inartful infodumps are characterized by "As you already know" while stating the obvious."

Which is a matter of writing, not a matter of self-censorship of detail. All of this can be done badly, certainly. It can be clunky, overly didactic, and/or plain old boring. It's a matter of execution more than anything.

My original comment, in fact, was merely about adding the magic words "special frame of reference" if and when describing an FTL drive. Short, fits in nicely with the rest of the technobabble, won't mean anything to those who don't know the relevant physics, will mollify those who do, and short. No speeches about time travel, no long exposition about curved spacetime. Nothing, and I mean nothing to get worked up about, unless one is actively hostile to mentioning anything about physics in a science fiction story.

Tony said...

Raymond:

"What, everyone has to write like Cormac McCarthy? Don't get me wrong, I like Cormac, but I don't want everything to be written like that."

Never read any of his stuff, so I can't comment.

"You've mentioned the Culture series before, and indicated you were a fan. Are Banks' digressions about his fiction's physics a major stumbling block? How about Dune? Starship Troopers? Hitchhiker's Guide to the Galaxy?"

Not a fan at all, just an interested observer (more about that in a bit). And I find a lot of what Banks writes to be gratuitously repetitive. He reuses scenes without even filing off the serial numbers, for example. What I find interesting in his books is the expansive setting and the large concepts. Strangely enough, those are introduced straightforwardly and without much to do at all. It's the minutiae and rhetorical cuteness that hangs the stories up.

"I'd recommend taking your own statement at face value and stop assuming the 'vast majority' of SF fans are like yourself."

Pretty much the expected response. I think I'll stand pat.

"They don't stop in the middle of the movie and present a mini-documentary on TIE fighters, turbo-lasers, and hyperspace motors."

Nobody here is suggesting they do.


The point is that if they did, it would be the cinematic equivalent of infodumps.

Rick said...

I take considerable perverse pleasure from finding that one of the most heated arguments ever in these comments is about what makes for good SF.

That said, I'll make the standard request to be duly careful when handling explosive materials.

As for comment on the substance, pretty obviously I need a full post on this stuff. Suffice for here to to say that wrestling with some of these issues is why I'm blogging rather than, you know, writing SF.

And for those who haven't happened to come across it, my Tough Guide to the Known Galaxy (obvious h/t to Diana Wynne Jones).

Scott said...

If the radiation can pass through shielding without losing much energy, then it can also pass through people without doing much damage to them.

Yup, we called it the cookie analogy: You have 4 cookies, and 4 places to put them. You hold the alpha cookie in your hand (skin stops alpha radiation). You put the beta cookie in your pocket (clothing stops beta). You eat the gamma cookie (not easy to stop and therefore not likely to hurt you), but you throw away the neutron cookie (not easy to stop and very likely to hurt you). Learned that ~10 years ago now, stupidly easy to remember.
=====

About those movie infodumps. One of my favorite mecha-anime (yes, I'm one of those nerds), Gasaraki, has a 15-second scene where the team is shutting down the bots for transport out of the combat theater. That was the rough equivalent of a thousand-word infodump. In fact, it would take me, even writing in military style, about a thousand words to describe that scene.

Movies do their infodumps. Good screenwriters just make the infodump a visual event, not a big expository piece like the 'unobtanium' in James Cameron's Avatar.

One thing that's been bothering me a bit: Since most FTL drives seem to have fairly massive power input requirements, it is probable that you would also see a weaponized version of the FTL effect. The weapons would be much smaller than the generators, just like how a fission bomb is much smaller than a fission reactor.

Tony said...

Scott:

"One thing that's been bothering me a bit: Since most FTL drives seem to have fairly massive power input requirements, it is probable that you would also see a weaponized version of the FTL effect. The weapons would be much smaller than the generators, just like how a fission bomb is much smaller than a fission reactor."

Sure, you'd have the weapon, but just like nukes, it wouldn't be generally usefull.

Teleros said...

Raymond: "You've mentioned the Culture series before, and indicated you were a fan. Are Banks' digressions about his fiction's physics a major stumbling block?"

Less so that, say, David Weber in the Honorverse. I generally enjoy them, but even so the infodumping can be a bit excessive sometimes.

"I'd recommend taking your own statement at face value and stop assuming the "vast majority" of SF fans are like yourself."

Depends in part on the target audience. I suspect that most movie-going sci-fi fans are not as fond of infodumps as most book-reading fans are, for example. Hence why you don't see that "mini-documentary" about TIE fighters in the cinema, but may see one in the book(s).



Scott: "One thing that's been bothering me a bit: Since most FTL drives seem to have fairly massive power input requirements, it is probable that you would also see a weaponized version of the FTL effect. The weapons would be much smaller than the generators, just like how a fission bomb is much smaller than a fission reactor."

Been chucking ballistic missiles with FTL drives attached at the other side's planets for years y'know ;) .

As to whether you can weaponise the FTL drive itself, that really depends on how it works. Rather like with slow & fast burning explosives, or nuclear reactions & nuclear bombs - the mechanism has to have a way for the FTL mechanism to do something destructive.

A wormhole generator may be useable like this (use it to chop up objects by opening & closing wormholes inside them? Exploit a pressure difference?), but I'm not so sure about entering hyperspace.

It's been done of course - Warhammer 40,000 Warp drives can be very dangerous when they go wrong for example (see the defeat of Hive Fleet Behemoth), and you could use the inertialess field generated by Lensman ships to damage things if you can extend it close enough to the target, etc. And if you can force the other guy to emerge from hyperspace inside a gravity well (or an equivalent in your story) you can let nature blow his ship up.

Not sure I want to know what happens when you lob a demon-in-a-bottle at an enemy ship and cut off the tape recording of Welsh chanting :P .

TL;DR version: it depends on how your FTL tech works.

Jnani said...

Scott:

"One thing that's been bothering me a bit: Since most FTL drives seem to have fairly massive power input requirements, it is probable that you would also see a weaponized version of the FTL effect. The weapons would be much smaller than the generators, just like how a fission bomb is much smaller than a fission reactor."

Well, what are the rules? To me, it doesn't matter how the device works, but what the rules are. Some will allow huge FTL guns, some won't.

For instance: your FTL jump drive can jump you 10 light years at a time. The only problem? If it is operating in anywhere with more than .01 of earth's gravity operating upon it, it just won't work. And it can't arrive at any location where that same level of gravity would be acting upon it. So you could, in theory, blast an enemy fleet with an FTL cannon from Earth to Alpha Centauri, for instance, but never hit earth itself.

Why does it work that way? If you have a thorough background in physics, I'd be delighted to know in an appendix or something. If you don't, please don't fake it - I don't actually care that much.

Milo said...

ElAntonius:

"Given that most people know a Corvette is a sports car (probably the most popular, or at least most famous one, in America), and most people know that a 7.0L engine is very powerful for a car, the reality is most people have no idea how an ICE works, how the transmission works, or how the rear differential works."

People do know that a car moves by turning wheels on an axle to push against the road, though.



Horselover Fat:

"I was answering someone who wanted some form of teleportation (jump drives). If you have teleportation, increasing the speed of light or getting rid of it means your universe isn't broken by the teleportation. You stay clear of fun causality violations but also of a number of more practical exploits like laser strikes you can't defend against."

And you find "throwing out all of relativity + inventing teleportation" more believable than "introducing a special frame of reference + inventing teleportation"?

Once again, we already have a special frame of reference. (Cosmological coordinates.)

Oh, and what's that about laser strikes you can't defend against? If light is infinitely fast, then you definitely can't defend against it. And regardless, you couldn't defend against it anyway unless you had some sensors for detecting it that are even faster than the light itself.

jollyreaper said...

Regarding my artful comment, there's all manner if ideas that can be crammed into a story but being artless just ruins it. A really common sin in scifi and Big Idea novels is taking an essay-style rant and trying to turn it into a conversation with a "he said" at the end.

My general rule is that you can get away with it if you're good enough to get away with it.

I'm a fan of detailed worlds, don't get me wrong. I just want to see it done right.

Sabersonic said...

I find it rather interesting that the latest round of replies of this blog entry consists mainly about how one feels a proper SF novel should be written to accomidate the setting and technology presented without ruining the flow of the story to the reader.

Personally, I'm of the opinion that one should understand their potential audience to ensure that the author/director's vision comes across easily enough for them to understand, yet to occasionally throw in some curve balls that would characterize said story that would make the audience go "wow". If one can get away with the least amount of technobabble monologue, or at least weave it intelligently enough so that it doesn't feel like it to the reader, the better.

Of course, that's just my honest oppinion.

And speaking of infodumps and FTL mechanics, I admit that I was part of the audience who accepte the "go anywhere" FTL drives of space operas such as Star Wars and yes that when I do watch a movie I occasionally turn the logic portion of my brain to the lowest enough setting to enjoy the equivilant film. However, over the years my own sci-fi and space opera ideas have refined to accept limitations to handwave systems and decrease the "go anywhere" aspect of FTL drives so prevailent in other media. What I'm getting at is that nowadays, an author could get away with the basic description of an FTL drive able to get to one point to another in this amount of time but to make at least that portion of his/her novel's setting memorable enough amonst the competition is to have particular characteristics and limitations that could be the bane of the protagonist cast. Some examples being the distance out of a gravitational field before activation, or even the use of celestial bodies such as stars to open naturally occuring wormholes. Describing the cultural and social impacts of the FTL and it's characteristics can also give a more identifiable aspect of the novel.

And despite Horselover Fat's objections to FTL and the laws of physics as we currently know them in a bloody feud, I also feel that the more accurately portrayed the spacecraft is when faced with said issues, the more "authentic" it appears at first glance.

Or as I would so rudely summarise: The more one gets the science and math right, the more bull*cencored* they can potentially get away with.

Oh, and before I forget:

One thing that's been bothering me a bit: Since most FTL drives seem to have fairly massive power input requirements, it is probable that you would also see a weaponized version of the FTL effect. The weapons would be much smaller than the generators, just like how a fission bomb is much smaller than a fission reactor.
- Scott

To be honest, that comment brings to mind not only my own FTL Drive idea for my space opera setting, but also the Wave Motion Gun of the Space Battleship Yamato series. Not a direct corelation to what you had in mind with nuclear fission applications, but a close enough media example off the top of my head. I'm sure there are more examples of weaponized FTL technology, though I haven't the foggiest as to what they are.

- Hotmail Address
Gmail Address

Anonymous said...

Milo: 'And you find "throwing out all of relativity + inventing teleportation" more believable than "introducing a special frame of reference + inventing teleportation"?'
Of course not. That said a special frame of reference in that sense would kind of throw out relativity. That's why you brought it up. And teleportation kind of ruins believability anyway, especially if you have a special frame of reference where causality is preserved.
What I was saying is that keeping the speed of light makes things harder. If you can pull off the special frame of reference that's great. But if you can't and end up with illogical or impossible goings-on by your own rules, then yeah: I'd say it would be easier to suspend disbelief over the long haul if you pick the rules you want to use instead of making a show of picking more plausible rules only to ignore them. Let's face it: in our lives, the speed of light is not a factor. So in SF people often pretend the speed of light is much higher than it is because that makes things more intuitive.

'Oh, and what's that about laser strikes you can't defend against? If light is infinitely fast, then you definitely can't defend against it.'
If light is very fast the enemy can not see you before you can see it. More importantly, you can shoot back. Offense is the best defense. But if your ennemy is faster than light you're a sitting duck unless FTL is somehow crippled.
If you are faster than light too, you can defend by exploiting FTL as well. But a battle between ships trying to abuse FTL is going to be bizarre. I'm not saying it couldn't be fun (for adequately nerdy values of fun) but it's not going to look like a naval battle or typical SF. If you can pull it off, great. But it would take some thinking to keep it coherent and sensible as well as some skill to portay in an intelligible way.
Of course there are ways to fix the problem like FTL scanners. But you need to think about the problems that need fixing and the consequences of your fixes.
Like most impossible things, STL teleporation also needs some fixing by the way. It's not as bad as FTL but it can still be quite deadly.


Sabersonic: 'And despite Horselover Fat's objections to FTL and the laws of physics as we currently know them in a bloody feud, I also feel that the more accurately portrayed the spacecraft is when faced with said issues, the more "authentic" it appears at first glance.'
I agree in principle. But I'm afraid that the consequences of realistic FTL (nevermind the oxymoron) are not intuitive and that the people who only give this stuff one glance are going to be confused by an attempt at accuracy... unless you figure out an FTL technique that elegantly prevents problems from arising in the first place. I'm all for that but I think it would have to be somewhat complex. Complex isn't a problem if the FTL technique is also awesome in a way that simple techniques couldn't hope to be.

-Horselover Fat

Teleros said...

Horselover Fat: "'Oh, and what's that about laser strikes you can't defend against? If light is infinitely fast, then you definitely can't defend against it.'"

This would have a lot of other knock-on effects though (for one, just think about the Hubble telescope). Using hyperspace as a special frame of reference seems safer IMHO.

Anonymous said...

I agree... as long as no one is using it.
I assume you're referring to James Hinson's proposal. It is not simply a matter of saying "hyperspace is a special frame of reference". You must decide how that frame matches the mundane world and that's going to create a constraint on FTL because people are necessarily going to live outside of that frame (even more so if you use a cosmologically meaningful special frame as Milo seems to be suggesting).
And that frame will not be a good match for remote galaxies and stuff. I don't see how you can get around "Hubble problems".

Unless you are creating a story about cosmology, I'd say "Hubble problems" are the least of your concerns.
I'd say that having a setting in which human/alien/AI activity makes sense considering the options FTL gives people is more important. And that's not nearly as easy as it might seem.
I contend it's easier if you change the speed of light. While a special special frame of reference might well be the most elegant approach, it only deals with some FTL pitfalls.

-Horselover Fat

Raymond said...

Horselover Fat:

"I assume you're referring to James Hinson's proposal. It is not simply a matter of saying "hyperspace is a special frame of reference"."

That's certainly the one I had in mind, since it really does keep everything neat and orderly. Said special frame doesn't need to upend GR in realspace, either.

"You must decide how that frame matches the mundane world and that's going to create a constraint on FTL because people are necessarily going to live outside of that frame (even more so if you use a cosmologically meaningful special frame as Milo seems to be suggesting)."

One of the bonuses of using a particular frame for all FTL travel is you can use it for mundane things like timekeeping (as the special frame would give an ordering of events common to all points in spacetime and all reference frames), which also cuts down on dealing with the stranger and less-obvious consequences of relativity. The effects of a special frame on mundane life are a feature, not a bug.

"And that frame will not be a good match for remote galaxies and stuff. I don't see how you can get around "Hubble problems"."

I'm not quite sure what you mean.

"I contend it's easier if you change the speed of light. While a special special frame of reference might well be the most elegant approach, it only deals with some FTL pitfalls."

It deals with the causality issue, which is enough that it's useful. If you want to go one further and deal with local energy/momentum conservation, you can easily say that jumps have to be done near stars on both ends - the energy release upon jumping out won't matter so much, and you've got high-density stellar wind to draw from upon return. This also keeps a realspace travel element, for those who don't want sneak attacks with FTL missiles or battles occuring almost entirely in FTL.

Thucydides said...

The battleship example is a good illustration of where the author should go.

The writer needs to consult the reference so he understands the layout of the battleship as a minimum. When the character goes down the passageway, he is moving from on specific point to another and the author needs to know where the galley is (say) so he can meet another character for coffee. This can be considered the minimum effort.

