|
Astronomers have made high precision measurements of this radiation, finding that it arrives at Earth with the same intensity from all directions, to the extraordinary accuracy of about 1/1000 of a percent. Tracing the history of this radiation backwards in time, cosmologists conclude that the temperature and the density of matter in the universe must have been uniform to this accuracy when the cosmic background radiation was released, about 300,000 years after the big bang. Without inflation, this extreme uniformity of the early universe must be assumed, but cannot be explained. Calculations show that without inflation there would not have been nearly enough time for this uniformity to come about, so one is forced to assume, without explanation, that the universe was uniform from its very beginning.
Despite its name, the classical form of the big bang theory is not really a theory of a bang at all. It really describes only the aftermath of the bang. It describes how the early, hot, dense universe expanded and cooled; it describes how the light chemical elements were synthesized during this expansion, and how the matter coagulated to form galaxies and stars. But it says nothing about what banged or what caused it to bang, and therefore it makes no predictions about the uniformity of the universe just after the bang. |
|
