Big Bang

The Big Bang was the event which led to the formation of the universe, according to the prevailing cosmological theory of the universe's early development (known as the Big Bang theory or Big Bang model). According to the Big Bang model, the universe, originally in an extremely hot and dense state that expanded rapidly, has since cooled by expanding to the present diluted state, and continues to expand today. Based on the best available measurements, the original state of the universe existed around 13.7 billion years ago, which is often referred to as the time when the Big Bang occurred. The theory is the most comprehensive and accurate explanation supported by scientific evidence and observations.