Why is there a possibility for unification of GR and quantum mechanics when they are fundamentally in contradiction?

Question

To me it's quite obvious that these theories are mutually exclusive simply by fundamental logic.

QM at its very core is dependent on flat spacetime background and its implied conservation laws (momentum, energy etc) but in general relativity momentum for example or even energy are not conserved.this seems to me like an obvious logical contradiction.

First of all both relativity and QM have lots of extremely accurate predictions, but even in their own domains fail terribly in most instances. For example when you apply GR to cosmology you have the lambda cdm model in which we know that we don't know 95 percent of what makes the universe. So either this is a failure of GR(if there is no CDM) or if relativity is right that the standard QFT (STANDARD MODEL) is wrong because it doesn't apply to at least 95 percent of reality.. This is one example of the consequence of the fundamental contradictions in question.

Than there is the vacuum catastrophe, the fact that GR and QM give completely contradictory values of the ZPE.

I don't think it's a matter of being clever to come up with some math that will unify them, but a matter of simply finding the quantum nature of reality without forcing GR to come out as it's macroscopic realization.

Answer 1

QM has been developed primarily to describe phenomena that we can observe in the lab; GR primarily describes phenomena we observe astronomically. Of course our explanations of those phenomena are different, and of course the descriptions work best in their own domains.

A contradiction of that sort simply points out disagreement between such descriptions. The contradictions/disagreements are not built into the laws of physics; they are built into models (theories) we have constructed to describe the laws of nature as observed at different ranges of field strength, spatio-temporal geometry, energy, mass, etc. The disagreements are in ranges of those parameters that are currently beyond our experimental and observational reach. We hope to be clever enough someday to come up with a single, relatively simple, model that accurately describes physics at all ranges of those values.