What kind of resources does a university provide that are so important to a theoretical physicist? I pose this as a serious question. I know not all fields of theoretical physics are the same, but lets just take string theory for example. It seems to me that string theory at the moment is purely mathematical work. Which means all you really need is pen and paper, and maybe a laptop. So after someone obtains a PhD and all the knowledge that comes with it, what is the advantage of gaining a professorship at a university when you can do all that work from home? (other than collaboration with other scientists... and getting paid). I mean you wouldn't need to perform any experiments and you could submit your papers to scientific journals whenever you please, right?