The flagrant defiance of common sense by quantum phenomena is sometimes described as “quantum weirdness.” However, phenomena that are reasonable according to the laws of classical physics but apparently defy a quantum explanation are also possible; perhaps those should be labeled “anti-weird.” The Hanbury Brown and Twiss effect would be a prime example of anti-weirdness: Its explanation in the language of classical waves was straightforward, but the phenomenon appeared to defy quantum physics, at least at first. Arguments over its quantum description generated a rancorous—though ultimately fruitful—debate: The discovery of the HBT effect launched the field of quantum optics. 1 Although the effect was discovered during an attempt to create a tool for astronomy, its most useful applications turned out to be in nuclear and heavy-ion physics and, most recently, ultracold atom physics.
The history of the HBT effect is a colorful story of inspiration, dismay, controversy, and ultimate success....
