Re: starship-design: FTL idea and paradox

[kuo@bit.csc.lsu.edu (Isaac Kuo)]

Timothy van der Linden wrote:
>Lee and Kevin,

>I'm not so much bothered whether timetravel is possible and whether or not
>paradoxes are a fact.
>I'm only interested in what happens using current theories.

Kevin's speculations about random heart attacks and such may sound
way out, but they don't entirely fall outside the realm of current
theories.

Current theories view all the stuff in the universe to have a form
of both a wave and a particle--a "wave-particle".  We _know_ that
particles have wave-like properties because even electrons can
form interference patterns.

Viewing photons and electrons and other particles as particles
alone has been shown to be insufficient to explain their behavior.
In particular, an interference pattern results in a two-slit
interference generator even when the lamp is dimmed so low that
only one electron at a time is emitted.  If they really were
particles, how could an interference pattern result?  OTOH, if
you set up a detector which determines which slit the electron
entered, the interference pattern disappears and you get
particle-like behavior with two bright spots behind the two
slits.

The speculation is that so long as the effects of a wave-particle
are small, it behaves like a wave--as if it were going in every
possible direction rather than picking one randomly, but once the
effect becomes large enough, the wave collapses into one of the
possibilities picked randomly.  In the interference pattern
example, this collapse occurs either when you look at the
photographic plate or when you turn on the electron detector.
In the former case, you can't tell which slit any of the
electrons passed through, so an interference pattern as if
they "passed through both" results.  In the latter case,
you can tell which slit they went through, so no interference
pattern results.

The speculation about waveforms collapsing, however, is in a
certain sense just a speculation.  It might be that waveform
collapse _never_ occurs.  In that case, the "many worlds"
model of the universe long employed in fiction where the
universe splits apart like a branching tree every time a
random choice is made is accurate--except that it's an infinite
continuum of splitting apart and nearby "branches" actually
have an effect on each other (in the form of interference
patterns).

If you had a closed causality loop (due to time travel), then
any time paradox would interfere with itself out of the realm
of possibility.  On the one hand, this does handle time travel
paradoxes.  On the other hand, it implies that the nature of
the universe and its behavior is much more bizarre than we're
accustomed to.  By symmetry, what applies to "time travelling"
FTL would apply to "normal" FTL trips as well.  It'd be
something like using the Infinite Improbability Drive, except
much riskier.
-- 
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
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