Comments on Rocketpunk Manifesto: Rapid Transit

Luke: "Rick: Remember that even though th...

2010-12-30T11:08:00.037-08:00
Luke:

"Rick: Remember that even though the wormhole ends are traveling to other planets at sub-light speeds, due to time dilation effects those of us back on Earth do not need to wait that long. From the torchship thread, a 100 light year journey might only involve waiting 1 month after launching the wormhole, if the time dilation factor is 1200. It's like being on a relativistic starship, except that you get to stay home."

Except that frames of reference are not interpenetrable. Nor are they importable. At 1/1200 dilation, for every minute of time that passes at the wormhole mouth on Earth, only 1/20 of a second passes at the moving wormhole mouth. And yes, each wormhole mouth is a distinct object that exists in its own frame of reference. What happens to objects that attmept to transit form one frame of reference to the other, and how the extra-dimensional internalities of the wormhole handle that, is the interesting question.

Among other things, I can't go back in time to...

2010-03-29T11:09:20.633-07:00
Among other things, I can't go back in time to avoid having crossposted with Luke.

The really scary thing is that there are people - ...

2010-03-29T09:18:50.423-07:00
The really scary thing is that there are people - including commenters here - who understand General Relativity, or at least can use the mathematical tools.

Using wormholes as a Trek style transporter has some constraints (I believe), but no show stoppers. For that matter the constraints might limit the plot killing problem of getting out of jams too easily.

You can't just open a wormhole somewhere; you have to move the wormhole mouth to that location. But you can position it while the tunnel is smaller than a nucleus, then inflate it, so locked doors are no barrier.

And as you suggest, you'd have to station anti-boarder teams at all critical point, because the attacker is not limited to the airlocks.

ushumgal: With short range wormholes, you will sti...

2010-03-29T07:47:26.037-07:00
ushumgal: With short range wormholes, you will still need to worry about details like forming loops that allow you to go back in time by a microsecond, or returning one of the mouths back very close to the other one, or having a long term wormhole connection between two points with different gravitational potentials (and thus different gravitational time dilations), but you are right - the effect is less extreme and for the purposes you are talking about (instant transport from a spacecraft in orbit to a planet) you really don't need to worry unless the planet already has a pre-existing planetary wormhole transport network.

You do need to take into account local conservation of mass. When you your transporter wormhole lands on the planet, it will need to suck up a lot of stuff (air, dirt, sticks, hapless locals) in order to balance the mass of the guy you will send the other way. This could mean that if you are sending down a landing party of 12 men (1200 kg total, say, including gear), you only need to suck up 1200 kg from the planet plus whatever extra you need as a safety factor. The the natives trying to invade the spacecraft can't send much more than 1200 kg of boarding party onto your spacecraft before the wormhole collapses (probably chopping one of the invaders in half).

ushumgal said... "In fact, short range wormho...

2010-03-28T20:21:38.955-07:00
ushumgal said...
"In fact, short range wormholes would make boarding a viable attack method…indeed, perhaps the preferred method. Open a wormhole mouth in the engineering room of an enemy ship, send your boarders in and seize her."

Kirk: "Master-at-Arms! Post troops at all critical stations and prepare to repel boarders!"

Something you never hear on the original Star Trek, but it might have lent a slightly piratical air to some of the battle scenes...

Ferrell

I think my brain has finally imploded. Relativity...

2010-03-28T06:45:08.407-07:00
I think my brain has finally imploded. Relativity makes me want to curl up in a corner and weep...

However, if I’m not mistaken, short-range wormholes could easily avoid any of the time-machine issues, since the mouths of the wormhole could be moved at slow speeds, so avoiding getting mixed up with all that relativity stuff…

Someone on the other thread mentioned that local wormholes would make great space elevators. But could they not be used in the opposite direction? In effect, they could be a more plausible version of the Star Trek transporter. Starship Indefatigable goes into orbit around unexplored Planet X, sends a wormhole mouth down to the surface, the landing party (led by an unfortunate guy in a red uniform and with no last name) walk into the airlock which leads to the other wormhole mouth and they step onto the surface of the planet. One interesting ramification of this system is that, unlike the transporter, the wormhole works both ways, so conceivably the warlike natives, brandishing their spears and waving their antennae menacingly, could storm the ship via the wormhole. So the wormhole airlock area would likely be fortified in some way.

In fact, short range wormholes would make boarding a viable attack method…indeed, perhaps the preferred method. Open a wormhole mouth in the engineering room of an enemy ship, send your boarders in and seize her. Of course, your ship would be equally vulnerable to such an attack. Which means that those fancy battle-armored marines, not particularly useful in a universe where starships vaporize each other from enormous distances, suddenly become quite important. If wormhole mouths have mass, then they’s have to be shot into the hull of the other ship like a bullet (perhaps a proton-sized bullet), and then inflated. So armor would also be important, and most likely, engagements would take place at a dramatically close range. After all, where is the fun in opening your wormhole mouth in a ship clear across the system?

