> Physicists in Switzerland have confirmed that
> information cannot be
> transmitted faster than the speed of light.
Hmmm....the writers of the quoted article have made an
error in the above statement. It would be more correct
to say that it is confirmed that within the
experimental proceedures used, information WAS not
transmitted faster than the speed of light, not the
catch-all phrase that this one experiment proves that
information cannot be sent FTL, period.
> Nicolas
> Gisin and colleagues
> at the University of Geneva have shown that the
> "group velocity" of a
> laser pulse in an optical fibre can travel faster
> than the speed of
> light but that the "signal velocity" - the speed at
> which information
> travels - cannot
This group/phase/information/signal/front/blah
velocity stuff is getting old. Most of the experiments
I have seen fall into either:
A. The signal was distorted severely by its passage
through the medium in which "FTL" is supposed to take
place, thus making it "appear FTL". Usually the signal
is neither brief (compared to the dimensions of the
transmission path) nor sharp (usually a spread or
gaussian distribution)
B. It is "just" phase/group/whatever velocity which
moves super-c. Well, if it *is* moving super-c, and
not just some distortion, it is important to think
about this, regardless of whether or not we can use it
at the present time to transmit something.
C. They don't know what is going on for sure.
The last category is of course the most interesting.
Just my thoughts on this.
--Kyle
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