Is quantum mechanics nonlocal?

Various reasons have been given for supposing that quantum mechanics and the real world, insofar as quantum mechanics is an accurate description of it is nonlocal. These include: instantaneous collapse of a wave function when a measurement is made; the peculiar properties of entangled states of spatially separated particles, including violations of Bell inequalities; the finite extent in space of Newton-Wigner states in relativistic quantum theory. The talk will introduce and then analyze these ideas, with particular emphasis on entangled states, to see whether they indicate that quantum theory is nonlocal, or simply non-classical.