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starship-design: This and that.

Genny (actually Kevin) Houston writes:
 > To: Steve VanDevender
 > Re: Traveling Faster Than Light.
 > In message dated Sun Jun 15 1997 you write: (reformated)
 > > More importantly, relativistic physics, as we now know it, 
 > > does not in any way prohibit a material object from traveling 
 > > at any speed less than C, but does prevent anything from traveling 
 > > faster than that. 
 > It is my understanding (limited though it may be) that Einstein's
 > equations do not prohibit travel FASTER THAN the speed of light, 
 > but only prohibit travel AT the speed of light.  Is this not correct?

The problem is that if you go faster than light Einstein's equations
start producing complex numbers (that is, numbers with both real and
imaginary components) as results.  Nobody knows how to interpret the
imaginary components in a physical context, nor has any evidence of
physical phenomena with these quantities been seen.

 > To: Steve VanDevender
 > Re: Talking Faster Than Light.
 > In message dated Sun Jun 15 1997 you write: (reformated)
 > > The few FTL effects that are thought to exist in particle 
 > > physics don't translate to macroscopic objects, and even 
 > > when postulated don't transmit information or mass faster 
 > > than light.
 > Again, my limited understanding tells me that communication via
 > particle/wave duality phenomenom is possible.

Many people have thought so until they actually worked it out in detail.
For example, if you try to treat tachyons as quantum particles you can
either have particles that go faster than light that can't interact with
anything, or if they can interact with anything they have to go slower
than light.

The sci.physics FAQ has quite a bit of material on relativity and
quantum mechanics that is relevant to this discussion.  The primary
mirror is at


Also in hopes avoid the charge that I'm pooh-poohing FTL without having
studied up on it, I will recommend the book _Faster than Light_ by Nick
Herbert (who has also written a book on QM, _Quantum Reality_, that I
haven't read) which covers the issues around FTL and modern physics in a
fairly realistic (and even slightly optimistic) way, while still
recognizing the fairly substantial difficulties of reconciling FTL
against the way we currently see the universe to work.  His opinion is
that general relativity and quantum mechanics are the most likely to
have any possible FTL loopholes, but also explains why the various
proposed loopholes presented to date are physically implausible.