Re: Cheap Shots,

From: Damien Broderick (
Date: Mon Jun 12 2000 - 21:53:26 MDT

At 05:21 PM 12/06/00 -0400, Mike wrote:

>I would stipulate that at sub-relativistic speeds it violates commonly
>principles of conservation of momentum. For anything else, I personally would
>take the word of Prof. Cramer over most anyone on this list.

Yes, but since you're not telling us enough to judge what's being said by
Cramer, this is perilously close to argument from authority.

The rough sense I get of the process can be modeled like this (forgive me
if I'm way wrong):

You have a one-tonne ingot of steel down the back of the starship in
freefall, aimed up an electromagnetic launcher. You turn on your power
source and the coils click into brief action one after another, dragging
the ingot ever faster toward the prow.

When it gets to the nose of the ship, the lump is moving at 0.9999 c, say,
and masses 2.2 million megatonnes. It hits the plate at the end of the ship
and recoils, shoving the ship the hell forward (but the ship has meanwhile
been flying backward, hasn't it, impelled by this internal mass driver
effect?), and as it recoils down the launcher its energy and momentum are
sucked back into the ship, pushing it the other way, balancing the books.
Except that by the time it's slowed completely and reached the aft storage
container, it's back to massing a single tonne. So the books are *not*
balanced, there's been a net impulse forward when the ingot was *really
really heavy*, its m having been pumped up by all that injected e from the

This doesn't make a *hell* of a lot of sense to me, but is that something
like your story?

(Bearing in mind that there's no striker plate, because your asymmetrical
mass is actually rotating, all working parts being made from some
supernatural material, and that it isn't zillions of klicks long, and all
that pesky detail stuff...)


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