Speaker
Description
The photoelectric effect is often presented as the definitive experiment proving that photons exist. This is a misconception. In fact, several persistent myths appear in standard treatments of the photoelectric effect, including: (i) that classical physics cannot produce a frequency threshold for photoemission; (ii) that classical physics necessarily predicts long delay times before electrons are emitted; and (iii) that Einstein’s photoelectric equation, by itself, demonstrates the particle nature of light.
While these statements are widely taught, they are all wrong. The photoelectric effect does not establish the existence of photons. What it does show is that electrons in matter must be treated quantum mechanically, and that photoemission can be used as a sensitive mechanism for detecting individual quanta of light. Indeed, the photoelectric effect underlies photomultiplier tubes and enables the G2 experiment, which provides the correct, unambiguous evidence that photons exist, when it is performed with a single-photon light source.
In this talk, I will describe a conceptually clean and historically accurate way to teach the photoelectric effect without relying on these myths. This approach is part of a broader effort to re‑envision how quantum mechanics is introduced in the sophomore‑level modern physics curriculum.
