All those Theories!

All this while I have been studying all these theories. Some seem to co-exist, some seem to complement, and some contradict. Why so?

Why all these theories anyway? What is the use?

Every time I read about a theory, I seem to understand where its coming from, atleast superficially. But when I try to compare it with another theory, I come up with a blank. I don't know why... Its like there is some kind of block, that won't let me get to the depth of it.

Its like as I study, over time, science seems to go deeper and deeper into reality, and suddenly, as if someone slapped it, it takes a step back, and starts viewing things in a completely different perspective. And that slap part started with Quantum Theory. Its like it turned everything upside down. I have always had trouble visualizing it, and I am sure I am not the only one.

Even my education, I only now realize, had been like that. And perhaps that is why I found it confusing. My syllabus is college too had a big role to play in that. Every semester we were introduced to new and new subject and concepts without any background or any obvious correlation whatsoever. It was like, one day, you take the radio, pull it apart and study it. Next day you take the fan, pull it apart and study it. Third day you take your computer pull it apart and study it ... and so on. There was absolutely no structure to it.

But the most mind boggling part of all this is the question of which theory to apply where??

All learning happens in start and stops and not always in a straight line, and that is true for development of science too. But I wish I had a little more clarity.