Abstract
The ultimate fate of life in a universe with accelerated expansion is considered. Previous work [J.D. Barrow, F. Tipler, The Anthropic Cosmological Principle, Oxford Univ. Press, Oxford, 1986; L.M. Krauss, G.D. Starkman, Astrophys. J. 531 (2000) 22] showed that life cannot go on indefinitely in a universe dominated by a cosmological constant. In this Letter we consider instead other models of acceleration (including quintessence and Cardassian expansion). We find that it is possible in these cosmologies for life to persist indefinitely. As an example we study potentials of the form V∝φn and find the requirement n<−2.
Highlights
In 1979, Dyson first discussed the question of the ultimate fate of life in an expanding universe [3]
In other cases we considered, including quintessence and Cardassian expansion, we found that the de Sitter radiation cools off just rapidly enough to allow life to survive
We understand that there is a disagreement between Dyson on the one hand and Krauss and Starkman (KS) on the other hand as to whether or not there is a flaw in the premise
Summary
In 1979, Dyson first discussed the question of the ultimate fate of life in an expanding universe [3]. Barrow and Tipler [1] and Krauss and Starkman [2] followed the basic approach outlined by Dyson to consider life in a universe dominated by a cosmological constant. Other than a cosmological constant, alternatives include a decaying vacuum energy [6] [7], quintessence [8,9,10,11,12,13,14,15,16,17], and Cardassian expansion [18] as possible explanations for such an acceleration. The crucial difference between these cases and that of a cosmological constant is that the temperature of the cosmological Hawking radiation decreases in time, in many cases quickly enough to allow life to continue indefinitely despite the presence of the thermal bath. We argue that the inclusion of a cosmological Hawking temperature in Dyson’s classical argument correctly captures the quantum nature of the system and that Dyson’s conclusions are valid
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