RE: Solar sailing vs. laws of physics ?

From: Spike (spike66@comcast.net)
Date: Wed Jul 02 2003 - 21:04:51 MDT

  • Next message: Adrian Tymes: "Re: Solar sailing vs. laws of physics ?"

    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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