ABSTRACT
The development of Planck’s and Einstein’s ideas of quanta eventually became tied to the understanding of the simplest atom, hydrogen. But the road to hydrogen was a long and bumpy road extending all the way back to the fifth century BC when the idea of “atom” acquired some serious credibility by the teachings of Democritus. Later, Epicurus, in trying to explain his primacy of senses, used the idea of an atom as the agent that stimulates sensation. Epicurean philosophy has survived in the writings of Lucretius, a Roman poet (see Section 42.1.1).
