learning and understanding

CIP asked "from what books did you learn QM, QFT, and GR?"
I guess it depends on your definition of "learning" ...

I read several pop.sci. books as a kid, including Misner, Thorne & Wheeler 8-)
So I had some idea what physics was about before I went to university.

But I would say I learned relativity from the books of two Austrian physicists, Sexl & Urbantke.
I learned quantum theory from the Berkeley lectures and Landau & Lifshitz.
And I learned QFT from xeroxed lecture notes and Ryder.

Of course there are many good books available now and some really good online lectures, e.g. Lenny Susskind.
Wald, Zee and Zwiebach are good books imho.

But I should also mention that I learned a lot about quantum theory in a seminar with Anton Zeilinger, which included eye opening interference experiments with slow neutrons at a research reactor in Vienna.
I think I really learned relativity during my master thesis, writing a program to numerically integrate the equations to simulate the gravitational collapse of a scalar field into a black hole.
And I really learned something about QFT by writing programs to simulate lattice field theories; including attempts to simulate quantum gravity. We did not really succeed, but I learned quite a lot along the way ... in some sense moving from Itzykson & Zuber to Itzykson & Drouffe.

Last but not least, I should mention that our best theories contain several unsolved mysteries: naked singularities, closed timelike loops, the 'interpretation problem' of quantum theory (*), Landau poles, the 'direction of time' etc.
They are ultimately incomplete and even inconsistent and therefore one might say that nobody really understands them ...


(*) Physicists cannot agree if quantum theory describes one or many worlds, while I prefer a zero worlds interpretation.

alien math

Perhaps we should think more about alien math (pdf), since they seem to be everywhere now (see my previous post).

Or perhaps we should just try to solve some weird math problems, like this one:
"One day it started snowing in the morning at a heavy and steady rate.
A snowplow started out at noon, going 2 miles in the first hour and 1 mile in the second hour."
What time did it start snowing?"

You should assume that the snowplow's speed is inversely proportional to the height of snow.

You can find the solution here and I post this problem and link mostly for Lee, who likes math puzzles.
I think MindYourDecisions is a great source ...