If the mechanics of the ship are important, then more research is needed (how long does it take to fill the bunkers with coal? How many men are needed to do so? When will they need to refuel?), but this is usually given in a few sentences (H looked over the deck to the heaving mass of men hauling coal to the ship. The Admiral and the Captain had been breathing down his neck to get the job done, but there was no way to move any faster, it would take the rest of the day and all night to fill the bunkers to the top, and even then the cruiser would barely reach Port Arthur....) .

More detail requires even more work, but for less authorial payoff; knowing how thick the armour belt is and what shells are being fired might only result in "the shell burst through the bulkhead, filling the compartment with white hot fragments...).

I suspect technowank is a result of authors trying to actually use the thousands of words and hundreds of hours of research rather than distilling the essence onto the page.

Citizen Joe said...

I suspect that telling the story from the perspective of a bosun. While officers might get into the whole politics of the situation, the bosun has to deal with the day to day operational issues. People come to him with their problems, so if you need to point out some technology, you can just have it on the repair and inspection list.

Anonymous said...

Raymond:

How would a special frame for the purpose of preserving causality not upend GR? That sounds like wishful thinking to me. I understand a special frame as a way to preserve causality, not GR. Remember FTL, relativity or causality... pick and two?
Maybe I don't get the nature of the proposal but it seems to me you are proposing to preserve causality by saying causal relationships take place in a special frame (for that to work that frame can't be the typical SF hyperspace but must contain all mundane events). If that's what you're doing then you are necessarily saying that causality can be broken in all other frames. You are protected against paradoxes and you get a nice universal clock but consistent causality is gone which must mean other physical relationships will not hold in all frames. I don't see a way around that since the ban on FTL is necessary to keep the universe consistent in all frames.
So the impact on the mundane world I'm talking about is that causality will technically be broken for most observers. I did not try to work out the consequences but, if the special frame is close enough to the frame of all observers, I guess it will not be obvious as long as you don't have very fast FTL travel or communication (you could not attain infinite velocities outside of the special frame where most people live anyway). That more or less works in our galaxy if there are no machines that go very fast without FTL. But if you start looking with your telescope at objects which have relativistic velocities relative to the special frame...

"If you want to go one further and deal with local energy/momentum conservation, you can easily say that jumps have to be done near stars on both ends - the energy release upon jumping out won't matter so much, and you've got high-density stellar wind to draw from upon return."
How would that work? It means you'd have a technology that's able to build a ship including its crew out of solar wind by spooky action at a distance, right? If so you have a duplicating technology (and instant cloning as well if you don't allow for unphysical spirits). That would be insanely powerful. People would basically be gods and mundane stories would be out of the window.
Mabye you've figured another way it would work in practice but I feel like there's a general unwillingness to consider the practical consequences of FTL magitech around here.

-Horselover Fat

Raymond said...

Horselover Fat:

The Hinson article's got more of the nitty-gritty details, but basically the upshot is that as long as all FTL travel happens in the same reference frame, causality is conserved. Said frame doesn't necessarily have to be "privileged" by GR (ie an inertial frame which describes some new physics not found in any other inertial frame), so long as all FTL uses the same frame. If all FTL takes place in the same frame, all events have a definite order in that frame, and nobody can pull any causality hijinks. Not that it has to be "the" canonical frame, just as long as all FTL uses it, therefore all FTL sees one ordering of spacetime events.

"But if you start looking with your telescope at objects which have relativistic velocities relative to the special frame..."

...then AFAIK all FTL travellers will see the same effects and the same spacetime ordering, and therefore wouldn't be able to create any paradoxes. Remember, you have to be able to do FTL trips between two different frames to violate causality.

"It means you'd have a technology that's able to build a ship including its crew out of solar wind by spooky action at a distance, right?"

Not necessarily. First, you'd have to dump your rest mass when jumping (probably as an explosion), so no duplication. On the far end, I'd imagine it more as a mini-black-hole forming, drawing in mass and energy, and then instead of dissipating in a burst of energy, it dissipates in a burst of spacecraft.

Anonymous said...

Raymond:

I agree you can defeat paradoxes (I've said so). I also agree you can preserve causality in the special frame with no other tweak to physics than whatever allows teleportation faster than the speed of light (a biggie I would think). But this is not the same thing as preserving causality in all frames of reference. How would that possibly work?
I haven't read the full Hinson website but what I've read isn't very explicit. And you're not making it clear either with this talk of hyperspace actually being a frame of reference (generally the word refers to some kind of alternate universe with different physics) instead of describing its connection to a frame of our universe. I imagined it a bit differently but perhaps all FTL ships or transmitters are required to be in a predefinite inertial frame of reference before engaging the FTL magitech? That would feel arbitrary but in that case I guess you could preserve the remnants of relativity and make it so only events in which FTL magitech are implicated would violate causality in other frames. But causality would still be partially broken in those frames. And the velocities of stars relative to the special frame would be a big deal because they would affect the engines and fuel you need to reach hyperspace as well as the time required to travel between stars. If you picked a frame which is as close as possible to most stars in the neighborhood, travel to or from some stars would have very different requirements.

"you'd have to dump your rest mass when jumping (probably as an explosion), so no duplication"
Why? If you've got something obviously magical it doesn't need to be explained but if it's going to be a reasonable-sounding technology that allows teleportation without violating any physical laws what is the grounds for requiring the original ship to be destroyed? Your technology is able to materialize stuff without violating thermodynamics, the conservation of momentum and so on so why could it not be used to replicate?
Honest magic tends to be more believable than magitech because magic resits examination while technology should not.

-Horselover Fat

Brian said...

Personally as a sci fi fan I don't need FTL, just give me a rocket that gets me to the nearest star at a good fraction of the speed of light, say 99.999999% :-) Unfortunately, I don't think we have anything like that yet...I heard that even a fusion rocket would get you maybe 30% of c :-( Does anybody know of a rocket considered plausible that would get you to 90% of the speed of light? What if you used an ion drive and just kept accelerating for a long time, it is plausible to get to 90% c that way?

But if it doesn't give me c, then at least freeze me and/or put me in stasis then wake me up when we get there :-) it is okay for the journey to take 10,000 years of ship time if I am in stasis :)

As far as FTL, the Alcubierre drive does basically what I always envisioned the Warp Drive in Star Trek to do. Make a distortion in spacetime and move that distortion faster than light. Although I'm torn about artificial gravity in star trek. Clearly, the warp drive would not cause you to feel an acceleration; you would just be floating there. However, it could be said that if a civilization can make a warp drive, they can probably make artificial gravity as seen in ST. What do you guys think about that? :)

--Brian

Brian said...

btw what is the current status of the plausibility of the Bussard Scoop Rocket? The one where you bring in interstellar hydrogen with a powerful magnetic field, and fuse it? It seems that Robert Zubrin (the "mars direct" guy) said it wouldn't work because there would be a drag effect, although said drag effect would be useful in slowing down an interstellar craft, because when you got close to a star you could turn on the magnetic field, and be slowed down by deflecting the solar wind.

Raymond said...

Horselover Fat:

"But this is not the same thing as preserving causality in all frames of reference. How would that possibly work?"

Not considering FTL, the order of events is relative depending on frame. The speed of light prevents anything happening to break causality - an event in your future may be in someone else's past, but she can't tell you about it in time for you to change anything. With a special frame for FTL, she could go FTL to tell you about it, but as soon as she does, she takes on the special frame. Depending on your relation to the special frame, either her FTL trip is still further in the future than the event in question, or the event is already in your past according to the special frame. Hinson explains it better (and with diagrams!).

Basically, the lightspeed barrier keeps everything consistent in realspace, and the FTL frame keeps everything consistent WRT travellers going FTL.

"And you're not making it clear either with this talk of hyperspace actually being a frame of reference (generally the word refers to some kind of alternate universe with different physics) instead of describing its connection to a frame of our universe."

I'm probably butchering it (and this is why I don't write SF myself). So let me back up and try again. If you're doing the hyperspace-as-alternate-universe thing, declaring that all of hyperspace has a particular frame of reference at all points with respect to realspace allows you to dodge the FTL paradoxes. If you're doing the go-outside-the-universe-and-go-back-in thing, you can even specify the comoving coordinates Milo mentioned (or something similar).

"And the velocities of stars relative to the special frame would be a big deal because they would affect the engines and fuel you need to reach hyperspace as well as the time required to travel between stars."

This is where conservation of energy and momentum at both ends is a feature instead of a bug - taking on the momentum of local mass gets you into the local frame without additional requirements.

"Why? If you've got something obviously magical it doesn't need to be explained but if it's going to be a reasonable-sounding technology that allows teleportation without violating any physical laws what is the grounds for requiring the original ship to be destroyed?"

Local conservation laws. The energy of your craft's rest mass has to go somewhere when you jump out, and needs to come from somewhere when you jump in. The ship (and its attendant information) is only moved around, not duplicated.

"Your technology is able to materialize stuff without violating thermodynamics, the conservation of momentum and so on so why could it not be used to replicate?"

For the same conceptual (NOT mathematical) reason quantum teleportation of photons destroys the original. You're just moving stuff around, not actually making duplicates. Or rather, you're moving the information around, not copying it.

Say you're creating a wormhole to another universe: you'd make the wormhole and dive in, with your mass in this universe added to the wormhole. You arrive in Otherspace, and the wormhole closes in a burst of light (equal to your rest mass) just like an evaporating black hole. When you want to come out of Otherspace, you build another wormhole back into our universe. This wormhole sucks up local mass, taking on its momentum in the process. You come back through this new wormhole, and when it dissipates it leaves behind your ship. Nothing is duplicated this way - just moved around.

Raymond said...

Brian:

"What if you used an ion drive and just kept accelerating for a long time, it is plausible to get to 90% c that way?"

Ion drive still obeys all the rocket equation limitations on power, exhaust velocity, and mass ratio - in fact, most fusion rockets can be viewed as beefed-up ion drives which generate their own power.

Your best bet for significant fractions of c is actually not even antimatter, but artificial black holes - at around a million tons or so, they give off enough Hawking radiation to give a wicked power/mass ratio, but still last about 400 years, so you've got some time to work with it.

Bussard ramjets are pretty much off the table for anything past 0.12c because of the drag effect, and that's ignoring the problems of proton-proton fusion. If you bring your own power supply, you can use the interstellar hydrogen only for reaction mass, and that gives a much higher maximum speed - you don't have to slow the hydrogen down nearly as much, so your Bremsstrahlung losses from the scoop are much less.

Milo said...

"If light is very fast the enemy can not see you before you can see it."

Light travels both ways. Barring some mechanism that can make you fail to notice someone even when they have a causal relationship to you (i.e., stealth in space), you will both notice each other at the same time.

Of course, while I see you at the same moment you see me, I do not yet know whether you are opening fire. Nonetheless, if you do open fire, I will already have been returning fire for an entire minute (or however far apart we are) before your attack hits me.

Maybe that's what you're getting at - that both sides get to do a certain amount of free damage to the enemy before they're destroyed, no matter how outgunned they are. (This is also a potential problem with missile-based craft.)


"If you are faster than light too, you can defend by exploiting FTL as well. But a battle between ships trying to abuse FTL is going to be bizarre. I'm not saying it couldn't be fun (for adequately nerdy values of fun) but it's not going to look like a naval battle or typical SF. If you can pull it off, great. But it would take some thinking to keep it coherent and sensible as well as some skill to portay in an intelligible way."

If you have jump or hyperspace FTL (and you were talking about jump FTL), then ships can't spend all their time in FTL. Maybe you need special jump gates, or the jump drive takes time to warm up. Between jumps, you can still have pseudo-naval battles.

If you have free-flight FTL, then yes, you need either some exotic FTL weapon or some very creative tactics (laser minelayers?).


"You must decide how that frame matches the mundane world and that's going to create a constraint on FTL because people are necessarily going to live outside of that frame (even more so if you use a cosmologically meaningful special frame as Milo seems to be suggesting)."

Having the special frame of reference be the one we live in would violate the mediocrity principle, which I already raised a few threads ago as opposed to hard SF.

It isn't even an inertial frame!


"And that frame will not be a good match for remote galaxies and stuff. I don't see how you can get around "Hubble problems"."

Actually, cosmological coordinates do work equally well for all galaxies in the universe. That's the attraction.


"I'd say that having a setting in which human/alien/AI activity makes sense considering the options FTL gives people is more important. And that's not nearly as easy as it might seem."

Who was it that pointed out that the "acyclic graph of time-dilating wormholes" system was the one model that could actually justify all alien civilizations being at a similar level of technological advancement?

Milo said...

"Remember FTL, relativity or causality... pick and two?"

That's a saying that's blindly repeated by people who keep forgetting about special frames of reference. It isn't true.

Relativity is consistent with a special frame of reference, provided relativity remains accurate (and therefore the special frame has no meaningful effect) under normal conditions, just as relativity reduces to Newtonian mechanics under normal conditions.


"If that's what you're doing then you are necessarily saying that causality can be broken in all other frames."

No. It is possible for an event to happen "before" another event that caused it, according to some frame, but these events will be far enough apart (spacelike separation in relativity jargon) that they will have no causal relationship in either direction without FTL. There is no observer in any frame that will assert that a closed timelike loop (i.e., a violation of causality) is taking place.

If you accept a special frame of reference, then you would hold that all appearance of events happening in improper chronological order is an "illusion", no more disturbing than receiving two signals in reverse order because one got slowed down in transmission.


"You are protected against paradoxes and you get a nice universal clock but consistent causality is gone which must mean other physical relationships will not hold in all frames."

Not true. All frames of reference still agree on, say, which objects are gravitationally attracted to each other. While some frames may see you going "backwards" in time, they would not perceive anything to be exerting gravitational attraction backwards in time (unless you have FTL tractor beams).


"I did not try to work out the consequences but, if the special frame is close enough to the frame of all observers,"

Cosmological coordinates, while not exactly the frame we live in, are relatively close - only some 627 km/s apart, which gives a gamma factor of only 1.000002 (or about one minute per year).

Milo said...

Brian:

"Does anybody know of a rocket considered plausible that would get you to 90% of the speed of light?"

90% c = 116 exajoules/ton kinetic energy (27.8 gigaRicks), versus the 90 exajoules/ton of matter-antimatter annihilation. (Matching up the numbers exactly would give 86.6% c, or sqrt(3/4). Counting only the mass of the antimatter and ignoring the equivalent amount of matter used for annihilation would give 94.3%, or sqrt(8/9).) So it's just kinda plausible, if you have a real whole lot of antimatter, or some other energy-producing magitech. Note that the amount of solar irradiation that strikes all of Earth in one year only equals 61 kilotons of antimatter. The worldwide electricity generation of today equals some 2/3rds of a ton of antimatter per year.

The only other option is a Bussard ramjet, which scoops up the energy from outside the ship while in transit.

Also don't forget that if you don't have inertial compensators that would let your crew survive accelerations of much more than 1 Earth gravity, then the shortest possible flight that can accelerate to 90% c and slow down again would take 1460.6 days according to the rest frame and 1041.5 days according to the people on the ship. Hope you like spending three years in a tiny ship stuffed with many times your own weight in antimatter!


"What if you used an ion drive and just kept accelerating for a long time, it is plausible to get to 90% c that way?"

No. You'll run out of reaction mass.

I consider a rocket with a delta-vee of several hundred km/s (0.1% c) to be quite optimistic, and sufficient for in-solar-system travel (Earth-Saturn in 100 days). 1% c, faster than the velocity of most objects relative to cosmological coordinates, does Earth-Saturn in 11 days and Earth-Eris in 78 days.


