Doubts about the Evidence for Penrose’s Cyclic Universe

A strange paper by Gurzadyan and Penrose hit the Arxiv a week or so ago. It seems to have generated quite a lot of reaction in the blogosphere and has now made it onto the BBC News, so I think it merits a comment.

The authors claim to have found evidence that supports Roger Penrose‘s conformal cyclic cosmology in the form of a series of (concentric) rings of unexpectedly low variance in the pattern of fluctuations in the cosmic microwave background seen by the Wilkinson Microwave Anisotropy Probe (WMAP). There’s no doubt that a real discovery of such signals in the WMAP data would point towards something radically different from the standard Big Bang cosmology.

I haven’t tried to reproduce Gurzadyan & Penrose’s result in detail, as I haven’t had time to look at it, and I’m not going to rule it out without doing a careful analysis myself. However, what I will say here is that I think you should take the statistical part of their analysis with a huge pinch of salt.

Here’s why.

The authors report a hugely significant detection of their effect (they quote a “6-σ” result; in other words, the expected feature is expected to arise in the standard cosmological model with a probability of less than 10-7. The type of signal can be seen in their Figure 2, which I reproduce here:

Sorry they’re hard to read, but these show the variance measured on concentric rings (y-axis) of varying radius (x-axis) as seen in the WMAP W (94 Ghz) and V (54 Ghz) frequency channels (top two panels) compared with what is seen in a simulation with purely Gaussian fluctuations generated within the framework of the standard cosmological model (lower panel). The contrast looks superficially impressive, but there’s much less to it than meets the eye.

For a start, the separate WMAP W and V channels are not the same as the cosmic microwave background. There is a great deal of galactic foreground that has to be cleaned out of these maps before the pristine primordial radiation can be isolated. The fact similar patterns can be found in the BOOMERANG data by no means rules out a foreground contribution as a common explanation of anomalous variance. The authors have excluded the region at low galactic latitude (|b|<20°) in order to avoid the most heavily contaminated parts of the sky, but this is by no means guaranteed to eliminate foreground contributions entirely. Here is the all-sky WMAP W-band map for example:

Moreover, these maps also contain considerable systematic effects arising from the scanning strategy of the WMAP satellite. The most obvious of these is that the signal-to-noise varies across the sky, but there are others, such as the finite size of the beam of the WMAP telescope.

Neither galactic foregrounds nor correlated noise are present in the Gaussian simulation shown in the lower panel, and the authors do not say what kind of beam smoothing is used either. The comparison of WMAP single-channel data with simple Gaussian simulations is consequently deeply flawed and the significance level quoted for the result is certainly meaningless.

Having not looked looked at this in detail myself I’m not going to say that the authors’ conclusions are necessarily false, but I would be very surprised if an effect this large was real given the strenuous efforts so many people have made to probe the detailed statistics of the WMAP data; see, e.g., various items in my blog category on cosmic anomalies. Cosmologists have been wrong before, of course, but then so have even eminent physicists like Roger Penrose…

Another point that I’m not sure about at all is even if the rings of low variance are real – which I doubt – do they really provide evidence of a cyclic universe? It doesn’t seem obvious to me that the model Penrose advocates would actually produce a CMB sky that had such properties anyway.

Above all, I stress that this paper has not been subjected to proper peer review. If I were the referee I’d demand a much higher level of rigour in the analysis before I would allow it to be published in a scientific journal. Until the analysis is done satisfactorily, I suggest that serious students of cosmology shouldn’t get too excited by this result.

It occurs to me that other cosmologists out there might have looked at this result in more detail than I have had time to. If so, please feel free to add your comments in the box…

IMPORTANT UPDATE: 7th December. Two papers have now appeared on the arXiv (here and here) which refute the Gurzadyan-Penrose claim. Apparently, the data behave as Gurzadyan and Penrose claim, but so do proper simulations. In otherwords, it’s the bottom panel of the figure that’s wrong.

ANOTHER UPDATE: 8th December. Gurzadyan and Penrose have responded with a two-page paper which makes so little sense I had better not comment at all.


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62 Responses to “Doubts about the Evidence for Penrose’s Cyclic Universe”

  1. [...] This post was mentioned on Twitter by S.C. Kavassalis and Mark Tibbetts, Peter Coles. Peter Coles said: Doubts about the Evidence for Penrose's Cyclic Universe: http://wp.me/pko9D-281 [...]

