As far as we know, it happened only once.
According to the believes of physics and the big bang, we know that the big bang was both big and a bang. Since we are still receiving radiation from the big bang, So considering that factor I would say that it was big and a bang. What do you believe?
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How did it what? - It isn't known what caused the Big Bang, if that's what you mean.
The big bang created itself.
big bang: This is the big bang theory
Some questions about the Big Bang theory and its implications for the origin of the universe include: What caused the Big Bang? How did the universe evolve after the Big Bang? What evidence supports the Big Bang theory? What are the implications of the Big Bang for our understanding of the universe's beginning and future?
There are two questions commonly asked:1. Is it real, or did God create the universe ex nihilo?2. Did the Big Bang create more than one universe?3. How can the big bang account for dark matter and dark energy?
The big bang is a theory.
Big Bang theorist believe
Everything we know of happened after the Big Bang.
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