"But if it doesn't give me c, then at least freeze me and/or put me in stasis then wake me up when we get there :-) it is okay for the journey to take 10,000 years of ship time if I am in stasis :)"

Sure, if you don't plan to ever come back.

We can do colonization that way, but not empire, war, trade, communication, or research. If you want the story to be set in a single star system which just happens to not be the same one as ours so that you can alter some of its characteristics to suit the plot, then sure, you can say that people got there by a sleeper ship. But you can't have space travel as the focus of the plot, unless you set the story onboard a generation ship.



Raymond:

"Local conservation laws."

So something I don't get about the supposed importance of these local conservation laws... if you have wormholes, then wouldn't the origin and destination be considered next to each other (and thus satisfying local conservation of whatever moves between them) due to the topological defect that makes the wormhole work in the first place?

Thucydides said...

In the penultimate chapter of the "Millenial Project" Marshal Savage postulates system spanning mass drivers capable of accelerating pods to a large fraction of c. In a fully developed Interstellar Empire, receiving systems have equally large mass drivers which can be used to intercept the pods and decelerate them. Aiming and control is an exercise left for the reader.

The two objections to this are that each pod is, in fact, a relativistic KKV capable of hammering a planet or causing massive solar flares if it misses the target and hits an object (or is actually aimed and guided in on the final approach). The other one is while time will pass slowly on the pod, tens, hundreds or even thousands of years might pass in inertial space until arrival; there may not be a civilization with a mass driver to meet you any more.

Raymond said...

Milo:

"So something I don't get about the supposed importance of these local conservation laws... if you have wormholes, then wouldn't the origin and destination be considered next to each other (and thus satisfying local conservation of whatever moves between them) due to the topological defect that makes the wormhole work in the first place?"

I'm trusting the math of others on this one, but it makes sense to me. If it weren't that way, it would seemingly violate thermodynamics by allowing perpetual motion machines.

Did you ever play Portal? Much as I love that game (miss you, Companion Cube!) it's chief mechanic was a demonstration of this. Raise one end of a wormhole above the other. Let something fall into the lower one, and it'll fall out the upper one. If conservation applies locally, as it seems to with GR wormholes, you can only extract the gravitational potential energy you used to raise the wormhole in the first place - the upper wormhole end will eventually dissipate when you've taken all its mass away, and thus you can only extract gravitational potential energy equal to the mass of the wormhole end, to which you had to add that energy to raise it up anyways. If conservation laws don't apply locally, then you've got a perpetual motion machine and unlimited energy.

Frankly, as far as constructing a setting goes, it's a blessing in disguise. It gives FTL jumps/wormholes/hyperspace access points some constraints and consequences, and encourages realspace travel as a necessary component.

Thucydides:

Yeah, that's why I'm less than sanguine about even high-fraction-of-c travel. Either you've got extinction-level guided missiles or extinction-level cannons. I actually like the STL-warping idea slightly better.

Rick said...

My my my ... head exploding stuff.

Horselover Fat - by 'changing the speed of light' do you mean a gizmo that changes it locally around a ship, or simply asserting that in the world of the story c is much greater than 300,000 km/s?

To me, the latter would be much more problematic than traditional FTL - not for any logical reason, but because it forces me to wrap my head around a new and unfamiliar line of jive, in place of one so familiar (conventional SF FTL) that the reader can take it as stipulated and thenceforth ignore it.

YMMV, but for practical purposes the actual pseudo or alt physics of FTL can simply be blown off with a buzz word or two (like 'FTL'), unless the various funkitudes play a direct role in the story.

Tony said...

Thucydides:

"The battleship example is a good illustration of where the author should go.

The writer needs to consult the reference so he understands the layout of the battleship as a minimum...

If the mechanics of the ship are important, then more research is needed...

More detail requires even more work, but for less authorial payoff; knowing how thick the armour belt is and what shells are being fired might only result in "the shell burst through the bulkhead, filling the compartment with white hot fragments...)."


This, I think, is where a lot of authors get themselves into all sorts of trouble. The theoretical framework upon which battleships were built is often taken as some kind of real world system that dictated how they fought. But it's not. Because battleships represented a lot of, well...capital, they weren't risked beyond a certain point, except in desperation or frustration. And when they did meet, battlships tended to have all sorts of idiosynchratic fates. The loss of British batlecruisers at Jutland is notorious, but had probably less to do with poor design and/or inadequate armor, and everything to do with poor ammunition handling discipline. Bismarck was lost due to having her steering gear torpedoed. Most thought that an unlikely and fortuitous (for the British) turn of events. But the Japanese battleship Hiei was also lost to a steering gear casualty, caused by insanely close range cruiser gunfire in a night melee where opposing formations actually interprenetrated. Kirishima was lost a couple ofn ights later in what amounted to a nautical ambush. While concentrating fire on the USS South Dakota, she was targetted by radar from the USS Washington and battered into wreckage in just a few minutes.

All of these things -- radar, the vulnerability of steering gear, night actions at knife-fighting range, poor crew discipline -- and many others, like suprise attacks in port by torpedo-equipped aircraft, were never considered by the battleship designers, and never seem to come up in discussions of technical merits. But if you're an SF author trying to imagine how ships in space might fight each other, you would do well to consider previous IRL naval history, and never presume formula outcomes.

"I suspect technowank is a result of authors trying to actually use the thousands of words and hundreds of hours of research rather than distilling the essence onto the page."

Which can only be a disservice to the reader. It's the author's job to do the research and digest the data. The reader's only task is to buy books, which he ain't gonna do if the author puts showing off before entertainment.

Teleros said...

Horselover Fat: "Unless you are creating a story about cosmology, I'd say "Hubble problems" are the least of your concerns.
I'd say that having a setting in which human/alien/AI activity makes sense considering the options FTL gives people is more important. And that's not nearly as easy as it might seem.
I contend it's easier if you change the speed of light."


Consider though, what the galaxy will look like if the light from a distant supernova 50,000 LY distant arrives and zips on past Earth in nothing flat.

Also consider that the electromagnetic force is carried, I believe, by photons - ie, it'll be affected by the speed of light. IIRC, there was a story by Stephen Baxter in which *slightly* tweaking the speed of light resulted in a region of space that humans couldn't live for long in - and which also blew most of their computers and such. In other words, there is A LOT of fallout from changing the speed of light.

Whilst it could work, I'd expect such a change in accepted physics to be a major part of the story, because (unless we're using an "it's magic" excuse), I'd expect you to show that you've done your homework & understand most (if not all) the consequences.

"How would a special frame for the purpose of preserving causality not upend GR? That sounds like wishful thinking to me. I understand a special frame as a way to preserve causality, not GR. Remember FTL, relativity or causality... pick and two?"

The idea I think is that whilst "hyperspace is a special frame of reference" does technically break GR, if you don't have access to hyperspace you won't realise it.



Milo: "If you have free-flight FTL, then yes, you need either some exotic FTL weapon or some very creative tactics (laser minelayers?)."

There's always the good old gravity wells to force you out of hyperspace. Can your setting build "hyperspace entry jammers" or somesuch?



Raymond: "I'm trusting the math of others on this one, but it makes sense to me. If it weren't that way, it would seemingly violate thermodynamics by allowing perpetual motion machines."

The way I understand it is that if you link two closed systems (eg universes linked by a wormhole), they become a single system. Once the wormhole closes, you've two separate closed systems again - no conservation laws are violated.

Luke said...

Milo:

So something I don't get about the supposed importance of these local conservation laws... if you have wormholes, then wouldn't the origin and destination be considered next to each other (and thus satisfying local conservation of whatever moves between them) due to the topological defect that makes the wormhole work in the first place?

Local conservation laws are only guaranteed to hold in the weak field limit where gravity acts like Newtonian gravity (plus a few extras, such as gravitational waves). It you have something that strongly warps space and time, energy and so on become non-local within the region of stongly distorted space time. At first, this seems to give you an "out".

However, any conservation law can be expressed thusly: for a closed space-like surface (which also needs to be space-like, since we are considering space and time dimensions), the total amount of the conserved quantity inside that surface only changes by the amount of the conserved quantity that passes through that surface. This means that if you have a region of strongly curved space-time but if you can entirely enclose the region with a closed surface which is far enough away that the entire surface is in the weak field limit (called asymptotic flatness), then the total amount of conserved stuff inside the surface again only changes when that conserved stuff goes through the surface.

So take a wormhole. It is strongly curved, but the region of strong curvature has a finite extent. If you go far enough away you get to the Newtonian limit again. So enclose one end of that wormhole with an imaginary shell out in the weak field region. You can say that there is a definite amount of energy inside that shell (you could measure this by the gravitational attraction, for example, which is proportional to mass, and by equivalent methods such as the period of an orbit around the wormhole). If a spacecraft goes from far away and enters the wormhole, as it crosses the shell it adds its energy to the stuff inside the shell. Since it goes through the wormhole and seems to disappear but its energy remains imprinted in the gravity coming from the wormhole, it appears that the wormhole acquired extra energy. Note that it general relativity, not only energy but also momentum and angular momentum have gravitational effects which can in principle be measured, so the same argument applies to them.

Here's another way to think of it. Local conservation laws are mathematically equivalent to the field-line picture of electrostatics. You can think of gravity as coming from a gravitational field represented by field lines. Field lines only start at a source (positive charge, positive mass) and only end at a sink (negative charge, negative mass if this were possible). They radiate away from a source in all directions, and enter a sink from all directions. If you take a source that is initially very far away from a wormhole, the field lines look like the field lines of any free-space source. Now bring it close to the wormhole. Since the field lines had previously not entered the wormhole, they cannot break so as to go in to the wormhole now. Thus, the field lines curve around the wormhole. As the field source enters the wormhole, the field lines exending out to infinity still must stay intact, so now they come out of the wormhole, sticking out like the legs of a very large spider just eaten by a small frog. Since the field lines are radiating out of the wormhole, the wormhole appears to have acquired a source of field - it has gained charge or mass.

The math is treated rigorously in
Valery P. Frolov and Igor D. Novikov, Phys. Rev. D, Vol. 42, pg. 1057 (1990)

Luke said...

Minor correction - local dynamical conservation laws are only guaranteed to hold in the weak field limit. Non-dynamical conservation laws, such as the conservation of electric charge, are thought to hold everywhere.

Anonymous said...

Raymond (and Milo as far as the first paragraph is concerned):

I gave Hinson's page a more thorough read.
It looks like we have a semantic problem. I used "causality" and "paradox" the same way as Hinson but I don't think I've aligned my use of "consistent" with his. So let's drop "consistent". He says FTL breaks causality. Milo calls that break an "illusion" but as far as I can tell we're talking the same thing. His special frame of reference trick is supposed to prevent paradoxes, not to somehow rescue causality from FTL. Look at his explanation: there is no paradox but past and future are jumbled from some observers.
But, now that I've read it more thoroughly, I'm not at all sold on his implementation of a special frame of reference as an effective way to prevent paradoxes. He probably isn't sold on it either since he says it's intended to "produce a clear illustration". It's confusing but seems to come down to a rationalization of arbitrary FTL denial. It also sounds like it could be exploited. If you allow anyone to do FTL magic at the flip of a switch, you have a problem. Simply saying "special frame of reference" is no more a way out than teleportation is: you've got to enforce limitations on FTL and his implementation doesn't seem to have a predictable and generally applicable enforcement mechanism. I think there may be better and simpler ways (like limiting jump FTL to things which are at rest with a pre-defined special frame).

"This is where conservation of energy and momentum at both ends is a feature instead of a bug - taking on the momentum of local mass gets you into the local frame without additional requirements."
But teleportation which doesn't conserve relative velocities is a bug if you want to avoid paradoxes, right? In practice it's not much of a problem since the relative velocities of stars are moderate so I think limiting teleportation to stars and taking on local momentum would work within our galaxy (or most of it anyway) provided teleportation takes some time.

"For the same conceptual (NOT mathematical) reason quantum teleportation of photons destroys the original."
Why should a macroscopic technology be limited by quantum entanglement concepts? It seems completely arbitrary. Magic might be limited in such a way because of the made-up principle of the "non-local conservation of essence" or something. I think it would be easier to believe for me if local conservation laws were obviously violated because that would imply that something other than information has travelled through "otherspace" and is necessary for the ship to be materialized.

"If conservation laws don't apply locally, then you've got a perpetual motion machine and unlimited energy."
If locally is near a star you've essentially got a perpetual motion machine right there anyway.


Milo:

"Light travels both ways. Barring some mechanism that can make you fail to notice someone even when they have a causal relationship to you (i.e., stealth in space), you will both notice each other at the same time."
FTL implies stealth in space because it breaks the normal causal relationship. Say I jump 1 light-minute away from you. You won't see me for a minute. I'll see you right away.

"Actually, cosmological coordinates do work equally well for all galaxies in the universe. That's the attraction."
They're far from our frame for the purpose of relativity, right?. If you use the comoving frame (which is not inertial) as a special inertial frame, it would have to involve some sort of local approximation and I figure that would not work for distant objects. I'm not sure how it would work out with the expansion of space.

(continued)

Anonymous said...

Rick:

"simply asserting that in the world of the story c is much greater than 300,000 km/s?
To me, the latter would be much more problematic than traditional FTL"
That's exactly what I meant. It is problematic for sure but traditional FTL is such nonsense. It feels like a really tired joke. Anything but that.


Teleros:

"The idea I think is that whilst "hyperspace is a special frame of reference" does technically break GR, if you don't have access to hyperspace you won't realise it."
FTL breaks the causality we know and love one way or the other (see above).

"I'd expect such a change in accepted physics to be a major part of the story, because (unless we're using an "it's magic" excuse), I'd expect you to show that you've done your homework & understand most (if not all) the consequences."
That is not how you (and many, many others) treat FTL. Myself, I don't expect realism from a setting which has FTL for obvious reasons. But, as with stories about princesses and dragons, I'd still like the setting to make sense. Unfortunately, settings with FTL rarely do.
The whole point of changing the speed of light is to avoid the homework that so many people are unwilling to do. Often times, the speed of light is increased without mentionning it anyway because it's simpler that way.

-Horselover Fat

Anonymous said...

It looks like Blogger aate the following...

Raymond (and Milo as far as the first paragraph is concerned):

I gave Hinson's page a more thorough read.
It looks like we have a semantic problem. I used "causality" and "paradox" the same way as Hinson but I don't think I've aligned my use of "consistent" with his. So let's drop "consistent". He explicitely says FTL breaks causality. Milo calls that break an "illusion" but as far as I can tell we're talking the same thing. His special frame of reference trick is supposed to prevent paradoxes, not to somehow rescue causality from FTL. Look at his explanation: there is no paradox but past and future are jumbled from some observers.
But, now that I've read it more thoroughly, I'm not at all sold on his implementation of a special frame of reference as an effective way to prevent paradoxes. He probably isn't sold on it either since he says it's intended to "produce a clear illustration". It's confusing but seems to come down to a rationalization of arbitrary FTL denial. It also sounds like it could be exploited. If you allow anyone to do FTL magic at the flip of a switch, you have a problem. Simply saying "special frame of reference" is no more a way out than teleportation is: you've got to enforce limitations on FTL and his implementation doesn't seem to have a predictable and generally applicable enforcement mechanism. I think there may be better and simpler ways (like limiting jump FTL to things which are at rest with a pre-defined special frame).

