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Is the expansion of the universe proof of the Big Bang theory?

Or are there other proofs?

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I have edited the question to improve the English. It is still too short. @Kilise, note I took out the word 'exploded' as the Big Bang was not an explosion IN space, it was a rapid expansion OF space. If English is not your first language, the distinction may not be clear. This question could be improved by explaining what you have already learned about the Big Bang theory, from where, and maybe shay prompted your question. – Jeremy May 18 '14 at 19:58
up vote 2 down vote accepted

In and of itself, no the expansion of the universe is not proof of the big bang. Other theories could be constructed that would also be explained by the expansion. For example Fred Hoyle and others proposed the Steady State Theory which proposed that new matter was constantly being created thus causing the expansion. A the time there was no other evidence for either theory so either could have been true.

However, when you couple the expansion with other evidence such as the cosmic microwave background radiation discovered in 1964 then it does strengthen the case for the big bang being the cause.

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The ratio of hydrogen to helium in the universe is easy to measure, and is exactly what is predicted by the Big Bang theory. – Marc May 23 '14 at 1:25

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