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How Did the Universe Begin?

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Big Bang Theory

Big Bang Theory

NASA
Question: How Did the Universe Begin?

The question of how the universe began is probably nearly as old as mankind. Answers to the question have ranged from the mystical to the religious to various scientific theories.

Answer: According to the most widely believed theory of the creation of the universe, the Big Bang Theory, the universe began sometime between 10 million and 20 million years ago from a cosmic explosion at a single point. The exact time, location and size of that initial super-powerful explosion can not be determined because that cataclysm created space and time, as well as all the matter and energy the universe will ever hold.

The early universe was extremely small, dense, and hot. For the first fraction of a second, only energy existed. It has since been expanded in all directions and has evolved from a primordial dense and hot state in a finite time in the past and continues to grow until today.

As the universe expanded and cooled, the four fundamental forces (gravity, electromagnetism, and the strong and weak nuclear forces) became distinct.

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