What is the initial force of universe expansion?

AI Thread Summary
The initial force driving the universe's expansion at the Big Bang is primarily attributed to the energy released during the event itself. Dark energy becomes significant in influencing the expansion rate as the universe evolves, particularly when the expansion accelerates. Initially, the expansion was dominated by radiation and matter, but as the universe expanded and cooled, dark energy's role increased. The transition to dark energy's dominance is crucial for understanding the current accelerated expansion of the universe. This discussion highlights the complex interplay between these forces throughout cosmic history.
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When the universe started expanding at the big bang, was it mainly driven by the force of the big bang ? Does dark energy start to play the major role in driving the expansion only when it is accelerating?

(I would prefer to have this question answered by a PF Science Advisor or someone who actually knows about it.)
 
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