[FOM] why should we, in computer science, be excited about the possibility of speeds exceeding speed of light

meskew at math.uci.edu meskew at math.uci.edu
Tue Nov 22 16:06:42 EST 2011

This is probably just my ignorance about physics, but why would these
experimental results say anything about time travel or "acausal
processes"?  It is my understanding that if the experimental results are
valid, then relativity will have to be fundamentally rewritten.  In this
case, from what theory would you be deducing time travel?  Or are you
saying that general relativity can hold true in the face of the results,
with the explanation that closed-timelike curves were influencing the


> Dear Friends,
> You may have heard about a recent experimental re-confirmation of
> neutrinos traveling faster than light; see, e.g.,
> http://www.nature.com/news/neutrino-experiment-replicates-faster-than-light-finding-1.9393
> While this confirmation is not final and doubts remain, you may have seen
> speculations about the possibility of time traveling to the past, about
> the related paradoxes of time travel, etc. You may have been curious about
> this interesting physical phenomenon, but most of you are probably not
> relating it to computing.
> Actually, we computer scientists should be following these experiments
> with even larger interest than physicists. Indeed, the relation between
> computing and acausal processes has been analyzed in the past, and the
> conclusion is as follows. If such faster-than-light acausal processes
> indeed exist, then:
> * On the one hand, the time travel paradoxes will most probably indeed
> prevent actual time travel (so do not yet buy tickets to the past :-(). In
> other words, new physics will emerge but not as revolutionary as some
> journalists make us believe.
> * On the other hand, acausal processes can potentially lead to a drastic
> computation speed-up -- including the possibility of solving NP-hard
> problems in polynomial time. In other words, new computations can emerge.
> (see a short explanation below, with references to more detailed papers).

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