Re: Cheap Shots,

From: Michael S. Lorrey (
Date: Mon Jun 12 2000 - 12:07:38 MDT wrote:
> Mike Lorrey writes, quoting Hal:
> > > I thought your gadget was something which you could put in empty space,
> > > turn it on, and it would start accelerating off in some direction,
> > > without shooting anything back the other way. It acquires net momentum,
> > > doesn't it?
> >
> > From energy. This is why Cramer beleives it can work with masses working
> > at near relativistic velocities, because of the dissonance between
> > momentum and velocity at those speeds. If there is such a dissonance,
> > then Special Relativity also violates your strict interpretation of
> > conservation of momentum...
> I didn't ask where it got momentum, only whether it acquired net momentum.
> The answer is yes, I believe, and that is enough to tell us that it
> doesn't work. No more discussion is needed about whether momentum can
> come from energy, or from wishing, or from any other unlikely place.
> Momentum comes from momentum, and if it comes from somewhere else then
> momentum is not conserved.

So there is no such thing as explosives, exothermal chemical reactions, fusion,
fission, radiation, etc? You are claiming that the only momentum in the universe
is that which is pre-existing? Thats rather thin.

Lets say I use a laser to propel myself. I'm not expending any reaction mass,
but I am generating thrust. How is that conserving momentum? It's obviously
using e = m * c^2 to replace mass with energy, as light has no mass.

Lets say I have two particle beams, one shooting identical numbers of protons at
.9 C and the other shooting protons at .99 C. You also have two spaceships going
at .8 and .89 C respectively. When the two beams hit the two spaceships,
Spaceship A's perception of the momentum of the protons from the first beam are
different than Spaceship B's perception of the momentum of the protons of the
second beam, even though the velocity differential between the two pairs is
exactly the same. Where does the extra momentum of the second beam come from?

This archive was generated by hypermail 2b29 : Thu Jul 27 2000 - 14:13:09 MDT