Sen 2013 says,

...we apply Euclidean gravity to compute logarithmic corrections to the entropy of various non-extremal black holes in different dimensions [...] For Schwarzschild black holes in four space-time dimensions the macroscopic result seems to disagree with the existing result in loop quantum gravity.

How serious a problem is this for LQG? Does this mean that LQG doesn't have GR as its semiclassical limit? Does that mean it's a dead theory, or maybe just that it needs to be modified? Is the technique using Euclidean gravity reliable?

Since I'm not a specialist, I'd be interested in a hand-wavy explanation of what the Euclidean gravity technique is about.

Sen, http://arxiv.org/abs/arXiv:1205.0971

  • 2
    $\begingroup$ LQG has spun off a large number of different models, none of which have gone very far towards recovering the classical limit. So any predictions made at any stage of the research program are not robust, and therefore it can keep coming back. $\endgroup$ – Mitchell Porter Jul 1 '13 at 4:36
  • $\begingroup$ related: physics.stackexchange.com/q/69098 $\endgroup$ – user4552 Jul 1 '13 at 10:14
  • $\begingroup$ Cross-posted here physicsforums.com/showthread.php?t=699647 , got some interesting comments. $\endgroup$ – user4552 Jul 3 '13 at 0:44

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