Re: Faster Than Light Travel

Andy Skinner writes:

@:) Transmission as tachyons?  I don't know anything about tachyons
@:) except they were supposed to move faster than light.  I don't even
@:) remember whether they were theoretical, hypothetical, or
@:) fictional.

  They used to be mostly theoretical and I think now they're
considered mostly fictional.

@:) Aren't the effects of gravity supposed to be effective immediately
@:) across distance?

  Actually no, or at least that's what I hear.	Gravity is probably
transmitted by particles like the other forces.

@:) So could you postulate some sort of gravitational signal that
@:) would be instantaneous?

  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.

  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.

@:) I really gotta be quiet.  I don't know what I'm talking about.

  Never stopped me.

-joachim