  2. I can’t think of a single previous /observational/ result of Penrose’s – by which I mean one whose validity depended on experimental data. He’s good at the mathematical stuff, no doubt, but this may be the first serious encounter with statistics …

    And why didn’t he just walk next door from the Mathematical Institute in Oxford and find a dozen or so perfectly competent cosmologists to discuss the CMB with?

  3. On the theory side, I haven’t seen a derivation of this effect in the paper, just explanation in words, and reference to an appendix in Penrose’s popular book for background. Anyone with a little bit of experience will wonder if he really has a working model, which is sufficiently under control to make any claims precise enough to compare to observations. Maybe it is all OK, but the lack of detail does not precisely inspire confidence.

    • Anton Garrett Says:

      Just like his suggestion that quantum gravity effects are necessary for consciousness in the brain. He took several hundred pages to say: “Here’s one thing we don’t understand. Here’s another. So the two are probably related.”

      Penrose did some brilliant work, but that was a long time ago.

    • I’d like to speak up a bit on behalf of Roger Penrose, in that at least he’s prepared to be radical about things rather than going with the masses. Even if he’s wrong, he tends to be wrong in interesting ways!

      This reminds me a bit of Jim Peebles – a truly great physicist in my opinion – who, having spent the early part of his life doing much to establish the Big Bang theory, spent his later years trying to get people to question it a lot more. He’d paid his dues, so he had earned the right to rock the boat and I think it’s to his immense credit that he’s carried on trying to think outside the box.

    • telescoper Says:

      I should get a prize for the number of metaphors I mixed in that comment.

    • Anton Garrett Says:

      “Even if he’s wrong, he tends to be wrong in interesting ways!”

      Maybe about other things. (What did you have in mind?) But not about consciousness.

    • I enjoyed enough hours of admiring twistors to forgive Penrose anything. Just wish I could understand what he was saying more precisely.

      One comment about being radical, just because it amused me, with no relation to the current discussion. I remember reading a survey of early universe cosmology written in 1979, a few months before inflation, and pre-big-bang theories (i.e. universes with infinite past) were pretty much the accepted picture. Not the only place where yesterday’s conservative view is today’s radical one (isn’t this supposed to be the other way around?).

    • telescoper Says:

      Good question. Do you think string theory is radical? Or has it already become a form of concervatism.

      In general I’d say that scientists should be “radical” about generating new ideas but “conservative” when it comes to evidence.

    • I think being conservative or radical is a marketing strategy more than any well-defined characteristics that we can discuss in some inter-subjective way. I’m just amused how many of the ideas labeled “radical” are wishes to return to the glory days of pre-something (quantum, relativity, inflation,…). Probably just best to evaluate things on the merits instead of worrying too much about how to label them.

    • Anton Garrett Says:

      Moshe,
      Twistors are simply part of a higher-dimensional Clifford Algebra, the conformal geometric algebra of spacetime; and you get a lot more for your money if you admit the entire algebra. Admittedly this viewpoint embeds twistors within algebras of spacetime, whereas the original motivation for twistors was the reverse – that they should exist at a pre-metric level, so that the spacetime interval between points emerges from a certain 2D quantum inner product, which in turn hints at a route to quantum gravity in which distance is a quantum observable. But a generation later the early promise of this approach has not been fulfilled, and I much prefer the Clifford-algebraic view which has shed light on so many things – an algebra which unifies all of vectors, tensors, spinors, twistors, quaternions, spin matrices, etc. It is as superior to these as complex analysis is to 2D vector analysis; indeed it *is* the generalisation of complex analysis to higher dimensions, and the natural mathematical language for physics. In particular, the Dirac equation and GR look a lot simpler phrased in this way. For more, see the book “Geometric algebra for physicists” by Doran and Lasenby; twistors are covered in Chapter 10, section 7.
      Anton

    • “This reminds me a bit of Jim Peebles – a truly great physicist in my opinion – who, having spent the early part of his life doing much to establish the Big Bang theory, spent his later years trying to get people to question it a lot more.”

