Newton, gravity, and the apple

Isaac Newton and his apple (image: LadyofHats)

Among the numerous problems in this famous videoclip from South Africa (which I have previously mentioned) are some serious misunderstandings regarding Isaac Newton, gravity, and the apple story. According to William Stukeley (writing in 1726), “After dinner, the weather being warm, we went into the garden, and drank tea under the shade of some apple trees; only he [Newton], and myself. Amidst other discourse, he told me, he was just in the same situation, as formerly, the notion of gravitation came into his mind. ‘Why should that apple always descend perpendicularly to the ground,’ thought he to himself; occasion’d by the fall of an apple, as he sat in a contemplative mood. ‘Why should it not go sideways, or upwards?’

Of course, Newton was hardly the first person to think seriously about gravity. About 2,000 years earlier, Aristotle had recorded his theories on the subject. These had a great influence on the Greek-speaking world, the Muslim world, and Western Europe, up until the time of Galileo. Galileo demonstrated several flaws in Aristotle’s approach, and made measurements which showed that falling objects follow parabolic paths.

Parabolas traced out by a bouncing ball (photo: MichaelMaggs)

Newton’s genius lay in being able to explain both Galileo’s findings and Kepler’s laws of planetary motion using a single mathematical equation: F = G m1 m2 / d 2. This articulated the strength of the gravitational force, while leaving the true nature of gravity mysterious. Consequently, Newton’s work was hardly the last word on the subject. Einstein’s general relativity made considerable advances in the understanding of gravity, but several questions still remain.

The scientific understanding of gravity neither started nor ended with Newton, which means that the speaker in the video linked above is quite wrong in saying: “Western knowledge … is saying that it was Newton and only Newton who knew and saw an apple falling and out of nowhere decided gravity existed and created an equation and that is it. Whether people knew Newton or not‚ or whatever happens in Western Africa‚ Northern Africa‚ the thing is the only way to explain gravity is through Newton, who sat under a tree and saw an apple fall.

Western knowledge says nothing of the kind, of course. It is a sad thing that “decolonisation” is being driven by such radical misunderstandings, when what is needed may in fact be a review of the humanities and improvements in basic education.


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