What *is* a photon?

Video Description

This video was supported by Screen Australia and Google through the Skip Ahead initiative. Animations by the extremely talented Kathy Sarpi: https://kathysarpi.com Link to the full series: https://www.youtube.com/playlist?list=PLg-OiIIbfPj3mDFx5zjVPtgiGwZMM4Erw Links to other photoelectric effect videos: This one has a very simple at home set up: https://www.youtube.com/watch?v=A9SSfZBMaH8 For this one you'd need to buy the device he uses, but the video is so well explained: https://www.youtube.com/watch?v=oYnp0WZDhYQ Here's an alternate way to do the experiment with an aluminium can: https://www.youtube.com/watch?v=WO38qVDGgqw There's so many other good ones! If you see one you think I should add to this list, please leave the name of the video and the channel in a comment! Huygen's optics' video about photons (highly recommended): https://youtu.be/SDtAh9IwG-I?si=8kWz13_ZEFnfAu-Y Confining the light causes it to have more colours. This is explained well in an excellent video by Ben Miles. But at first glance, the experiment seems to be a totally different one than what I explained in the video- so I'll explain what the connection is. In particular, it's only the "single slit" version of the experiment that's relevant for us. I said that the researchers confined a laser to a small space. The technique they used to do this was to have two lasers- one which is the source, and the other which is used to turn on and off a "switch" of sorts. What the switch does is it makes the material in the experiment go from transparent to reflective very quickly, then back. The source laser is shining continuously at the material. But the idea is that for the short while that the material is reflective a little section of the laser beam is reflected. That's the "confined" light- they took a laser beam that's always on and constant and isolated a small section, confining the whereabouts of the light. They then measured the colours of that light and find it's spread out. (This result is at the 8 minute mark) https://www.youtube.com/watch?v=NsVcVW9GI60 especially from 7:07