I was working today with a mathematics grad student, and in the lull of the work he asked me about why physicists insist on there being a unified field theory that unites all four forces of the universe into a single equation. I sort of paused for a moment and thought before I answered, and I ended up hand waving a bit and said that the logic of the physicist is that since nature does seem to operate logically and predictably, and that we've defined how nature works mathematically pretty well so far, that it stands to reason that there should be some unification of all the forces that control the universe. He pointed out that didn't really answer the question as to why we think there 'needs' to be a UFT. I bowed to that and just said, no, I suppose there doesn't need to be one ultimately. The universe could just have completely separate mechanisms for gravity and the other forces. I wasn't really happy with that, but I wanted to leave and he started ranting about how he thinks physicists just made up the idea of tensors, so I just peaced out. But it got me thinking more about it and I was wondering what you guys who obviously have lived and breathed this idea of a unified field theory for years think about why there needs to be, or maybe a more reasonable way to say it would be why does it 'look' like there is a UFT. What do you think?