🚀 go-pugleaf

gnb@baby.bby.com.au (Gregory N. Bond) says:

> Current antiproton production is geared towards physics, not
> rocketry.  It is probably possible to create antimatter more
> efficiently if that is the primary goal.

This is probably incorrect, for two reasons:
* Antiproton production and capture  efficiency limits the rate
  at which antiproton storage rings can be filled.  If easily
  obtainable improvements were available, I expect that they
  would have been used already.
* A rocket fuel needs to be cheaply contained.  Storage rings
  are expensive.  Unfortuantely, antiprotons are created moving,
  so they will need to be brought to rest to simplify the containment
  problem.  This is an additional manipulation that the physicists
  don't need to perform.

> However the energy cost is
> huge because conservation tells you that you only create antimatter
> with at least E=mc^2 input energy.
> It will release twice this amount when mixed with ordinary matter.
> Now if we could generate antiprotons with better than 50% efficiency,
> we have an inexhaustible energy supply......

There is no free lunch.  Baryon number is conserved.  This means it costs
the same 2mc^2 (at least) to make an antiproton that one gets back when
it annihilates.