      I might be wrong, but my impression was that Peebles was playing devil’s advocate, rather than really doubting. Which brings me to one of the candidates for the best one-liner of all time. At the 2000 IAU General Assembly in Manchester, Ruth Daly showed some lambda-Omega diagrams illustrating what parts of parameter space were allowed by her work. Peebles said that if he understood things correctly, there would still be enough room for him to live in the Einstein-de Sitter part of the diagram. Bob Kirshner then called out “But you would be alone!”

  4. My impression is that they had found a single example and used Monte Carlo to get the significance, yet didn’t state how many examples where sort through. If the probability of significance is any were near the ratio of accepted to rejected then it’s not significant result. Like finding the letters SH written in the CMB.

  5. [...] Today 10., Nature 13.10.2010) NACHTRAG: Überzeugende Evidenz für ein zyklisches Universum steckt übrigens nicht in den [...]

  6. I think you didn’t quite understand what the news is here, the theory by itself of a cyclical universal “big bang” isn’t new, nor is it being introduced here by Sir Penrose.

    Here we have the first attempt at providing the mathematical basis alongside observational data, that is what is significant here.

    Indeed it is by no means the end of the debate, rather the beginning.

    But at least there is observational evidence for this theory, whereas the Big Bang theory remains just theory, so in that sense it slightly more plausible in scientific terms.

    • telescoper Says:

      Ahem. There is a huge amount of evidence in favour of the Big Bang, gleaned from careful statistical analysis of relevant data. Obviously you aren’t aren’t aware of the progress that has been made in the last decades, or have chosen to ignore it.

    • If anything all more recent collected data has only has weakened an easy comprehensible big bang theory and it looks like it’s still quite far from “complete”.

    • telescoper Says:

      Everyone knows the Big Bang theory isn’t complete, but please justify your assertion that “all recent collected data has weakened” the theory.

    • Well because big bang theory relies as much on assumption as it does on the fitted collected data, it doesn’t do much in the way of negating other theories.

      If i were to make the assumption the universe is cyclical and that the expansion speeds up and slows down in cycles, effectively it can be argued that more recent data would corroborate this.

      And there are of course a lot more recent findings that do not sit well with big bang theory, so in that sense the theory is not as strong as it used to be before we had collected all this data. There is still a lot to be ignored to make it work.

      And if this proposition holds up to further scrutiny it would pretty much be quite a big nail in the coffin of big bang theory.

    • And there are of course a lot more recent findings that do not sit well with big bang theory, so in that sense the theory is not as strong as it used to be before we had collected all this data. There is still a lot to be ignored to make it work.

      Would you care to give some examples of these recent findings? As someone who makes a living doing cosmology, I’d really like to know.

    • For instance the fact that the expansion of the universe appears to be accelerating.
      http://www.eso.org/public/news/eso0804/

    • That’s perfectly compatible with the Big Bang. It just means the cosmological constant (which has been part of general relativistic cosmology since 1916) is not zero.

    • Indeed i guess that depends on whether one explains the acceleration as a constant or as a cyclical event.

  7. John Peacock Says:

    This is not the only claimed example of rings on the CMB sky: see http://arxiv.org/abs/1005.3923. This is on a different (larger) angular scale and is a signature of anomalous mean temperature in the rings, rather than anomalous variance. Also the significance sounds more like the sort of hairy could-be-real thing you might believe could be pulled out of WMAP with careful processing (3sigma is the claim). But unlike Gurzadyan & Penrose, this is (a) an accepted paper; (b) contains careful treatment of masks and analysis of fake data; (c) is based on a published theoretical prediction (a particular in inflation model, with no relation to Penrose’s work). It’s an impressive piece of work, and shows how this sort of thing should be done. Needless to say, Gurzadyan & Penrose don’t cite it.

  8. It always looks suspicious when physicists – let alone renowned ones like Penrose – choose book-writing or proceedings-writing over peer-reviewed papers to spread their ideas. It means they can say a lot without anyone being in a position to question or evaluate it. Also it’s rather annoying to be referred to a N-hundred-page popular science book for the definition of the theory that this paper is supposed to be testing.

  9. … There is a suggestion going around that the apparent 5 degree periodicity is just a manifestation of the known excess CMB power around l=40, magnified by a particular choice of centre on the sky.

