Ontology of Causal Dynamical Triangulation

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Discussion Overview

The discussion revolves around the concept of Causal Dynamical Triangulation (CDT) and its treatment of space and time, particularly in relation to the views expressed by Sabine Hossenfelder in a video. Participants explore the implications of CDT on the nature of spacetime and the distinction between space and time.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants inquire about Sabine's assertion that CDT treats space and time differently, questioning the implications for the reality of spacetime.
  • Others clarify that this differential treatment suggests a lack of manifest relativistic covariance in CDT.
  • There is a suggestion that CDT may deny the reality of spacetime, as indicated by Sabine.
  • One participant connects CDT to Hořava gravity, noting that both frameworks treat space and time differently.
  • Questions arise regarding the nature of space in CDT, specifically whether it is continuous or discrete, given Sabine's comment about the finite size of triangles being a mathematical aid.

Areas of Agreement / Disagreement

Participants express uncertainty and differing interpretations regarding the implications of CDT on spacetime and the nature of space, indicating that multiple competing views remain without a clear consensus.

Contextual Notes

Limitations include the ambiguity surrounding the definitions of space and time in the context of CDT, as well as the unresolved nature of whether space is continuous or discrete.

TheHeraclitus
Messages
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TL;DR
Does CDT involve gravitons? How many dimensions? Presentism, Eternalism or Agnosticism about time?
Also, what does Sabine mean in this video by the sentence: (5:51 in the video)
It treats space and time differently which Einstein thought us not to do.

Thank you!
 
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TheHeraclitus said:
Also, what does Sabine mean in this video by the sentence:
It means that space and time are not treated on an equal footing. In other words, it's not manifestly relativistic covariant.
 
Demystifier said:
It means that space and time are not treated on an equal footing. In other words, it's not manifestly relativistic covariant.
So it denies the reality of Spacetime?
 
TheHeraclitus said:
So it denies the reality of Spacetime?
According to Sabine, yes.
 
Demystifier said:
According to Sabine, yes.
Interesting, that would make sense since Wikipedia says CDT is related to Hořava gravity where space and time are treated differently too.
I am also a bit confused about the nature of space in CDT. Sabine says finite size of the triangles is only a mathematical aid.
Does this mean space is continuous or discrete in CDT?
 

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