How can a fundamental particle decompose?

Question

Reading about the muon [1]: "... the muon is not thought to be composed of any simpler particles; that is, it is a fundamental particle ... Muon decay almost always produces at least three particles, which must include an electron of the same charge as the muon and two types of neutrinos".If the muon is not composed of other particles, how can it end up as a set of other particles?[1] https://en.wikipedia.org/wiki/Muon

pfortuny · Accepted Answer

It is because they are always very energetic. This, together with random quantum behavior, allows the “energetic-muon” to decay (not decompose) into different particles (usually electron etc.).
This is a quantum effect, and it is not a decomposition but the disappearing of the muon and the appearing of the others (+ a lot of energy in between, coming and going).
An electron is an electron. However, when moving between orbitals in an atom, it “gets” a photon if it jumps “out”, it “loses” a photon when jumping “in”. But it is just an electron (with more or less energy).

aristofun · Answer

I suppose the root of your confusion is in meaning of words.
With quantum mechanics there are no “real” particles to think about in terms of everyday life.
They all are just mathematical abstractions that help build models predicting the behavior of systems.
Nothing is really composed or decomposed in our everyday meaning. It’s just there are no better words to speak about such abstract concepts.

ffhhj · Answer

Is a grenade composed of a rapid expansion wave, fire, and a loud bang?