    The link is here
    http://motls.blogspot.com/2010/11/penroses-ccc-cosmology-is-either.html

    which includes a lot of other opinions on the alleged theory too…

    The main points here are I think:
    – The ‘CCC’ causal diagram is isomorphic to the inflationary one: both include a long period of accelerated expansion
    – Whatever sort of violent events happen in CCC before the LSS could also happen in inflation, although at a much higher energy and much faster
    – The CCC requires us to identify an energy scale smaller than all nonzero particle masses (the cosmological constant scale) with one larger than most known particle masses (the minimum temperature required in a hot early Universe). This seems kind of impossible. It means equating a hot early universe, filled with radiation and containing a very large vacuum energy, with a super-cold late universe filled with radiation and a very small vacuum energy.

  10. I’m really lousy at maths, but I still try to understand the universe. So, what I like this idea is that the same thing is presented in Hindu Cosmology.
    “As in modern physics, Hindu cosmology envisaged the universe as having a cyclical nature. The end of each kalpa brought about by Shiva’s dance is also the beginning of the next. Rebirth follows destruction.”
    http://www.hinduwisdom.info/Hindu_Cosmology.htm
    And that knowledge has many other points too, which have been confirmed by modern science. :)

    • Anton Garrett Says:

      Odd then that science emerged in a Christian milieu…

    • “Odd then that science emerged in a Christian milieu…”

      Of course, it depends on how one defines “science”. I would certainly think that a few Ancient Greeks, some mediaeval Chinese and Arabic folks did something quite similar to what we understand “science” to mean today. Maybe the first modern scientist was Copernicus, or Kepler, or Galileo, or Newton, or Leonardo da Vinci. While not open atheists and perhaps religious in some sense, all suffered some degree of opposition from the Church. Whether or not they were religious (and, if so, whether or not they were heretics), it doesn’t seem that religion played a big role in their scientific lives.

  11. I take it back that Penrose et al. have actually “rediscovered” the L=40 bump in the WMAP spectrum. They didn’t simply because if they had, they would know about the right scale – or value of L. As my e-mail exchanges with the Armenian author showed, they are not aware of any scale or special values of L.

    Instead, they are impressed by “any” concentric circles of “any size”.

    The graphs showing that the variations in the circles are bigger than the “noise” are of course totally misleading because the graphs with the large variations were drawn relatively to the centers of skies where the concentric variations are large – they were cherry-picked. So of course, it would be nonsensical to expect that the cherry-picked would-be centers of the concentric circles will show the same kind of “noise” as random points. Of course that they will show bigger signal – that’s how they were cherry-picked.

    The authors haven’t provided any quantitative evidence that there is any other statistical effect. In fact, it’s pretty clear that there’s none and if there would be such circles, at least with some typical radii, they would impact the spherical harmonic coefficients as well.

    The evidence for a new effect is really non-existent and their analysis was far less sophisticated, not more sophisticated, than the usual expansions into spherical harmonics.

    • telescoper Says:

      I’m not sure it can be just the l=40 bump, although that might play a role. It’s more than likely a combination of things.

      But you’re right in your comment about the a posteriori selection involved. There will be some points on the sky that have peculiar properties like this, and one must be sure to compare them with similarly extremal points in the simulations, not with “typical” points.

      Unfortunately the Gurzadyan-Penrose paper doesn’t really give enough details for one to be able to reproduce their analysis easily.

  12. I do think it’s nice that he’s suggested some physical motivation and then hunted it with data. Many authors simply pick some statistical anomaly and then spend the whole time proving that their anomaly is really ‘anomalous’ – a-posteriori usually. However, we discussed this paper in the Kavli journal club the other day and the overwhelming opinion was that the statistics were wrong. I don’t understand the bottom plot above, surely that plot is just gaussian noise not a gaussian cmb realisation. running the same test on a gaussian cmb realisation, I find the plot to look much more like ln(x) than a flat line. Looking at the concentric circles plot (the BBC plot), am I right in thinking that the region includes the galactic plane? As Peter explains, even with a conservative cut, these findings can be consistent with incorrectly-removed foregrounds, particularly when you consider the morphology of the dust emission.

