Inflation Theory
According to the standard cosmology model, in the current phase in the history of the Big Bang, the universe began about fourteen billion years ago. Initially the universe was hot and dense with interacting particles. It has been conjectured that prior to this phase, the universe underwent a brief period of accelerated expansion known as inflation when quantum fluctuations, stretched to cosmologically large scales, became the seeds of the universe’s stars and galaxies. According to inflation theory, as the universe expands exponentially fast, its geometry becomes flat—this geometry was confirmed experimentally around 2000. Theorists then had to use the laws of physics to solve the problem of how to make the inflation stop so that the universe cools and structure starts to form.