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Thread: the mirror that looks back in time

  1. #1 the mirror that looks back in time 
    Forum Ph.D.
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    here was a little thought experiment i did.
    if we place a perfect mirror, 4 light minutes out in space, say, the size of the moon,
    or some ridicolous proportion like that
    and we look at that mirror from earth, we'd be looking back at earth as it was 8 minutes ago?


    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
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  3. #2  
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    That's right. I gues it would be like watching a delayed videotape.

    The round trip time to the moon is a few seconds. The round tirp time to Mars varies from about 6 minutes to over 40 minutes, depending on how far apart the planets are. This creates a real problem when they try to steer the surface probes.


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  4. #3  
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    This experiment has already been done some 50 or 60 years ago -- not with light but with radar reflected of the planet Uranus. Naturally, the signal had a round trip time of several hours. The purpose, I believe, was to determine the planet's period of rotation.

    Clearly it is possible to encode the beam with information, such as a live video image, and there you go!
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  5. #4  
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    well, my idea is, if theres an unexpected event, such as a crime, all you'd have to do to find out who did it or where the escape car went, is look back a few minutes or hours in time.
    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
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