More on Penrose's Conformal Cyclic Cosmology

[bcrowell]

We had a discussion of Penrose's conformal cyclic cosmology last month: https://www.physicsforums.com/showthread.php?t=427567 His popular-level book Cycles of Time was published first in the UK, but is now available in the US. I got a copy and have read it, so I can report on a few of the additional things I've learned. I'm going to give a talk next week for students on this and Smolin's cosmological natural selection.

Crowell, you remember the Carlip paper summarizing how several approaches to QG converge on the idea of "spontaneous dimensional reduction" with decreasing scale.

My take on this is that it is possible that degrees of freedom are killed off or numbed by crunching the scale.

I think the key point in Penrose' paper is where he makes an unjustified assumption that DoF survive unaffected by shrinking to Planck scale. His argument for a "Basic Conundrum" (motivating his cosmology idea) fails, unless this unjustified assumption is granted

The book has a lengthy discussion of loss of degrees of freedom on pp. 186-190. He believes that information *is* lost in black holes, and unitarity is violated. This is linked to his views on quantum mechanics: "The replacement of $\psi$ with the particular choice $\psi_i$ that Nature comes up with is referred to as the reduction of the quantum state or the collapse of the wavefunction, for which I use the letter R...it is my contention that the R phenomenon represents a deviation from the strict adherence of Nature to unitarity, and that this arises when gravity begins to become seriously (even if subtly) involved." He gives some references, the most recent of which is R. Penrose (2009), "Black holes, quantum theory, and cosmology" (Fourth International Workshop DICE 2008), J Physics Conf ser 174 012001. I find it truly, deeply annoying that Penrose only publishes these ideas in conference proceedings and doesn't put anything on arxiv.

He has some arguments that the recycling of one aeon into the next is a classical process rather than a quantum-mechanical one. p. 204: "The point of view of CCC is to agree that when radii of curvature approach the Planck scale, the madness of quantum gravity (whatever it is) must indeed begin to take over, but the curvature in question must be Weyl curvature ... Accordingly, the radii of curvature involved in the Einstein tensor...can become as small as they like, and the space-time geometry will still remain essentially classical and smooth so long as the Weyl curvature radii are large on the Planck scale..."

He is no longer talking about light charged particles, which seemed obviously ill-conceived to me. He hypothesizes that rest mass falls off over very large time scales. He has an argument that this is OK, because although elementary particles are normally taken to be irreducible represenatations of the Poincare group, if the cosmological constant is nonzero, the relevant symmetry group might not be the Poincare group but the symmetry group of de Sitter spacetime, and m is not a Casimir operator of that group. This is not as obviously impossible as light charged particles, but it disappoints me because it means he's back-pedaling from maknig definite testable predictions about particle physics. The time-scale of the mass reduction is not specified -- and where the heck does such a time-scale come from?

He describes attempts to test CCC by looking for large-scale circular patterns in the CMB, which would have arisen from gravitational waves from supermassive black hole collisions in the previous aeon. A grad student at Princeton named Amir Hajian looked for such correlations in the data. Penrose seems to think there are positive hints, but it's not so clear whether Hajian and his advisor felt sure enough to publish the result.

-Ben

 

[marcus]

... I'm going to give a talk next week for students on this and Smolin's cosmological natural selection.
...

You undoubtably saw where the official signature prediction of CNS was falsified.
In the 2006 "Current status of CNS" paper he says 1.6 and they just found
a 1.97 solar mass pulsar. Beautiful measurement technique relying in part on astronomical good fortune.

It should be a badge of honor to wear proudly. A theory of why the standard constants are what they are SHOULD be falsifiable---by a beautiful creative and fortuitous method of measurement. Much to CNS credit that it was so falsified.

And CNS might come back to life after somebody thinks better about the insides of neutron stars and what particles and forces are there. It is only dead for the time being.

The essential idea is that if you can find some criterion according to which the array of standard constants is locally near optimal, then that criterion might be related to a form of spacetime reproduction.

The form of reproduction doesn't have to be the natural formation of astrophysical black holes. The standard constants don't have to be at a local optimum for that. It might be something else. If they are optimal for anything at all.

The core craziness of Smolin's idea is still intact and still walks the earth. Only one detailed manifestation has been shot down.

