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Originally Posted by Jamie Michelle
Quote:
Originally Posted by trish
Hi Jamie.
I still have to differ with you on
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General relativity is not known to be inconsistent with quantum mechanics.
Einstein’s classical theory of gravitation predicts a binary star system will lose energy at a continuous rate in the form of gravitational radiation. The prediction is at odds with quantum theory which holds that all mechanical systems gain or lose energy discretely. The two conceptions of nature are mutually incompatible. One of the theories must be dropped or modified. The procedures for modifying and adapting a classical field theory to quantum theory are somewhat standard, but far from universal; i.e. the fittings have to be handcrafted. For example, the correct Hamiltonian operator for the quantized field theory is usually inspired by but not determined uniquely by the form of the Hamiltonian for the classical field theory. So there are many different reasonable ways to attempt a quantization of the general relativity. The problem is none of the quantized theories of GR that have been constructed so far is consistent with nature. For example, the Feynman-Weinberg quantum gravity is not normalizable. ...
Again, it's a popular misconception that general relativity contradicts quantum mechanics, since that's how it's often incorrectly described. But as Prof. John Donoghue and Dr. Tibor Torma have shown, the Feynman-Weinberg Lagrangian has not contradicted experiment, and it will not contradict experiment so long as the renormalized values of the infinite number of new coupling constants are adequately small. ...
And how does this address the issue of continuous orbital decay as opposed to discrete orbital decay? It doesn't. We don't need experimental evidence that two theories are mutually incompatible when they make conflicting predictions. When (or if) we have experimental evidence of the existence of gravitons, then we'll have experimental evidence of the conflict between GR and QFT, if you so require it.
That is not to say some modification of GR won't be found that's compatible with QFT...that is everybody's hope afterall. It hasn't been found yet. You said yourself that in Tipler's theory the relevant series diverge. Let's use the example of a satellite again. If the series expansion for the wave function of a satellite diverges, then the theory can make no predictions about the position of the satellite. You can add up the first 100 terms and base a prediction on that, but that would your prediction, not the prediction of the theory (which requires all the terms to be summed). If you add up the first thousand terms instead, you'll get a different prediction because the series is not stabilizing, it is...afterall...diverging.