More on PI Early Universe Videos

[skydivephil]

I watched a few of the videos on line at the PI
http://pirsa.org/C11008
Some thoughts: it seems to me Penrose did show some new material on observational evidence of CCC, in particular he argued that families of 3 or 4 concentric circles were observed more frequently than a Gausian analysis. I don't think the comparison he had in the talk was what was in his arxiv paper so I think its new, but I am going off memory so might be wrong.

Hiranya Peiris said that if there were bubble collisions in the ealry universe, PLanck will find them.

Alan Guth argued the measure problem is not specific to inflation but is true for cyclic comsology.

This was echoed in Turoks talk, a lot of the the audience agreed with him in what he outlined as the challenges but disagreed that these problems were specific to inflaiton.

Neil Turok was challeneged by the audience on the unlikely nature of inflation given calculation using loop quanutm gravity. I presune they were referring to the Ashkebar/Sloan paper . He simply said he didn't believe it, they must have made a mistake. I would be intrgued if he could fill this out rather than argue from personal incredulity. There seemed to be little loop stuff browsing through the video descriptions, I have no idea why this is.

 

[Chalnoth]

I watched a few of the videos on line at the PI
http://pirsa.org/C11008
Some thoughts: it seems to me Penrose did show some new material on observational evidence of CCC, in particular he argued that families of 3 or 4 concentric circles were observed more frequently than a Gausian analysis. I don't think the comparison he had in the talk was what was in his arxiv paper so I think its new, but I am going off memory so might be wrong.

These supposed concentric circles were just a complete failure to understand the statistics of the CMB. Basically, he took random to mean uncorrelated. But the whole thrust of CMB science is about understanding the correlations in the CMB: fluctuations on the CMB tend to have a certain characteristic angular size on the sky. That characteristic angular size is important, and relates directly to the physics of what happened before the emission of the CMB.

All that Penrose saw in that paper were effects of this characteristic size scale.

Hiranya Peiris said that if there were bubble collisions in the ealry universe, PLanck will find them.

Perhaps you're thinking of this result? http://arxiv.org/abs/1012.3667

This is much better science than Penrose's case. It will be interesting to see what Planck has to say.

Alan Guth argued the measure problem is not specific to inflation but is true for cyclic comsology.

The measure problem is a hallmark of any infinite cosmology.

 

[skydivephil]

yes that is the paper. Hiranya Peiris is the lead authors PHd supervisor.
Guth had an interesting analalogy quoting Arthur Eddington who refused to accept black holes as we could never understand them. Similairly I think he was arguing the universe doesn't owe us a finite easier to understand reality.

 

[Chalnoth]

yes that is the paper. Hiranya Peiris is the lead authors PHd supervisor.
Guth had an interesting analalogy quoting Arthur Eddington who refused to accept black holes as we could never understand them. Similairly I think he was arguing the universe doesn't owe us a finite easier to understand reality.

Well, I've become very interested in the recent finite universe models, where the degrees of freedom of the horizon are sufficient to explain anything that we would otherwise consider going on "outside" the horizon. This is analogous to recent work in understanding black holes where degrees of freedom on the event horizon of the black hole can be used to represent everything that happens inside it.

 

[skydivephil]

any refernces to such models?

 

[Chalnoth]

any refernces to such models?

For example:
http://arxiv.org/abs/1104.3315
And a blog post around a similar idea (with further references therein):
http://blogs.discovermagazine.com/c...many-worlds-and-the-multiverse-the-same-idea/