"Lawson English" wrote in message
...
"Daniel Prince" wrote in message
...
"Steve Harris"
wrote:

Unless of course it contains time machines, FTL drives,
force-field "shields", antigravity, Wesley Crusher, or
workable libertarian utopias. Then it's okay to laugh
all
you like. g.

There is one type of force-field "shield" that is
possible. It is a
magnetic field that can shield a ship or station against
certain types
of radiation (charged particles only).
--


Actually, there is already a force field in use that acts
as an air valve
(plasma valve).

I see no reason why you couldn't create such shields of
any arbitrary power
(e.g., Star Trek's deflector shields), except, of course,
that the power
requirements would be beyond insane.

http://www.bnl.gov/bnlweb/pubaf/pr/2003/bnlpr052803.htm



COMMENT:

This "shield" is made of matter (plasma = ionized gas), not
force. As a small curtain of flow, it's no different in
principle from the hail of slugs from a phalanx gun on a
carrier. Doesn't count as a "force field". And even if it
did, plasma magnetic confinement in 3-space, has proven (so
far) impossible for decent times except in interiors of
masses (if it was easy we'd have fusion power). For a nice
exterior shield or plasma confinement field, we're back to
the idea that was already brought up. The Bussard sort of
thing. I personally doubt it's possible except with gravity
(and for that you need mass of a star). Plasmas are clever
and slippery.

But I would love to be proven wrong, of course.