List the four fundamental interactions of nature.
A negative muon (μ−\mu^-μ−) is an unstable particle. State the products of the decay of a free negative muon.
Explain which of the fundamental interactions is responsible for the decay of the negative muon.
The electromagnetic force between two approaching protons causes them to repel and change their directions of motion. Explain, using the concept of exchange particles, why the proton paths change.