Chapter Fourteen, Reflections on Cosmology Summary and Analysis

The standard model of cosmology existed before string theory. It is based on Einstein's equations, and recognizes that the universe began with an enormous explosion, the Big Bang. The next three minutes after the Big Bang were when most of the hydrogen and helium neuclei formed, in a period called primordial nucleosynthesis. After a billion years or so, stars, galaxies, and planets began to form. Scientists see remnants of the Big Bang in cosmic background radiation, which is microwave radiation still expanding from the initial Bang. NASA's Cosmic Background Explorer confirmed that the universe is permeated with microwave radiation whose temperature is about 2.7 degrees above zero. The entire universe was condensed to the Planck length before the Big Bang at an incredible density and temperature. In the extreme moments after the Big Bang...