Re: Sensor Range Question [Evasion]

On Thu, 29 Apr 1999, Andrew Evans wrote:

> Ah ha!   A Physicist.   This is also my Doctoral subject, although
some
> while ago now.   I have been watching this thread and thinking -
although
> not saying - that in fact fast-than-light travel - at least by Special
> Relativity is not impossible.  The equations come up with some weird
answers
> (involving the square root of -1 if I remember rightly) and what those
> answers might mean is unknown but the problem is, I believe, that
travelling
> AT the speed of light is impossible and thus (or even hence) getting
to FTL
> speeds from this sub-light state is impossible.   If however you
already
> were travelling at those speeds then the equations do produce answers,
> just - from memory - imaginary numbers, right?

This is more or less right, but the real problem in getting to
lightspeed
is that your mass goes to infinity as you get closer to lightspeed.  In
other words, it becomes harder and harder to go any faster to the point
where you need an infinite amount of energy to actually -reach-
lightspeed.  The idea you're talking about is basically the tachyon
argument:  if I have a particle that is travelling faster than light
then
it requires an infinite amount of energy to slow it down to lightspeed. 

But there's no way for us to interact with these particles, so it's
something that's hard to theorize about.  Pretty neat though...

Now, effective faster-than-light travel is -not- prohibited by general
relativity (for different reasons), and therein I think lies the
loophole
for stardrives.

Keith

kwatt@astro.umd.edu
Univ. of Maryland Astronomy