Quantum theory of fluctuating space?

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Discussion Overview

The discussion revolves around the concept of emergent space within the context of loop quantum gravity (LQG) and related approaches. Participants explore the idea of phases in which space can be either non-geometric or geometric, while time is treated as non-emergent. The conversation touches on theoretical frameworks and models, including causal dynamical triangulation and various research papers relevant to the topic.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about progress on emergent space in LQG, specifically looking for models that demonstrate phases with and without a well-defined spatial metric.
  • Another participant mentions that in causal dynamical triangulation, a form of deSitter space emerges at large scales.
  • Several research papers are referenced as potentially relevant to the discussion, including works by Jonathan Engle and a summary by Hellmann on the situation in 2+1D.
  • A participant expresses the belief that the problem of emergent space might be easier to tackle if the quantization of time were not a critical issue, suggesting a connection to the effectiveness of AdS/CFT compared to other models.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the progress or challenges related to emergent space, indicating that multiple competing views and uncertainties remain in the discussion.

Contextual Notes

The discussion includes references to specific research papers, but the implications of these works and their relevance to the emergent space problem are not fully resolved. There is also an acknowledgment of the complexities involved in quantizing time, which may affect the understanding of emergent space.

Physics Monkey
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Hi all,

This is partially motivated by the thread on Ashtekar's new review and by old results on emergent spacetime in condensed matter models.

Has any progress been made on the problem of emergent space (not emergent spacetime) in LQG or allied approaches? By this I mean problems that take as given a non-emergent time and are able to demonstrate two phases - one without a well defined spatial metric (non-geometric) and one with a spatial metric (geometric)?
 
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In Causal dynamical triangulation something like deSitter space emerges at large scales
 
Interesting. I would have thought this problem would be a lot easier if "quantizing" time or seeing time "emerge" was the critical stumbling block. I think this is part of the reason why AdS/CFT works so well while flat/? and dS/? are still in their infancy.
 

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