Are We Going to Get a Whole New Theory of Gravity?

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Have you ever heard of Le Sage gravity? It’s an attempt to come up with a mechanical explanation for why massive objects move towards each other. It’s three hundred years old, but some modern scientists think it might still be the best way to think about gravity.

The Le Sage theory is sometimes called the Fatio theory, but not often, because it follows the one immutable law of physics—nothing is named after the person who first came up with it. Nicolas Fatio de Duillier is one of those people whose life could be turned into a mini-series, except none of the watchers would believe it. While still at teenager he corresponded with and then worked with Jean Dominique Cassini. Later, he traveled around Europe, meeting Christiaan Huygens, Jacques Bernoulli, and Edmond Halley. He got into a feud Gottfried Leibniz. In 1687 he uncovered and foiled a plot to assassinate the Prince of Orange. A few years after that, in 1690, he came up with an explanation for why objects seem to move towards each other due to an invisible force.


This theory was not much regarded until it was refined by George-Louis Le Sage, a quiet man who practiced medicine, read philosophy, and tutored aristocratic children in mathematics. Today he’s best remembered for inventing an early telegraph, which had one wire for every letter of the alphabet. His legacy may change if somehow his theory of gravitation works out.

The Fatio-Le Sage theory supposes that the world is full of tiny little particles, none of which we can see. These exert a constant pressure on us from every angle. If we’re floating in space, then the pressure from all those moving particles equalizes just as it would if we were floating in a tank of water. When one object gets close to another object, the objects shade or shelter each other from the particles. This absence of particles, or corpuscles, between the two objects, means that the corpuscles hitting the outside of the two objects would push them together. Since we can’t see the particles, to our eyes it looks like the objects are falling towards each other because of some invisible force.

The idea has its devotees and has been discarded and revived since it was first published. Today, in light of the idea that gravitons govern the gravitational interaction between two objects, some scientists believe that Fatio and Le Sage might have been on to something, even if their ideas have to be modified.


Image: ESA/Hubble & NASA