I am pleased to hear that you are giving a talk on Smolin CNS, and on the visionary vagaries of Penrose---watching whom, as signpost to ultimate truth, resembles Roman prophesy by observing the flight of birds. His ideas could be flying in the right direction and indeed quite likely are, but why nobody knows.

 

[unusualname]

He gives some references, the most recent of which is R. Penrose (2009), "Black holes, quantum theory, and cosmology" (Fourth International Workshop DICE 2008), J Physics Conf ser 174 012001. I find it truly, deeply annoying that Penrose only publishes these ideas in conference proceedings and doesn't put anything on arxiv.

-Ben

the paper is (freely available) here

along with the whole conference proceedings (and many others)

 

[bcrowell]

Thanks, marcus and unusualname, for the info! The 2-solar-mass pulsar paper is here: http://arxiv.org/abs/1010.5788 No, I hadn't heard about it.

-Ben

 

[Coin]

The book has a lengthy discussion of loss of degrees of freedom on pp. 186-190. He believes that information *is* lost in black holes, and unitarity is violated. This is linked to his views on quantum mechanics: "The replacement of $\psi$ with the particular choice $\psi_i$ that Nature comes up with is referred to as the reduction of the quantum state or the collapse of the wavefunction, for which I use the letter R...it is my contention that the R phenomenon represents a deviation from the strict adherence of Nature to unitarity, and that this arises when gravity begins to become seriously (even if subtly) involved."

This is an idea I've seen in Penrose's writings before... this "R operation" idea, that the collapse of the wavefunction is a specific physical phenomenon which is nonunitary and irreversible, and is to be differentiated from the "U operation" (the normal evolution of the schrodinger equation). In Road to Reality he gives some straightforward-looking thought experiments trying to demonstrate the idea that waveform collapse is irreversible, which looked convincing, but I expect I'm pretty easy to bamboozle.

It seemed weird to me at the time, and still seems pretty weird, that Penrose can just assert this and there's no particular grounds to refute him. The party line (aka the "shut up and calculate interpretation") seems to be that the different QM "interpretations" are just different ways of looking at the same mathematics, and it makes no difference which you pick because you get the same answers to questions about observables either way. But Penrose here makes what looks like a decision about "interpretation" (seemingly simply choosing to take the copenhagen interpretation seriously) and it has real physical consequences (the thought experiments in road to reality, the long-term consequences in his cosmology model due to black hole information loss). I feel like what Penrose has been saying here about the U/D operations ought to be taken more seriously than it is, even if only to the extent of taking it seriously enough to bother refuting it...

On a similar note, don't the "decoherence" people claim to have worked out the math such that repeated composition of reversible "U operations" produces something that looks an awful lot like copenhagen-interpretation "waveform collapse" and/or Penrose's irreversible "R operation"? (In which case, if I understand things correctly, the information-loss/irreversible part of Penrose's "R operation" is not real but just an artifact of a mathematical approximation?) If the decoherence program can produce such math then doesn't that make Penrose's call to recognize the "R operation" as physically real and having real-world side effects unnecessary?

 

[Coin]

By the way bcrowell, you made an extremely interesting point in the other thread that I'd be curious to see revisited:

Here's something that bothers me about Penrose's idea. He says the universe can only proceed to its rebirth if all massive particles are first converted into massless particles. But regardless of whether we're talking about a pseudo-Riemannian geometry or a conformal geometry, light-cones are still well defined, and therefore we still have a notion that different regions of spacetime can become causally disconnected because of the accelerating expansion caused by the cosmological constant. So if there were only one hydrogen molecule remaining in the entire universe, how would that hold up the reincarnation process? That molecule is only causally connected to its own little piece of spacetime. How can it have a global effect? I guess the argument gets a little complicated because although causal connection of particles is transitive, causal connection of regions of spacetime is not.

Does this get addressed or explained to your satisfaction in the book? It seems like a real problem for Penrose's model.