"This is where conservation of energy and momentum at both ends is a feature instead of a bug - taking on the momentum of local mass gets you into the local frame without additional requirements."
But teleportation which doesn't conserve relative velocities is a bug if you want to avoid paradoxes, right? In practice it's not much of a problem since the relative velocities of stars are moderate so I think limiting teleportation to stars and taking on local momentum would work within our galaxy (or most of it anyway) provided teleportation takes some time.

"For the same conceptual (NOT mathematical) reason quantum teleportation of photons destroys the original."
Why should a macroscopic technology be limited by quantum entanglement concepts? It seems completely arbitrary. Magic might be limited in such a way because of the made-up principle of the "non-local conservation of essence" or something. I think it would be easier to believe for me if local conservation laws were obviously violated because that would imply that something other than information has travelled through "otherspace" and is necessary for the ship to be materialized.

"If conservation laws don't apply locally, then you've got a perpetual motion machine and unlimited energy."
If locally is near a star you've essentially got a perpetual motion machine right there anyway.


Milo:

"Light travels both ways. Barring some mechanism that can make you fail to notice someone even when they have a causal relationship to you (i.e., stealth in space), you will both notice each other at the same time."
FTL implies stealth in space because it breaks the normal causal relationship. Say I jump 1 light-minute away from you. You won't see me for a minute. I'll see you right away.

"Actually, cosmological coordinates do work equally well for all galaxies in the universe. That's the attraction."
They're far from our frame for the purpose of relativity, right?. If you use the comoving frame as a special inertial frame (it's got to be inertial) I figure that would only work locally (as a sort of approximation). I'm not sure how it would work out with the expansion of space.

-Horselover Fat

Raymond said...

Teleros:

"The idea I think is that whilst "hyperspace is a special frame of reference" does technically break GR, if you don't have access to hyperspace you won't realise it."

Depends on your definition of "break". As long as the special frame for FTL doesn't also constitute a canonical frame for things like energy conservation, it's debatable whether it would break GR or simply extend it.

"The way I understand it is that if you link two closed systems (eg universes linked by a wormhole), they become a single system. Once the wormhole closes, you've two separate closed systems again - no conservation laws are violated."

If you have a large black hole which forms a wormhole, you still get conservation of energy in this universe, as any mass that goes into the black hole will eventually be radiated out via Hawking radiation. Mass and energy don't disappear from this universe, and don't appear from others (it was also found that white holes were unlikely-to-impossible, as the time reversal of a black hole is another black hole, not a white hole).

Raymond said...

Horselover Fat:

I think we're still dealing with semantic confusion.

"His special frame of reference trick is supposed to prevent paradoxes, not to somehow rescue causality from FTL."

Preventing paradoxes does rescue causality from FTL. Even if the order of events gets jumbled from one observer's frame, as long as nobody can cause a paradox it's alright. Event ordering is entirely relative anyways. The only thing a special frame does is ensure all FTL travellers see the same one.

"But teleportation which doesn't conserve relative velocities is a bug if you want to avoid paradoxes, right?"

Oh, you mean pre-jump relative velocities? Actually, no. Pre-jump relative velocities are what get you into causality trouble in the first place.

"Why should a macroscopic technology be limited by quantum entanglement concepts? It seems completely arbitrary."

Nothing to do with quantum entanglement, just me trying to use an analogy and muddying the water instead. Luke explained it better than me.

"If locally is near a star you've essentially got a perpetual motion machine right there anyway."

Practically, yes, for human-scale time. Theoretically, no, and it's the theory which would be violated if it were otherwise.

"FTL implies stealth in space because it breaks the normal causal relationship. Say I jump 1 light-minute away from you. You won't see me for a minute. I'll see you right away."

I'm not understanding what you're trying to say. If I jump a light-minute away from you, it'll then take a minute for either of us to see what happens to the other post-jump.

Anonymous said...

What I'm saying (and it should be obvious) is that the craft which used FTL can see other crafts without being seen. The craft using FTL can use a laser on a target which is not accelerating without being seen and the target will therefore not be able to accelerate randomly to avoid the beam as it would if it knew an enemy was within firing range. In turn the craft using FTL can be gone before its target gets a chance to shoot back. This is a huge tactical advantage, to the point of making the craft using FTL undefeatable is FTL is not limited.
This is one of the many ways in which FTL can be abused. As someone suggested earlier, keep it very far away from any interesting places (gravitational wells disturbs the field or whatever mumbo jumbo you want to use) if you want to avoid dealing with this mess.

"The only thing a special frame does is ensure all FTL travellers see the same one."
I agree that would be best but that's not what Hinson's proposal did.

"Pre-jump relative velocities are what get you into causality trouble in the first place."
You allowed them by saying jumps wouldn't conserve relative velocities.
If you only allow objects at rest with respect to a magical frame to jump, you conserve relative velocities and the problem is solved.

-Horselover Fat

Brian said...

hey guys I found this Constant Acceleration calculator. it does not take relativity into account

http://tinyurl.com/26mj4w9

here is one that has Long Relativistic Journeys, it does take relativity into account, although it doesn't calculate final velocity:

http://tinyurl.com/4aegelt

--Brian

Raymond said...

Horselover Fat:

"What I'm saying (and it should be obvious) is that the craft which used FTL can see other crafts without being seen."

How so? The Alcubierre-style warping doesn't allow interaction with the rest of the universe. You could get hit-and-run attacks, but there wouldn't be any way to acquire your target in FTL.

"You allowed them by saying jumps wouldn't conserve relative velocities."

Conserving relative velocities is in fact the problem.

If you're jumping into a piece of spacetime, conserving energy and momentum locally requires you to take on some frame of reference, with its attendant momentum. If the jump process is performed with respect to a special frame, you get this:

Frame A -> Special Frame -> Frame B

If everybody using FTL uses the same special frame, there's no paradoxes (you can't enter Frame B in time to create a paradox). And if energy and momentum are conserved locally, you can't bring Frame A with you. Paradoxes are formed when Frame A can travel FTL and interact with Frame B, and vice versa.

"If you only allow objects at rest with respect to a magical frame to jump, you conserve relative velocities and the problem is solved."

Only allowing objects at rest with a particular frame to enter FTL would be an additional constraint. Useful for preventing FTL abuse, but that would actually technically break GR more than FTL merely assuming a special frame. Semantics, perhaps, but good to note.

Milo said...

Teleros:

"Consider though, what the galaxy will look like if the light from a distant supernova 50,000 LY distant arrives and zips on past Earth in nothing flat."

Hmm? If you increase the speed of light, then we will see supernovas that are taking place right now rather than supernovas that took place 50000 years ago, but they will not be any longer, shorter, brighter, dimmer, etc. than ours.



Horselover Fat:

"Say I jump 1 light-minute away from you. You won't see me for a minute. I'll see you right away."

...Oh, now I get it. You're seeing light that was transmitted before you warped in.


"If you use the comoving frame as a special inertial frame (it's got to be inertial) I figure that would only work locally (as a sort of approximation)."

To my understanding, you can think of comoving coordinates as a "curved" inertial frame. At every point in the universe, there is a proper/flat inertial frame "tangent" to the comoving frame at that point.

Nonetheless, I think (I don't understand the math well enough to check) that they satisfy the one condition that actually matters for paradox-free FTL, namely that it is impossible, using known STL laws, to travel backwards in time in comoving coordinates. That's all you need from a special frame.


"I'm not sure how it would work out with the expansion of space."

Comoving coordinates already account for the expansion of space... again, that's how they're defined.

Comoving coordinates deal with the expansion of space by ignoring it entirely. This means that two objects which are both at rest in comoving coordinates will be perceived as moving away from each other (due to expansion) in any proper frame. It also means that comoving distances aren't quite measured in "meters" as we know them, since how they align with proper meters gradually changes over time. (This could have the peculiar result that the efficiency of FTL drives increases as the universe ages, since galaxies drift farther apart by normal measurement but remain equally far apart by comoving coordinates. Or not, if you introduce some other technobabble to countermand that. This isn't an issue over the expected timespan of any civilization we can comprehend, anyway.) Movement from the expansion of the universe is thus not treated as "true" movement, even though it behaves as such in relativity. This allows galaxies all across the universe to be "nearly at rest".

Think of the "balloon model" of expanding space, where you draw some galaxies on a balloon and then slowly inflate it, watching the galaxies move farther apart from each other without any one galaxy actually being in the middle. Now imagine that you also drew a simple coordinate grid on the balloon. As the balloon expands, the coordinate grid will expand with it, but remain well-defined. Those are comoving coordinates.

None of this is very important since while you do indeed need a special frame of reference, that frame's time coordinate is much more important than its position coordinate. The position/distance coordinate is maybe useful for determining FTL trip times, but is not relevant for avoiding paradoxes.



+Raymond:

"Preventing paradoxes does rescue causality from FTL. Even if the order of events gets jumbled from one observer's frame, as long as nobody can cause a paradox it's alright. Event ordering is entirely relative anyways."

Think of it as reading a flashback scene in a book. The author might show events in a totally jumbled order, but (unless the author botched his writing job), it's plainly obvious what order the events "really" happened in.

It matters not one bit which order observers receive events in, as long as all observers can agree on one "canonical" ordering that "actually" happened.

Anonymous said...

Ok, so your 100 ton starship jumps from star A to star B; 100 tons of solar wind dissipears from around where your starship appears and 100 tons of extra solar wind appears around the area where your starship jumped from Star A; at star B your ship has acqiured the velocity of the solar wind it had displaced and the extra solar wind that appears at star A now has the same velocity as your starship, pre-jump. Everything equals out and only the energy used to initiate the jump is expended in normal space (I'm guessing that half is dissapated around star A and half is dissapated around star B). So, so long as the trip does not take negative time to acomplish, then there is no violation of causality? Now, if you use the inflation of extra dimentions as your FTL method, so long as your path doesn't involve negative time, then there is also no violation of causality? I'm guessing that wormholes are the problem due to their perchant for distorting time.

Ferrell

Raymond said...

Milo:

"Think of it as reading a flashback scene in a book. The author might show events in a totally jumbled order, but (unless the author botched his writing job), it's plainly obvious what order the events "really" happened in."

Or rather, for two distant characters, Alice's measurement of what's happening to Bob right now will be different than Bob's, but it doesn't matter as long as they're not using cellphones. Alice goes for lunch then goes back to her hotel. Bob waits in line at the airport. The exact order doesn't matter (and may appear different in relativity), but the story's consistent until Alice meets Bob as he gets off the plane.

If Bob calls Alice to let her know what gate to meet him at, then you have to have some reference frame to say for certain whether Alice is done her lunch yet and where in line Bob is.

Ferrell:

You'd have to find some frame of reference for all jumpers to determine what value of "right now" is used at each point.

Teleros said...

Horselover Fat: "FTL implies stealth in space because it breaks the normal causal relationship. Say I jump 1 light-minute away from you. You won't see me for a minute. I'll see you right away."

Not quite.

Suppose you jump from 2 lightminutes away from your target to 1 lightminute away. You jump at T=0. No FTL sensors are used here.

T=0: You jump from 2LM to 1LM away. You see the target 1 minute ago.
T=1: The target sees you appear 1LM away.
T=2: The target sees you disappear 2LM away.

The T=1 event occurs because there's usually some light flitting around in space: you appearing there means some of that light will strike your ship & be reflected back to the target. A similar explanation is why you see the target where you do at T=0.

"What I'm saying (and it should be obvious) is that the craft which used FTL can see other crafts without being seen."

See above. It's a fine tactic if you've got lightspeed weapons & a nice static target though, because they'll get no warning.

"This is one of the many ways in which FTL can be abused. As someone suggested earlier, keep it very far away from any interesting places (gravitational wells disturbs the field or whatever mumbo jumbo you want to use) if you want to avoid dealing with this mess."

Or add in FTL sensors (& thus comms) too ;) . Should lead to some quite interesting tactics if your lasers have to obey the speed of light but your sensors can spot the other guy near-as-damnit-instantly.





Brian: "hey guys I found this Constant Acceleration calculator. it does not take relativity into account"

Yeah I've found a fair few calculators as well, although nothing that quite has all the features I want. In all, I'd like to see something like this (anyone here any good at Java or w/e?):

1. Option 1 for starship: Constant accel X for Y distance or units of time. Accel not adjusted.
2. Option 2 for starship: Accel X from rest for mass Y for Z distance or units of time. Accel adjusted as ship's mass increases.
3. Additional option for 1 & 2: Report when velocity # is reached in addition to above results.
4. Elapsed time: Earth, starship, outside-universe / special frame of reference (possible?).
5. Dilation: time & space for starship.
6. Additional option: starship to decel to stop from 1/2way point yes/no?

Scott said...

First, you'd have to dump your rest mass when jumping (probably as an explosion), so no duplication. On the far end, I'd imagine it more as a mini-black-hole forming, drawing in mass and energy, and then instead of dissipating in a burst of energy, it dissipates in a burst of spacecraft.

This implies that you would be able to detect the departure of a spacecraft pretty easily ("With a bright flash, the Constellation jumped out-system."), but FTL arrivals would be pretty subtle.

That could present some nasty military storytelling possibilities.

Thucydides said...

Some of what Raymond said sounds a bit like "Memento". While living in a universe designed by Christopher Nolan would be interesting, it would also be unsettling after a while.

I'm going to guess that there is, in fact, some sort of strong prohibition against causality violation, otherwise there would be some sort of noticeable effects already from cosmological defects.

So this would mean that there is some unknown defect in GR and SR which can be exploited, or FTL is impossible, meaning we would be limited to a Solar Empire and groups heading out on one way journeys to the stars. If we want to write about Interstellar Empire, then the handwave would be figuring out the exploitation of the defect, and imagining various consequences that would come from it.

Brian said...

I forget who it was who said that sleeper ships are not of much use in hard sf, but, perhaps they have not seen Avatar? It is a hard sf movie; the star ships used are based on the hypothetical Valkyrie spacecraft, which uses matter/antimatter annihilation to get to 90% c.

http://tinyurl.com/2wdxfkd

http://tinyurl.com/4kyj99e

The crew is in suspended animation until they get to the target (the movie shows them being awakened). I think suspended animation is going to be something we use a lot in the future, unless it turns out that FTL is practical. Even at 99% the speed of light, all but the closest stars are far enough that it would desirable to go cold. If the journey is going to take 20 years each way (ship time), it is probably better to freeze the crew! :)

--Brian

Teleros said...

On the subject of sleeper ships, "House of Suns" is a book in which the main characters spend most of their time frozen, being woken up to trade with the various civilisations they bump into on their endless circuits around the galaxy.

Citizen Joe said...

Scott: This implies that you would be able to detect the departure of a spacecraft pretty easily ("With a bright flash, the Constellation jumped out-system."), but FTL arrivals would be pretty subtle.

I did a variant in a Traveller game like that. The ships used a hydrogen bubble/cloud during jumps but the military ships had capacitors strong enough to store up all of the neutrinos before the jump, allowing them to dump it all before the jump and arrive with no significant signature. Merchant vessels had to process as they went, resulting in a large burst as they entered jump, then a trail (not very noticeable) through jump space and then a large burst as they re-entered normal space.

My current favorite flavor means dumping local momentum in the form of spatial distortions and then inverse distortions on the other side to balance out the inbound vector. This would be analogous to a fish jumping through the air in a pond, ripples on the surface representing the spatial distortions.

Spatial distortions aren't noticeable until they interact with matter. So, you'd need some sort of 'tremor' sensors to pick up jumps. Of course, the sudden appearance of a very hot fusion reactor is also a dead giveaway.

Raymond said...