One could hypothesize that there are many or few n...

2010-03-18T09:39:48.603-07:00
One could hypothesize that there are many or few natural wormholes in which the time dilation has already propagated and thus no time travel with their use. Those natural wormholes, from a story perspective would probably require some sort of difficulty accessing them. i.e some sort of lost tech gate opening device. New wormholes could also be created by man with some new tech, however these wormholes would need time to 'mature' by either propagating to their end point or have bad time travel issues. As such, a setting could have both distant transport wormholes as well as time traveling wormholes as the plot demands. Personally, I'd put serious deleterious effects on the time travel ones.

I think the detectability of wormholes, like most ...

2010-03-17T20:20:00.353-07:00
I think the detectability of wormholes, like most things about them, is currently author's choice. In fact the only really mandatory element, in story terms, is FTL restrictions that rule out timelike paths (and make loops very restrictive).

Usability as weapons, detectability, physical stargate structures or otherwise, location on a planet or in deep space, all seems that it can be pretty much finagled as desired.

@ Rick: "Lasers, I assume, are more about qua...

2010-03-17T19:49:20.913-07:00
@ Rick: "Lasers, I assume, are more about quantum mechanics, and in any case have not yet been used in anger as weapons in their own right, at least that I know of."

Dazzler weapons have been used by police and military forces in limited roles. And at least one moron in my city was hit with criminal charges when he shone his laser-pointer at aircraft. Including the police helicopter.

Ian_M

"To bring the discussion back a little closer...

2010-03-17T11:30:48.671-07:00
"To bring the discussion back a little closer to reality, how might a wormhole transportation network be detected at interstellar distances?"

I'm not sure. Given Luke's description of the effect of wormhole mouths on electric charge and gravitational fields, I wonder if a wormhole mouth might create the opposite of gravitational lensing (a diverging rather than converging lens effect). If that were the case, how big would the effect be? No idea. Could we detect it? Maybe (YMMV).

Jean Remy: The geometry of threading one wormhole ...

2010-03-17T10:43:58.800-07:00
Jean Remy: The geometry of threading one wormhole through another works out, and there are no known physical mechanisms that would prevent this from happening. Whether there are unknown physical mechanisms that would cause problems is an issue for the author to sort out.

You can think of it like this - imagine a ball with two handles - loops that are stuck onto the ball like coffee-cup handles, sort of like this
http://ecx.images-amazon.com/images/I/41LOeGWN3cL._SL500_AA280_.jpg .
The two handles are the wormholes, and the ball is our normal space (just space now, not space-time). The places where the handles are attached can move around the surface of the ball, just as we can move wormhole mouths around. Now note that the surface of the handles is just an extention of the surface of the ball. There is no reason one end of a handle couldn't drift up onto the surface of the other handle, then go across it and out through the other end. That's how the geometry of moving one wormhole through another would work - except in 3+1 dimensional space-time rather than a 2 dimensional spatial surface.

Luke

Matthew: Like Eric, it looks to me like your metho...

2010-03-17T10:32:13.749-07:00
Matthew: Like Eric, it looks to me like your method for creating loops out to work. Also like Eric, it looks to me like you will need to be careful about keeping your time lags carefully tuned. As with the four-leg-loop, you can gain a bit of tolerance by putting the ends of the wormhole that completes the loop several light hours away from the ends of the first two legs.

As for the question of what happens when you have wormhole ends on planets with different gravities - the answer is that we simply do not know. As far as I am aware, all theoretical investigations of wormholes have had isolated wormhole mouths in otherwise flat space-time. However, we can make some guesses as to what happens. To do so, I will make an analogy with the behavior of electric charges and fields as they approach a wormhole.

Imagine a positive charge located some distance away from a (uncharged) wormhole mouth. Field lines radiate away from this charge in all directions. It is important to note for our purposes that field lines can only start on positive charges and can only end on negative charges. Since the source charge is initially far away from the wormhole, almost none of its field lines will go through the wormhole - they radiate away into the more or less flat space-time.

Now imagine bringing the source charge closer to the wormhole. Those field lines cannot break - they must remain outside the wormhole mouth. These field lines are bending away from the wormhole mouth, as if they are being repelled by it. This is the same behavior as if the wormhole had acquired an electric dipole, with the positive side of the dipole pointing toward the source charge and the negative side pointing away.

As an aside, you can now see why the wormhole will acquire the charge of anything that goes through it. If you send the source charge through the wormhole, the field lines must still connect back into the flat space-time region where the source charge used to be. They will thread through the wormhole to emerge through the mouth, looking for all the world like a positive charge.

