The document discusses several cosmological theories including the Big Bang theory, inflation theory, and 2012 theory. It provides a brief overview of each theory, noting that the Big Bang theory proposes the universe rapidly expanded from an initial extremely dense and hot state around 13.7 billion years ago, while inflation theory was developed to address perceived issues with the Big Bang theory. The document expresses skepticism about the 2012 theory claiming the world will end in 2012.