"It seems odd to assume that just because throughout history we've unified more and more concepts that all of physics can be unified. What if there's a limit?"

"It seems odd to assume that just because throughout history we've unified more and more concepts that all of physics can be unified. What if there's a limit?" Think of that question as akin to Hilbert second problem[1]: he wondered if the axioms of arithmetic were consistent -- back then, it seemed likely. Gödel came along and showed that no proof of it can be carried out within arithmetic itself. In a sense, the problem isn't entirely solved; but we now do know that we can't know. Perhaps someone will come along one day and give a similar answer in physics. [1]: http://en.wikipedia.org/wiki/Hilbert's_problems http://en.wikipedia.org/wiki/Hilbert's_problems