The Early Universe

Abstract

“Once upon a time ...” Children’s stories and fairy tales often start with these words, but they could equally well usher in a different kind of story, the history of the Universe: “Once upon a time, there was a very tiny Universe that was very, very hot, and in it lived dark matter, neutrons, protons, electrons, antineutrinos, and photons.” This scenario forms part of the cosmologic gospel, whose list of early inhabitants is based on the relic background radiation, the laws of nature, and the results of astronomical and laboratory experiments. It developed from the work of Alpher, Follin, and Herman on primordial nucleosynthesis and has enabled cosmologists not only to deduce which events occurred as the Universe evolved but also, with increasing accuracy, to pinpoint the times of their occurrences.