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From: andrew@orca.UUCP (Andrew Klossner)
Newsgroups: net.sf-lovers
Subject: Re: FTL Travel
Message-ID: <1622@orca.UUCP>
Date: Thu, 18-Jul-85 17:41:25 EDT
Article-I.D.: orca.1622
Posted: Thu Jul 18 17:41:25 1985
Date-Received: Sun, 21-Jul-85 02:31:25 EDT
References: <2702@topaz.ARPA>
Organization: Tektronix, Wilsonville OR
Lines: 46

>> Actually, according to Special Relativity, faster-than-light travel
>> is just plain impossible.  All the sqrt(v^2 / c^2) terms turn
>> imaginary...
>
> I'm sure this shows a shocking naivitee on the subject of relativistic
> physics, but this argument never made much sense to me.  So what if
> the multiplier turns imaginary.  Imaginary numbers have rights too.
> Besides, since everything on the ship would have an imaginary mass,
> their ratios would still be real.  I've always been surprised that
> physicists would throw up their hands at this and say "it's
> impossible" rather than finding out just what the consequences of
> having imaginary mass, velocity and time would be

First, let me state my bias.  There are two camps: those that believe
that FTL can never be achieved, period, there's no point talking about
it; and the rest of us.  I'm one of the rest of us.  Mankind has been
overcoming "insuperable" limits throughout history.  It wasn't so long
ago that many of the best brains in aerodynamics were convinced that
no aircraft would ever reach the speed of sound.  Now to the math ...

FTL problems predicted by special relativity don't center on objects
going faster than light, but rather are concerned with objects
accelerating up to and through the speed of light.  The mass equation,
for example, is

	m = m0 / sqrt(1 - (v^2)/(c^2))

where m is mass, m0 is rest mass, v is your velocity as perceived by
some observer, and c is the speed of light.  If an observer sees you
achieve the speed of light, that observer would also see your mass
become infinite (m0 / 0).  I think it's legitimate to throw up my hands
and say that infinite mass is impossible.

When I contemplate achievement of FTL, I imagine a mechanism that
involves changing your velocity from sub-light to super-light without
going through light.  This would be a discontinuous, "catastrophic"
change.  You would then avoid the infinite mass and go directly to
imaginary mass.

Of course, we still have the problems of violation of causality.
Tachyon theory avoids this by stating that there can be no interaction
at all between a sub-light and a super-light object, so the tachyon
cannot communicate information to the sub-light observer.

  -=- Andrew Klossner   (decvax!tektronix!orca!andrew)       [UUCP]
                        (orca!andrew.tektronix@csnet-relay)  [ARPA]