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No. 606:
Newton and the Apple

Today, let's ask about Newton and his apple. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

For a long time I thought the story of Newton and the apple was just another fable. I thought it was a made-up story, like Washington chopping down the cherry tree. It is not.

Cambridge University closed down in the Summer of 1665 when the plague broke out. Newton, a student there, went home to Lincolnshire. He stayed home for two years while the disease ran its course in the area around London.

The 23-year-old Newton spent that time studying and laying the foundations for his greatest work, the Principia. One day he sat thinking in his garden, when an apple fell. Then he realized. The direction the apple fell, along with every other object on this round earth, was always toward Earth's center.

It wasn't just that the apple fell, but that it tried to go to Earth's center. That was Newton's Eureka Moment. He realized that Earth had drawn the apple to it. He realized that every object in the universe draws every other object -- probably in proportion to its mass.

Newton didn't publish his Principia until 20 years later. But he formulated the Law of Universal Gravitation there in his Lincolnshire garden. He showed us that what was true of apples and the earth was true of planets and moons as well.

Now enter a surprising character. The person who popularized the apple story was none other than Voltaire. The French Voltaire sided with Newton in Newton's bitter fights with Leibnitz. Voltaire's brilliant mistress, The Marquise du Châtelet, created the first French translation of the Principia while Voltaire was writing Candide. In Candide Voltaire ridiculed Leibnitz. The character Dr. Pangloss, who went about insisting that we live in the "best of all possible worlds," was Voltaire's version of Leibnitz.

We might chalk Voltaire's apple story up to partisan license. But the story has good corroboration. Newton told it to close friends, who also recorded it for us.

If you've ever done anything creative, you'll recognize the plausibility of the apple story. You'll remember your own moment when some small and commonplace event revealed a great truth to you. That's the way creativity works. It's almost always the recognition of a great truth out of context.

Why did I so mistrust the apple story when I first heard it? No doubt it was simply too pat. For that apple of knowledge in Newton's garden of Eden changed our science -- and it changed our very lives.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Roberts, R.M., Serendipity: Accidental Discoveries in Science. New York: John Wiley & Sons, Inc., 1989, Chapter 4.

Note added, August 13, 2020: Reader Sadler Barnhardt writes to point out a chronological error in this text (from 1991). It turns out that Voltaire probably expressed his dislike of Newton's opponent, Leibnitz, in Candide after du Chatelet's death in 1749. Candide was not published until 1759.