Is Conformal Cyclic Cosmology a Viable Explanation for the Big Bang?

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Discussion Overview

The discussion revolves around Roger Penrose's theory of conformal cyclic cosmology (CCC) as a potential explanation for the Big Bang. Participants explore the viability of CCC, its assumptions, and its reception within the scientific community, including comparisons to other pre-Big Bang models.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants express skepticism about Penrose's theory, particularly regarding the concept of information loss and its implications for the second law of thermodynamics.
  • One participant notes that the broader scientific community has not widely accepted CCC, with initial empirical evidence being criticized and deemed unconvincing.
  • Another participant mentions that while CCC has not garnered significant attention, other models like loop quantum cosmology and eternal inflation have attracted more research and publications.
  • Concerns are raised about the assumptions underlying CCC, such as the decay of all matter to radiation, with specific reference to proton decay and the longevity of black holes.
  • A participant highlights a previous paper that negatively impacted the perception of CCC, suggesting that it was based on a misunderstanding of the cosmic microwave background (CMB) statistics.

Areas of Agreement / Disagreement

Participants generally express skepticism about the viability of CCC, with multiple competing views regarding its acceptance and the validity of its assumptions. The discussion remains unresolved, with no consensus on the theory's merit.

Contextual Notes

Limitations include the dependence on specific assumptions about matter decay and the lack of empirical support for CCC. The discussion also reflects differing levels of engagement with the theory within the scientific community.

tdecelles
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Hey everyone,

I wanted to share this new interview I found with Roger Penrose wherein he discusses his theory of conformal cyclic cosmology:

http://www.ideasroadshow.com/issues/roger-penrose-2013-07-12

I was wondering, are you convinced by his theory? I find it intriguing but I'm skeptical of the notion of information loss, or "transcending" the second law.
 
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My impression is that Penrose has not convinced the community of his model.

I would hazard a guess that most will say they haven't paid any attention to it at all, those that have think its at best a neat idea but not convincing enough. Certainly the initial empirical evidence he presented was not bought by the community, it was totally shot down in fact.
However since then K Meisner et al who are bit more respected in the field I believe did have some positive things to say about CCC, even agreeing there is evidence for it in WMAP data. I don't know if they still think that after PLanck .
http://arxiv.org/abs/1207.2498

One of the biggest assumption in the theory is that all matter decays to radiation, but proton decay for example is ruled out for about 10^33 years. Of course with 10^100 years for black hole decay I guess Penrsoe has a lot of time to play with. But he still has to assume something like the Higgs field itself decays, However he doesn't have to assume extra dimensions or supersymmetry or even any novel quantum gravity affects.
 
I also think i should add that there many proposals for a pre big bang scenario and CCC is one of them. But in my opinion there are only two models that have attracted a significantly wider community of researchers. One is loop quantum cosmology and the other is eternal inflation. both of these have many researchers around the world publishing a lot of papers every year.
Of course that doesn't mean either of these models are correct or that CCC is wrong, but if you want to know what has attracted researchers and what has not in terms of these sorts of scenarios that's my take. I wonder if others agree?
 
tdecelles said:
Hey everyone,

I wanted to share this new interview I found with Roger Penrose wherein he discusses his theory of conformal cyclic cosmology:

http://www.ideasroadshow.com/issues/roger-penrose-2013-07-12

I was wondering, are you convinced by his theory? I find it intriguing but I'm skeptical of the notion of information loss, or "transcending" the second law.
This idea has been severely tainted by an exceedingly bad paper published about it a few years ago, where Penrose and Gurzadyan misunderstood the basic statistics of the CMB, and used that misunderstanding in an attempt to claim evidence for their idea.

As it stands, however, it's a pie-in-the-sky idea with no supporting evidence for it, and nearly all such ideas are wrong.
 

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