What is the speed of gravity?

Today’s scientists theorize that gravity might travel in space at light speed, as a massless particle called a “graviton.”

The “speed limit” of gravity, so to speak, is thought to be the speed of light.

Gravity was first scientifically explained by Isaac Newton in the late 1600’s. He thought that gravity existed as a force between two objects, and that gravity traveled instantaneously across space – that, for example, Earth immediately “felt” the sun’s pull, and that, if the sun disappeared, Earth would instantly fly out of orbit into the void of space.

But when Albert Einstein developed his special theory of relativity in 1905, he concluded that no signal in the universe could travel “instantaneously.” He believed that nothing could travel faster than the speed of light – about 300 thousand kilometers, or 186 thousand miles per second. Not even the tug of gravity.

Gravity, Einstein proposed, is not a force that travels out from a massive object to tug instantly on everything around it. Rather, gravity is a “field” that bends space and time.

Today’s scientists theorize that gravity may be mediated in space by a particle called a “graviton.” According to this theory, this particle is massless, and transmits gravity at the speed of light.

Work in discovering and testing this particle is still ongoing.