I'm not doing physics at college but I want to dabble in the concepts and the mathematics of it. I already know the basic physics of motion, force and etc. (physics without calculus so far) and now I want to do something more advanced. My mathematics is fine ( basic calculus, complex algebra, linear algebra etc.) even though I have a lot of multi-variable calculus yet to learn. The point is, with mathematics I have all the resources I need and I find it easy to take it to any level I want. With Physics however, I don't know any good books or websites to get me beyond this elementary stage in physics. This is because I am self-taught. I would be so grateful if people could recommend me some books or websites bearing in mind the following: - My Physics knowledge is elementary, despite my maths knowledge - I do not want to become a physicist, I just want to have an understanding of the important equations in relativity and quantum physics. I am not interested in doing long drawn out mechanics problems but I am willing to slog a fair bit to get to my goal (just not too much!). It's having a mathematical understanding of the concepts I'm after. - The cheaper the better! I'm poor and I can't afford to spend a hell of a lot. This aside, I am willing to fork out a bit if you really think the book is worth the money it's demanding. Thank you very much!