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Name: Thomas
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Question:
Yesterday, I was at the Stephen Hawking lecture at Cal Tech. He described Einstein's Black hole as a very large "dent" in space-time created by super dense and heavy objects. He gave the example of a rubber sheet and something like a lead ball. The ball will create a "black hole" in the rubber sheet. The objects will fall into the dent and this is Einstein's gravity. If this is gravity than density and weight would not effect the size of the dent and only the mass or size of the object would effect the gravity. Stephen Hawking described that using the uncertainty principle that light can go faster than 186,000 miles per second and can therefor escape from the Black hole. How does this redefine the theory of relativity? (2008)



Replies:
In a sense yes. The classical theory of relativity assumes classical mechanics. What Hawking did was to apply the Heisenberg Uncertainty Principle to black holes. The Uncertainty Principle is a quantum mechanical concept. At a sufficiently small scale there is not ever an infinite sharp boundary, there is always a small but non-zero probability that a particle, even light, can "tunnel" through a finite barrier. Far be it for me to contest Hawking's interpretation, but regardless of how you want interpret the phenomenon, black holes can "leak".

Vince Calder


Thomas,

It does not redefine relativity. This is the place where neither quantum physics nor relativity applies correctly: a large, very dense bundle of matter. When things are very small (an electron or an atom) and not TOO fast, quantum physics works well. When things are far apart and very fast, relativity works well. When things are not too small and not too fast, Newtonian physics works well. Isaac Newton's theories are an average effect of quantum physics and a small-speed approximation of relativity. When you get to situations like black holes, things are too massive and too fast for quantum physics. Things are too close together for relativity. This is why string theory is being developed. Quantum physics works well with electromagnetic force and atomic forces. Relativity works well with gravity. String theory is an attempt to find the link between relativity and quantum physics, to find a theory that applies in all cases. Neither quantum physics nor relativity is perfect.

Dr. Ken Mellendorf



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