Scott:

"This implies that you would be able to detect the departure of a spacecraft pretty easily ("With a bright flash, the Constellation jumped out-system."), but FTL arrivals would be pretty subtle."

I'm assuming, of course. I don't know how you'd do the requisite wormhole to a pocket universe, nor how you'd set up the warping mechanism, nor how you'd arrange to exit. (Given what Luke said earlier about needing to do the above to avoid requiring more rest mass than the observable universe, that is.) I'm still partial to wormholes (or maybe cosmic strings), as they seem a little more...usable.

It also may not be as clean as I'm suggesting. It might be that when expanding the wormhole upon arrival, you gather up and subsequently radiating a significant amount of mass-energy in excess of what is strictly required by the rest mass of the ship. Which would give a characteristic burst of light upon arrival, just not as bright as departure.

"That could present some nasty military storytelling possibilities."

That it could. It'd also give a more coherent framework than the usual pop-out-anywhere FTL. Even if you don't use Alcubierre-style warping, some of the same principles would apply to entry/exit to/from magic-space. Local mass requirements + sensor limitations make it difficult to jump straight into a planetary atmosphere or into an enemy formation. They would, though, with a little bit of cleverness, make for some interesting FTL missiles or boarding vehicles...

Brian:

We could use a decent suspended-animation system even for longish interplanetary trips.

Don't use Avatar's figures as gospel, though. The original Valkyrie design seemed to have unrealistic mass ratios, and Avatar's were even worse. Antimatter beam-core engines have a specific impulse topping out around 0.6c.

Thucydides:

"So this would mean that there is some unknown defect in GR and SR which can be exploited, or FTL is impossible..."

If the causality protection conjecture holds, then all we have to do is figure out how to construct wormholes. (Easier said than done, I know.)

jollyreaper said...

Funny thing about what people consider plausible: from my personal bias, I'd consider a Niven stasis field for a sleeper ship to be more plausible than cryogenic sleep. They're both handwaves but at least the stasis field relies less on crazy assumptions about human physiology. Your mileage may vary, of course.

I'll accept using constructed wormholes for "walk through a portal" teleportation but Star Trek transporters are pretty much voodoo magic with disassembling people and shooting them through a matter stream, far greater suspension of disbelief.

Raymond said...

jollyreaper:

Suspended animation may be as (comparatively) simple as splicing in some tardigrade genes. Those fsckers are tough.

jollyreaper said...


Suspended animation may be as (comparatively) simple as splicing in some tardigrade genes. Those fsckers are tough.


Maybe. But then there's the question of how much we'd age in hibernation. I wouldn't want to lose five years of my prime life on a fifty year voyage to planet wherever.

Straight knock-out transport would work for an emergency situation, of course. It's one of the ideas I was surprised I never saw in standard SF when looking at trying to evacuate people when there's not enough life support. Sedate the evacuees, only leave a few medical personnel up and active to check on them. The only caveats to that idea I can think of are a) the mass of people is worse than the mass of extra oxygen and b) people bouncing off the walls in panic aren't using up all that much more oxygen than when they're asleep.

But what do I know? I just found out there's such a thing as modern genocentrism!

http://en.wikipedia.org/wiki/Modern_geocentrism

Rick said...

My suspicion is that fancy genetic modding, including hibernation, is going to turn out much trickier (and thus effectively limited) than anticipated. Knowing the Greek alphabet doesn't mean you can write in Greek.

(But who knows?)

Changing the speed of light means, among other things, changing the value of good old E = mc^2. Big consequences!

But that edge of the discussion really defaults to the meta question of what SF is or should be all about.

Stay tuned ...

Raymond said...

jollyreaper:

Induced comas reduce life-support costs by approximately half - not to mention people not being bored and not needing much space.

As for five years of prime life, well, would you rather spend it cooped up in a tin can for years, or asleep?

Rick:

We're getting pretty good at splicing. Not only do we know the Greek alphabet, but we can say "hello" and "where's the bathroom?" When we can write short "my summer vacation" essays, we're in business.

Brian said...

hmm I don't think suspended animation/stasis/cryogenics is necessarily a wave of the hand. Lower animals go into hibernation regularly. It is not as if it violates the laws of physics (although I speak as a layman who only has a high school diploma, some college courses, and is "Qualified in Submarines" (silver dolphins)). Observe this Scientific American article about mice going into suspended animation when exposed to gases in the sewer:

http://tinyurl.com/4ohgnwo

It seems reasonable to me that we would eventually learn to induce this in humans.

btw Raymond, are you the author of the Atomic Rocket site? :-/ because that person doesn't seem to find the Avatar ship implausible. :-/

--Brian

Thucydides said...

But that edge of the discussion really defaults to the meta question of what SF is or should be all about.

Indeed.

Just jumping about without reference to causality or GR is Hornblower in Space. Exploring the consequences of changing the speed of light ("E does not equal MC^2? What sort of nonsense is that Mr Scott?") and especially if this is integral to the plot makes it SF in my mind.

Raymond said...

Brian:

"btw Raymond, are you the author of the Atomic Rocket site? :-/ because that person doesn't seem to find the Avatar ship implausible. :-/"

Oh, no, Atomic Rockets is Nyrath, and I've read the whole thing thrice.

The Avatar craft is more realistic than many, certainly. But it doesn't go to 0.9c, even according to the design docs (0.75c, actually), and it's supposedly accelerated by laser sail when leaving Sol and when returning, with the antimatter engines only used for deceleration at Pandora and acceleration for the return trip.

I've also read the original Valkyrie proposal (elements of which went into the Avatar craft's design, thus the name), and they made a lot of assumptions with regard to mass ratios and specific impulse.

The hiccup with antimatter engines is that so much of the energy of proton-antiproton annihilation is released as gamma rays or neutral pions, both of which are useless for propulsion. The paper I've got sitting in my library somewhere indicates that only about 25% of the energy of the antimatter is actually usable for propulsion - with perhaps up to 60% if one can use Compton scattering somehow for the gamma rays produced. This starts making the mass ratios obscenely high for velocities above 0.4c or so - and even then, you'd need staging.

So implausible on the whole? No. Implausibly high fraction of c? I suspect so.

Luke said...

Re: changing the speed of light.

The speed of light is, ultimately, a constant of proportionality between your units of distance and your units of time. Changing this speed really just means choosing a new set of units to measure distance and/or time in. If you change the speed of light, but this also causes, for example, the radii of all atoms to increase by the same amount, all your distances also change and there is no physical difference.

This is really the problem when talking about changing constants with units - all this amounts to is rescaling your units. What makes a physical difference is changing the dimensionless constants of nature. For example, the fine structure constant is (electron charge)^2/(Planck constant * speed of light), and has the value (in our universe) of approximately 1/137. It has no units. Changing the fine structure constant would have significant effects on measurable properties. Notably, significant changes in the fine structure constant would drastically alter the nature of chemical bonding. Altering other ratios of combinations of physical constants with no units would also have physical changes.

Scott said...

"Qualified in Submarines" (silver dolphins)

Alright, another bubblehead!

looping all the way back to Raymond's first comment, the Peacemaker series of novels end up involving a physical fact about the FTL entry to ensure the survival of the main character. (not a mary su-ism, character was previously established as a math whiz and seriously hotshot FTL pilot). To kinda tie this in to the complaints about how infodumps happen in writing, this was mentioned once in passing early in the book, as the pilot shakes her head about the badly-tuned drive on another ship giving a visible flash. Then, when lives are riding on the effect, she intentionally mistunes the drive for a larger FTL 'entry-flash'.

The setup helps the eventual use not feel like a deus ex event.

Raymond said...

Scott:

"The setup helps the eventual use not feel like a deus ex event."

Which is always the trick.

There is a class of SF stories - usually the ones listed as "hard SF" instead of "military SF" or "space opera" - in which the implications of this or that (somewhat-to-highly technical) construct are in fact the point. My favorite novel of the last decade, Blindsight, was about the value of sentience, or rather the lack thereof. You just can't explore that without getting technical, without exploring complex concepts in biology and neuroscience. And you can't assume the audience knows jack about it in the first place. So the info has to be dumped. In pieces instead of essays, in digestible chunks instead of monologues, but you've gotta put it in or the point is lost.

Milo said...

Jollyreaper:

"Funny thing about what people consider plausible: from my personal bias, I'd consider a Niven stasis field for a sleeper ship to be more plausible than cryogenic sleep. They're both handwaves but at least the stasis field relies less on crazy assumptions about human physiology. Your mileage may vary, of course."

I'd bet on us simulating hibernations in humans (probably more by genetic engineering or drugs than freezing) before I'd bet on our ability to alter the known flow of time. Then again, if we're considering FTL travel then we'd already have fancy new ways of playing with spacetime...

We already have the ability to keep coma patients alive for years in hospitals. Add an artificial coma-inducing drug, and human immortality so the body is still fit when it wakes up, and you're set. Figuring out how to provide immortality is left as an exercise for the reader.



Raymond:

"Suspended animation may be as (comparatively) simple as splicing in some tardigrade genes. Those fsckers are tough."

Tardigrade genes tell you how to keep tardigrade bodies in working condition. They do not tell you how to keep human bodies in working condition.

Splicing tardigrade healing genes into a human is kind of like trying to fix a machine using blueprints and tools for a different machine.

We might learn a few things from studying tardigrades, but applying what we've learned is going to be more difficult than copying some DNA sequences.



Rick:

"Knowing the Greek alphabet doesn't mean you can write in Greek."

More to the point, having read a really good book written in Greek doesn't mean you can make your own book better by splicing in passages from the one you read.

Anonymous said...

Raymond:

Would keeping one's initial frame of reference when jumping always have the potential to create causality problems, even over relatively short interstellar distances? I ask because the FTL system I described in one of the other threads involved doing exactly that.

A torchship would accelerate to a few thousand km/s, jump into hyperspace at a certain distance from the star, travel through hyperspace at a speed determined by the ship's velocity when jumping, then jump back to normal space and retain the initial velocity, as though it had travelled the interstellar distance in normal space. Finally it would decelerate to reduce its velocity relative to the destination planet/asteroid/habitat.

The underlying theory I had come up with was that if 3d normal space could be visualised as the 2d surface of a sphere, then 'hyperspace' was a smaller sphere inside the normal-space sphere, where corresponding points were a smaller distance apart. Hyperspace could be reached by moving 'down' from the surface of the normal-space sphere, through the 'third dimension' (in reality, a fourth spatial dimension), to the 'hyperspace' sphere, travelling across its surface to the desired destination, then moving back 'up' to normal-space. I had thought that since 'hyperspace' had a point to point correspondance with normal space, that momentum would be conserved with no problems.

R.C.

Luke said...

R.C.

Would keeping one's initial frame of reference when jumping always have the potential to create causality problems, even over relatively short interstellar distances? I ask because the FTL system I described in one of the other threads involved doing exactly that.

Yes. As an example, if you jump 1 light hour in 0.36 seconds and you hand off a message to a spacecraft moving at a speed of 60 km/s relative to you, that spacecraft can jump back to give you the message just before you left. Note that 60 km/s isn't all that fast for astronomical objects - Earth's orbital speed around the sun is about 30 km/s, and Barnard's star is moving at about 140 km/s with respect to the sun.

A torchship would accelerate to a few thousand km/s, jump into hyperspace at a certain distance from the star, travel through hyperspace at a speed determined by the ship's velocity when jumping, then jump back to normal space and retain the initial velocity, as though it had travelled the interstellar distance in normal space. Finally it would decelerate to reduce its velocity relative to the destination planet/asteroid/habitat.

Let's say you are traveling at 3000 km/s. You jump 10 light years instantly. You meet another spacecraft moving at 3000 km/s in the other direction, to whom you give a message. That spacecraft then jumps back to where you started. It arrives 73 days before you left.

I had thought that since 'hyperspace' had a point to point correspondance with normal space, that momentum would be conserved with no problems.

You lost me there.

Raymond said...

Milo:

"Tardigrade genes tell you how to keep tardigrade bodies in working condition. They do not tell you how to keep human bodies in working condition."

Proteins are proteins. We do trans-species modifications pretty routinely now. The dehydration mechanism tardigrades use to enter hibernation may be as simple as a couple proteins and an enzyme or two, in which case it'd be comparatively easy to integrate it into a human genome.

"More to the point, having read a really good book written in Greek doesn't mean you can make your own book better by splicing in passages from the one you read."

Sure it does. Biology has no problem with plagiarism; in fact, it rather encourages it. Steal snappy one-liners with abandon. Lift scenes wholesale with minor tweaks and character names changed.

Besides, I was actually understating recent progress in genetic manipulation. We're not only saying "hello", we're writing poetry. Literally. There's a poet who's encoding not one, but two poems in a gene, then inserting the sequence into Deinococcus radiodurans (Conan the Bacterium). The genes encode the first poem, which codes for a protein, which is a second poem and rejoinder to the first. See:

http://www.law.ed.ac.uk/ahrc/script-ed/vol5-2/editorial.asp
http://www.rifters.com/crawl/?p=1821

We're getting very good at this.

Raymond said...

Luke:

"Let's say you are traveling at 3000 km/s. You jump 10 light years instantly. You meet another spacecraft moving at 3000 km/s in the other direction, to whom you give a message. That spacecraft then jumps back to where you started. It arrives 73 days before you left."

Does that happen with observers moving through wormholes at high velocity, too?

jollyreaper said...


Yes. As an example, if you jump 1 light hour in 0.36 seconds and you hand off a message to a spacecraft moving at a speed of 60 km/s relative to you, that spacecraft can jump back to give you the message just before you left. Note that 60 km/s isn't all that fast for astronomical objects - Earth's orbital speed around the sun is about 30 km/s, and Barnard's star is moving at about 140 km/s with respect to the sun.


So is there no universal time that everyone is operating off of here? Let's say both ships start their timers at the same time. So that first ship makes the 1 light hour jump. .36 seconds is on the clock. If that ship then jumps the light hour to where the first ship used to be, then wouldn't you no longer be there, a second or so on both clocks?

The only hole I'm guessing is if I'm assuming that time is the same for both? The whole time and space-like separation thing. Is assuming that they both have the same clock the whole problem with the universal frame of reverence?

What would all this look like to the observer standing back at a distance? I would think it would look like the first ship disappearing from one point, reappearing by the second ship, the second ship disappearing and reappearing right by where the first one was.

If I were a general getting messages from different units in a battle, the delivery order might get jumbled depending on how the battle's going but I could put them back into order by sorting them chronologically. Is this presuming something that won't work with relativity?

Anonymous said...

Raymond said:"You'd have to find some frame of reference for all jumpers to determine what value of "right now" is used at each point."

Ok, how about either cosmological time or a central beacon connected to a master clock? Any other civilization would use a different clock, so time distortions would be possible between different civilizations, but not between travellers of the same civilization? So if everybody used cosmological time, then the possibility of time distortions (i.e. time travel paradoxes) should be low? So if FTL doesn't need relitavistic velocities to work, then the possibility of paradoxes is again low? This all sounds more like regulations rather than natural law, but it should work...

Ferrell

Anonymous said...

Ok, another thought: the master clock and beacon need to be FTL comms to work...so long as there is no need to use relitavistic velocities, this should work. Have I missed something?

Ferrell

Luke said...

Raymond:

Does that happen with observers moving through wormholes at high velocity, too?

Not for one wormhole, because in this case the trip takes place with respect to the frame(s) of reference described by the wormhole.

