OK, so give us *actual* observations where either general relativity or quantum mechanics fail. Every single observation we have ever made is consistent with both. But we also know that the two theories don't like to work well together. And yes, we also know that we would need to use both for the center of a black hole, but *we don't have any actual data from the center of a black hole*.<quoted text>
"Quantum Mechanics is a well-tested theory and has withstood ALL the tests"
Now pay close attention here bobby,
If anyone finds a case where all or part of a scientific theory is false, then that theory is either changed or thrown out.
So here's the question: if you're trying to figure out what happens in the depths of a black hole, where an entire star is crushed to a tiny speck, do you use general relativity because the star is incredibly heavy or quantum mechanics because it's incredibly tiny?
Well, that's the problem. Since the center of a black hole is both tiny and heavy, you can't avoid using both theories at the same time. And when we try to put the two theories together in the realm of black holes, they conflict. It breaks down. They give nonsensical predictions. And the universe is not nonsensical; it's got to make sense.
So, we have a situation where two theories both work incredibly well, they are mutually inconsistent, but we have no *data* to determine what the next step should be. But people have made attempts: string theory is *one* of the theories that merges general relativity and quantum mechanics, loop quantum gravity is another. But we need observations and data that would be used to distinguish between them. We do not have this data and are not likely to get it soon because of the energies involved.
And this is yet another point: the realm where GR and QM start having issues with each other is *far* beyond any energy level we have been able to access. For anything we have actually been able to test, they both work quite well. Unless you are actually dealing with the center of a black hole, there is no problem. And if you can provide data from the center of a black hole, you can get a Nobel Prize, I promise you.