what is a light wave a disturbance of?
It’s not a disturbance of any substance, but of electromagnetic fields. If you have charged objects at rest, they produce an electric field. If the charges are moving in a regular way, you get a magnetic field. If the charges change the way they’re moving, the electromagnetic field changes, too, but it doesn’t do so instantaneously. It’ll change first close to the charges, with the changes spreading out around them. This spreading change in the field is a light wave. So you already see how light can be a particle, and it can be a wave, too. But how can it be both at once? Well, it can’t, really. Some experiments will definitely show that light is a particle: Einstein’s Nobel Prize was actually for the photoelectric effect, where he showed that light carries energy in discrete amounts, a certain amount per particle. And some experiments also show that light is definitely a wave: It exhibits interference patterns, which is something that only waves do. But there is no experiment which ca
