I'm Sorry, Most of you are wrong.
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First off, light IS a electromagnetic wave, so therefore, speed of electromagnatism = speed of light. The effect of magnatism travels at the speed of light.
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Secondly, Gravity doesn't have a speed really. light and electromagnatism are made up of exchange particles called photons that travel at the speed of light. Gravity is theorized to be composed of exchange particles called gravitons, though no one has observed them, and there's not a lot of hope that anyone ever will.
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The catch is that Gravity is not a classic force field like Electromagnatism, the Strong and the Weak forces. According to General Relativity, Gravity is best thought of as an effect. The typical illustration is that of a bowling ball resting on a sheet of rubber. The bowling ball would warp the surface of the rubber sheet as a result of its weight. A marble rolling on the warped surface of the rubber sheet would follow a curved path similar to the path of the Earth as it orbits the Sun.
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Gravity is simply the warping of the fabric of space caused by the presence of mass. If we Imagine the rubber sheet without a bowling ball it would be flat. As we rest the bowling ball on the rubber sheet a depression is formed, small at first and confined to the immidiate vicinity of the bowling ball. But as the bowling ball sinks deeper, the depression spreads outward from the center of the bowling ball.
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The same thing would happen with the Sun. The spreading effect of the warping of space in the presence of mass is the closest you'll ever come to the \"speed\" of gravity. That being said, your question is what exactly is that speed? Newton thought as some of the posters here thought, that this effect would make its presence felt instantaneously across any distance. General Relativity predicts though, that this effect decreases at the square of the distance and does so at precisely the speed of light.
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Ergo the answer to your question, Gravity, does it have speed? is Yes, and that speed is 186,282 miles per second.
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A more interesting question is, Why does the effect of gravity propigate at the speed of light? ?
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One last point before I go. In the above illustration regarding the rubber sheet and the bowling ball to explain gravity (an illustration I did not come up with BTW), the bowling ball represents the Sun, the rubber sheet represents the fabric of space-time, and the marble represents the Earth. ?
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What does the pull of gravity on the bowling ball and marble represent?
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Why do we invoke gravity as an integral part of an illustration explaining gravity?[/b]