Saturday, January 27, 2018

The apple draws the Earth

Newton's Apple Tree (click to enlarge)
The apple tree that dropped the apple that so enlightened Isaac Newton is still alive. That's it above. As entertaining as the common version of the story is, the apple didn't actually bounce off his head. As he recounted to his biographer William Stukeley:

After dinner, the weather being warm, we went into the garden and drank the, under the shade of some apple trees ... he told me, "he was just in the same situation, as when formerly, the notion of gravitation came into his mind. It was occasion'd by the fall of an apple, as he sat in contemplative mood. Why should that apple always descend perpendicularly to the ground, thought he to himself ... Why should it not go sideways, or upwards, but constantly to the Earth's centre? Assuredly, the reason is, that the Earth draws it. There must be a drawing power in matter. If matter thus draws matter, it must be in proportion of its quantity. Therefore the apple draws the Earth, as well as the Earth draws the apple."

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