Re: Faster Than Light Travel

At 08:57 12/09/97 -0400, you wrote:
>  No but - there are certain weird situations in which things appear
>to happen faster than light.  In particular there's this quantum
>thingie (can you tell this isn't my field?) where you take apart an
>object (usually a particle) and the parts retain a certain
>relationship to each other that they got from being the same particle
>(spin or charm or something - I get the impression it's a conservation
>law).	Anyway the idea is that this relationship is continuously
>maintained no matter how far apart the particles are moved.  So if you
>move them a billion light years apart, and change one, the other
>changes as well, instantaneously.  Sounds like FTL communication to
>me.
Indeed. It's spin. The idea is you take a neutron (I think it was) and
split it into an electron and it's opposite, a positron I think. A
consequence of this fission process is that one spins clockwise and the
other spins anticlockwise. You can then separate them. If you use (I
think)
a magnetic field to affect the spin of one, it also seems to affect the
spin of the other simultaeneously. Whether this is FTL or at the speed
of
light was being argued, but I *think* it has actually been done
experimentally rather than just being a theory. Going form that to an
efficent telecoms system is another kettle of fish though.   Note that
another side effct is that such communication would have no maximum
range
or suffer from interference. Sorry if I'm a bit vague on this but it was
just happening when I dropped out of a physics degree..
 
>  Unfortunately it's not.  But don't ask me why I just read this stuff
>in Scientific American - I pay taxes for other people to understand
>it.  If anyone here is a quantum physicist and can tell me why no
>information is transferred in the above situation I'd love to know.
In essence the information isn't transferred. The change in spin of the
particle isn't information, it's just physics. You might as well ask why
does heat travel from warm to cold objects, or why the colours of the
spectrum are arranged the way they are, or every chemical reaction loses
a
tiny piece of mass/energy. Some things there are no explanations for,
they
are just THE WAY THINGS ARE. Only when you place some significance
behind
the change in spin does it become a piece of information. It's not
actually
unusual in quantum physics (or even newtonian physics) to have thinsg
which
seem impossible. For instance, I've been waiting for years for someone
to
explain where the matter that gets sucked into black holes goes. Indeed,
I
always thought near light speed travel would be impossible in 'normal
space' because as you approach light speed, your density increases,
therefore I always thought that at some point close to C you would
become
dense enough to attain singularity and 'drop out' of the universe.
Anyway..

>@:) I really gotta be quiet.  I don't know what I'm talking about.
>  Never stopped me.
But surely, the first person to think something up never knows what they
are talking about. Becuase no-one has ever told them :).
				TTFN
					Jon
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