Math in Theoretical Physics

I have a casual interest in cutting-edge theoretical physics, which causes me to read books like Lee Smolin's The Trouble with Physics. Unfortunately, I do not have enough training in either theoretical physics itself or the math involved in the most interesting stuff (e.g., particle physics, string theory, quantum gravity) to get a full understanding of any of the parts of it. That's why I hope that the approach to the current problems that turns out to be correct happens to be the one with the easiest math. In other words, please not string theory.