For 10 points, name this principle of quantum mechanics which in its original formulation states that you cannot precisely know a particle's position and momentum at any given time.
A generalization of this statement to arbitrary operators gives an inequality featuring one half the magnitude of the expectation of the commutator of those two operators. That generalization of this statement is named for Robertson and is a special case of a statement named for Schroedinger. Thought experiments such as a box lined with mirrors from which one photon is allowed to escape were used in a series of debates between Bohr and Einstein over this principle. One of these exists for any pair of noncommuting (*) observables, while considering the evolution of an arbitrary operator allows one to find one of these for energy and time. For 10 points, name this principle of quantum mechanics which in its original formulation states that you cannot precisely know a particle's position and momentum at any given time.
A generalization of this statement to arbitrary operators gives an inequality featuring one half the magnitude of the expectation of the commutator of those two operators.
Heisenberg uncertainty principle