In this example, if one wormhole connected two points located 10 light years apart and, say 9 years apart, then if spaceship A zips through the wormhole at 3,000 km/s it just comes out 10 light years away and 9 years in the future still moving at 3,000 km/s relative to the wormhole. Then if it relays its message to spaceship B moving the other way at 3,000 km/s (say this takes a millisecond, and transit through the wormhole takes another millisecond, for a total elapsed time of 3 milliseconds for everyone to go through) then spaceship B goes back in time by 9 years and comes out 3 milliseconds after spaceship A left.

The problem came from the initial assumption that each spacecraft jumped in its own reference frame.

Rick said...

I have only the sketchiest knowledge of genetics! My cautious view is based mainly on the fact that genetic engineering has (so far!) been a huge letdown for big pharma, failing to produce the new generation of profitable drugs envisioned a decade ago.

But whether that really bears on the potential for human hibernation is above my bio pay grade.

Anonymous said...

Luke:

Sorry, I still don't intuitively get why time travel occurs in this situation, assuming hyperspace is a special frame of reference. As for momentum being conserved, I had imagined that if every point in normal space has its equivalent point in hyperspace, and if a ship is travelling along a line of points in hyperspace at a speed proportional to its speed in normal space when it jumped into hyperspace, that when it jumps back to normal space, momentum would be conserved by the ship retaining its original normal-space speed, as though it had travelled the same course in normal space.

R.C.

Anonymous said...

Sorry again. My comment above is replying to Luke's reply to me, not his reply to Raymond's comment asking about wormholes.

R.C.

Luke said...

Jollyreaper:

So is there no universal time that everyone is operating off of here?

By the initial assumption, no. You can't do this if each spacecraft is jumping in its own reference frame.

Let's say both ships start their timers at the same time.

And right here is where you run into problems. In relativity, there is no "same time". You have to choose a coordinate system, and the time coordinates within that system depend on the velocity of the coordiante system.

Let's call our spacecraft A and B.

So lets say that event 0 is when and where spacecraft A enters jump, at x0 = 0 and t0 = 0.

Ignoring small corrections to the position of spacecraft B due to its drift at 60 km/s over 0.36 seconds, we can say that in spacecraft A's coordinate frame spacecraft B is at x1 = 3600 light seconds and t1 = 0. Call this event 1 and say that spacecraft B starts its clock at event 1. This makes event 1 as x1'= 0 and t1'= 0 in spacecraft B's reference frame. It also makes event 0 as x0'= -3600 ls and t0'= 0.7205 s in spacecraft B's frame of reference

Spacecraft A now jumps to the position of spacecraft B. This is event 2 at x2 = 3600 ls and t2 = 0.36. Applying the Lorentz transformations for relativistic change of coordinate systems, this makes event 2 have coordinates x2'= 0 and t2'= 0.36 seconds in spacecraft B's frame of reference. Now spacecraft A hands off its message to spacecraft B, and spacecraft B jumps back to where spacecraft A just was. Since this takes 0.36 seconds in spacecraft B's frame of reference, spacecraft B ends up at coordinates x3'=-3600 ls, t3'= 0.72 s. You will note that this is 0.0005 s before spacecraft A left in spacecraft B's coordinate frame. Transforming back to spacecraft A's coordinate frame, this event happens at x3 = 0, t3 = -0.0005 s, again 0.0005 s before spacecraft A left.

Summarizing our results:
Event 0 - spacecraft A enters jump, spacecraft A starts its clock
x0 = 0 t0 = 0 x0'=-3600 ls t0'= 0.7205 s

Event 1 - spacecraft B starts its clock
x1 = 3600 ls t1 = 0 x1'= 0 t1'= 0

Event 2 - spacecraft A exits jump, gives spacecraft B a message, and spacecraft B enters jump
x2 = 3600 ls t2 = 0.36 s x2'= 0 t2'=0.36 s

Event 3 - spacecraft B exits jump
x3 = 0 t3 =-0.0005 s x3'=-3600 t3'=0.72 s

And everyone agrees that event 3 occurs before event 0. Spacecraft B has 5 milliseconds to give spacecraft A's message back to spacecraft A before spacecraft A makes its jump. Causality has been violated.

Is assuming that they both have the same clock the whole problem with the universal frame of reverence?

Yes.

Raymond said...

Luke:

That's what I thought; just had a brief attack of self-doubt. The same would hold for wormholes without timelike separation, correct? (If they'd been synchronized via equal dilation on both ends, that is.)

Jollyreaper:

"So is there no universal time that everyone is operating off of here?"

Nope. Not unless your FTL method defines one for all FTL travellers.

"The whole time and space-like separation thing. Is assuming that they both have the same clock the whole problem with the universal frame of reverence?"

That's exactly the problem, yes.

"If I were a general getting messages from different units in a battle, the delivery order might get jumbled depending on how the battle's going but I could put them back into order by sorting them chronologically. Is this presuming something that won't work with relativity?"

Even disregarding FTL, as said general you might find one's unit's request to another being acknowledged before it was sent, even after correcting for delays. So yes, assuming you can piece everything back in its proper order is a false assumption by relativity.

Luke said...

R.C.:

I still don't intuitively get why time travel occurs in this situation, assuming hyperspace is a special frame of reference.

Ah, your original post asked "Would keeping one's initial frame of reference when jumping always have the potential to create causality problems". This is true if jumping within one's own frame of reference. If all jumps take place with respect to a special reference frame, then the problem goes away.

As for momentum being conserved, I had imagined that if every point in normal space has its equivalent point in hyperspace, and if a ship is travelling along a line of points in hyperspace at a speed proportional to its speed in normal space when it jumped into hyperspace, that when it jumps back to normal space, momentum would be conserved by the ship retaining its original normal-space speed, as though it had travelled the same course in normal space.

This leads to global but not not local conservation of momentum. It also always violates the conservation of angular momentum.

jollyreaper said...


"The whole time and space-like separation thing. Is assuming that they both have the same clock the whole problem with the universal frame of reverence?"

That's exactly the problem, yes.


Ok. So right now when we're not using FTL, this isn't a problem? A star goes nova 2000 lightyears away from Sol. Observers see the same event from Alpha Centauri, Rigel, and Epsilon Irandi. So we from Earth say "Aha! That nova occurred around 11 AD. Bully for it!" If we then shot a message via the interstellar com laser to those other observers asking if they saw the nova and asked how long ago it appeared to them, when we got the answer back all the numbers would tie, right? If Rigel was a thousand lightyears away, it appeared to them a thousand lightyears ago, plus the delay involved in us asking the question and waiting for their reply.

In such a situation, what would we call our frame of reference? How big can a frame be?

What if we decided that Sol was sending out a coded timekeeping signal that everyone would base their observations on, we'll call it our Astronomicon just to tweak Gamer's Workshop. So if a ship went FTL and jumped out a lightyear from Earth, it should be catching the time code from a year before its departure, just reaching it at that very second. If the ship beamed a signal back to Earth and jumped back to where it started, in a year's time it should see the "Hello, world! The time is X" from its self from a year ago. And that would appear no stranger than an observer from Alpha Centauri did the same. Four years roughly for the signal to get there, four years for the reply.

I guess the thing that gets me is the frame of reference thing always struck me as the explanation for what happens when you travel at .99c and turn on the headlights. The photons don't bunch up in front of you, the headlight beam appears to shoot out like normal, it's heading away at c. Your CPU will operate just like normal inside the ship, your neurons will fire properly. Everything moving at your speed seems normal. The rest of the universe will look damn strange. And to anyone observing you you're booking along but the headlights aren't going any faster than c away from you.

I'm desperately groping to understand the problem.

jollyreaper said...


And right here is where you run into problems. In relativity, there is no "same time". You have to choose a coordinate system, and the time coordinates within that system depend on the velocity of the coordiante system.


So how large can a coordinate system be? Can it encompass the universe or just large portions of it? Can we consider the milky way galaxy a coordinate system?

Applying the Lorentz transformations for relativistic change of coordinate systems

Ok, this is where the voodoo's happening.

http://en.wikipedia.org/wiki/Lorentz_transformation

I don't understand why we're seeing that effect. Once I figure that out I'll be able to understand why FTL involves causality violation and time travel. For now I'm just not "getting" it.

jollyreaper said...

The Lorentz transformation was originally the result of attempts by Lorentz and others to explain how the speed of light was observed to be independent of the reference frame, and to understand the symmetries of the laws of electromagnetism. Albert Einstein later re-derived the transformation from his postulates of special relativity. The Lorentz transformation supersedes the Galilean transformation of Newtonian physics, which assumes an absolute space and time (see Galilean relativity). According to special relativity, this is a good approximation only at relative speeds much smaller than the speed of light.

I know there's slight time dilation with atomic clocks in orbit, stuff we can actually measure to prove the theory. But I thought for the most part that unless we were travelling at significant fractions of C, we weren't going to have to worry about our frame of reference. Someone in our spiral arm of the galaxy and someone two arms over observing a gamma ray burst from the heart of our galaxy, if they asked each other when they saw it occur, would end up with similar answers. If we set out in a .9c ship from our arm to the other arm and got there 5000 years later, the phone home signal we sent back on arrival would get back in 5000 years -- 10,000 years after departure as observed by the people back home even though the subjective experience to us on the ship would be shorter due to dilation. That relativistic voyage screws with our clock, not the rest of the universe's. Or does it? This calls for beer.

Raymond said...

Jollyreaper:

"If we then shot a message via the interstellar com laser to those other observers asking if they saw the nova and asked how long ago it appeared to them, when we got the answer back all the numbers would tie, right?"

Nope. Depending on their motion relative to each other and to the nova, they'll all come up with slightly different answers. You can do the Lorenz transformations between them and those will agree, though.

"What if we decided that Sol was sending out a coded timekeeping signal that everyone would base their observations on, we'll call it our Astronomicon..."

If the ship that jumps back and forth remains at rest with respect to Earth, then yes (although you'd have to break a few other conservation laws to do so). But everything in the universe is moving, and as Luke showed above, it doesn't take much relative velocity nor much distance FTL to muck things up.

"So how large can a coordinate system be? Can it encompass the universe or just large portions of it? Can we consider the milky way galaxy a coordinate system?"

Doesn't work that way. It's about relative velocities, not size. You can have objects at rest WRT each other scattered across the galaxy (however unlikely that is) and they'll agree on time. But it's about the relative motion. "Frame" is just a term, not an indication of boundaries.

Anonymous said...

Luke:

So it isn't possible for a ship to enter hyperspace, move with respect to the special frame while in hyperspace, then return to its initial frame of reference when returning to normal space?
If a ship is moving at a few thousand km/s relative to the star of its origin system when it jumps, and then, if I understand Raymond correctly, must use local mass in the target system, moving at lower orbital speed, to re-emerge into normal space, where does the extra kinetic energy go?
Finally, does the ship's velocity in hyperspace being proportional to its speed when jumping violate conservation of momentum/angular momentum?

R.C.

jollyreaper said...


if I understand Raymond correctly, must use local mass in the target system, moving at lower orbital speed, to re-emerge into normal space, where does the extra kinetic energy go?


The way I did it for jump drives was add the matching of velocity for the target system to the start of the jump. You make your burn out of orbit to get clear of the planet to jump but also added the final velocity you wanted for the target system, either matched with the planet you're heading to or at a high differential if you're making an attack. You get that burn in before making the jump.

With the hypersail system, the adjustment would be made upon exiting hyperspace. The hypersails move the ship in realspace and you can try to get your velocity right. It's not entirely perfect so once you drop the hyperfield you're stuck neatening up your speed with reaction engines.

It's not exactly hard science, I'll call it science-flavored fantasy. Still better than Star Wars. lol

Luke said...

Jollyreaper:

So right now when we're not using FTL, this isn't a problem?

It is not a problem without FTL because everyone agrees on the time ordering of events that can be causally connected at light speed or slower. There is no way to lorentz transform something in my past with a time-like separation to where I am now so that they see it in my future. However, any event that has a space-like separation relative to where I am now can be either ahead of me or behind me in time depending on the reference frame.

I have said it before, but coordinates are not physical. They are a handy way of keeping track of relationships between events, which are physical. So what one observer or another measures as a time in his coordinate frame has no physical meaning. This, I think, is the source of a lot of people's confusion.

(proper time - the time elapsed along a particular path through space-time - is physical)

A star goes nova 2000 lightyears away from Sol. Observers see the same event from Alpha Centauri, Rigel, and Epsilon Irandi. So we from Earth say "Aha! That nova occurred around 11 AD. Bully for it!"

If Sol, Alpha Centauri, Rigel, and Epsilon Eridani all have the same velocity, they will all agree on the time coordinate. If their velocities are different, their time coordinates will be different.

So how large can a coordinate system be? Can it encompass the universe or just large portions of it? Can we consider the milky way galaxy a coordinate system?

Your frame of reference covers the entire universe, from infinitely far in the past to infinitely far into the future (insert whatever caveats you want about not going back before the big bang, extending the reference frame to alternate universes, and so on. They are not relevant to this discussion).

I don't understand why we're seeing that effect. Once I figure that out I'll be able to understand why FTL involves causality violation and time travel. For now I'm just not "getting" it.

I don't know if this will help, but a Lorentz transformation is mathematically equivalent to a rotation by an imaginary angle. A rotation takes the form
x' = cos(theta) x + sin(theta) y
y' = -sin(theta) x + cos(theta) y
for an angle theta. Note that it mixes the two coordinates x and y. The new coordinate x' contains part of the old coordinate x and part of the old coordinate y. For a boost (boost is the term for changing speed in a Lorentz transformation), you can define an imaginary rotation eta (called the rapidity), eta = atanh(v/c) for v = speed and c = speed of light. Then the Lorentz transform of this boost becomes
t' = cosh(eta) t + sinh(eta) x
x' = sinh(eta) t + cosh(eta) x
and you can see the two coordinates x and t are again mixed up, and the new t' coordinate, for example, contains part of the old t coordinate and part of the old x coordinate.

If you are not familiar with the hyperbolic trigonometric functions
cosh(x) = (exp(x)+exp(-x))/2
sinh(x) = (exp(x)-exp(-x))/2
tanh(x) = sinh(x)/cosh(x)
atanh(tanh(x)) = x
and exp(x) means raise the number e (the base of the natural logarithm) to the power x. Any scientific calculator should have these functions (for example, the native Windows, Red hat, and Ubuntu calculator applications can be easily set to scientific mode, to let you use these functions).

I know there's slight time dilation with atomic clocks in orbit, stuff we can actually measure to prove the theory. But I thought for the most part that unless we were travelling at significant fractions of C, we weren't going to have to worry about our frame of reference.

It doesn't have a large effect for small velocities - but the small effect it does have can still break causality if you allow faster than light travel (without taking pains to preserve causality, such as by invoking Hawking's chronology protection postulate).

jollyreaper said...


It doesn't have a large effect for small velocities - but the small effect it does have can still break causality if you allow faster than light travel (without taking pains to preserve causality, such as by invoking Hawking's chronology protection postulate).


Hmm. So I take it Hawking's idea is a cosmic force preventing that sort of thing from happening? And barring that, it would take a rigorous application of law to prevent people from abusing this sort of thing. Makes the argument about the dangers of allowing private and unregulated ownership of torch ships seem like a quaint little problem. Causality-violating weapons would have the potential of causing all of the timeline to become a snafu in a way that makes a mexican standoff look rock-stable. If a time war starts at any point in history it would eventually spill over to all points unless the combatants end up negating their own existences.

In a setting with no guarantee as to what happens when causality is violated but the absolute knowledge it can happen, I'm thinking that ship's computers would be programmed to prevent such a thing from ever happening and if a violation was detected, a self-destruct would instantly occur to prevent the ship from screwing anything up.

