In virtually every popsci book you read there's a discussion of a fundamental incompatibility between general relativity and quantum mechanics. Specifically, talk is often made of calculations that return infinite probabilities- which are obviously meaningless. I'm curious as to what it is specifically that we cannot calculate? Also, are there any other areas of tension between the two formulations? The only other one I know of is that if one takes the collapse of the wavefunction to be "true" (i.e. to provide an ontological description of reality, rather than describing what we know about reality) then this cannot be made lorentz covariant (as it happens instantaneously, and simultaneity is a relative concept), so cannot be conceptually reconciled happily with special relativity (despite the fact that we have relativistic equations such as the Dirac and Klein-gordon equations). I'm a second year (UK) undergrad in maths and physics if that helps pitch an answer to the highest level I could understand. Thanks in advance for your help!