I am brand new to Qunatum Mechanics, and I have just been reading through my first text assignment. I have really been blown away by some of the difficulty in this stuff. I had some questions, and I was hoping that here might be a good place to get them answered... 1) There is a proof that asks me to show the relation between the uncertainty in position and the uncertainty in the energy. I know the actual inequlaity and how to show the steps via the generalized uncertainty principle. My question is, how come there is uncertainty in the energy? I thought that there are specific and discrete states of total energy. Therefore why isn't the uncertainty in the Hamiltonian zero? 2) I am having some difficulty in understanding how a commutator functions. I understand its physical significance, but I do not understand how to find [A, B] for any given operators. Again, I am very new to this stuff, and I am sure that my questions may seem dumb to some people. However, if you could please help me out with understanding this initial stuff, I would really appreciate it! I am glad that there is a forum like this available with so many knowledgeable people to help us tyros.