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Time travel isn't forbidden. At least, there are solutions to the Einstein field equations that allow for the existence of wormholes between two points in space
by openasocket 10y ago
Time travel isn't forbidden. At least, there are solutions to the Einstein field equations that allow for the existence of wormholes between two points in space-time. But that doesn't mean there are wormholes in our universe, or that wormholes could be created (that last part is a little tricky, it's not easy to talk about causality when dealing with time travel). There could well be other laws of physics that prevent time travel, but general relativity seems to allow it.
- M_Grey 10y agoIt's a solution that assumes things like a perfectly uniform sphere of gas collapsing from infinity (Schwarzschild geometry), without any angular momentum. Even then, the ERB isn't traversable. A lot of the talk around wormholes and time travel suffers from map-territory issues. For example, if you look at the maximally extended Schwarzschild geometry (the Kruskal-Szekeres extension) you see two asymptotically flat regions of spacetime connected by a "wormhole". It's probably just an artifact of the model though, and not anything physical. A lot of the, "Math allows" stuff probably falls into that category, which is why when it comes to relativistic masses and velocities, you can't ignore quantum effects either.