    I would have to disagree with the comment that the “Giant Rings” paper is a better treatment and should be cited in their work. I am not a huge fan of anomalies papers, and as such will always turn to Bayes’ Theroem to assist in ruling out oddities. Look how similar the ‘ring score’ and the WMAP scan strategy map are. Coincidence? They say “Repeating this test on 10,000 randomly generated maps (masked with the KQ75 mask), only in 14 cases the peak was as stable. This implies a 3σ deviation from thestatistically isotropic CDM model. I could choose any arbitrary statistic I like and find a 3 sigma deviation from randomly generated models. This doesn’t mean I’m 3 sigma confident of different underlying physics. Until I can repeat this study with any detail I’m very unconvinced by the Penrose paper. Let’s see who referees it…

    • telescoper Says:

      A point I try to make over and over again is that P(D|M) is not the same as P(M|D)….

    • John Peacock Says:

      Chris: I think you’re a bit hard on the “giant rings” guys. They defined their statistic in advance, based on a physical theory, and didn’t trawl through different aspects of the data looking for an “anomaly”. Certainly, you can readily come up with 3-sigma “detections” in the latter way. But when you only do it once , with a pre-defined statistic, then a 3-sigma result demands to be taken seriously from the statistical point of view. As you suggest, one may end up concluding there is a systematic in the data – but that’s a different issue.

    • “I think being conservative or radical is a marketing strategy more than any well-defined characteristics that we can discuss in some inter-subjective way.”

      Consider Screaming Lord Sutch of the Monster Raving Loony Party, whose platform included things like the right to vote at 18 and private radio stations. What was radical then is not radical now.

    • A point I try to make over and over again is that P(D|M) is not the same as P(M|D)….”

      Data: person is pregnant. Model: person is female. Probability of the data, given the model: about 3%. Probability of the model, given the data: 100%. Big difference.

  13. Readers of German might want to check out the popular write-up in the December issue of bild der wissenschaft. It mentions the “rings on the sky” prediction but not the observations. Something I didn’t know: according to the article, Penrose and M.C. Escher corresponded and the author goes as far as suggesting that the inspiration for some of Escher’s works came from Penrose.

  14. Kolmogorov map of CMB is presented here, for example..

    http://www.aanda.org/articles/aa/full_html/2009/14/aa11625-09/img16.png

    I don’t see any apparent concentric ring feature here, some “6-σ” in relevancy the less. What I’m looking for is the true appearance of “concentric circles” in CMBR data – not some hand-drawings of them.

    It all looks like too wild guess for me.

  15. [...] two skeptical papers that just appeared on the arxiv. (Hat tip to David Spergel. Peter Coles was an early skeptic.) A search for concentric circles in the 7-year WMAP temperature sky [...]

  16. [...] two skeptical papers that just appeared on the arxiv. (Hat tip to David Spergel. Peter Coles was an early skeptic.) A search for concentric circles in the 7-year WMAP temperature sky [...]

  17. Commonsensical Cosmic Rebirth

    I. Now:

    Cosmic rebirth
    “Circular patterns in the universe’s pervasive background radiation suggest that the Big Bang was not the beginning of the universe, but only the latest of its incarnations.”
    http://www.sciencenews.org/view/generic/id/66525/title/Cosmic_rebirth

    Commonsense not acceptable. Highfalutin verbiage inspires authoritative acceptance…

    II. Way back:

    Universe’s Missing Mass ???
    ALL Universe’s Mass Is Accounted For !

    A. “Revealing the galaxy’s dark side”
    Excess of gamma rays at Milky Way’s center may indicate universe’s missing mass
    http://www.sciencenews.org/view/generic/id/64825/title/Revealing_the_galaxy%E2%80%99s_dark_side

    B. Be self-confident. Apply your plain commonsense, a good scientific approach.

    E=Total[m(1 + D)]
    Rethink Astronomy And The Universe,
    even without Quantum Unique Ergodicity, but with plain commonsense.

    Galactic clusters formed by dispersion, not by conglomeration. The proof of this is their behaviour, including acceleration, as Newtonian bodies.

    These bodies formed at the start of inflation, when all energy was still in mass format, and the inflation was the start of reconversion of cosmic mass into energy.

    Rethink
    - A Basic Physics Tenet. SpaceDistance in lieu/addition of SpaceTime.
    - The universe in which we live. It is a dual-cycle array.

    1) Neutrino quick-change artist caught in the act
    A transformation from one ‘flavor’ to another confirms the elusive elementary particles have mass and suggests a need for new physics.
    http://www.sciencenews.org/view/generic/id/59825/title/Neutrino_quick-change_artist_caught_in_the_act

    2) Adopt

    - Each and every particle has mass.
    - Dark energy and matter YOK. Cosmic mass and energy are are ALL accounted for with
    E=Total[m(1 + D)]
    - Higgs field/particle YOK. E = m at D = 0.
    - Do not be afraid of embarrassingly obvious answers. Adopt space-distance in lieu of space-time.

