In article ,
Geoffrey A. Landis wrote:
Despite a recent article in New Scientist, a solar sail does not break
the laws of physics.

In an article in New Scientist recently, maverick astronomer Thomas
Gold cast doubt about solar sails:
"Thomas Gold from Cornell University in New York says the proponents
of solar sailing have forgotten about thermodynamics, the branch of
physics governing heat transfer. Solar sails are designed to be
perfect mirrors, meaning that they reflect all the photons that strike
them. Gold argues that when photons are reflected by a perfect mirror,
they do not suffer a drop in temperature. "

http://www.newscientist.com/news/news.jsp?id=ns99993895

Dang, I don't know what to say. Gold is a putz, and I thought New
Scientist was better than that. I didn't realize a solar sail was a heat
engine.
--
"Is that plutonium on your gums?"
"Shut up and kiss me!"
-- Marge and Homer Simpson