The more powerful our telescopes become, the more we are able to see earlier and earlier remnants of Guth Inflation. Assuming that it makes sense to associate a location, BB, in space-time where the Big Bang occurred, then test particles (luminous or otherwise) have been decelerating away from BB ever since. When viewed through our telescopes, i.e.: when viewed in time reversed order, a test particle decelerating away from BB would appear to be accelerating away from us. We usually attribute this acceleration away from us as propelled by “Dark Energy”, and any study to understand Dark Energy is equivalent to a study of what propelled Guth inflation in the first place. I am sure that I am not the first to think of such a straight forward interpretation of Dark Energy, but I do not see it in any of the popular literature on Cosmology. This implies that my thinking is probably incorrect. Can somebody point out the flaw?
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$\begingroup$ I won't pretend to understand this: Dark Energy and the False Vacuum: arxiv.org/abs/astro-ph/0612245 $\endgroup$– Wayfaring StrangerCommented May 16, 2020 at 15:58
1 Answer
One flaw is saying that the big bang occurred at a location. It didn't: the whole universe was once part of the big bang. So the stuff about deceleration being seen as acceleration isn't true.
Secondly, shortly after the big bang, the universe behaves "ballistically" (although following the rules of General Relativity, not Newtonian gravity). It was initially decelerating and the influence of dark energy was negligible.
But in the popular $\Lambda$CDM model (the prevailing model at the moment), the dark energy density is constant, so as the universe gets bigger it becomes more influential and the universe began to accelerate a few billion years ago.
None of this has much to do with inflation, which, if it happened, happened in the first tiny fraction of a second, when the universe was dominated by some energy density, similar in effect to dark energy (in that makes space expand), but much, much stronger. Exactly what this energy density was is still speculative, and inflation remains a "bolt-on" to the big bang model to explain why space is flat and why different parts of the universe appear very similar.
