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Comment on"CCC-predicted low-variance circles in CMB sky and LCDM"

In a recent preprint ("CCC-predicted low-variance circles in the CMB sky and LCDM"), Gurzadyan and Penrose (2011) claim for the second time to find evidence for pre-Big Bang activity in the form of concentric circles of low variance in the WMAP data. The same claim was made in November 2010, but quickly shown to be false by three independent groups. The culprit was simply that Gurzadyan and Penrose's simulations were based on an inappropriate power spectrum. In the most recent paper, they now claim that the significance is indeed low if the simulations are based on the realization-specific WMAP spectrum (ie., the one directly measured from the sky maps and affected by cosmic variance), but not if the simulations are based on a theoretical LCDM spectrum. In this respect, we note that the three independent reanalyses all based their simulations on the LCDM spectrum, not the observed WMAP spectrum, and this alone should suffice to show that the updated claims are also incorrect. In fact, it is evident from the plots shown in their new paper that the spectrum is still incorrect, although in a different way than in their first paper. Thus, Gurzadyan and Penrose's new claims are just as wrong as those made in the first paper, and for the same reason: The simulations are not based on an appropriate power spectrum. Still, while this story is of little physical interest, it may have some important implications in terms of scienctific sociology: Looking back at the background papers leading up to the present series by Gurzadyan and Penrose, in particular one introducing the Kolmogorov statistic, we believe one can find evidence that a community based and open access referee process may be more efficient at rejecting incorrect results and claims than a traditional journal based approach.


THE LOW-VARIANCE RING CLAIMS
In November 2010, Gurzadyan & Penrose (2010) posted a paper on the arXiv preprint server claiming to find evidence of pre-Big Bang activity in the cosmic microwave background temperature fluctuations as measured by WMAP. These signatures were defined in terms of concentric rings of "low variance", presumably the result of violent collisions between super-massive black holes and corresponding shock waves. The statistical significance of these detections were reported to be more than 6σ. If true, this would indeed be a spectacular result.
However, three independent analyses by Wehus & Eriksen (2011), Moss, Scott & Zibin (2011 and Hajian (2010) (the two former published on the very same day) quickly showed that the results were flawed. The problem was simply that Gurzadyan and Penrose had based their simulations on an inappropriate power spectrum, effectively assuming that the CMB consists of uncorrelated white noise in pixel space.
Very recently, in a paper called "CCC-predicted low-variance circles in the CMB sky and LCDM", Gurzadyan & Penrose (2011) Gurzadyan and Penrose note) that their ΛCDM spectrum leads to a significantly lower variance than in the observed data. Since this curve represents an average variance quantity, it is given fully by the power spectrum, and it must therefore (up to cosmic variance) have the same mean as the observed WMAP realization. The fact that it is lower implies that the spectrum used for generating the simulations is also lower.
• Gurzadyan and Penrose also note that the observed WMAP variance profile drops with decreasing radius, while the simulated profile does not. This feature was also noted in our original reanalysis paper (Wehus & Eriksen 2011): This function has to behave like this, simply because the CMB field is correlated and smoothed with an instrumental beam. On very small scales, the CMB variance converges to zero due to smoothing. The fact that the simulated example does not fall, therefore implies that it is wrong.
• Third, Gurzadyan and Penrose also note that the simulated map in their Figure 5 is notably "greener" than the observed map in Figure 4, corresponding to having values closer to the average. This statement is fully equivalent to saying that the simulation has less power than the observed dataand therefore that the simulation is wrong.
It is difficult to say exactly what went wrong in the generation of these updated simulations. At least they have a non-flat power spectrum, which is a clear improvement over the first version. Still, it is also clear that the present claims are still not correct, and the same criticisms that were presented by Wehus & Eriksen (2011), Moss, Scott & Zibin (2011 and Hajian (2010) still apply: When making claims similar to those of Gurzadyan & Penrose (2011), it is essential to construct the underlying simulations with absolute data fidelity.

REFEREEING PROCESS
While the physical importance of Gurzadyan and Penrose's recent claims in our opinion are marginal at best, we do believe that there are some interesting points in terms of science sociology and the currently accepted refereeing process. While performing the first reanalysis of Gurzadyan and Penrose's claims, we read through most of the papers cited in their original paper, trying to understand the background for their claims.
In particular, one apparently central line of reasoning of Gurzadyan & Penrose (2010) was based on the notion of the "Kolmogorov statistic", as introduced by Gurzadyan & Kocharyan (2008); Gurzadyan et al. (2009) and references therein. This statistic measures the degree of "randomness" within a set of stochastic variables. In particular, Gurzadyan et al. (2011) applied this statistic to the small disks in the WMAP sky maps, and measured the degree of randomness within each disk. The main conclusion drawn from this work was that only 20% of the signal was "random", while 80% of the signal was "non-random".
When reading these papers, it seems clear to us that Gurzadyan et al. confuse randomness with correlation: While the CMB field is (most likely) a random field, it is not uncorrelated. Instead, the CMB field is a smooth field on scales comparable with the instrumental beam, and it has a well-defined non-flat power spectrum. Thus, the real-space correlations are strong. Of course, the instrumental noise is virtually uncorrelated, and so there are indeed two components here, one correlated and one uncorrelated. But neither is non-random.
The interesting part of this story, though, is the fact that at least five papers on this very topic have been accepted and published by the reputable (and refereed) journal "Astronomy and Astrophysics". One of these papers (called "A weakly random universe?") was even published as a Letter, with an abstract stating that "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." These are truly extraordinary claims, and in our view have no root in reality. Further, these claims are not irrelevant, as clearly demonstrated by the most recent developments concerning the concentric rings: They have, at the very least implicitly, led to an excessive amount of publicity in the general public, potentially damaging the public perception of cosmologists in a wider sense. In our view, this is a clear demonstration of the potential weaknesses of the established refereeing processes: Marginal, or even plain wrong, work can be published due to an unattentive referee.
Contrary to this, it is interesting to note the reaction that came after the first Gurzadyan and Penrose paper was put on the arXiv in November 2011: In only a matter of weeks, three independent groups refuted the original claim. Of course, this reaction was largely triggered by the massive media attention that the original story got, and which most papers will never experience. Nevertheless, we believe that this particular case is a good demonstration of the power of community review outside the established journals: The open community can be a far more efficient reviewer than a somewhat arbitrary referee appointed by a given journal.