- #36
kaplan
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bhobba said:Exactly why do you believe QFT doesn't describe gravity:
http://arxiv.org/abs/1209.3511
It isn't valid beyond about the Plank scale - but then again neither is QED, the Electroweak theory, or QCD.
Thanks
Bill
The standard model would be valid to arbitrarily high energy scales if it wasn't coupled to gravity. In other words it's gravity that causes all the problems.
How do I know gravity isn't a QFT? I don't, for sure - for example gravity (or really string theory) in asymptotically anti-de Sitter spacetimes is a QFT. But if gravity is a QFT it has to be in some very non-trivial sense like that one. For one thing, cross-sections in gravity grow like the center of mass energy s (because the radius of a black hole is proportional to its energy), and QFTs don't do that.