Quantum non-locality, black holes and quantum gravity

It is now generally taken for granted that quantum gravitational effects will appear at Planck scale and no earlier. However, there is no theory of "quantum gravity". Since Planck scales will not be experimentally accessible in the foreseeable future, purely speculative theories have been proposed, whereby the desired effects could appear at scales before the Planck scale. There has been no experimental support for these theories. On the other hand, Penrose has forcefully argued that the tests of Bell's inequalities demonstrate nonlocality of Nature at the quantum level that is incompatible with the usual picture of spacetime at meter and and even kilometer scales. He has also argued that the state vector reduction is due to the effect of quantum gravity. In this paper the onset of quantum gravity is probed by confronting the extreme quantum (a photon) by the extreme of a gravitational field (a black hole).