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Speed Of Gravity...

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Posted by nåte/">nåte on October 10, 1998 16:37:16 UTC

Here is something I found very interresting and exactly what was concerning me about gravity... read on... :)

"When the subject of "black holes" first comes up in physics classes, a frequently asked question is "If nothing can escape the event horizon because nothing can propagate faster than light, how does gravity get out of a black hole?" The answer usually provided is that the field around a black hole was frozen into the surrounding space-time prior to the collapse of the parent star behind an event horizon, and has remained in that state ever since. By implication, there is no need for continual regeneration of the external field by causal agents from the source.

However, let us suppose we have a binary black hole, with the two collapsed stars in elliptical orbits around one another. Then each field must be continually updated by a changing contribution from the orbiting field of the other. How does each field know what it is supposed to do if it is no longer communication with its source mass hidden behind an event horizon? If the curvature of space-time at a point near black hole A becomes zero because black hole B is equally distant, what makes it non-zero again once black hole B recedes?"

  • Another cool pic of time/space graph dipiction...

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