The Survival of a Neutron
Table of contents THE SURVIVAL OF A NEUTRON View my previous article here - Weak Interaction View the next article here - Cosmic Rays ----------------------------------------- (In this article, and in several others, u means up quark and d means down quark. Similarly, u with a bar on top means anti-up quark and d with a bar on top means anti-down quark.) Let us consider this puzzle: all of the atoms that make up the Universe (apart from hydrogen atoms) contain neutrons as well as protons in their nuclei. Yet free neutrons (that is, those not inside nuclei) undergo beta decay with a half-life of about 10 minutes. In the early Universe, soon after the Big Bang and before atoms formed, there are believed to have existed equal numbers of protons and neutrons. So why didn’t the neutrons all decay at that time, leaving a Universe made only of hydrogen? What do you think? 🤔 Apart from hydrogen, nuclei made solely of protons cannot exist . Neutrons are necessary...