A typical atomic nucleus is 100,000 times smaller than the surrounding electron cloud, which is itself a million times smaller than the width of a human hair. At such close quarters, the electrical repulsion between the protons in the nucleus, left unchecked, would send them flying off at nearly the speed of light. Instead, atomic nuclei are held together by an even stronger force, unimaginatively dubbed the “strong nuclear force.” The strong force binds together the protons and neutrons in atomic nuclei. Neutrons are electrically neutral—hence the name—but they feel the strong force just like
...more
