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The Question

(Submitted September 05, 1998)

I am a first-year college student and I have a questions about gravity. Is it known how fast gravity waves travel?

The Answer

Gravitational waves, just like photons, are waves that travel at the speed of light. However, even now, astronomers can not detect them directly, but can observe their effect on the bodies emitting them.

Gravitational waves are believed to be emitted close to compact stars, like a neutron star or a black hole. Just as ripples spread away from a stone tossed into a pond, so gravitational waves spread across space, bending it up and down. Two scientists at the University of Massachusetts, Taylor and Hulse, were able to prove their existence from observing a binary system of pulsars. They proved that gravitational waves do exist and were awarded the 1993 Nobel prize in Physics.

David Palmer & Samar Safi-Harb
for Ask an Astrophysicist

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