1. The problem statement, all variables and given/known data This is a true or false question on a practice test. I'm having a hard time making sense of it. Here it is: Two operators A and B do not share eigen states a(n) and b(n) where n=1,2,3,etc. A measurement of A is made and the system is found to be in state a(1). If the measurement of A is repeated at some later time, and if A does not commute the Hamiltonian H, the system may be found to be in a state other than a(1) (True or False). 2. Relevant equations N/A 3. The attempt at a solution My guess is true, but I'm not sure how the phrase about the Hamiltonian plays into this. Thanks for your help!