Ive seen a lot of comparisons between the conflict of electromagnetism and classical mechanics before relativity fixed it and the conflict of quantum mechanics and relativity. I know why classical mechanics and electromagnetism could not both be true (e.g. E&M says c is constant but CM doesnt). Are there any similar examples of things that are true in GR or QM but are not true in the other? All I know of is that QM says that when particles tunnel they travel at faster than c. However this isn't really impossible in GR as long as the mass is imaginary (which I believe it is while a particle is tunneling).