  We review studies of the fluctuations of light made accessible by the
invention of the laser and the strong interactions realized in cavity QED
experiments. Photon antibunching advocating the discrete (particles), is
contrasted with amplitude squeezing which speaks of the continuous (waves). The
tension between particles and waves is demonstrated by a recent experiment
which combines the measurement strategies used to observe these nonclassical
behaviors of light [Phys. Rev. Lett. 85, 3149 (2000)].
