How long does an electron live?

Is the electron a stable particle? Much of physics goes on the assumption that it is. Electron stability is a necessary consequence of the law of conservation of charge since all particles lighter than the electron are electrically neutral and therefore it cannot decay into them and conserve charge at the same time. A lot of elementary‐particle “spectroscopy” has been built on the assumption that the electron (along with the proton) represents a kind of “ground state” than which there is no lower. But as H. K. Moe and F. Reines point out in The Physical Review for 22 Nov. [140, B992 (1965)], “regardless of how attractive a law may appear theoretically, its validity rests on experimental evidence. The danger in the application of conservation laws to unexplored domains can be seen in the dramatic failure of parity conservation for weak interactions.” In this spirit experiments are seeking evidence of electron decay. So far they have not found it. They have succeeded only in putting greatest lower bounds on the electron lifetime; that is, they conclude that an electron must live longer than certain lengths of time that they calculate.