What is an Electron a Wave In?

If particles are waves, then they are waves of what?Every wave has peaks and zeroes of something - sound is compressions and expansions of the medium, EM waves are varying electric and magnetic fields etc. What exactly is varying in electron or proton waves? Is the medium of propagation just empty space?
- Khushro (age 55)
Pakistan

Great question. So far as we know currently, these elementary particle waves are just what the world is made of, not waves in some more fundamental medium. That goes for electromagnetism too, made of photon waves. It wouldn't be surprising if at some point a deeper theory is developed, in which the current elementary particles appear as waves in some more fundamental field, e.g. some string field. 

Will this business of finding deeper mediums reach a rock-bottom or go on forever? No one knows.

Mike W.

(published on 01/01/2018)