Cosmology: escaping the end of the universe (Introduction)

by David Turell , Monday, April 06, 2015, 14:44 (3520 days ago) @ dhw

DAVID: It is April's fools day, I think:
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> http://arxiv.org/pdf/1503.08130v1.pdf
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> dhw: Thank you so much for this invaluable reference. I was in despair after Professor Miyagawa's MIT had rejected my application for a research grant (see "Origin of Language", 5 April at 14.15), but hope springs eternal... I shall now apply to the Harish-Chandra Research Institute. And I have a new theory to develop: our universe is made of a renewable substance called zogipantopyrussurypotnapigoz, which means it can NEVER END. They can't possibly turn me down, can they?-Appears not to be a hoax. Even serious scientists can daydream:-http://www.hri.res.in/~sen/ -"A few days ago I wrote an essay with the title `Riding Gravity Away from Doomsday'. In this essay I discussed the best possible future course of action for the humankind to prolong its life given two assumptions: 1) that our universe is not absolutely stable and could undergo a phase transition in the future, and 2) that the accelerated expansion of the universe that we see today is due to a cosmological constant. The first one is a theoretical possibility that has been discussed since 1970's by many people and current experimental knowledge could at best put an upper bound of one in ten billion per year to the probability of such an event. The second one is the most widely accepted interpretation of the observed expansion rate of the universe although there are certainly alternative proposals. Both assumptions are natural in string theory, but can be discussed independently of string theory.
 
"Few days after I submitted the essay to the arXiv, one of my colleagues drew my attention to a blog where some discussion on this essay had appeared. Upon visiting the blog, I was amused to see the passionate attack on eternal inflation and the multiverse that the essay had generated, while the essay itself was based only on the assumptions stated above and the standard rules of classical general theory of relativity. Indeed, a word search shows that none of the words eternal, inflation or multiverse appear anywhere in the abstract, text or the figure captions. Of course, many of the physical and mathematical results used in this essay are borrowed from the corresponding results in eternal inflation since our universe is now entering the same kind of accelerated expansion phase that is postulated to exist during inflation."