But now lets take this analogy to gravitation. A nearby mass will have its gravitational field lines repelled so as to bend around the wormhole. It will appear as if the source mass induces a mass dipole in the wormhole mouth. This will be superimposed on any mass that the wormhole already has. Since the direction of force is always along the field lines and the magnitude of the force is proportional to the density of field lines, as you approach the wormhole mouth the gravity of the planet will seem to fade away and you will be left with only the gravity due to the mass of the wormhole end.

To be rigorous, we would need to solve this problem using Einstein's field equations for general relativity rather than the Newtonian approach of treating gravity as a field. However, this analogy does work in other situations, so it might not be too far from the truth here.

Luke

Threading a wormhole through a wormhole? Isn't...

2010-03-17T10:28:44.819-07:00
Threading a wormhole through a wormhole? Isn't that asking for trouble? Is that even possible? It seems to me even trying that would cause a lot of weird interactions. I mean you're basically sending space warped into non-Euclidean geometry *through* space warped into non-Euclidean geometry.

This sounds like the kind of thing that could create a paradox that will destroy the Universe. Or we could get lucky and it is localized and will only affect our Galaxy.

To bring the discussion back a little closer to re...

2010-03-17T09:36:52.876-07:00
To bring the discussion back a little closer to reality, how might a wormhole transportation network be detected at interstellar distances?

Matthew, that wormhole trio scheme you mentioned l...

2010-03-17T08:34:37.538-07:00
Matthew, that wormhole trio scheme you mentioned looks crazy enough it just might work. You'd have to be exceptionally careful during transit, though, to avoid making even a slightly timelike path when you've just gone through the first wormhole connection carrying your worm-minihole. Get the movement and/or timing wrong and you could make someone very angry when their wormhole suddenly collapses/explodes/wings off into the void. Once you've made it to your final destination (without wrecking the rest of the network along the way), as long as you're extremely careful about the Δt differences between your wormhole and the others along that path, your new connection ought to be fine.
Once again, any loop will need constant adjustment to make sure it doesn't turn into a timelike path (your margin of error is going to be proportional to the distance between mouths of consecutive WH's in the loop relative to the distance between the mouths of a single wormhole, i.e. the distance of a few light-hours relative to the distance of several light-years in the case of the Interstellar Transit Loop - means a tiny margin for error).

Luke, I have some concerns with the overall premi...

2010-03-17T06:01:47.353-07:00
Luke,
I have some concerns with the overall premise of having point-to-point wormhole connections to distant planets.

I understand that the local conservation of mass-energy (as viewed from asymptotically flat space, yadda yadda) removes the problem of the two planets being at points of different gravitational potential energy, but I don't see how the space-time patch between the mouths would handle them being in different accelerating frames of reference.

Let's say one end in on Earth's surface and the other on the Moon's. I'm not sure how the 9.8 m/s^2 accelerating frame would mesh with with 1.6 m/s^2 accelerating frame through the wormhole connection.

Obviously these problems operating on different planetary surfaces would be multiplied during the process of shooting one mouth out of an electric cannon towards another star.

Is there some natural way that the accelerating frames of reference should mesh, or would you need to dynamically maintain extreme density distributions of mass-energy to make it happen?

-Matthew

Going back to the idea of a bypass line from Terra...

2010-03-17T05:39:36.902-07:00
Going back to the idea of a bypass line from Terra Nova to Johnsworld to avoid the congestion at Earth:

If wormhole mouths can be inflated/deflated at will, Terra Nova could just create a wormhole pair, set the mouths to the size of a packing crate, and ship one end through the Terra Nova-Earth wormhole, and then through the Earth-Johnsworld wormhole. The new wormhole could then be inflated up to train-car size creating a direct link between Terra Nova and Johnsworld.

The new connection is essentially completely space-like since the wormhole network connects Terra Nova to Johnsworld at the same time in the co-moving reference frame, and the transport of the new wormhole mouth occurred at non-relativistic speeds. So the resulting loop is no closer to time-like than the original pair of wormholes connecting the three stars.

-Matthew

Ferrell: While we can put some bounds on what is p...

2010-03-16T23:01:46.344-07:00
Ferrell: While we can put some bounds on what is possible, and deliver a few simple theoretical examples, there is a lot we do not know about wormholes. From the point of view of an author, this is a good thing! If the author wants his wormholes to have 1,000 km long tunnels, that must be carefully navigated by trained experts, he can have it so. If he wants characters that are still recognizably human to not be able to go where they will, he can say that the minimum mass of a wormhole is slightly more than that of Jupiter - far beyond what people are capable of engineering - and all travelers have to use ancient relics of a long vanished race.

