Question: Is it true that a banana produces a small amount of photons because of the anti-matter that reacts with the radiation produced by the potassium?

Lucien Heurtier answered on 30 Mar 2023:

Haha, that’s a fun question, thanks for that!

Absolutely, yes! The potassium can indeed be radioactive, so it emits (very slowly) some positrons (the anti-electron). Once this positron interacts with an electron, that produces photons.

I believe bananas are not the only one actually. Wood for instance can be dated using the radioactivity it contains, so I believe wood emits some light as well!

Now, to be honest, if you put a banana in the dark, you won’t see much light, for two reasons: 1) the light it emits is very low energy, so very likely in the microwave regime, that is light is not visible to the bare eye. And 2) because the number of photons produced is very small. Bananas are not that much radioactive (otherwise it would be dangerous to eat them), so the number of positrons produced is not that huge…

I hope I answered your question well enough! Feel free to ask more, and don’t forget…

… to vote for your favorite scientist 😉