Since we have enough wireheads on this group to appreciate it, I'll fill in
Stewart's explanation of negative matter.
> NEGATIVE MATTER
> Negative matter simply has *negative* mass, so that the force is negative, or
> *repels* all other matter. This is *not* anti-matter, which so far only has
> been found with positive mass.
Not only that, but you stick a negative number into *every* mass-dependent
formula, so that, eg, when a negative mass accelerates, its momentum
and energy *decrease*.
> In some book I read (I can't remember the name, but can find out), someone
> proposed a spaceship drive which involved mounting a plate of negative matter
> next to a plate of positive matter, and then charging the two. The result is
It was Robert Forward. I read his article in Analog; it may have been
printed elsewhere also.
> a forward force, although I'm not sure why.
OK, here's what happens. (I don't remember any need for electric forces,
though.)
Start with Universal Gravitation--it now looks like Coulomb's law, with
a negative sign, so like mass charges attract, and opposite mass charges
repel. If you've got two plates, you get
Forces:
> __ __
> | | | |
> | | | |
> <--|+| |-|-->
> | | | |
> | | | |
Now, the cool part. Newton's second law is *also* affected, so if you
push on a chunk of negative matter, it accelerates *toward* you!
Thus we get acceleration that looks like this:
> __ __
> | | | |
> | | | |
> <--|+| <--|-|
> | | | |
> | | | |
That is, if you leave equal masses of positive and negative matter
sitting next to each other, they tend to accelerate off uniformly
along the line of their centres of mass--howdy reactionless Drive!
Note that no conservation laws are broken, because the increase in
energy and momentum of the positive mass is exactly balanced by a
decrease in the energy and momentum of the negative mass.
Aha! I've just figured out where electric charge would come into it.
The key to the effect is the perverse reaction of negative matter
to an applied force, and since electric forces are 40 orders
of magnitude stronger than gravity, you can generate the force much
more easily with two oppositely electrically charged plates, one of
which being negative matter (though as I recall, Forward's actual
design used storage rings for reasons of practicality. He also got
some bonus out of the geometry of that arrangement, but I don't
recall what it was.)
- --
colin | she told me to read between the lines and tell her exactly what i
roald | got out of it. i told her 'affection' has two f's. (sloan)