There is a similar problem I'm seeing, which may just be a byproduct of my limited knowledge or failure to read the book. It seems like, if Penrose's heat-death end state is indeed "equivalent" to a big bang, then as we approach heat death there should be "patches" of spacetime that hit this state first. Never mind that these patches maybe are not causally disconnected from the rest of the universe, and a marauding electron or something might come screaming in from the next patch over at any time. That shouldn't matter, since I thought GR tells us that each patch of space, each point even, has its own frame of reference that ought to be something you can consider in isolation from everything else, at least until the light cones from events in neighboring space hit you. What actually happens, to this isolated patch which within itself if only for a moment or so has reached the state where it's locally conformal to the big bang? Does the patch just start bigbang-ing, then stop when an electron from the larger neighborhood wanders in? Surely not. Are these questions sensible?

EDIT: Two things: I said "U/D" in the above post where I meant to say "U/R", if it matters; and two, after reading the EPAC 2006 writeup linked in the other thread, I think I see that the error I was making here with my question about "patches" of space is in failure to understand what Penrose means by the "future boundary"... but I'm not totally certain how to sensibly interpret what Penrose does mean by the "future boundary" :|

 

[Jack21222]

Paper hit the arXiv a few days ago:

http://arxiv.org/abs/1011.3706

 

[bcrowell]

Does this get addressed or explained to your satisfaction in the book? It seems like a real problem for Penrose's model.

No, it didn't seem to be addressed.

Paper hit the arXiv a few days ago:

http://arxiv.org/abs/1011.3706

Interesting! They claim 6-sigma significance, in both WMAP and Boomerang data. Hard to tell, however, whether the statistics are trustworthy.

 

[MTd2]

I cannot see any clear circle around the center pointed on figure 3. And the sigma pointed there does not make sense given that the map has so many points that the some of them are likely to have more or less homogeneous distributions.

 

[bcrowell]

I cannot see any clear circle around the center pointed on figure 3. And the sigma pointed there does not make sense given that the map has so many points that the some of them are likely to have more or less homogeneous distributions.

There's no reason to expect that these correlations should necessarily be visible to the eye on an image of the CMB. But yeah, in general it's pretty dicey to judge levels of statistical significance in this kind of thing. This kind of analysis is a variation on a theme. The theme is that you have a spectrum with some peaks in it, and you want to judge the statistical significance of the peaks. If the null hypothesis was that the spectrum was flat and featureless except for Poisson fluctuations, it would be easy to judge statistical significance. But when the spectrum has backgrounds that need to be subtracted out, it gets a lot more ambiguous.

 

[Fra]

The form of reproduction doesn't have to be the natural formation of astrophysical black holes. The standard constants don't have to be at a local optimum for that. It might be something else. If they are optimal for anything at all.

The core craziness of Smolin's idea is still intact and still walks the earth. Only one detailed manifestation has been shot down.

This is also how I see this.

Ever since I read about Smolins CNS I never felt much attraction to his specific suggestion about BH production, I rather read his views rooted in an insight that there can't be an objective scientific notion of timeless law, and that evolution of law (be it fundamental or effective) seems to be unavoidable. Any ideas of timeless an eternal law seems to always resort of form of realism that seem inherently non-scientific and irrational. He and Unger has made several philosophical talks on this.

Then, I see his CNS as an attempt to implement a specific falsifiable theory in line with that thinking. But if that specific implementation has now failed IMO means nothing to the much deeper spirit of intent.

I also see a remote connection between evolution of law, and Penrose connection between collapses and gravity, but while Penrose seems to seek some sort of realism or objective collapse (unless he changed his mind) I see it the other way around, that it's the undecidability and subjectivity of information updates that yields gravity.

Does anyone know if Penrose is still seeking these objective realist type of solutions to these quests? This is what I don't like about his reasoning, but otherwise I like that he is bold enough to insist that QM may need revision, a vision I also share, but in a possibly different direction.

As I see it the main argument for unitary is that it implies decidability. Non-unitarity impless loss of decidabiity. But the point is (if you see it a certain way) is that a lot points to that this undecidability is real, not artifacts of mathematical models.

