What evidence is there that the Universe began in a big bang?

The earliest and most direct observational evidence of the validity of the theory are the expansion of the universe according to Hubble's law (as indicated by the redshifts of galaxies), discovery and measurement of the cosmic microwave background and the relative abundances of light elements produced by BBN.

Explanation:

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Answer: For me personally i have a Biblical faith and first of all there is evidence that looks convincing that the big bang made the universe, but man wants answers and God in the Bible says he created the universe for us it is hard to believe it but i have faith.