# I Probability of not entering de Sitter

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1. Mar 22, 2017

### durant35

As far as we know, the universe is undergoing accelerated expansion and heading towards empty de Sitter space. It is assumed that eventually the observable universe will be emptied out of matter and all radiation.

Now if we take in account quantum mechanics, there's always non zero probability of a thermodynamical miracle, let's say that a planet with its civilization survives the general death of stars until indefinite future. What's worse, in many worlds interpretation this anomaly will happen.

Famous physicist Don Page [https://arxiv.org/pdf/hep-th/0612137.pdf] wrote this: "Furthermore, in an Everett many-worlds version of quantum theory (e.g., [8]), the universe will always persist in some fraction of the Everett worlds (better, in 4 some measure), but it is just that the fraction or measure will decrease asymptotically toward zero. This means that there is always some positive measure for observers to survive until any arbitrarily late fixed time, so one could never absolutely rule out a decaying universe by observations at any finite time, though sufficiently late ordinary observers would have good statistical grounds for doubting the astronomical decay rate suggested here."

Now my question is - does this conflict the hypothesis that the whole universe will eventually empty out? If we take MWI literally, how would different branches achieve simultaneous emptying out which seems necessary, how would those branches with late-universe-structures empty out so that the Universe becomes a dead, empty place? If we imagine an object placed in the universe right before entering de Sitter space, what would happen to it and how would it "escape" the observable universe without delaying its eventual entrance to a empty, de Sitter phase?

My take is that the rate of thermodynamical miracles asimptotically decreases to zero while heading to de Sitter, but that's open for further elaboration.

There are many questions here, but I hope the basics are understandable.

Thanks in advance

2. Mar 22, 2017

### nikkkom

"heading towards empty de Sitter space" and "whole universe will eventually empty out" is not the same.
1/x tends to 0 when x->+infinity, but it never reaches zero.

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