Plainpicture/Mia Takahara
How do we know that gravity has the same speed as light? And why is this the case?
Ron Dippold
San Diego, California, US
In Newtonian physics, gravity was thought to be instantaneous. But in Albert Einstein’s general theory of relativity, the speed of light, c, is the fastest possible speed for any interaction that carries information, not just light. Gravitational waves carry a lot of information, which we measure with detectors like LIGO and Virgo.
Unfortunately, gravity is by far the weakest force, so the speed of gravity hasn’t yet been precisely measured in a laboratory. Instead, we have…
