One of the most frequent questions in this forum is why there is a contradiction between General Relativity and Quantum Mechanics. The most frequent answer is that, in high-energy conditions, some integrals diverge, giving nonsense. I could not find a mention of which integrals one is talking about. Could someone give me a corresponding link? Thanks. Notes: (1) Other favorite answers concern, more or less in this order of frequency: (a) that the combined theory turns out to be non-renormalizable (but since there are non-renormalizable theories which work, this in itself is not a condemnation). (b) the continuity of GR and the discontinuity of QM (but it seems the consensus on that is that GR is an approximation to QM) (c) the locality of GR and the non-locality of QM (but non-locality seems to have won out), (d) the differences in symmetries (e) the arrow of time (f) Schrödinger's equation goes haywire (but no specifics were given in that answer) (2) I was not sure whether this question should go under the Relativity Threads or the Quantum Mechanics Threads.