Virtual Particles and the Four Forces
William J. Mullin · Oxford University Press eBooks · 2017
The four forces in nature—electromagnetic force, strong nuclear force, weak nuclear force, and gravitational force—arise from the exchange of virtual bosons: photons, gluons, W bosons, Z bosons, and gravitons. Coulomb’s law and Newton’s law represent the long-range electric and gravitational forces, respectively, while the two nuclear forces are short range and are involved in α, β, and γ radioactivity. In virtual particle exchange, the interacting particles make temporary transitions to an excited state in which a boson is exchanged between the interacting particles. Feynman diagrams give a graphical description of these processes. The graviton is the quantum of gravity waves, the latter recently observed at LIGO. The proton and neutron are each made up of three quarks, which exchange gluons to provide the nuclear interaction. The weak interaction arises from the exchange of W and Z bosons. The Standard Model is the current theoretical understanding of elementary-particle interactions.