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23 votes

How did Ptolemy know that days were unequal lengths?

You are right: at the time of Ptolemy they could not measure the length of a day directly. Actually Ptolemy never discusses any clocks in his book, he probably used some crude devices record the ...
Alexandre Eremenko's user avatar
9 votes

Where did the popular idea of spacetime come from?

A nice history was given by Archibald, R.C. (1914), "Time as a fourth dimension", Bull. Amer. Math. Soc., 20 (8): 409–412 Regarding Wells, ...
Batiatus's user avatar
  • 431

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