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Galileo's Refutation of the Speed-Distance Law of Fall Rehabilitated

Norton, John D. and Roberts, Bryan W. (2012) Galileo's Refutation of the Speed-Distance Law of Fall Rehabilitated. [Published Article]

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    Galileo's refutation of the speed-distance law of fall in his Two New Sciences is routinely dismissed as a moment of confused argumentation. We urge that Galileo's argument correctly identified why the speed-distance law is untenable, failing only in its very last step. Using an ingenious combination of scaling and self-similarity arguments, Galileo found correctly that bodies, falling from rest according to this law, fall all distances in equal times. What he failed to recognize in the last step is that this time is infinite, the result of an exponential dependence of distance on time. Instead, Galileo conflated it with the other motion that satisfies this ‘equal time’ property, instantaneous motion.

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    Item Type: Published Article
    Additional Information: Published in Centaurus
    Keywords: acceleration, freefall, foundations of physics, Galileo, history of physics
    Subjects: Specific Sciences > Physics
    Conferences and Volumes: [2010] &HPS3: Integrated History and Philosophy of Science 3 (Bloomington, IN; 23-26 September 2010)
    Depositing User: Bryan Roberts
    Date Deposited: 26 May 2012 09:09
    Last Modified: 26 May 2012 09:09
    Item ID: 9123
    Journal or Publication Title: Centaurus
    Official URL:

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