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Name: Mike
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Location: AL
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Question:
Can an intra/intergalactic Gamma Ray Burst's "gravity wave" arrive in the solar system prior to the "light wave" of such a burst?



Replies:
Best evidence to date is all forms of waves -- gravity and electromagnetic -- travel at the same speed, the speed of light.

Vince Calder


Mike,

No! Nothing carrying energy can travel faster than the speed of light! In fact, it is believed that gravitational effects travel at exactly the speed of light.

This is equivalent to saying that the graviton (the particle that carries the gravitational force as the photon carried the electromagnetic force) has zero mass and so travels at the speed of light.

If you search the web, you can easily find sites that argue that gravitational waves must travel at infinite speeds or else the earth, for example, would spiral into the sun (http://www.metaresearch.org/cosmology/gravity/speed_limit.asp). That is because the sun would look to the earth as if it were in a position where it was eight minutes ago (the time it takes for light to travel from the sun to the earth). The sun would not then exert a central force on the earth (always towards the center of the earth's orbit) but would be pulling back on the earth.

The answer to that (I believe) is that the earth IS spiraling into the sun due to this effect. The effect, however, is small and further can be explained that the earth-sun system is emitting gravitational radiation that carries away the angular momentum of the earth around the sun that is lost.

In fact, measurements on a binary pulsar, http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html, indicate that the speed of gravitational waves equal the speed of light to within an accuracy of 1%

Best, Dick Plano, Professor of Physics emeritus, Rutgers University



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