Three papers as the tip of an iceberg

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Discussion Overview

This discussion revolves around three recent papers published on arXiv, exploring their implications and connections within theoretical physics, particularly in the context of string theory, black hole microstates, and gravity theories. The conversation delves into the significance of these papers, their interrelations, and the broader implications for understanding quantum gravity and related concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses a desire to explore the meaning of three unrelated papers, suggesting potential connections between the first two through twistor string theory.
  • The participant highlights Maldacena's prominence in theoretical physics, suggesting that his papers are now essential for tracking advances in the field, particularly regarding AdS/CFT.
  • A technical advance is noted in Maldacena's paper, where conformal gravity with a specific boundary condition reduces to Einstein gravity, which some participants find useful for understanding the landscape of gravity theories.
  • The discussion raises the expectation that quantum gravity in de Sitter space may eventually be understood as clearly as AdS gravity, based on new results presented in Maldacena's paper.
  • Confusion is expressed regarding the implications of a gravity-gravity relationship between conformal gravity and de Sitter space, which some participants find novel and potentially significant.
  • References to other literature are made, suggesting that certain assertions about the relationship between dS and AdS may provide insights into the new findings in Maldacena's work.
  • Simon Caron-Huot's paper is mentioned as part of the effort to solve N=4 super-Yang-Mills, with connections drawn to the Goncharov symbol technique and its implications for correlation functions in higher-dimensional theories.
  • Another participant discusses the rigidity of hyperbolic spaces and their transcendental volume properties, suggesting a complex relationship with the findings in the discussed papers.
  • The crossover phenomenon between dimensions in the context of the discussed papers is noted, with speculation on its relation to a broader "motivic synthesis" in theoretical physics.

Areas of Agreement / Disagreement

Participants express a range of viewpoints, with some proposing connections between the papers while others highlight uncertainties and complexities that remain unresolved. No consensus is reached on the implications of the findings or their interrelations.

Contextual Notes

The discussion reveals limitations in understanding the implications of the findings, particularly regarding the relationships between different theories of gravity and the mathematical frameworks involved. Some assumptions and definitions remain unaddressed, contributing to the ongoing complexity of the topic.

  • #31
http://arxiv.org/abs/0811.1341"
 
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  • #32
It still looks like turtles all the way down to me.
 
  • #33
Yeah I don't know about the unitarity thing. It really annoys me that it's not explored more. Conformal gravity seems like a potentially very useful theory. I don't know if solving its problems is just hard, likely impossible, shown to be impossible, or what? For example, why do witten and berkovits write a whole paper about conformal gravity ( http://arxiv.org/abs/hep-th/0406051 ) and say:
This simple observation suggests that four-dimensional conformal supergravity theories
might be relevant to the real world – perhaps with the aid of some mechanism of
spontaneous breaking of conformal invariance. However, they in fact are generally considered
to be an unsuitable starting point for describing nature, because they lead to fourth
order differential equations for the fluctuations of the metric, and thus to a lack of unitarity.
We have no reason to question these beliefs and we will later describe some facts that
illustrate them.
Really, no reason to question these beliefs? Then why write a paper about something that doesn't make any sense...this is just beyond me..I mean, this ghost stuff in CG is just in perturbation theory (as far as I know). Non-perturbatively it might be ok. It just sounds silly to me to disregard the theory so easily
 
  • #34
Mitchell, that is in fact the only paper I knew. Is there really nothing more comprehensive out there? I'm particularly interested whether there's anything like the KLT relations in conformal gravity. Very interestingly, eq 4.14 shows that the 4 point ConformalG amplitude is proportional to the EinsteinG amplitude. I wonder if this holds for higher points?

And more generally, given the supposed non-unitarity of CG, does its S-matrix make any sense? Non-unitarity means probabilities not adding up to 1 due to ghosts, right? How about just tree level?
 
  • #35
negru said:
Really, no reason to question these beliefs? Then why write a paper about something that doesn't make any sense...this is just beyond me..
It's the equivalent for theory of OPERA's FTL neutrino paper. They "know" it doesn't make sense, but it's "there" (in the twistor string), so they tell the world what they found and maybe the world will explain it for them.
negru said:
I'm particularly interested whether there's anything like the KLT relations in conformal gravity.
Maybe yes - http://arxiv.org/abs/1108.3085" .
 
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