Ok, I am by no means an expert in this field I've just read a few books about it (poplular science books) and I'm going to begin a physics major next year. I've got a few questions though: 1. There are many different theories for quantum gravity, what makes physicists think one might be more correct than another? It seems to me like they are shooting in the dark. When one looks at the evolution of science what you see isn't educated guesses but reasoning based on empirical data - like I said I'm not too educated on QG but it seems to me like this is not what's happening, feel free to tell me that I'm completely misinformed. 2. What makes us believe there is such a thing as quantum gravity? Is is just because we think that it just should be that way? Is it because QM and GR are incomplete or make predictions that don't appear to be correct? Is there a chance that there is no QG or ToE? 3. Are there any books which deal with the above questions? I was thinking Lee Smolins newest book might. Sorry if I've insulted anyone who has devoted there lives to this sort of research, I too wish to study physics and possibly quantum gravity. I am merely seeking a greater understanding of why the search is on. Also sorry if this sort of thread is commonplace. I'm sure I've got more questions I just can't seem to think of them right now.