In the Singularity Sky setting, the Eschaton post-singularity AI god uses time travel wormholes as part of its mind and forbids ANYONE from violating causality within its historic light cone upon pain of death. Barring that kind of quasi-divine injunction, I just don't see how you can avoid the inevitable jerk who's going to try and do it.

Luke said...

R.C.:

So it isn't possible for a ship to enter hyperspace, move with respect to the special frame while in hyperspace, then return to its initial frame of reference when returning to normal space?

If your "hyperspace" has a special frame of reference, according to which all jumps are made, then this does not break causality.

If a ship is moving at a few thousand km/s relative to the star of its origin system when it jumps, and then, if I understand Raymond correctly, must use local mass in the target system, moving at lower orbital speed, to re-emerge into normal space, where does the extra kinetic energy go?

It leaves it behind. For example, if a 100 ton spacecraft makes a jump connection to another star system, sucks in 100 tons of asteroidal gravel, and swaps place with that gravel, you end up with your spacecraft moving at the same speed as the gravel used to be moving and the gravel moving at the same speed the spacecraft used to be moving. In both cases you still have 100 tons moving at the original velocities - it is just the nature of that 100 tons that has changed. The gravel has the kinetic energy and momentum and angular momentum as well as the position and velocity that the spacecraft originally had, and vice versa.

Finally, does the ship's velocity in hyperspace being proportional to its speed when jumping violate conservation of momentum/angular momentum?

Whatever magic you have going on in hyperspace doesn't matter as long as momentum and angular momentum are already balanced in normal space. But I have to ask - speed when jumping in what frame of reference? The hyperspace special frame? How fast is that frame moving with respect to other people? If the hyperspace frame is already moving at 500 km/s with respect to Earth, then I start out with this speed for free when jumping.

Luke said...

Jollyreaper:

Hmm. So I take it Hawking's idea is a cosmic force preventing that sort of thing from happening?

It is the same thing we were discussing previously with wormholes and quantum fluctuations.

Suppose you jump in such a way to make a time machine. Now some tiny quantum fluctuation can hitch a ride with you, then ripple through space through all the other legs of the time machine until it ends up at the same time and place as it started. This means it builds on itself, doubling its amplitude, then tripling its amplitude the next time around, then quadrupling it, and so on. You have a perfect resonator for building up the amplitude of this quantum fluctuation, so the fluctuation builds up to immense intensities. Most machines don't like extreme intensities coursing through them, and tend to do unpleasant things like break or melt or something. Thus, as soon as you are about to form a time machine, you get destroyed.

There are other somewhat more benign versions that just bounce you away from a time machine configuration as if you had hit an impenetrable wall. This is not necessarily better (especially at high speed).

Raymond said...

jollyreaper:

"That relativistic voyage screws with our clock, not the rest of the universe's. Or does it?"

Your clock is always right for you, no matter where, when or how fast.

"This calls for beer."

Yup. If you were in Toronto, I'd buy you one myself. (Unfortunately, my beer-over-IP server is down.)

" If a time war starts at any point in history it would eventually spill over to all points unless the combatants end up negating their own existences."

The one bright spot is that you can't go back any further than when the war started, at least by somebody's frame of reference.

RC:

"So it isn't possible for a ship to enter hyperspace, move with respect to the special frame while in hyperspace, then return to its initial frame of reference when returning to normal space?"

That would violate local (not global) momentum, and violate angular momentum both local and global. So no, unless you want to rewrite those laws too.

The thing with angular momentum is that you're pretty much always rotating with respect to something. The Earth, the sun, the galaxy, something. Said angular momentum is a part of any rotating frame. The reason gravity assist maneuvers seem to speed up a spacecraft is that you're actually stealing a bit of angular momentum from a rotating body (usually a planet, where it's not noticed much). If your ship disappears, so does the angular momentum of anything you're interacting with gravitationally - which is sorta the definition of violating conservation.

"If a ship is moving at a few thousand km/s relative to the star of its origin system when it jumps, and then, if I understand Raymond correctly, must use local mass in the target system, moving at lower orbital speed, to re-emerge into normal space, where does the extra kinetic energy go?"

Left behind, along with your rest mass, momentum, and angular momentum. Imagine you're building a wormhole to get to hyperspace - that wormhole takes on your ship's mass, energy, etc. It could sit there on the same orbit as your ship was, it could slowly diffuse like a gas, it could explode like a matter-antimatter reaction, however you want to set up your FTL. I guess the easiest way to visualize it is to pretend there's an equivalent mass swap: whatever is over there "right now" (according to the reference frame of hyperspace) swaps places with your ship. The other stuff is where your ship was, with the same velocity, and you're where the other stuff was.

"Finally, does the ship's velocity in hyperspace being proportional to its speed when jumping violate conservation of momentum/angular momentum?"

Luke would have a better idea than me.

Raymond said...

Sorry, Luke, I'm not trying to parrot your responses (but without the math to back it up). I'm just not getting your signal until mine's on its way. Damn spacelike separations...

Anonymous said...

Luke:

Would the gravel still swap places with the ship if the jump was not instantaneous? Say the drive is similar to the one Raymond described earlier, where the ship creates a wormhole to hyperspace, enters it, adding its mass to the wormhole and the wormhole then dissipates in an explosion once the ship has entered hyperspace. The ship spends a day in hyperspace reaching its destination, then creates another wormhole back to normal space, which draws in gravel equivalent to the ship's mass, then dissipates, leaving behind the ship. Is the explosion left by the ship at its starting point made up of the gravel from the destination system, moved back in time one day?

Regarding 'speed when jumping', I meant in the frame of reference of the system the ship jumped from.

The idea of needing mass equivalent to the ship's mass at the other end of an FTL journey does have some interesting implications. If the destination point had very low matter density, the wormhole would presumably form very slowly. It would also have potential as a weapon, since a wormhole forming too close to a habitat or another ship could tear pieces off. It might be worthwhile for high-traffic destination points to have rubble-pile asteroids, possibly artificial, placed nearby as a source of mass.

R.C.

Raymond said...

Ferrell:

"Ok, how about either cosmological time or a central beacon connected to a master clock?"

Only if the reference frame the clock was in had some intrinsic connection to the FTL method. And no, regulations wouldn't be enough (the Causality Protection Conjecture is about physical laws preventing paradoxes, not regulations or timecops or the like).

RC:

Since I made the analogy, I should take my lumps when it gets misunderstood. The mass-swap thing would only be if the jump were instantaneous according to the hyperspace frame. If there's a non-zero time involved, then (most likely, and for the sake of argument):

- When you leave, say you disappear into a black hole (-ish thing) of the same mass as your ship, which then dissipates by Hawking radiation (rather quickly, for such low mass). Result: a burst of light equal to your rest mass, moving at the same velocity as your ship was. Big boom.

- On arrival, a black hole-ish thing appears and swallows up enough gravel to equal your rest mass. When it dissipates, your ship is left behind. It would probably suck in more mass than your ship, and make an additional flash, since entropy tends to increase (and you'll get some radiation from the accretion disk of the emerging black hole).

Anonymous said...

Raymond:

I'm having the same problem, since your post has answered some of the questions I just asked Luke, but I couldn't see it until I published my post.

If objects in normal space still had a gravitational effect upon objects in hyperspace, and vice versa, would that conserve angular momentum?

R.C.

Raymond said...

RC:

"If objects in normal space still had a gravitational effect upon objects in hyperspace, and vice versa, would that conserve angular momentum?"

AFAIK (and correct me if I'm wrong, Luke) that would imply hyperspace is actually a part of (or extension of) normal 3+1 space, and a wholesale supersession of general relativity. Versions of extra-dimension theories are fairly common, but it wasn't until the LHC that we could start testing any of them.

I don't know how you'd reconstruct conservation laws, but they'd probably be fairly different than the ones we know (and have tested extensively).

Luke said...

Raymond:

Sorry, Luke, I'm not trying to parrot your responses (but without the math to back it up). I'm just not getting your signal until mine's on its way. Damn spacelike separations...

No worries. These things are to be expected.

R.C.:

If objects in normal space still had a gravitational effect upon objects in hyperspace, and vice versa, would that conserve angular momentum?

No, it is not a matter of gravity.

Consider your spacecraft before its jump, from the point of view of an observer moving toward it. The spacecraft has some energy and some momentum, but because the observer is moving directly toward the spacecraft, it has no angular momentum.

Now let the spacecraft do its FTL thing, and end up someplace else so that the original observer is no longer moving straight at the spacecraft. If the spacecraft is to conserve momentum it must be traveling at the same speed. But if it is moving but it is not moving straight at the observer, it has a non-zero angular momentum. Unless something else ends up with the opposite angular momentum, angular momentum is not the same before and after the jump. Angular momentum conservation has been violated.

If something else does end up with the opposite angular momentum, how do you reconcile this with conservation of energy and momentum, and can you enforce this in all reference frames? Further, none of the conservation laws hold locally, only globally.

Raymond said...

Luke:

WRT angular momentum, would it be conserved globally if the FTL method only allowed travel in perfectly straight lines? (Either in normal curved spacetime, or in some special frame the FTL is using, whichever if either works.)

Luke said...

Raymond:

WRT angular momentum, would it be conserved globally if the FTL method only allowed travel in perfectly straight lines?

No. Consider a specific case of a 1 kg object. Choose a reference frame where the allowed direction of FTL travel is in the z-coordinate spatial direction, and where just before warping the object has a velocity of (1,0,0) m/s and a location of (1,0,0) m. I use (x,y,z) to refer to the x, y, and z components of a vector. The angular momentum is the mass times the cross product of the location and velocity vectors, which in this case is (0,0,0) kg m^2/s.

Now warp the object up to a position of (1,0,1) m. The angular momentum is now (1,0,0) kg m^2/s. You can see that the angular momentum is now different than before the warp.

For any sort of "disappear here, reappear there" sort of effect (warping, teleportation, vanishing into hyperspace, or whatever) you can always find frames of reference where angular momentum is violated (infinitely many frames of reference. In facts, it is only a very special subset of possible frames in which angular momentum is not violated - those frames moving in the same direction as the warp effect).

Raymond said...

Luke:

Makes beaucoup sense, thanks. Been a while since undergrad physics, and I'd forgotten the cross-product bit.

Milo said...

R.C.:

"Would keeping one's initial frame of reference when jumping always have the potential to create causality problems, even over relatively short interstellar distances?"

If it is possible to jump in multiple different frames of reference, then causality can be broken. You would do this by:
1. Making a jump in your current frame.
2. Accelerating to a different frame in which your departure point appears to be in your future. (You can do this because the departure point is spacelike from your current location.)
3. Making a jump in your new frame.

Step 2 might be non-trivial in practice (accelerating to relativistic speeds is not easy), but as long as it's theoretically possible, you have a bit of a problem.

Then again, it could be amusing to see a setting where scientists have proven time travel to be theoretically possible through this method, yet are frustrated by being unable to actually do it due to the engineering challenges of a relativistic ship.

The problem with that is that whenever we do figure out how to travel through time, we can go back in time and tell our past selves how to do it...


"The underlying theory I had come up with was that if 3d normal space could be visualised as the 2d surface of a sphere, then 'hyperspace' was a smaller sphere inside the normal-space sphere, where corresponding points were a smaller distance apart. Hyperspace could be reached by moving 'down' from the surface of the normal-space sphere,"

Hmm. I like that explanation. (Although I assume you mean the 3D surface of a 4D hypersphere.)

This would mean that hyperspace isn't one "place", but that you can go shorter or longer depths into the fourth dimension. How deep you could go could depend on the technical tolerances of your hyperdrive. Also, deeper layers of hyperspace would be more strongly curved than the outer shell, which could have ramifications on the laws of physics in there...

One thing, though - wouldn't travelling up and down across the fourth dimension be of comparable difficulty to travelling laterally? If hyperspace works like a sphere in 4D Euclidean space, then I would expect that a shortest-path trip would be at best 63.66% (2/pi) of the normal-space distance. Not a great improvement.

You could cram things down further if hyperspace was a four-dimensional hyperbolic geometry rather than Euclidean. In the simple case (if our universe is a 3D Euclidean space embedded as a horosphere in 4D hyperbolic space, then travelling a distance of a (as measured in normal space) would require travelling only a chord distance of c=2*asinh(a/2/R)*R=2*asinh(a/2*sqrt(-K))/sqrt(-K) in hyperspace, where R=1/sqrt(-K) is the hyperbolic geometry's "radius" (measured in units of distance) and K=-1/R^2 is its (negative) Gaussian curvature, which you can set to whatever value is convenient for the plot. (The short version of this is that travel times through hyperspace increase only logarithmically with the distance you want to travel. Yay!) If our universe is positively or negatively curved, the equations are messier, but the same principle applies. You can also make the math conveniently nightmarish by giving hyperspace a non-constant curvature if you need more wiggle room for things to travel at the speed of plot.

None of this is even considering relativity or whatever.

(PS. Sorry for using the prefix "hyper" for multiple meanings throughout this post. Meaning 1: four-dimensional geometry. Meaning 2: negatively curved geometry. Meaning 3: an empty sci-fi magitech buzzword. Not my fault, I didn't invent any of those words!)

Milo said...

Raymond:

"Proteins are proteins."

Knowing how to smelt iron doesn't tell you how to fix a complex piece of clockwork that happens to be made of iron. Your general knowledge might, at best, be able to help clean some rust, but rust is far from the only thing that causes machines to fail with age.

We're coming to understand the language of DNA and proteins, which is the equivalent of knowing how to smelt iron. We're a long way from understanding how to competely alter your physiology.


"We're not only saying "hello", we're writing poetry. Literally."

Parlor tricks! The poetry doesn't do anything biochemically useful. In our iron analogy above, it's the equivalent of bending iron bars into letters. None of this tells you how to build real clockwork.



Jollyreaper:

"What if we decided that Sol was sending out a coded timekeeping signal that everyone would base their observations on, we'll call it our Astronomicon just to tweak Gamer's Workshop."

How an interstellar civilization chooses to make their calendar is their business. What they superficially name any moment in time is irrelevant to whether or not they have any causality problems, however.

If there is a known special frame of reference, then I expect they will tune their calendars to this special frame, to the best accuracy their equipment is capable of. By defining their clocks on a universal standard, they could trust that clocks everywhere will remain synchronized regardless of whether they can keep in touch by ansible or not.

If there is a time-dilating wormhole network, then I expect people will measure time through the wormholes. So if we send a wormhole to Sirius, then someone who walks through the Sol end of the wormhole on 3000 AD (Sol calendar) will arrive at Sirius on 3000 AD (Sirius calendar), although a telescope on Sol which is looking at Sirius through space ignoring the wormhole, would first detect a signal from your arrival at 3017.1 AD (Sol calendar), then back-calculate that this means you arrived on 3008.5 AD (Sol calendar) as measured in Sol's frame of reference. But most people, except for wormhole engineers, wouldn't care about the 3008.5 AD number, and would define your arrival as 3000 AD (interstellar calendar).

I hardly see a reason to use a measure of time defined by Earth's light cone when you already have FTL travel. Such a calendar would allow superficial "time travel": i.e., moving from 3008.6 AD (Sol calendar) to 3000 AD (Sirius calendar), which isn't actually a causality violation and is more like how crossing time zones works on Earth. On Earth, we put up with the inelegance of time zones due to the importance of the day/night cycle and the desire to have the clock match it. There is no obvious reason to put up with Sol and Sirius's calendar being 8.6 years out of tune with regards to how people actually travel.


