Is light a particle or a wave?
Physicists have decided by saying that it is a wave or a particle depending on whether we are thinking on a large scale or "almost" the infinitely small of quantum mechanics
We have an argument to claim that on a large scale it is a wave
By the way, did you know that a liquid wave is made up of water molecules that jostle each other from the point of a shock that set them in motion and which gradually spread to the shore? A sound wave is molecules of air, wood, iron etc. jostling each other, depending on the medium in which the sound propagates.
Each molecule after having jostled the following returns to its place due to the attraction of the other surrounding molecules of the gas or the solid in which the waves are propagated. The'inertia of these molecules cause them to exceed their equilibrium point and they swing like a pendulum around their position until friction eventually brings them to a halt, unless there is no friction as in a plasma or some other synchronized shock occurs.
This could make physicists think about what a quantum of action might be. And why not a corpuscle whose quantity of matter plus its energy would be equal to this indivisible elementary energy. The fundamental brick of the universe... while waiting for something better, of course.
Ok, it's brain storming... Sorry if I upset you, I thought I saw a quantum apple falling, I must have dreamed.