Could you explain what you mean by non-linear and acoustic?

Originally published at: Could you explain what you mean by non-linear and acoustic?

Well, it is a difficult concept, and actually, non-linear physics is a fairly recent development, but basically, in non-linear physics, the traditional forms of forces - electromagnetism, acoustics, gravity, strong and weak nuclear forces and so on - comprise a linear subset of a much wider range of things. The fundamental change is in the…