"So how large can a coordinate system be? Can it encompass the universe or just large portions of it? Can we consider the milky way galaxy a coordinate system?"

A coordinate system encompasses the entire universe.

The Milky Way does not exactly constitute a coordinate system, since not all objects in the Milky Way are in the same frame of reference. However, the differences between the frames of different objects in the Milky Way are usually smaller than the difference between the average frame of all matter in the Milky Way (i.e., the frame of our center of mass, or whatever) and the average frame of all matter in some other galaxy.

Milo said...

Raymond:

"The one bright spot is that you can't go back any further than when the war started, at least by somebody's frame of reference."

Why not? If you have freeform-FTL-derived time travel, then you can go back arbitrarily far. (10 years into the war, jump 1000 lightyears away. The start of the war is still spacelike to you, since 1000>10, so you can accelerate until the start of the war appears to be in your future. Now jump back.) If you have the "can only jump to existing time machines" type time travel that fiction sometimes uses, then you can jump back to whenever time machines were first invented in your civilization, which may be before or after the outbreak of this war.

Unless, of course, you argue that bringing the war to a past time period extends your definition of when the war "started". But this isn't moving when the war's casus belli took place. You can still have shots fired before the casus belli occurs. Of course it could be that you end up with a time loop where each side thinks the other side attacked first...



R.C.:

"Is the explosion left by the ship at its starting point made up of the gravel from the destination system, moved back in time one day?"

As long as you're jumping more than one light-day away, this apparant time travel does not violate causality with a single jump. However, you're still in trouble with multiple concurrent jumps. (I jump from Sol to Sirius. Meanwhile, at the same time, you jump from Sirius to Sol, timed so you depart immediately before my arrival. We can then move a clump of rocks at Sol back in time.)

However, you could deal with this by having hyperspace act as a "bank" that just keeps some rocks in reserve, and lets you take loans. When you depart from Sol, some mass stored in hyperspace explodes out. Then later when you arrive at Sirius, you absorb mass and refill what you took from hyperspace. That mass then stays there, to be emitted on some later trip. As long as everyone eventually gives back what they take, and doesn't try to loan too much at once, mass is conserved.


"It would also have potential as a weapon, since a wormhole forming too close to a habitat or another ship could tear pieces off."

Maybe. Or maybe the wormhole doesn't work unless you already have some other means of tearing pieces off.

Also remember that not everything that can kill people is necessarily a good weapon. If it's deadly when left unchecked but easy to shut down if you take proper countermeasures, then it isn't very dangerous.



Luke:

"No. Consider a specific case of a 1 kg object. Choose a reference frame where the allowed direction of FTL travel is in the z-coordinate spatial direction, and where just before warping the object has a velocity of (1,0,0) m/s and a location of (1,0,0) m. I use (x,y,z) to refer to the x, y, and z components of a vector. The angular momentum is the mass times the cross product of the location and velocity vectors, which in this case is (0,0,0) kg m^2/s.

Now warp the object up to a position of (1,0,1) m. The angular momentum is now (1,0,0) kg m^2/s. You can see that the angular momentum is now different than before the warp."


What if you can only warp in the direction that you're travelling? (I.e., you warp somewhere that you would have arrived anyway given enough time, only now you get there FTL.) Now you can't warp to (1,0,1) m, only (2,0,0) m. To warp from (1,0,0) m to (1,0,1) m, you would need to first adjust your velocity to (0,0,1) m/s (or (0,0,0.5) m/s, or (0,0,0.0001) m/s).

Raymond said...

Milo:

Your posts are, as usual, trapped in the warp storms. You should really placate your machine spirit.

"Knowing how to smelt iron doesn't tell you how to fix a complex piece of clockwork that happens to be made of iron. Your general knowledge might, at best, be able to help clean some rust, but rust is far from the only thing that causes machines to fail with age."

We're compiling a library of small gears and springs we can smelt, as well. Still far from designing and building our own clocks, but we can start making repairs or modifications to some.

"We're coming to understand the language of DNA and proteins, which is the equivalent of knowing how to smelt iron. We're a long way from understanding how to competely alter your physiology."

We are, however, beginning to successfully use gene therapy on ourselves. Crude molds, perhaps. It'll take a while before we get folding and useful alloys - but the Human Genome Project is only a decade old. Early days, yes. What I'm talking about isn't in the distant future, though.

"Parlor tricks! The poetry doesn't do anything biochemically useful. In our iron analogy above, it's the equivalent of bending iron bars into letters. None of this tells you how to build real clockwork."

The Mechanical Turk was a parlor trick too, not clockwork. But it fooled so very many, and made us think about intelligence differently. Don't deny the power of a well-placed, well-executed parlor trick.

Also note that bending iron into letters allows the printing press (to stretch the analogy well past the breaking point).

"Why not? If you have freeform-FTL-derived time travel, then you can go back arbitrarily far. (10 years into the war, jump 1000 lightyears away. The start of the war is still spacelike to you, since 1000>10, so you can accelerate until the start of the war appears to be in your future. Now jump back.)"

I'm pretty sure you wouldn't be able to, not on your own. You'd have to somehow take on a frame of reference in which the start of the war was in the local future without accelerating yourself. Accelerating would merely redshift or blueshift your original frame, depending on the acceleration vector, but it won't actually change the origin. To do what you propose, you'd have to jump into a frame moving in the opposite direction to your original one, and somehow assume that frame without accelerating yourself to match (said acceleration would blueshift your frame of origin, and you wouldn't possibly be able to return at the same point in time, much less before).

Bear in mind that Alcubierre-style warping retains the original frame. And despite what I've told Ferrell, RC and Jollyreaper, I have no idea how you'd actually affect anything in the destination frame in such a manner as would allow you to reappear, which would be required for you to assume that frame.

FTL trips to recruit allies with the appropriate frame, however, wouldn't be ruled out. I suppose that would technically allow the war to expand backwards in time.

"However, you could deal with this by having hyperspace act as a "bank" that just keeps some rocks in reserve, and lets you take loans. When you depart from Sol, some mass stored in hyperspace explodes out. Then later when you arrive at Sirius, you absorb mass and refill what you took from hyperspace. That mass then stays there, to be emitted on some later trip. As long as everyone eventually gives back what they take, and doesn't try to loan too much at once, mass is conserved."

But if you're moving mass around globally instead of locally, conservation is already either broken or heavily modified. My little mass-swap analogy only really works if the jump is instantaneous.

Brian said...

I would argue that things going into and out of hyperspace do not violate conservation, because hyperspace is part of the universe. At least, in my opinion, the word "hyperspace" suggests higher dimensions or another plane of existence within our universe, so nothing is actually disappearing. :-/ I mean, if you walk along the edge of the balloon, and I walk through the inside of the balloon, I didn't disappear, I just took a different route. Conservation of angular momentum, I'm not sure, but conservation of mass/energy and just straight momentum shouldn't be an issue, because you never left the universe.

--Brian

Milo said...

Raymond:

"Your posts are, as usual, trapped in the warp storms. You should really placate your machine spirit."

Any suggestion on what kind of offering would be suitable?

I think Blogger has decided my IP address belongs to a spammer, or something.


"We're compiling a library of small gears and springs we can smelt, as well. Still far from designing and building our own clocks, but we can start making repairs or modifications to some."

I am not denying that we might be on our way to figuring out how to design serious genetic upgrades to humans. But we will need to design them. What I'm saying is that we won't be able to do it by pulling a gear out of a tardigrade and sticking it into a human. A tardigrade gear, installed into a human, will just clog up the machinery.

Bats didn't copy bird wings. They invented their own from scratch.


"I'm pretty sure you wouldn't be able to, not on your own. You'd have to somehow take on a frame of reference in which the start of the war was in the local future without accelerating yourself. Accelerating would merely redshift or blueshift your original frame, depending on the acceleration vector, but it won't actually change the origin."

Note: In this post, bold coordinates are measured in Earth's rest frame. Italics coordinates are measured in another frame that will be defined later. Units: ly=lightyears, y=years, c=speed of light=ly/y.

Okay, say the war breaks out at (0 ly, 0 ly, 0 ly, 0 y). Ten years later - (0 ly, 0 ly, 0 ly, 10 y) - I hire a Welsh poet and hop over to (1000 ly, 0 ly, 0 ly, 10 y). Once there, I accelerate from (0 c, 0 c, 0 c) (the rest frame I started out from) to (0.5 c, 0 c, 0 c). I am now in a new frame wherein - defining my own position as (0 ly, 0 ly, 0 ly, 0 y), I determine the start of the war to have taken place on (-1990/sqrt(3) ly, 0 ly, 0 ly, 980/sqrt(3) y). I also determine Earth's "current" location in my new frame to be (-1500/sqrt(3) ly, 0 ly, 0 ly, 0 y) (and moving away from me at (-0.5 c, 0 c, 0 c)), which corresponds to (0 ly, 0 ly, 0 ly, -490 y). I splice genes encoding my Welsh poetry into my navigator, and thereby warp to this location. I now decelerate back to (0 c, 0 c, 0 c), putting me back in Earth's rest frame at (0 ly, 0 ly, 0 ly, -490 y). I have now arrived 490 years before the outbreak of the war, ample time to locate and assassinate my enemy general's ancestors.

Did I make any mistakes in my math?

Teleros said...

Luke: "This leads to global but not not local conservation of momentum. It also always violates the conservation of angular momentum."

I wonder if we need a post here on the ways FTL breaks these (and any other) conservation laws...

*Waves at Rick*

Tony said...

Teleros:

I'm not sure that's even a side issue, much less a primary one. SF authors that I am familiar with have been have been remarkably consistent with conservation of momentum. Whatever the means of FTL, spacecraft are pretty much presumed to end with the same velocity vector, WRT their point of origin. With wormholes/jump-points/jump-gates, the conservation is generally expressed WRT the mouth/point/gate. With free form FTL, the conservation is WRT some body in the vicinity of the origin, usually a star or planet. So if you whip off to another star system, you have to match velocities with that system at some point. If you crossed the Galaxy, you'd have a big velocity change to make, since system on the other side of the core are moving in the opposite direction, WRT galactic coordinates. In any case, authors seem to know that these things have to be taken care of.

Raymond said...

"Any suggestion on what kind of offering would be suitable?"

Blood for the Blood God, Milo, blood for the Blood God.

"I am not denying that we might be on our way to figuring out how to design serious genetic upgrades to humans. But we will need to design them. What I'm saying is that we won't be able to do it by pulling a gear out of a tardigrade and sticking it into a human. A tardigrade gear, installed into a human, will just clog up the machinery."

But we already use gene sequences from one organism and copy them wholesale into another. Whether this results in a useful modification depends on what we're copying, what kind of cell we're splicing it into, etc. True, the more complex the sequence and the more physiological systems it interacts with, the more tweaking you have to do to the inserted sequence. The simpler the mechanism, though, the easier it is just to drop in. And we've done so already. Granted, with pretty simple things, but that doesn't preclude doing so with more complex ones given proper understanding of the relevant interactions.

It's not like we have to design every sequence we currently insert somewhere from scratch. Most of what we're already doing is cut-and-paste jobs.

If the tardigrade hibernation mechanism is simple enough, it becomes fairly close to cut-and-paste. I'm not saying it is that simple, just that it could be.

"Did I make any mistakes in my math?"

There's something intuitively unphysical in that solution, and it's something to do with changing your reference frame post-jump, and then extending your coordinates in the manner you do to take something which was in your local past in the original frame and making it in your local future in the new frame.

The acceleration phase will necessarily be non-zero, of course, and I'm not home right now so I can't do the math to determine the effects on distant points during said acceleration. (Anyone who can? Luke, if you're so inclined?) I suspect that your assumption of instant acceleration may be the problem, but I'm honestly not sure.

My initial guess would be that the acceleration phase deforms your coordinates sufficiently to have all points originally in your local past remain there in the new frame - but I could be wrong on that.

Citizen Joe said...

Just because time dilates for you, doesn't mean you're going back in time. Your 500 year trip still takes 500 years to the outside reference frame, you just experience it as though it were 10 years.

Sabersonic said...

The following comment was something I just HAD to respond to.


"The underlying theory I had come up with was that if 3d normal space could be visualised as the 2d surface of a sphere, then 'hyperspace' was a smaller sphere inside the normal-space sphere, where corresponding points were a smaller distance apart. Hyperspace could be reached by moving 'down' from the surface of the normal-space sphere,"

Hmm. I like that explanation. (Although I assume you mean the 3D surface of a 4D hypersphere.)

This would mean that hyperspace isn't one "place", but that you can go shorter or longer depths into the fourth dimension. How deep you could go could depend on the technical tolerances of your hyperdrive. Also, deeper layers of hyperspace would be more strongly curved than the outer shell, which could have ramifications on the laws of physics in there...
- Milo

Sound's a bit too much in how hyperspace works in Babylon 5 as explained in this Web Page Article if you ask me.

Though personally, I figured that if "hyperspace" is real, then it would be more like an alturnate but parallel space-time like our own normal space-time and numerous others like it. Not sure how physically correct it may be, but I simply work with what I currently know, which is not alot now that I think about it...

Though to be honest, I am curious as to how any possible Hyperspace magitech Jumps would be able to avoid the conservation of angular momentum as Luke Mentioned, if only to make my own FTL idea not break too many fundimental laws of physics beyond the whole "FTL Magic Drive" part of the equation.

- Hotmail Address
Gmail Address

Luke said...

Milo:

Did I make any mistakes in my math?

I went through your example and came to the same conclusion you did. I looks correct to me.

Luke said...

Citizen Joe:

Just because time dilates for you, doesn't mean you're going back in time. Your 500 year trip still takes 500 years to the outside reference frame, you just experience it as though it were 10 years.

That is not what happens in relativity. In relativity you do go back in time if you can engage in FTL from different frames of reference. I encourage you to read up on Lorentz transformations and work out several examples so that you can understand this issue better, if you are really interested in it.

Byron said...

I wrote a long post on causality and event ordering, among other things. Then blogger ate it.
High points:
Event ordering doesn't matter unless the events are causally linked. Then all observers will agree on order.
I tend to like a universe with a lot of background, and a decent bit of it showing.

Raymond:
Haven't we been over genetic engineering before? (The octupi are restless)

Raymond said...

Byron:

We have - and most of it was assumed away for convenience. (I want my gills and tail, dammit.)

Byron said...

So? I don't think you'll get them. Plus, it didn't make sense. Water adaptation is a very poor one for spaceflight.

Byron said...

Also, wouldn't the wormhole graph be an undirected acyclic graph? The wormholes aren't directed.

Raymond said...

Byron:

"So? I don't think you'll get them. Plus, it didn't make sense. Water adaptation is a very poor one for spaceflight."

I want them IRL, actually.

"Also, wouldn't the wormhole graph be an undirected acyclic graph? The wormholes aren't directed."

In terms of traversability, yes. In terms of timelike separation and expansion vectors, it's directed.

Raymond said...

Byron:

Sorry, I should also note that Luke pointed out ways in which you can have cycles within the graph, as long as you're paying careful attention.

Byron said...

Makes sense. That wasn't specified in either your original post or in Rick's blog entry.
And why do you want gills? What is there underwater that's worth that? (I'm assuming they replace lungs)

Raymond said...

Byron:

"And why do you want gills? What is there underwater that's worth that? (I'm assuming they replace lungs)"

An addition, not a replacement. And have you ever been scuba diving? I'd spend a huge chunk of my time underwater if I could afford it.

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