I am an undergraduate student of phyiscs major. If i want to work on Quantum Gravity then do i need to continue MSc Physics? Or Others like High energy phyiscs or particle physics or Astro? My aim is to be a teacher at a top University and Research on Quantum Gravity & String theory. Can you guide me? I mean which brunch of physics should i choose, which one is bad for career,how should i advance etc.. just like that. Thank you.