How the surprising muon revolutionized particle physics

Heavier elements also had more charge, but argon and potassium were an exception: argon only had a charge of +18 units, but a mass of ~40 atomic mass units, while potassium had a charge of +19 units, but a mass of ~39 units. The 1932 discovery of the neutron took care of that one, teaching us that the periodic table should be sorted by the number of protons in the atomic nucleus. Certain types of radioactive decay — beta decays — appeared to not conserve energy and momentum, leading to Pauli’s 1930 hypothesizing of the neutrino, which wouldn’t be discovered for another 26 years. And the Dirac equation predicted negative energy states, which corresponded to antimatter counterparts for particles like the electron: the positron. <a href="https://medium.com/starts-with-a-bang/how-the-surprising-muon-revolutionized-particle-physics-e6cbe571c542">Read More</a>