/Fredrik

 

[marcus]

http://arxiv.org/abs/1012.1268
A search for concentric circles in the 7-year WMAP temperature sky maps
I. K. Wehus, H. K. Eriksen

http://arxiv.org/abs/1012.1305
No evidence for anomalously low variance circles on the sky
Adam Moss, Douglas Scott, James P. Zibin
Sean Carroll pointed these out. Looks like Penrose circles not confirmed.
http://blogs.discovermagazine.com/cosmicvariance/2010/12/07/penroses-cyclic-cosmology/

 

[marcus]

New paper by Penrose and Gurzadyan today:
http://arxiv.org/abs/1012.1486
More on the low variance circles in CMB sky
V.G.Gurzadyan, R.Penrose
2 pages
(Submitted on 7 Dec 2010)
"Two groups [3,4] have confirmed the results of our paper concerning the actual existence of low variance circles in the cosmic microwave background (CMB) sky. They also point out that the effect does not contradict the LCDM model - a matter which is not in dispute. We point out two discrepancies between their treatment and ours, however, one technical, the other having to do with the very understanding of what constitutes a Gaussian random signal. Both groups simulate maps using the CMB power spectrum for LCDM, while we simulate a pure Gaussian sky plus the WMAP's noise, which points out the contradiction with a common statement [3] that 'CMB signal is random noise of Gaussian nature'. For as it was shown in [5], the random component is a minor one in the CMB signal, namely, about 0.2. Accordingly, the circles we saw are a real structure of the CMB sky and they are not of a random Gaussian nature. Although the structures studied certainly cannot contradict the power spectrum, which is well fitted by LCDM model, we particularly emphasize that the low variance circles occur in concentric families, and this key fact cannot be explained as a purely random effect. It is, however a clear prediction of conformal cyclic cosmology."

 

[twofish-quant]

Then, I see his CNS as an attempt to implement a specific falsifiable theory in line with that thinking. But if that specific implementation has now failed IMO means nothing to the much deeper spirit of intent.

I like Smolin's ideas because they are testable via observations. As an *assumption*, the idea that there are universal and invariant rules that govern the universe isn't a bad one. The problem is that it becomes unscientific dogma, if there is no way of testing that idea.

Also, they are different. Coming up with a different idea that is testable is non-trivial.

I see it the other way around, that it's the undecidability and subjectivity of information updates that yields gravity.

And I see all these things are just "poetic inspiration". What matters to me is whether or not you can get me something that I can make some sort of machine out of.

 

[tom.stoer]

T... don't the "decoherence" people claim to have worked out the math such that repeated composition of reversible "U operations" produces something that looks an awful lot like copenhagen-interpretation "waveform collapse" and/or Penrose's irreversible "R operation"?

Yes and no.

Assume you have a macroscopic object like a soccer ball and that you can prepare it to be in a qantum state being in two soccer goals A and B at te same time. Decoherence explains why this state decoheres immediately to one where the ball is located in exactly one goal, but decoherence does not explain why it decoheres to the state located in A (and not B). It does not explain what choses A or B. So I think even with decoherence you need somethig like many-worlds.

I don't know how the R operator can make this selection.

 

[MTd2]

You people missed this paper, which is related to this work, and is cited by the new paper:

http://arxiv.org/abs/1011.3711

A weakly random Universe?
Authors: V.G.Gurzadyan, A.E.Allahverdyan, T.Ghahramanyan, A.L.Kashin, H.G.Khachatryan, A.A.Kocharyan, S.Mirzoyan, E.Poghosian, D.Vetrugno, G.Yegorian
(Submitted on 16 Nov 2010 (v1), last revised 23 Nov 2010 (this version, v2))

Abstract: The cosmic microwave background (CMB) radiation is characterized by well-established scales, the 2.7 K temperature of the Planckian spectrum and the $10^{-5}$ amplitude of the temperature anisotropy. These features were instrumental in indicating the hot and equilibrium phases of the early history of the Universe and its large scale isotropy, respectively. We now reveal one more intrinsic scale in CMB properties. We introduce a method developed originally by Kolmogorov, that quantifies a degree of randomness (chaos) in a set of numbers, such as measurements of the CMB temperature in some region. Considering CMB as a composition of random and regular signals, we solve the inverse problem of recovering of their mutual fractions from the temperature sky maps. Deriving the empirical Kolmogorov's function in the Wilkinson Microwave Anisotropy Probe's maps, we obtain the fraction of the random signal to be about 20 per cent, i.e. the cosmological sky is a weakly random one. The paper is dedicated to the memory of Vladimir Arnold (1937-2010).

