Regular readers know, and newcomers may guess from the blog title and header image, that I have a weakness for traditional space technology. This is the technology of Clarke and Heinlein, and it has the virtue that it actually works. Even the much maligned Shuttle truly has been a workhorse for a generation, its two catastrophic losses more the result of mismanagement than its design flaws. (And at that they were just the disasters that writers of the rocketpunk era expected.)
Thus I have avoided discussion of FTL, or even such minor technomagics as antigravity and sublight warp drives. In part it is because these technologies are so speculative that it is hard to pin down their capabilities and limitations, in part because I just plain prefer roaring rockets (or, in a different context, flashing swords) to magical mumbo jumbo.
But physics rears its head in surprising ways, and it showed up in the wonderful, astonishing comment threat on Torchships to point out that FTL, with certain constraints, does not violate General Relativity. (GR itself is surely not the Final Word on the subject, but its findings are no more likely to be tossed out wholesale than Newton was.)
In particular, commenter Luke raised the subject of wormholes, and explored some of the relevant concepts. I recommend the discussion, though you may wish to inbibe the ethanol mix or herb of your choice before your head explodes.
The mainstream convention in science fiction is to treat FTL as a handy interstellar rapid transit system, allowing ships to travel at the speed of plot while otherwise leaving them as more or less familiar, recognizable spaceships. My own preference, back when I was playing with traditional FTL in demi operatic settings, was to treat starships as hardly different from interplanetary ships except that they had a gizmo somewhere containing a young lady singing in Welsh to hustle things along.
But there is no particular reason to think that wormholes, or other plausible ways of making an end run around Einstein, would work that way. If wormholes can be traversed at all, we may be able to anchor them to planets, so you could simply walk through, or at least drive through like the Holland Tunnel. Stargates of this sort are by no means rare in SF, to be sure; the first I encountered was in Heinlein's Tunnel in the Sky.
Such details are (within broad constraints) purely a matter of conjecture, and I prefer to suppose that the technology of passing through a wormhole requires a 'fixed guideway' of some sort, AKA a railway structure, making it truly a rapid transit system to the stars. While the underlying principles may involve head-exploding physics, much of the operation might be more recognizable - stations, switching systems and interlockings, scheduling trains, and of course a nifty system map inspired by the London Underground map.
So get out your fare card and head for the turnstiles.
Photo Note: San Francisco loves its transportation history, and here a historic (ex-Philadelphia) PCC streetcar arrives inbound, the N Judah line evidently having been rerouted from Sunset/Parkside to Messier 88, 50 million light years from Embarcadero Station. Streetcar image by David Pirmann from NYSubway.org; galaxy from Astronomy Picture of the Day.