Siara, on 28 July 2010 - 05:18 PM, said:
My understanding of relativity is that you can't reverse time, you can only change the pace at which it goes forward. So the grandfather paradox could never arise.
That is through conventional space travel. General Relativity appears to allow the creation of wormholes, and there appears to be no difference between creating a wormhole to a different region of space and a wormhole to a different period in time (or, of course, a combination thereof).
Now obviously
making a wormhole is currently impossible, and might
always be impossible, since we'd need some very strange forms of exotic matter to build one.
However the mere possibility that a suitable arrangement of mass/energy could create a wormhole, and therefore allow time travel, gives theorists headaches trying to create a paradox-free Universe.
Siara, on 28 July 2010 - 05:18 PM, said:
My belief is that if we ever develop warp speed maybe we could send zillions of cameras focused on earth out in a massive shell around our planet. If the cameras had been transported faster than the speed of light and each one somehow represented a few pixels on a giant screen we could conceivably watch reruns of our history (the cameras would record images that happened before those cameras launched because they beat the light into space). We will never be able to go back in time.
Yup, I know this is weird.
If you can travel faster than the speed of light, you can travel back in time.