- #1

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http://arxiv.org/abs/1105.0183

I offer this link as a starting point for the discussion, but I'm curious if there has been any further progress in the professional and/or academic ranks that would either support or refute this theory.

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- Thread starter Feeble Wonk
- Start date

- #1

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http://arxiv.org/abs/1105.0183

I offer this link as a starting point for the discussion, but I'm curious if there has been any further progress in the professional and/or academic ranks that would either support or refute this theory.

- #2

websterling

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http://arxiv.org/cits/1105.0183

This paper looks to be a good reference/undergrad introduction-

http://arxiv.org/abs/1409.0105

- #3

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Any idea regarding how this concept is being received within the cosmological/theoretical physics community? Is it considered extremely "fringe", or is it being taken seriously?

- #4

Chalnoth

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His central conceit is that the concept of time we use in physics is incorrect. He points out that there's no such thing as an ideal clock: the actual behavior of any clock actually depends upon the structure of the entire universe (naturally, things further away have less and less impact on the clock, but it is technically true that the structure of the entire universe has some impact). He uses this idea to claim that time should not be considered a parameter in the theory, or even a fourth dimension, but instead as an emergent property. He produces a theory which seems to replicate the results of General Relativity with no time parameter and using only three dimensions (with time being calculable from the configuration of the space).

I didn't really understand his theory, and it didn't seem to me that his criticisms of the standard paradigm were well-founded, but I thought it was an interesting idea.

- #5

websterling

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I saw a talk by Barbour on this topic a few years back. It was rather interesting.

Maybe this is the talk?

http://www.perimeterinstitute.ca/videos/shape-dynamics-and-general-relativity

His web site is-

http://www.platonia.com/index.html

- #6

Chalnoth

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Looks like the same talk, yes. Different venue, but same basic talk.Maybe this is the talk?

http://www.perimeterinstitute.ca/videos/shape-dynamics-and-general-relativity

His web site is-

http://www.platonia.com/index.html

- #7

Chronos

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- #8

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By "dual" I mean the two theories are locally equivalent, everywhere giving the same equations of motion. This is similar to the ADS/CFT correspondence except at a fully classical level.

This trading of symmetries allows them to resolve two facets of the long standing "Problem of Time" which has plagued Quantum Gravity research, "many fingered time" and the "frozen formalism".

Some recent papers:-

"The shape dynamics description of gravity"

Tim Koslowski

http://arxiv.org/abs/1501.03007

"The Solution to the Problem of Time in Shape Dynamics"

Julian Barbour, Tim Koslowski, Flavio Mercati

http://arxiv.org/abs/1302.6264

"Identification of a gravitational arrow of time."

Julian Barbour, Tim Koslowski, Flavio Mercati

http://arxiv.org/abs/1409.0917

"A Shape Dynamical Approach to Holographic Renormalization"

Henrique Gomes, Sean Gryb, Tim Koslowski, Flavio Mercati, Lee Smolin

http://arxiv.org/abs/1305.6315

There was an interesting exchange between Lee Smolin and Julian Barbour at the end of Barbour's presentation at the Perimeter Institute where Smolin asks something like "rather than eliminate time haven't you found a universal time?" Barbour agreed that was a reasonable interpretation.

- #9

wabbit

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http://arxiv.org/abs/1302.7037

Tim Koslowski

http://arxiv.org/abs/1303.0060

Henrique Gomes, Tim Koslowski

- #10

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There was an interesting exchange between Lee Smolin and Julian Barbour at the end of Barbour's presentation at the Perimeter Institute where Smolin asks something like "rather than eliminate time haven't you found a universal time?" Barbour agreed that was a reasonable interpretation.

I'm intrigued by this exchange. It's essentially consistent with the supposition that Smolin made in his book, "Time Reborn". He referenced Barbour's work in the theory of Shape Dynamics, but argued that rather than relegating time to being only an emergent quality, as previously proposed, it instead suggests that time is THE fundamental physical parameter, and that spatial dimension is emergent. My understanding was that this position was part of his larger assertion that time is the ONLY constant, and that spatial dimension as well as the physical laws themselves are all emergent qualities evolving through a series of successive universes that are born through black holes.

If any of you have read that book, was that the conclusion that you arrived at as well, or did I misunderstand his argument.

- #11

wabbit

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Haven't read this but this sounds intuitively more natural to me, from a far more basic perspective : any internal frequency is sufficient for an observer to experience time, while complex interactions with other systems are required to even define space.I'm intrigued by this exchange. It's essentially consistent with the supposition that Smolin made in his book, "Time Reborn". He referenced Barbour's work in the theory of Shape Dynamics, but argued that rather than relegating time to being only an emergent quality, as previously proposed, it instead suggests that time is THE fundamental physical parameter, and that spatial dimension is emergent. My understanding was that this position was part of his larger assertion that time is the ONLY constant, and that spatial dimension as well as the physical laws themselves are all emergent qualities evolving through a series of successive universes that are born through black holes.

If any of you have read that book, was that the conclusion that you arrived at as well, or did I misunderstand his argument.

- #12

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I don't see how it can be made consistent however as one of the guiding principles in Time Reborn is a sort of cosmological version of Leibniz' Principle of Sufficient Reason, where all effects have a cause which is within the universe. This seems to be broken if the universe is emerging from somewhere now causally disconnected. It leaves the same explanatory gap as the initial singularity in BBT.

Smolin and Unger appear to disagree about the importance of Leibniz though so hopefully there will be some decent discussion on this point in the latest book.

- #13

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(Edit to correct post number)

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