At the heart of physics* are two theories: Relativity, developed by Einstein a century ago, and quantum mechanics, which has been built over the last 60 years. Both theories are, in and of themselves, perfect. Every experiment run with either of them has confirmed their findings. Were it not for the existence of the other, there would be no question of their effectiveness. And yet, they are theoretically incompatible. Simply put, relativity requires a version of space that quantum mechanics cannot allow. There's also something about black holes, which is cool because black holes are cool.
Because the two theories are perfect in practice, there is no desire to discard either of them.