From: Spike (spike66@comcast.net)
Date: Wed Jul 02 2003 - 21:04:51 MDT
Subject: Solar sailing vs. laws of physics ?
A fun little conundrum.
Solar sailing breaks laws of physics
http://www.eurekalert.org/pub_releases/2003-07/ns-ssb070203.php
Best, Jeff Davis
I know the answer to this one. {8-]
Shall I provide spoiler space for those who want to
ponder it a while longer? OK, for those who can't
wait, see below:
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The reflected photon would have the same frequency
as the pre-reflection photon only if the light source and
the reflector are stationary with respect to each other.
If the reflector is moving away from the light source,
there is clearly gravitational potential energy coming
from somewhere. The reflected photons are red shifted
by the receding reflecting surface. Photon's momentum
is transferred to the sail, no energy is lost, no
conundrum or paradox, no physically illegal precedures.
spike
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