|The general assumption is that General Relativity in its current
form must break down near the Planck scale, since at that scale quantum
effects become important, and straight quantization of General
Relativity does not give a consistent theory. |
That means that we don't know what replaces our ideas of a spacetime continuum at that scale. It would not be meaningful to talk of time travel if there were no variable like our large-scale time in which to travel.
(published on 10/22/2007)