Greg brought up an interesting conundrum when it comes to use of teleportation – is it possible to call the “you” that comes out the other side someone different? For many methods of teleportation, this is debatable – it depends on what you consider to define identity. For more on this topic, check out Identity.
Today, however, I wanted to talk about the one form of teleportation that I believe avoids the identity problem, and which also might have the most reasonable chance of being possible, although with quite a few “ifs”:
2. Wormholes (Gates)
All massive objects distort spacetime. You can imagine the fabric of the universe as a rubber mat of some thickness suspended over, well, nothing (!), and that all objects with mass sit on top of it, sinking down into the fabric and distorting it into wells. Supermassive objects will distort it enough to break it at the bottom – these are singularities.
So now you could imagine distorting spacetime by a bit in one location and by a bit in another faraway, creating two gravity wells – and then punching through the surface of spacetime to join the two wells. This joining tube between two locations in the rubber sheet is called a wormhole. (Alternately, if spacetime folds around by itself – as in, sometimes two apparently faraway locations are actually on top of one another – then you can naturally create a wormhole via one well.) The kind of wormhole I described is very unstable – any mass that passes through it will destroy it, since all mass distorts spacetime, and the wormhole are MADE of spacetime. To stabilize it, we need something called “exotic matter,” which is like negative matter – it pushes the walls out (gravitational repulsion) and stabilizes the wormhole.
Anyway, in theory that’s how it works. So, if spacetime happens to fold itself, or if we can punch from one gravity well to another, and if exotic matter exists and we can find it, and when we have a process for directed spacetime distortion… then we can “teleport” via wormholes!
Once a wormhole is created, you should be able to drag around the “mouths” to change the distance it spans. (By the way, if you can drag a “mouth” at near-light speed, you can create a time machine… assuming the exotic matter disperses radiation moving through it. I’ll talk more about this in Time Travel.) So I think you would have a transportation agency moving mouths around to major transit points, and a lab or few making them (given the constraints of exotic matter and the energies required to make a wormhole, I think there would not be very many Wormhole Creation Facilities.)
Wormhole travel is not instantaneous. You still have to move at regular speeds through the tunnel. This would require short range (miles rather than light-years) space vessels. So probably the character of transportation is our current airline system, with bigger voyages (more like cruises?) and longer range.
Science fiction has many examples of wormhole travel – Star Trek, Stargates, the farcasters from Hyperion, and any space travel that does faster-than-light travel without a special spacetime-bending technology (FTL drive).