I listened to a podcast discussing gravity and had this question. My apologies if it has been aptly answered somewhere else.
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Possible duplicates: https://physics.stackexchange.com/q/2767/2451 and links therein. – Qmechanic Aug 18 '19 at 15:01
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Light is also a wave that doesn’t require any medium. – G. Smith Aug 18 '19 at 16:36
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Spacetime is the medium. – user45664 Aug 18 '19 at 16:48
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Gravity is described classically by General Relativity, and yes it also has gravitational waves :
Gravitational waves are disturbances in the curvature of spacetime, generated by accelerated masses, that propagate as waves outward from their source at the speed of light. They were proposed by Henri Poincaré in 1905 and subsequently predicted in 1916 by Albert Einstein on the basis of his general theory of relativity. Gravitational waves transport energy as gravitational radiation, a form of radiant energy similar to electromagnetic radiation.
So it is a wave distortion of space time due to changes in gravitation, not a medium in the sense of matter.
In efforts of quantizing gravity the graviton is proposed to build up the classical general relativity wave in a way similar to photons building the electromagnetic wave.
anna v
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Thank you. How is it that we know they travel at the speed of light? Why do they? Is the speed of a gravitational wave also absolute? – cadrello Aug 26 '19 at 01:36
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It is an assumption in the theory of gravitation, that is in all the mdels, and has not been invalidated.. It follows from the mathematics used, – anna v Aug 26 '19 at 03:19
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In general relativity gravitation is described by the curvature of spacetime and does not need any medium. Objects bend the spacetime and therefore other objects feel their gravitational force.
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