    3) And Rethink The Universe

    By the presently available data our universe is a dual-cycle array.

    One cycle, the present, started from singularity, with all cosmic energy in mass format, and it has been proceeding to reconvert all the mass resolved at the big bang back to energy, by expanding the cosmos, by accelerating away the galaxy clusters.

    The other cycle, the cycle that led to singularity, will re-start when the expanding cosmos consumes most or all mass that fuels the expansion. Gravity will then initiate reconversion of all the energy back to mass, to singularity, again.

    Dov Henis
    Comments From The 22nd Century
    http://www.the-scientist.com/community/user/profile/1655.page

    Cosmic Evolution Simplified
    http://www.the-scientist.com/community/posts/list/240/122.page#4427
    28Dec09 Implications Of E=Total[m(1 + D)]
    http://www.the-scientist.com/community/posts/list/184.page#4587
    “Gravity Is The Monotheism Of The Cosmos”
    http://www.the-scientist.com/community/posts/list/260/122.page#4887
    Evolution, Natural Selection, Derive From Cosmic Expansion
    http://darwiniana.com/2010/09/05/the-question-reductionists-fear/

    • “The other cycle, the cycle that led to singularity, will re-start when the expanding cosmos consumes most or all mass that fuels the expansion. Gravity will then initiate reconversion of all the energy back to mass, to singularity, again. ”

      Gravity without some mass seems unusual. If leptons don’t decay and escape the black holes they and energy would be about all that’s left. The resulting forces would probably be electrostatic. An outer shell of say positrons and and inner shell of electrons collapsing on each other could release enough energy to restart inflation. A cross section of an outer and inner shell might form images of concentric circles in the CMB. Only a suggestion.

  18. I think Penrose’s ideas on this are interesting though it’s been clear for a long time that he’s never been a great supporter of the inflationary universe model. (I believe he contends that it raises more questions than it answers.) He’s generally very confortable sitting well outside the scientific status quo and I suppose he deserves some credit for that but to be honest his notions regarding consciousness being a quantum computing phenomenon are best left unmentioned (a room temperature quantum computer, nice) and essentially amount to mystery-mongering.

    However, the general idea of his model has a certain appeal to me, i.e. that the universe begins with extremely low entropy, proceeds over trillions of years to unimaginably high entropy, but then becomes so incredibly dilute that the nothingness that is left undergoes a kind of a paradox, i.e. the idea that there is so little left, and so little going on, that time itself almost ‘breaks’ and interesting things happen. I imagine if you have an effectively infinite amount of time to play with all manner of things might happen, especially if time itself starts to have strange properties due to effectively ‘nothing’ happening.

    How this ties in with the idea of black holes destroying information is an interesting point to me also. I thought that Kip Thorne had effectively demolished Hawking’s argument that black holes destroy information, and instead demonstrated that they merely ‘scramble’ it. If this is the case then Penrose either disagrees or chooses to ignore this. I believe Penrose argues that the destruction of information in black holes reduces the universe’s overall entropy and allows for similar conditions to the big bang to arise (although how a singularity or near-singularity should appear I haven’t seen him argue).

    I have to confess I haven’t read the paper as I doubt I would make it through it without my head bleeding, but it’s fun to think about in general terms.

  19. [...] it and it doesn’t make it at all meaningful.  Doubters appeared quickly on the arXiv and in blogs, and Gurzadyan and Penrose quickly responded in kind (see NASA, this is how it’s [...]

  20. John Wimbledon Says:

    The most comprehensive work has been done on this by Amir Hajian:
    http://arxiv.org/abs/1012.1656
    He studied the patterns of those circles by comparing with a large number of simulations containing realistic noise properties similar to that of WMAP.
    He shows that none of the low variance circles are anomalous when compared to proper simulations. And that the data is consistent with a Gaussian CMB sky as predicted by a big bang model.
    He also keeps a general webpage for the public, with nice pictures that help to understand the matter better:
    http://www.cita.utoronto.ca/~ahajian/pBB.html

    • telescoper Says:

      Yes, that’s a nice paper. It arrived a day after the others I mentioned and doesn’t say much different.

