Inflation, first proposed by the physicist Alan Guth in 1981 and refined by Andreas Albrecht and Andrei Linde shortly thereafter, says that the very early universe expanded extraordinarily quickly for a minuscule fraction of a second—increasing in size by a factor of about 100 trillion trillion in about a billionth of a trillionth of a trillionth of a second—then resumed expanding much more slowly. This rapid expansion was driven by hypothetical “inflatons,” high-energy subatomic particles, which decayed into normal matter at the end of inflation.
