Solar sails - impossible?

"Robert Schneider" :

"Stanislaw Sidor" wrote in message
...
What do you think about the Thomas Gold's article:

arXivhysics/0306050 v1 5 Jun 2003
"The solar sail and the mirror"
Thomas Gold (Center for Radiophysics and Space Research, Cornell
University)

http://www.arxiv.org/html/physics/0306050

Is he right or not?

I think that he is probably right. If reflected photons still have the
same
momentum as incident photons, then a perfect mirror won't be able to gain
any momentum. However, I don't think that his ideas dismiss solar sailing
entirely. A sail that absorbs energy and radiates it preferentially in
specific direction might work.

--
(STS)

That is silly, if I throw a ball at you and it bounces off your head, does
the fact that the ball is still moving at the same speed prevent the pressure
on your head? The direction of the photon's momentum and to balance it the
momentum of the sail must also change.

Earl Colby Pottinger

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