String theory, the multiverse.

Or are you referring to UFO's and the 2012 end of the world?

The electric friction between molecules and poly ions. It spins on the string because of a force which is studied in physics.

Barton Zwiebach has written:

'A first course in string theory' -- subject(s): String models, OverDrive, Nonfiction, Physics

They aren't. You might be talking about the frets, which has to do with the physics of a vibrating string. Cutting a string in half increases the pitch one octave, so you need to shorten the length of the string less as the string shortens to get the same change in pitch.

You could do worse than consider the 15 science divisions at the head of the SCIENCE subdivision in this answers.com. That will give you a good start.

You'll find that several of the primary divisions in science have, in turn, subdivisions below them.