Final answer:
The Big Bang Theory explains the origin and expansion of the universe, supported by evidence like redshift and dark matter.
Explanation:
The Big Bang Theory is a cosmological explanation stating that the universe began around 13.7 billion years ago from a hot, dense state and has been expanding since then.
Evidence for an expanding universe: The redshift of galaxies and the cosmic microwave background radiation support the idea of an expanding universe.
Dark matter is a mysterious substance that does not emit light or energy but exerts gravitational effects on galaxies and the universe.
Learn more about Big Bang Theory and cosmology here:
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