How can someone studying theoretical physics for their undergrad degree get a phd in computational fluid dynamics? Does it still mean that they are studying theoretical or applied physics? Also in what sense can computational physics help you understand more about the nature of the universe (how does it relate to theoretical physics)? And finally why do people always say that science and math give us a model of the universe. I always though that what we call laws and theories are what govern the workings of the universe. And finally whats the closest subject from theoretical physics that overlaps with chem.engineering or vice versa?