physics has a philosophical bias towards monism. of course, most physicists have their head so far up their mathematical ass that they don't know anything about metaphysics, so they don't even realise that they are so biased.

on they go trying to "unify" all of their theories into one theory. this bias comes about as a result of the human enjoyment of simplicity rather than because of any philosophical or scientific justification. we apparently have to unify all the forces into one force, a "Grand Unified Theory" because the complexity of reality must all have one hidden deeper explanation. and ooooh electrons and protons just happen to have opposite charges, so we have to unify matter too! then we'll have to unify matter and forces, and unify that theory with gravity and relativity, and unify all THAT with dark matter and on and on and on. it's simply assumed that the universe has one underlying and rational nature which a theory of everything can explain. the universe could just as easily have several fundamentally distinct aspects that cannot be unified into one, but they ALWAYS try to unify, and RARELY try to split things apart. gravity could be the result of the push and pull of 20 different things for all we know.

monism may be correct. perhaps the universe does have one underlying nature, one origin, one explanation. but perhaps it has two, several or even many totally different and incompatible aspects. there's no way to know until you know the whole story, so stop being so simple minded and dragging us so heavily in one direction.