The laws of physics as we know them do not allow any object to pass at
greater than the speed of light by any other nearby object. We doubt
that Prof. Gott would disagree that this law of Special Relativity
applies to all objects big enough to be described without quantum
gravity.
As for another question, whether there are anomalies in the
structure of spacetime which might allow travel to remote parts of the
past or future, the theoretical arguments are not yet resolved. Gott
himself has supplied a reasonable summary of the current state of
knowledge:
"Time travel to the past is more difficult but it is a theoretical
possibility that seems to be allowed by Einstein's theory of general
relativity. There, space and time are curved, and you can have
solutions to those equations that are sufficiently twisted that allow
you to circle back and visit an event in your own past. This is in the
same way that Magellan's crew left from Europe, went steadily west, and
circled the globe. There are solutions like this to Einstein's
equations of general relativity: wormhole solutions, some that I found
involve cosmic strings, and so forth. However, the question is whether
these possibilities can be realized in our Universe or not. To
understand that, we may need to understand the laws of quantum gravity.
That is why gravity is particularly interesting project. We take
solutions to Einstein's equations quite seriously because they have
been tested. For example, light bending around the Sun and so forth.
Therefore, the time travel to the past is a topic under current
investigation. "
That idea has nothing to do with the issue of simply going faster
locally, but involves large-scale topological features of our
spacetime. (We suspect that due to causal anomalies no such travel of
any coherent information-bearer is possible, but as Gott says neither
the experiments nor the relevant quantum gravity theory are available
now.) It's unclear why you think that any of this contradicts our
answers, or why you think we are unaware of such speculations, which
have been well-known at least since the publication of a famous book by
Kip Thorne on the topic.
To what 'theorem' were you referring?
Mike W.
(published on 10/22/2007)
