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Gravity Probe B

Testing Einstein's Universe

Special & General Relativity Questions and Answers

Are there really such things as gravitons?

We do not know, but physicists believe that because gravity is a force that shares many technical similarities to the other three natural forces, it must also have a quantum particle that mediates it, and this is called the graviton. It is very unlikely we will ever detect individual gravitons because they interact about 10^40 times weaker than the electromagnetic force produced by photons.

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All answers are provided by Dr. Sten Odenwald (Raytheon STX) for the NASA Astronomy Cafe, part of the NASA Education and Public Outreach program.