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From: lew@ihuxr.UUCP (Lew Mammel, Jr.)
Newsgroups: net.physics
Subject: Re: C as speed limit
Message-ID: <1218@ihuxr.UUCP>
Date: Fri, 2-Nov-84 18:25:16 EST
Article-I.D.: ihuxr.1218
Posted: Fri Nov  2 18:25:16 1984
Date-Received: Sat, 3-Nov-84 07:48:17 EST
Organization: AT&T Bell Labs, Naperville, IL
Lines: 31

These remarks are not aimed at justifying the existence of a "speed limit",
but are an attempt to show the nature of its enforcement, so to speak, and
to show that in many ways it doesn't defy the intuition as bluntly as it
seems on first statement.

Many people (e.g. Robert Heinlein) conceive of C as a "wall" which can be
approached, like the sound barrier, but not broken through. Actually, it
is possible, under relativity, to go as fast as you please, in the sense
that you can gain arbitrarily large kinetic energy.

An objects kinetic energy is measured by "gamma". Slow objects, that is
objects travelling only a small fraction of the speed of light, have a
value of gamma nearly equal to one. Objects travelling near the speed of
light have gamma much greater than one. These are objects travelling at
"ultrarelativistic" speeds, speeds equivalent to a classical velocity
of many times the speed of light.

You could say that displacement per unit time becomes a poor measure of
intuitive speed in the ultrarelativistic region. A bullet with gamma
equal 2000 won't get to the target much faster than one with gamma equal
100, but it will hit one hell of lot harder when it gets there! That's
a good measure of speed, isn't it?

Even light obeys this intuition. If you run away from it, it is red-shifted
and becomes "soft" - you absorb much less energy from it. If you run into
it, it hits you harder, just as would a classical stream of particles.

Rather than banging your head against a wall that isn't there, try to
develop an intuition in line with the theory. It's not impossible.

		Lew Mammel, Jr. ihnp4!ihuxr!lew