RE: Solar sailing vs. laws of physics ?

From: Jeff Davis (jrd1415@yahoo.com)
Date: Thu Jul 03 2003 - 16:47:45 MDT

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    --- Spike <spike66@comcast.net> wrote:
    >
    > --- Spike <spike66@comcast.net> wrote:
    > >
    > > Subject: Solar sailing vs. laws of physics ?
    > >
    > >> 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.
    >
    > >Is this actually the case? Has it been
    > >observed experimentally with stationary
    > >versus moving mirrors? Best, Jeff Davis
    >
    > Jeff, if you have ever been caught speeding
    > by radar, you have observed this redshift/
    > blueshift phenomenon firsthand.

    Luckily, I've never had the displeasure, but I concede
    your point. But what about the frame of reference of
    the victim? Wouldn't he see the radar gun as a moving
    radiation source? And then wouldn't the radar pulse
    impinge and reflect with--from his point of view--the
    same frequency, with no loss of energy?

    To put it another way, if the victim has two radar
    receivers, one facing towards the incoming pulse to
    sample its frequency, and one mounted off a ways and
    pointed backwards to sample the reflected pulse,
    wouldn't they read the same frequency, and leave us
    back where we started?

    By the way, there's more discussion of this, by mere
    mortals/regular geeks at:

    More discussion of this, by mere mortals, ie, regular
    folks, can be found at:

    http://radiocomments.userland.com/comments?link=http%3A%2F%2Fradio.weblogs.com%2F0105910%2F2003%2F07%2F03.html%23a508&p=508&u=105910

    I'm lovin' it.

    Best, Jeff Davis

       "Everything's hard till you know how to do it."
                               Ray Charles

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