 

[Fra]

And I see all these things are just "poetic inspiration". What matters to me is whether or not you can get me something that I can make some sort of machine out of.

I fully agree that in the end something that makes a difference is what counts.

For someone that is not too alien to that poetry, it actually defines a research strategy (not a theory) that is meaningful until something that makes a difference is on the table. For those more alien to that poetry it is "just poetry" - until something out of nowhere arrives on the table.

I think of MOST discussions, including ST, NCG, LQG or what your favourite strategy is to try to figure from what direction it's most likely to come something that makes a difference - NEITHER of them has IMO produced much or anything at all that really makes a difference. So as far as I see, it's all poetry to me, still it attracts attention. There is just different kinds of poetry it seems.

I'm not a professional, meaning I have a minimum of time to spend on this, but I am indeed working on developing my own thinking along these lines and when/if I get testable predictions I will publish it. I haven't once mentioned anything but fragments simply because of what you say: it's not worth mentioning until it flies.

What I find remarkable though is that some research programs has survived for decades built merely on forests of fragments of poetry, and still nothing that flies.

/Fredrik

 

[marcus]

...
I think of MOST discussions, including ST, NCG, LQG or what your favourite strategy is to try to figure from what direction it's most likely to come something that makes a difference - NEITHER of them has IMO produced much or anything at all that really makes a difference. So as far as I see, it's all poetry to me, still it attracts attention. There is just different kinds of poetry it seems...

If you play by the rules of empirical science what "flies" and what "makes a difference" is what is testable. Some people seem not to have noticed that LQG has reached this point. It predicts a bounce cosmology which the phenomenologists tell us is testable.

 

[Fra]

If you play by the rules of empirical science what "flies" and what "makes a difference" is what is testable.

I agree. But I also mean that it should be major predctions, and it should fly more than anyone that can't fly can jump ;)

Some people seem not to have noticed that LQG has reached this point. It predicts a bounce cosmology which the phenomenologists tell us is testable.

I admit that I was over-generalizing in my statement there. You know LQG way better than me. I didn't mean to pick on anything in particular here. What I meant is as far as I know most of the big programs mentioned still has very minor if any significant predictions, and that major, significant predictions is what will elevate it from poetic research programs to something that will draw new attention. If you ask a ST theorist they have predictions too, but it's not specific or major enough to be what I call something that makes a difference.

/Fredrik

 

[Fra]

It's the fact that I have this opinon that is why I try to - until there is something that seems to REALLY fly - focus on the constructing principles and logic of reasoning. There are bits and pieces in several of the research major programs that I think is really good.

I'm really low on time atm, but my current focus is still reflecting up Knuths idea on posets, lattices and how he identifies observers with chains. There are some things missing there I'm trying to connect to my own counting procedures. There should also be a connection to this and the Fourier transform I haven't figure out yet. knuth also referred to futyre papers for details so I hope he develops it in a good direction.

/Fredrik

 

[marcus]

... If you ask a ST theorist they have predictions too, but it's not ...

... until there is something that seems to REALLY fly ...

I understand what you are saying, and realize you have little time atm to think about what's going on. I'll reply anyway, in case you or some other reader are feeling receptive.

The early universe is essentially the only empirical arena for QG. If extreme events involving black holes could be observed in sufficient detail that might constitute another. But practically speaking the main source of data is the CMB. Tons of data are coming in, and we can expect increasing detail with future instruments.

A QG theory must translate into quantum cosmology. To "REALLY fly" means to make predictions about observational detail in the CMB, based on a model of the early universe.

Modeling the early universe and predicting features to be seen in CMB is now the name of the game. Phenomenologists (not the Loop people themselves) have started treating Loop bounce cosmology as the main proposal on the table. Penrose is smart enough to see this even if others are not. Presumably Penrose would like phenomenologists to take a look at his version of the early universe as well.

Penrose had to present evidence of pattern in CMB---he had to see concentric circles, or believe he did---just to get into the game. Because half a dozen early universe phenomenologists (representative example Aurelien Barrau) are already proposing to test Loop with CMB polarization patterns.

