The Big Bang theory proposes that the universe originated from a singularity, a point of infinite density, about 13.8 billion years ago. It suggests that the universe began as an extremely hot and dense state and has been expanding ever since. As the universe expanded, matter and energy were distributed throughout space, allowing the formation of galaxies, stars, and other celestial structures. The theory also predicts cosmic microwave background radiation, which provides evidence for the early hot and dense state of the universe.
