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    Universe of the ancient Greeks.
    From: George Huxtable
    Date: 2006 Mar 3, 20:34 -0000

    Bill wrote, in a thread "Simple celestial navigation in 1897"
    
    | Currently working though the book Ken mentioned, Arthur Koestler's "The
    | Sleepwalkers."  (Not, *in my opinion* a light read--he gets you to the edge
    | of your seat crying, "But what about" then casually drops it in at the last
    | possible moment.)
    |
    | It did, and does not, come to me as a surprise that the obvious can be
    | totally ignored for much longer than a century. In the first stages of
    | Koestler's book we go from bizarre models of the solar system/universe (by
    | current thinking), to functional models of the solar system (Aristarchus of
    | Samos & Herakleides) but continued to ignore the obvious and kept trying to
    | pound an elliptical peg into a round, or square, hole for over a 1000 years.
    
    ======================
    
    Comment from George-
    
    Bill, it depends on what you mean by "obvious". Try to put yourself in their position.
    
    It was widely recognised, by the Greeks, that the Earth was indeed spherical, and approximately half
    of it was inhabited. But it was quite obvious, to the Greeks (most of them, but Aristarchus was an
    honourable exception) that the Earth was NOT spinning around. It was stable underfoot. If you threw
    a stone vertically upwards, it came back down in the same place. There was not a constant, powerful
    wind blowing, as there would have been if the Earth's surface was travelling so fast. Remember, they
    had no reason to know that the atmosphere was finite, giving way to empty space; there was no
    concept of such empty space. And they had no notion of Newtonian dynamics.
    
    Ptolemy, in the early pages of his "Almagest", in about 200 AD, considers the arguments for and
    against motion of the Earth, and decides that indeed the Earth is stationary at the centre of the
    Universe. I doubt if many of us would have argued otherwise, if we had found ourselves in the same
    situation, in the same state of knowledge.
    
    Indeed, Copernicus laboured under many of the same handicaps that the Greeks did, but had the vision
    to set the counter-objections to one side, in favour of the simplicity of the planetary motions that
    resulted if motion of the Earth, around its axis and around a fixed Sun, was contemplated.
    
    George.
    
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    

       
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