Fra, you say "ask a ST theorist", as if the situation were comparable. The analogy with ST does not work, not enough similarity. I wasn't suggesting that you "ask a Loop theorist". The person most clearly representative of the field is Rovelli--he has not claimed that LQG makes a testable prediction about what can be observed in the CMB. The job of deciding whether and how Loop is testable is, I think, properly left to the early universe phenomenologists---it's their specialty and they have the credentials.

Mairi Sakellariadou, at King's College London, uses the abbreviation EU because it has become such a common expression---this confused me at first because I thought it meant "European Union".
http://www.kcl.ac.uk/schools/nms/physics/people/academic/sakellariadou/
I gather she is interested in deriving some CMB-testable consequences from NCG-EU-cosmology. Still pretty nebulous.

 

[marcus]

http://arxiv.org/abs/1012.1268
A search for concentric circles in the 7-year WMAP temperature sky maps
I. K. Wehus, H. K. Eriksen

http://arxiv.org/abs/1012.1305
No evidence for anomalously low variance circles on the sky
Adam Moss, Douglas Scott, James P. Zibin
Sean Carroll pointed these out. Looks like Penrose circles not confirmed.
http://blogs.discovermagazine.com/cosmicvariance/2010/12/07/penroses-cyclic-cosmology/

New paper by Penrose and Gurzadyan today:
http://arxiv.org/abs/1012.1486
More on the low variance circles in CMB sky
V.G.Gurzadyan, R.Penrose
2 pages
(Submitted on 7 Dec 2010)
"Two groups [3,4] have confirmed the results of our paper concerning the actual existence of low variance circles in the cosmic microwave background (CMB) sky. They also point out that the effect does not contradict the LCDM model - a matter which is not in dispute. We point out two discrepancies between their treatment and ours, however, one technical, the other having to do with the very understanding of what constitutes a Gaussian random signal. Both groups simulate maps using the CMB power spectrum for LCDM, while we simulate a pure Gaussian sky plus the WMAP's noise, which points out the contradiction with a common statement [3] that 'CMB signal is random noise of Gaussian nature'. For as it was shown in [5], the random component is a minor one in the CMB signal, namely, about 0.2. Accordingly, the circles we saw are a real structure of the CMB sky and they are not of a random Gaussian nature. Although the structures studied certainly cannot contradict the power spectrum, which is well fitted by LCDM model, we particularly emphasize that the low variance circles occur in concentric families, and this key fact cannot be explained as a purely random effect. It is, however a clear prediction of conformal cyclic cosmology."

Continuing the story:
http://arxiv.org/abs/1012.1656
Are There Echoes From The Pre-Big Bang Universe? A Search for Low Variance Circles in the CMB Sky
Amir Hajian
(Submitted on 8 Dec 2010)
The existence of concentric low variance circles in the CMB sky, generated by black-hole encounters in an aeon preceding our big bang, is a prediction of the Conformal Cyclic Cosmology. Detection of three families of such circles in WMAP data was recently reported by Gurzadyan & Penrose (2010). We reassess the statistical significance of those circles by comparing with Monte Carlo simulations of the CMB sky with realistic modeling of the anisotropic noise in WMAP data. We find that the circles are not anomalous and that all three groups are consistent at 3sigma level with a Gaussian CMB sky as predicted by inflationary cosmology model.

==================

More about early universe phenomenology here:
https://www.physicsforums.com/showthread.php?p=3028777#post3028777

 

[ordered_chaos]

Continuing the story:
http://arxiv.org/abs/1012.1656
Are There Echoes From The Pre-Big Bang Universe? A Search for Low Variance Circles in the CMB Sky
Amir Hajian
(Submitted on 8 Dec 2010)

Awwww :(. After reading this paper it seems like a big knock against Penrose and his search for low variance circles; and I really like the idea of Cyclic Cosmology.

BTW that HEALPix software looks sweet. It reminds of the bit maps embedded on black holes which are suppose to represent the holographic principle.

 

[bcrowell]

Hajian was the grad student Penrose referred to in his book as finding promising hints of circles.

To me the thing that really kills the idea definitively is that in this paper http://arxiv.org/abs/1012.1305 they found concentric *triangles*!

 

[MTd2]

Another paper today:

http://www.technologyreview.com/blog/arxiv/26132/?ref=rss

These guys argue for evidence of concentric circles. They interpret as collisions with other universes though, given that the data analysis is not phenomenal but a program that just do circle-seeking, I think it could be use for that Penrose theory.