      These two pseudonymous posts come from the same IP address, which is registered in Toronto. If you’re going to push your own paper (which is fair enough), why not use your own name?

  21. You are missing a reference to the third paper that ruled the circles out:
    http://arxiv.org/abs/1012.1656

  22. [...] written about their preferred models, people like Steinhardt and Turok, Baum and Frampton, and Penrose (among others), are of course free to speculate. But physically, there’s no connection to [...]

  23. [...] Doubts about the Evidence for Penrose’s Cyclic Universe November 201051 comments 4 [...]

  24. [...] Has Roger Penrose seen events before the Big Bang, or are there other explanations? [...]

  25. I think that Penrose has the right idea, wrong track. The big thing that I can’t understand why cosmologists are not talking about is the cosmological event horizon, CEH. As the universe continues to expand at a faster rate, there comes a point where information expands faster than light, but since information is neither created nor destroyed, that information that crosses must be contained on the CEH. Because the expansion is increasing in rate this means that the CEH is coming towards each relative location, and the CEH event horizon is incapable of Hawking radiation because its getting smaller, because any attempt at radiating will end up back on the collapsing horizon before it gets the chance to radiate.

    When the CEH collapses to a maximum of information per planck area, after the Big Rip, the CEH keeps moves outwards (no singularity holding it fast) unleashing the pent up information, creating a new universe for each relative location, isolated in spacetime by every other new universe.

    This paradox of many new universes per each old universe is similar to the black hole paradox, the observer sees the black hole traveler appear to stop at the event horizon and become smeared on the horizon, while the traveler goes through the event horizon with no apparent effects. The traveler exists both on the event horizon smeared, and inside the event horizon, unsmeared. When the universe collapses, the same thing applies, except that instead of a traveler, its the entire universe. This idea does away with the need for inflation because the previous universe only collapsed to the maximum planck density, no singularity required. Nobody has talked about the CEH to much of an extent, but its coming towards us at light speed and its the final clock on our universe. Its seems like the elephant in the room that nobody is talking about, sort of like the rotational speed of galaxies being greater than gravity can account for.

    • “the previous universe only collapsed to the maximum planck density, no singularity required.”

      Note if the CMB actually represents the shape of the quantum universe, less than about 0.1% would be random, indicating a collapse to about 1000 planck volumes.

  26. Quoting the late great Clara Pelzer, “Where’s the beef”.
    Without seeing the actual mathematics to support Penrose’s “doubters”, these comments are mere nonsensical musings! As an undergraduate, my first professor of both Theoretical Physics and Relativistic Physics was a gregariously brilliant Milanian. In his humorous Italian – laced English, he uttered the most inspiring message of our universe.
    “The Universe practices the Principle of Maximum Laziness”.
    Those words could not have been more true!
    The key to unlocking the riddle of our universe’s creation is to realize that it is utterly elegant in its simplicity! I’ve scanned some of that 11 – D nonsense known as String Theory! Although the mathematics may seem interesting, the illogical basis of the argument permeates throughout the calculations! We live in a 4 – D space and as such, our answers will be found in this realm as well. In fact, the target of your research should be in the area of Dark Matter, Dark Energy, and its possible gravitational effects on the supposed immutability of the velocity of c. This may give you a “clearer” perspective on what you’re seeking. The cyclical model is in fact, the most probable and viably acceptable description of our universe from a “childish” 21st century prism.

    • telescoper Says:

      Thank you for offering your own musings. I think you need to beef them up if they’re not also to be regarded as nonsensical.

  27. [...] infamous) paper by Gurzadyan and Penrose about evidence for the Conformal Cyclic Cosmology that I blogged about last [...]

  28. [...] case of celebrity physics? Maybe so. Standards flying high, no doubt. This entry was posted in Humor, Omniclimate, [...]

  29. […] it’s apppropriate for a Professor of Public Understand of Science to indulge in such hype. It reminds me of a recent episode involving another famous Oxford mathematician, Roger Penrose. Perhaps he’ll get together with […]

  30. I’ve tried to find the raw data for these circles but not had much luck. Regardless the idea of the cyclic universe makes sense if you say matter is being returned to bosons in black holes, as that’s probably where it came from in the first place. Just a thought.

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