The Big Bang theory is an effort to explain what happened at the very beginning of our universe.The Big Bang theory is the prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution According to the standard theory, our universe sprang into existence as singularity around 13.7 billion years ago.After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms. Giant clouds of these primordial elements later coalesced through gravity to form stars and galaxies.

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