Re: FTL communication


Spaceman wrote:
> <snipped from http://en.wikipedia.org/wiki/speed of light >
>
> It has long been known theoretically that it is possible for the group
> velocity of light to exceed c. One recent experiment made the group velocity
> of laser beams travel for extremely short distances through caesium atoms at
> 300 times c.
>
> If such is true,
> a group velocity travels 300 times FTL.
> It is simple to send info FTL
>
> simply use 2 setups
> 1 turned on only if by land,
> 2 turned on if by sea.

Nope. The information that it is turned on can't get there any
faster than c.

There used to be a nice online simulation of the 300c experiment.
It showed pretty clearly the difference between phase velocity
and group velocity. It let you turn the pulse train on and
off. When you first flip the switch, the information travels
at c. It is only after that change propagates through the
channel that you start seeing pulses "propagating" at
300c.

Turn the switch off and again the information travels
to the other end at c.

- Randy

.

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