The Terror of Threes in the Heavens and on Earth

Physicists have long explored how phenomena in groups of three can sow chaos. A new three-body problem, they warn, could lead to not only global races for new armaments but also thermonuclear war.

New York Times Science cover

Isaac Newton was baffled. He was already famous for discovering how gravity holds the universe together and for using that knowledge to predict the movements of celestial bodies, such as the moon’s path around the Earth. Now, by taking the sun’s gravitational tugs into account, he sought to improve his lunar predictions. Instead, it made them worse.

The setback, Newton’s friend Edmond Halley reported, “made his head ache, and kept him awake so often, that he would think of it no more.” Newton felt his defeat so keenly that he recalled it more than once in his old age.

Today it’s called the three-body problem. Famous in science and science fiction for orbital perturbations and chaotic phenomena, it’s recently become a concern of atomic experts and military 

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