Q:

How did the universe begin?

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Quick Answer

The universe began with the Big Bang around 13.6 billion years ago. The Big Bang was a rapid expansion of the universe from a tiny single point. This hot expansion has continued since then, resulting in the expansion of the universe in every direction.

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Full Answer

At the time of the Big Bang, the universe and all of its matter was concentrated in a single point. As the Big Bang started, this matter was heated to very high temperatures and expanded rapidly.

Several scientific observations have convinced astronomers that the Big Bang theory is correct. One of the strongest pieces of evidence is called the cosmic microwave background, or CMBR. This is the remaining heat from the Big Bang that can be seen in all directions when looking into the universe. As the universe has expanded, the initially hot material has cooled, so that it now emits light as microwaves.

By looking at distant galaxies and stars, scientists have also discovered that everything seems to be moving away from the Earth. The further away a galaxy is, the faster it appears to be moving. This shows that the universe is still expanding, although there is debate as to whether this expansion will continue forever.

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