Ask Ethan: Is Light Fundamentally A Wave Or A Particle?
“I wonder if you could help me to understand John Wheeler - the delayed choice experiment and write an article about this.”
Imagine that you’ve got a photon, and you’re performing an experiment on it. You send it through a beam splitter, so that there’s a 50% chance it goes down one path and a 50% chance it goes down the other. You have a mirror along each path, and they reflect the light to the same point, where you have a detector. So you fire the photon, and then, one light-travel-time later, you see it at the detector either following path #1 or path #2. But what if, just before the photon arrives, you put another beam splitter in there just before the detector?
Will you see an interference pattern, or did the photon simply take either path #1 or path #2? That’s the delayed choice experiment; find out what reality says today!
