10/06/2024
If electrons have no size, how can two electrons collide?
Now that is an interesting question!
And the answer is… electrons don’t collide. Well, not in the conventional sense anyway.
That is to say, electrons do not interact with electrons directly. (Or, in the language of quantum field theory, the electron field is “linear”, free of self-interactions.)
However, electrons do interact with the electromagnetic field: i.e., they emit and absorb photons. And they, on account of their electric charge, act as sources of the electromagnetic field, changing its properties.
When two electrons get close to each other, each electron begins to respond to the changes in the electromagnetic field due to the other electron. Or, if you wish to use that language, they exchange virtual photons at a growing rate. The closer they are, the more furious this exchange gets, manifesting itself as a repulsive force between the electrons. As a result, the two electrons “bounce off” each other (even though they never actually touch), an event that we describe as a collision.
