Details view: Invisible because sudden

Views
Add
Edit
- Edit page
- Delete page
Share
Login
- Member login
- Register now for a free account
🔎

Invisible because sudden These 1 #115216 If the jump to low entropy takes place all at once, rather than in steps, it would not be observed. The usual presumption is that such fluctuations will take this form. The paper cited below disputes this (see sibling node).

Immediately related elementsHow this works

The Arrow of Time »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

▲

The physics of time »The physics of timeThe physics of time☜Is our subjective sense that time has a direction from past to future reflected in impersonal physical processes and laws? Is it better - from the impersonal viewpoint - to look asymmetries in time rather than a direction (to the future) of time?☜FFB597

▲

The thermodynamic arrow »The thermodynamic arrowThe thermodynamic arrow☜The Second Law of Thermodynamics implies an arrow of time in the sense that the entropy (or disorder) of an isolated system such as the whole universe never decreases - it either increases or remains constant.☜59C6EF

▲

Why do we see an entropy gradient? »Why do we see an entropy gradient?Why do we see an entropy gradient?☜We find ourselves in an observable universe in which entropy increases consistently in one direction, thereby showing time asymmetry - an arrow of time. Yet the vast majority of underlying dynamical processes are time-symmetric. How to account for this? Two broad approaches are considered here.☜FFB597

▲

Asymmetric boundary condition »Asymmetric boundary conditionAsymmetric boundary condition☜We see entropy increasing because: 1. An isolated system in a less than maximal entropy state will spontaneously evolve toward higher entropy. 2. We inhabit a universe (or part thereof) at less than maximal entropy. Both must be true for the explanation to work.☜59C6EF

▲

Past hypothesis »Past hypothesisPast hypothesis☜We inhabit a universe - or part thereof - characterized by a low-entropy past that has enabled the evolution of intelligent observers to occur. This together with Boltzmanns probabilistic argument (see sibling node) implies entropy will increase over time toward thermal equilibrium.☜9FDEF6

▲

Why low entropy in the past? »Why low entropy in the past?Why low entropy in the past?☜How do we account for the low entropy of the early universe reflected in the extreme - but not perfect - homogeneity of the distribution of matter and energy shortly after the Big Bang? When gravity is prominent - as in the early universe - a smooth distribution is unstable and of low entropy.☜FFB597

▲

Anthropic selection »Anthropic selectionAnthropic selection☜Several explanations have been offered that rely on (weak) anthropic selection to explain the low entropy past. They all note that conscious observers can only exist in an environment far from thermodynamic equilibrium, but differ on how the we came to be in such a state.☜59C6EF

▲

Low entropy generators »Low entropy generatorsLow entropy generators☜In a universe/multiverse of large - possibly infinite - extent extremely improbable events can be expected to happen in at least some locations and times. Such events will include fluctuations into a low-entropy configuration. There are several hypotheses as to the nature of such fluctuations.☜9FDEF6

▲

Source of low-entropy states »Source of low-entropy statesSource of low-entropy states☜What processes could give rise to the existence of regions of spacetime well away from thermodynamic equilibrium required in order for conscious observers to evolve? Several proposals are appended to this node☜FFB597

▲

Can observers see low entropy? »Can observers see low entropy?Can observers see low entropy?☜How will downward entropy fluctuations appear to observers in them? If the thermodynamic arrow determines the psychological arrow they will be indistinguishable from upward fluctuations. If not, their appearance will depend on whether they are sudden or gradual. Which is likely to be true?☜FFB597

■

Invisible because suddenInvisible because sudden☜If the jump to low entropy takes place all at once, rather than in steps, it would not be observed. The usual presumption is that such fluctuations will take this form. The paper cited below disputes this (see sibling node).☜59C6EF

Heading

Summary

Click the button to enter task scheduling information

Details

Enter task details

Message text

Select assignee(s)

Due date (click calendar)

RadDatePicker

Open the calendar popup.

Calendar

Title and navigation
Title and navigation
<<	<	November 2024	>	<<

November 2024
	S	M	T	W	T	F	S
44	27	28	29	30	31	1	2
45	3	4	5	6	7	8	9
46	10	11	12	13	14	15	16
47	17	18	19	20	21	22	23
48	24	25	26	27	28	29	30
49	1	2	3	4	5	6	7

Reminder

Ready to post Copy to text

Task assignment(s) have been emailed and cannot now be altered

Lock

Comment graphing options

Choose comments:Comment onlyWhole threadAll comments

Choose location:To a new mapTo this map

New map options

Select map ontology Graph to private map

+Kommentare (0)

- KommentareKommentar hinzufügenNewest firstOldest firstShow threads

+Verweise (1)

- VerweiseHinzufügenList by: CiterankMap

Link[1] Out of equilibrium: understanding cosmological evolution to lower-entropy states

Zitieren: Aguire, Anthony and Carroll, Sean and Johnson, Mathew
Zitiert von: Peter Baldwin 3:21 AM 11 August 2011 GMT
Citerank: (2) 113880Updated Boltzmann-SchuetzThere have been some recent attempts to combine the basic Boltzmann-Schuetz idea with modern cosmology - especially theories that envisage a multiverse. This overcomes a key defect of Boltzmann-Schuetz - the fact that our observable universe is not old or large enough to provide the fluctuations.959C6EF, 115218Observed by Boltzmann brainOne response to the original Boltzmann-Schuetz hypothesis is that the most probable form in which observers could arise from a low-entropy fluctuation would be as a fully formed brain with a minimal environment. If formed gradually, rather than in one step, it would observe declining entropy.959C6EF
URL:

http://arxiv.org/PS_cache/arxiv/pdf/1108/1108.0417v1.pdf

Auszug -

It would therefore be useful to better understand the precise nature of these excursions, which are acknowledged but vaguely described in the cosmological literature. It is often imagined that these fluctuations are sudden and dramatic transitions, or that they do not admit any classical description. We will argue that cosmological fluctuations o lower-entropy states should be thought of as the time reverse of a - generally smooth, or at least gradual - natural evolution from a low-entropy state into equilibrium.

+About

- About

Eingabe von: Peter Baldwin
NodeID: #115216
Node type: Position
Eingabedatum (GMT): 8/11/2011 3:20:00 AM
Zuletzt geändert am (GMT): 8/11/2011 3:25:00 AM
Show other editors
Eingehende Kreuzverbindungen 0
Abgehende Kreuzverbindungen 0
Durchschnittsbewertung 0 by 0 Nutzer

x Select file to upload