In My Time of Dying: How I Came Face to Face with the Idea of an Afterlife

by Sebastian Junger

It was a deeply counterintuitive reversal that got its start in 1900, when a moderately promising German physicist named Max Planck decided to solve an arcane but stubborn problem involving thermal radiation, the energy given off by hot bodies. In a single evening, Planck invented the “quantum of action.” A quantum is the smallest possible unit of energy that can be given off by an electron, and Planck showed that energy is radiated in units rather than waves. In the macroscopic world, when a pendulum swings, it does not “jump” from one position to another; it moves in a smooth and continuous way. At the subatomic level, however, electrons are either “here” or “there,” but never in between. They do not swing, in other words; they leap. The formula that predicts how electrons leap from one energy level to another is called Planck’s constant and is considered one of the basic laws of nature, along with gravity and the speed of light.