Photons and the loss of determinism
PROFESSOR: Determinism. And it all begins with photons. Einstein reluctantly came up with the idea that light was made of quanta-- quanta of light called photons. Now when you think of photons, we think of a particle. So everybody knew that light was a wave. Maxwell's equations had been so successful. Nevertheless, photoelectric effect-- Planck's work-- all were leading to the idea that, in some ways, photons were also particles. So when you think of a particle, however, there is an important difference between a particle in the sense of Newton, which is an object with zero size that carries energy and has a precise position and velocity at any time, and the quantum mechanical idea of particle, which is just some indivisible amount of energy or momentum that propagates. So light was made of photons-- packets of energy. And a photon is a particle-- a quantum mechanical particle. Not in the sense that maybe it has position and velocity determined or it's a point...