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Sean Carroll
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The Arrow of Time
The Arrow of Time ☜A map exploring some issues concerning the nature of time that lie at the boundary of physics and philosophy. The map follows up a talk to the Blackheath Philosophy Forum on 2 April 2011 by Huw Price, Professor of Philosophy and director of the Center for Time at Sydney University.☜F1CEB7
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The Arrow of Time
The Arrow of Time ☜A map exploring some issues concerning the nature of time that lie at the boundary of physics and philosophy. The map follows up a talk to the Blackheath Philosophy Forum on 2 April 2011 by Huw Price, Professor of Philosophy and director of the Center for Time at Sydney University.☜FFFACD
⇤
Information theoretic explanation
Information theoretic explanation☜A number of physicists and philosophers have claimed that remembering - by humans or computers - can only occur in a rising-entropy environment. Such claims generally draw on the requirements for persisting and utilizing information. Two approaches to formally demonstrating this link are addressed.☜FFFACD
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Entropy gradient explains agency
Entropy gradient explains agency☜The existence of a low entropy past explains why the future is mutable and the past is not.☜FFFACD
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Bolztmann's H-theorem
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Boltzmann's statistical imperative
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Why low entropy in the past?
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A brute fact
A brute fact☜In the paper cited below, philosopher Craig Callender argues that the low-entropy past is a brute fact that does not require any further explanation. He suggests that certain facts - including the low entropy past - may be just axiomatic in the same way as regularities classed as physical laws are.☜FFFACD
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Can do better
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Cyclical universe
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⇤
No reason for entropy reversal
No reason for entropy reversal☜There is no good reason to suppose that the entropy gradient will reverse and entropy decrease during the collapsing phase of the cycle. It would be extremely improbable for this to happen for just the reasons Boltzmann outlined in his statistical explanation of the Second Law.☜FFFACD
⇤
Inflationary universe
Inflationary universe☜Some cosmologists claim that the inflationary cosmological theory explains the extremely smooth distribution of matter and energy - and hence low entropy - of the early universe. The extremely rapid expansion effectively smooths out any initial irregularities.☜FFFACD
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Conscious observer requirement
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Boltzmann-Schuetz hypothesis
Boltzmann-Schuetz hypothesis☜Boltzmann and Schuetz claimed that in a universe that is near thermal equilibrium, and given sufficient time, there will be regions where there is a temporary deviation into a low entropy state, from which it will trend back to equilibrium. Anthropic selection accounts for us being in such a region.☜FFFACD
⇤
Boltzmann's Brain objection
Boltzmann's Brain objection☜Given that the probability of low entropy states diminishes exponentially, we would expect to find ourselves in the minimum entropy fluctuation consistent with conscious experience. This would not be the appearance of a whole universe - just a minimal Boltzmann brain.☜FFFACD
⇤
Fluctuations in de Sitter space
Fluctuations in de Sitter space☜Cosmologist Sean Carroll has proposed that low entropy may result from fluctuations in De Sitter space - a vacuum except for dark energy and the end point of expanding space time. Some fluctuations lead to cosmological inflation, giving rise to smooth low entropy baby universes - like ours.☜FFFACD
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Multiverse is a prediction
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Peter Baldwin
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Entry date (GMT):
8/12/2011 6:34:00 AM
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