M. D. Van Norman: After checking some of my refere...

2010-03-16T22:54:58.946-07:00
M. D. Van Norman: After checking some of my references, it looks like a cosmological constant will not suffice for propping open wormholes. Going into the reasons will probably bore people here, although I can drone on about the technicalities of weak energy conditions and null energy conditions if anyone wants to hear about it. Thus, unfortunately, dark energy does not serve our purpose. You are right, we still don't know much about it, although it is thought to be a property of the vacuum state of the universe.

Ok, after reading that last post, it really sounde...

2010-03-16T22:21:43.355-07:00
Ok, after reading that last post, it really sounded snarky...so I apologize for being so condicending.

Ferrell

So...the answer to my questions is...maybe? Kinda-...

2010-03-16T22:03:04.869-07:00
So...the answer to my questions is...maybe? Kinda-sorta? We think think so, yes? Wow. Pretty sure, until we actually find or make one of the silly things and find out how wrong or right we are about them.

Ferrell

Actually, I was thinking of “dark energy” and “neg...

2010-03-16T15:43:03.413-07:00
Actually, I was thinking of “dark energy” and “negative energy” as being the same thing. My mistake. Dark energy, then, would be the “cosmological constant” (AKA quintessence, AKA antigravity, etc.), the force that is continuing to accelerate the expansion of the universe.

I’m assuming we still don’t know much about the stuff. However, I figured it might be handy for prying open wormholes.

M. D. Van Norman: We know of several examples of n...

2010-03-16T14:00:15.488-07:00
M. D. Van Norman: We know of several examples of negative energy. It is generally not stuff that is there, but stuff that isn't there. Or perhaps a bit more accurately, precluding even the possibility of stuff being there. For, as it turns out, even the possibility of something is worth a bit of energy.

Perhaps a concrete example would make more sense. In perfectly empty space, you can have all sorts of electromagnetic waves - radio waves, microwaves, infrared, visible light, x-rays, and so forth. The possibility of each and every frequency, direction, and polarization (called a "mode") has a bit of energy. The sum of all those bits of energies-of-possibility (often called "zero point energy") ends us giving our reference point for what zero energy is - it is this value against which other values of energy are measured for determining space-time curvature (for the nit-picky - this neglects dark energy, which is a negligible effect over the scales which we use to build wormholes).

However, all electromagnetic waves are made of electric (and magnetic) fields. Electric fields can be shorted out by a conductor. So, if you have two parallel conductive surfaces, the only electromagnetic waves that can exist between them are those in which the electric field is zero at the surfaces. This restriction means you can only have an integer or half-integer number of wavelengths of EM waves between the two conductors. In particular, wavelengths of EM radiation that are longer than twice the spacing between the two conductors simply cannot exist between those two plates. Since the space between the plates does not allow the possibility of those waves existing, they cannot contribute their energy to the total energy of the space between the plates. Thus, the space between the plates has less energy than space in which there is no such restriction. Since we measure the energy relative to the energy with all the modes of EM radiation allowed, the region between the plates has a negative energy density.

Unfortunately for our purposes, the density of negative energy is very weak for reasonable plate separations. You would need your plates to be closer together than an atom to hold open useful wormholes - a meaningless distinction for materials made out of atoms. We might make use of similar effects from different kinds of barriers. We know that the event horizon of a black hole has a negative energy density from much the same sort of effect. Perhaps the space-time of a wormhole could be curved to only allow very restricted sets of modes of vibration - not only of EM radiation but also of gravitational radiation, gluons, weak vector bosons, leptons, and quarks. This might be able to hold up the wormhole, by using its own shape to support itself.

Of course, if you did find particles that naturally have negative energy, those would work, too.

I assume negative energy also creates negative gra...

2010-03-16T12:09:08.595-07:00
I assume negative energy also creates negative gravity, so the ability to shape it would certainly be useful. Getting some would be the problem.

Presumably tiny quantities could be produced in high-energy particle colliders, but I imagine that the big naturally occurring sources will be out in the intergalactic voids. We could be stuck needing “conventional” starships to collect significant quantities of the stuff.

Jean beat me to the punch: An assault rifle is sim...

2010-03-16T09:07:59.194-07:00
Jean beat me to the punch: An assault rifle is simply a musket - more precisely an arquebus - with rapid fire capability and some other refinements.

(A musket was originally an armor piercing super-arquebus. As armor disappeared it shrank back down to arquebus dimensions.)

Chemical explosives and propellants are so compact and powerful that even another scientific revolution may not displace them in weapons, just as nuclear energy has only displaced them for Really Huge Explosions.

Or it could go the other way just as well, with a new physics enabling 'disruptors' or whatever. In that case chemical-powered guns might fall out of use entirely, or survive for use in a pinch, more or less the way the bayonet has survived from the age of edged weapons.