 

[bcrowell]

Another paper today:

http://www.technologyreview.com/blog/arxiv/26132/?ref=rss

This is not a new paper. This is a blog entry discussing the original paper.

Here are a couple of other attempts to sort out the evidence:

http://blogs.plos.org/badphysics/2010/12/13/novemeber30th/?utm_source=feedburner&utm_medium=feedutm_campaign=Feed%3A+plos%2Fblogs%2Fbadphysics+%28Blogs+-+Bad+Physics%29

http://www.nature.com/news/2010/101210/full/news.2010.665.html

[EDIT] Oops, as marcus pointed out, the technologyreview post is mainly about eternal inflation, not Penrose & Gurzadyan. Thanks for the correction, marcus!

 

[marcus]

Another paper today:

http://www.technologyreview.com/blog/arxiv/26132/?ref=rss

These guys argue for evidence of concentric circles. They interpret as collisions with other universes though, given that the data analysis is not phenomenal but a program that just do circle-seeking, I think it could be use for that Penrose theory.

MTd2 thanks for pointing to this new paper! The paper is not about Penrose idea, as you observe, although the journalist makes a passing reference to Penrose & Gurzadyan. The paper is about eternal inflation--a very different matter from Penrose Conformal Cyclic!
You might well be right that the analysis in the new paper might be adapted to support Penrose CCC.

The paper that the MIT Tech Review reporter is discussing first appeared on arxiv 10 December. Here it is:

http://arxiv.org/abs/1012.1995
First Observational Tests of Eternal Inflation
Stephen M. Feeney (UCL), Matthew C. Johnson (Perimeter Institute), Daniel J. Mortlock (Imperial College London), Hiranya V. Peiris (UCL)
5 pages, 2 figures, companion paper forthcoming
(Submitted on 9 Dec 2010)
"The eternal inflation scenario predicts that our observable universe resides inside a single bubble embedded in a vast multiverse, the majority of which is still undergoing super-accelerated expansion. Many of the theories giving rise to eternal inflation predict that we have causal access to collisions with other bubble universes, opening up the possibility that observational cosmology can probe the dynamics of eternal inflation. We present the first observational search for the effects of bubble collisions, using cosmic microwave background data from the WMAP satellite. Using a modular algorithm that is designed to avoid a posteriori selection effects, we find four features on the CMB sky that are consistent with being bubble collisions. If this evidence is corroborated by upcoming data from the Planck satellite, we will be able to gain insight into the possible existence of the multiverse."

This appeared at arxiv.org preprint site on Friday 10 December.
At this point it seems like just a speculative notion. They need further data if they want to make a more of a real case.
The MIT Tech Review reminded readers of the "face" on Mars that at one time people saw sculpted in Martian terrain.

Thanks to MTd2 for spotting this item and tipping us to it.

I started thread on this in Cosmo forum earlier today. Just so there is no confusion I will quote the MIT Tech Review here:

The MIT Tech Review had this journalistic account (also mentioning Penrose Conformal Cyclic cosmology and the concentric circle evidence for it that was recently offered.)

==quote Tech Review==
Astronomers Find First Evidence Of Other Universes
Our cosmos was "bruised" in collisions with other universes. Now astronomers have found the first evidence of these impacts in the cosmic microwave background

There's something exciting afoot in world of cosmology. Last month, Roger Penrose at the University of Oxford and Vahe Gurzadyan at Yerevan State University in Armenia announced that they had found patterns of concentric circles in the cosmic microwave background, the echo of the Big Bang.

This, they say, is exactly what you'd expect if the universe were eternally cyclical. By that, they mean that each cycle ends with a big bang that starts the next cycle. In this model, the universe is a kind of cosmic Russian Doll, with all previous universes contained within the current one.

That's an extraordinary discovery: evidence of something that occurred before the (conventional) Big Bang.

Today, another group says they've found something else in the echo of the Big Bang. These guys start with a different model of the universe called eternal inflation. In this way of thinking, the universe we see is merely a bubble in a much larger cosmos. This cosmos is filled with other bubbles, all of which are other universes where the laws of physics may be dramatically different to ours.

