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some one states that the earth would travel in it path for 8 min if the sun vanished. The equations of gravity show the Moon would crash into the Earth and the Earth would head for Mars the instant the Sun is gone. Can someone show how there is a delta Time and the relaxing of the bend in space-time fields is finite?


marked as duplicate by John Rennie, Kyle Kanos, Emilio Pisanty, jinawee, Qmechanic Mar 16 '14 at 19:09

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  • $\begingroup$ The gravitational interaction is limited by the speed of light $c$, like all other interactions. $\endgroup$ – Danu Mar 16 '14 at 14:04
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    $\begingroup$ Related: physics.stackexchange.com/q/5456/2451 and links therein. $\endgroup$ – Qmechanic Mar 16 '14 at 14:11

Gravitational effects, as described by general relativity, are not instantaneous. Disturbances in spacetime travel as gravitational waves, with a velocity bounded by the speed of light $c$. If the sun were removed as you describe, we would experience the gravitational effects after a delay, depending on the speed of the gravitational waves.

The inability to act instantaneously is not a special property of gravity; the electromagnetic force mediated by the photon does not act spontaneously. Nor do any of the other fundamental forces, such as the strong force mediated by the gluon.


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