These bubbles probably had a violent past, jostling together and leaving "cosmic bruises" where they touched. If so, these bruises ought to be visible today in the cosmic microwave background.

Now Stephen Feeney at University College London and a few pals say they've found tentative evidence of this bruising in the form of circular patterns in cosmic microwave background. In fact, they've found four bruises, implying that our universe must have smashed into other bubbles at least four times in the past.

Again, this is an extraordinary result: the first evidence of universes beyond our own.

So, what to make of these discoveries. First, these effects could easily be a trick of the eye. As Feeney and co acknowledge: "it is rather easy to find all sorts of statistically unlikely properties in a large dataset like the CMB." That's for sure!

There are precautions statisticians can take to guard against this, which both Feeney and Penrose bring to bear in various ways.

But these are unlikely to settle the argument. In the last few weeks, several groups have confirmed Penrose's finding while others have found no evidence for it. Expect a similar pattern for Feeney's result.

The only way to settle this will be to confirm or refute the findings with better data. As luck would have it, new data is forthcoming thanks to the Planck spacecraft that is currently peering into the cosmic microwave background with more resolution and greater sensitivity than ever.

Cosmologists should have a decent data set to play with in a couple of years or so. When they get it, these circles should either spring into clear view or disappear into noise (rather like the mysterious Mars face that appeared in pictures of the red planet taken by Viking 1 and then disappeared in the higher resolution shots from the Mars Global Surveyor).

Planck should settle the matter; or, with any luck, introduce an even better mystery. In the meantime, there's going to be some fascinating discussion about this data and what it implies about the nature of the Universe. We'll be watching.
==endquote==
http://www.technologyreview.com/blog/arxiv/26132/

The new paper that MTd2 brought up is the one by Feeney et al concerned with the Eternal Inflation scenario.
It is important to distinguish between Penrose CCC and (Andrei Linde's if I remember right) Eternal Inflation. They are extremely different. And both different from Steinhardt Cyclic (clashing brane) cosmology. These could all be wrong. (I am inclined to suspect they are, in fact, wrong.) But no doubt something will be learned by people trying to work out the phenomenology and find some trace of these different pre-bang scenarios in the CMB. So I wish them well.

 

[marcus]

This is not a new paper. This is a blog entry discussing the original paper.

Here are a couple of other attempts to sort out the evidence:

http://blogs.plos.org/badphysics/2010/12/13/novemeber30th/?utm_source=feedburner&utm_medium=feedutm_campaign=Feed%3A+plos%2Fblogs%2Fbadphysics+%28Blogs+-+Bad+Physics%29

http://www.nature.com/news/2010/101210/full/news.2010.665.html

[EDIT] Oops, as marcus pointed out, the technologyreview post is mainly about eternal inflation, not Penrose & Gurzadyan. Thanks for the correction, marcus!

Certainly, you are most welcome! I should thank you for the Nature link. It looks to me like it does a very good job. It briefly chronicles the whole story and gives links to all 5 papers and lays out the issues clearly. Maybe that short one-page Nature news item wraps it up for Penrose Gurzadyan. I don't have a guess. I will just keep an eye out in case there is more.

Crowell, the trend I see is that even if we see Penrose immediately shot down this is a sign of things to come. I think a bunch of other people will be offering other pre-bang ideas. Like e.g. Feeney et al. just 3 days ago. A bunch of people are going to try to find phenom. checks to test pre-bang ideas. Maybe Feeney et al. will also be shot down. But as a general thing, these ideas for looking for pre-bang clues in the CMB are going to keep coming, I'm thinking. Does it seem that way to you?

And I'm not talking exclusively about "circles". Here are a couple by Aurelien Barrau that have the same general theme (phenomenologist looks for footprint in CMB of a cosmology model the goes back prebang)
arXiv:1011.5516
Inflation and Loop Quantum Cosmology
Aurelien Barrau
5 pages, Proceedings of the 35th International Conference on High Energy Physics, Paris, 2010 (ICHEP 2010)

arXiv:1011.1811
Observing the Big Bounce with Tensor Modes in the Cosmic Microwave Background: Phenomenology and Fundamental LQC Parameters
Julien Grain, A. Barrau, T. Cailleteau, J. Mielczarek
12 pages, 5 figures