The BICEP2 Bubble Bursts…

I think it’s time to break the worst-kept secret in cosmology, concerning the claimed detection of primordial gravitational waves by the BICEP2 collaboration that caused so much excitement last year; see this blog, passim. If you recall, the biggest uncertainty in this result derived from the fact that it was made at a single frequency, 150 GHz, so it was impossible to determine the spectrum of the signal. Since dust in our own galaxy emits polarized light in the far-infrared there was no direct evidence to refute the possibility that this is what BICEP2 had detected. The indirect arguments presented by the BICEP2 team (that there should be very little dust emission in the region of the sky they studied) were challenged, but the need for further measurements was clear.

Over the rest of last year, the BICEP2 team collaborated with the consortium working on the Planck satellite, which has measurements over the whole sky at a wide range of frequencies. Of particular relevance to the BICEP2 controversy are the Planck mesurements at such high frequency that they are known to be dominated by dust emission, specifically the 353 GHz channel. Cross-correlating these data with the BICEP2 measurements (and also data from the Keck Array which is run by the same team) should allow the identification of that part of the BICEP2 signal that is due to dust emission to be isolated and subtracted. What’s left would be the bit that’s interesting for cosmology. This is the work that has been going on, the results of which will officially hit the arXiv next week.

However, news has been leaking out over the last few weeks about what the paper will say. Being the soul of discretion I decided not to blog about these rumours. However, yesterday I saw the killer graph had been posted so I’ve decided to share it here:

cross-correlation

The black dots with error bars show the original BICEP/Keck “detection” of B-mode polarization which they assumed was due to primordial gravitational waves. The blue dots with error bars show the results after subtracting the correlated dust component. There is clearly a detection of B-mode polarization. However, the red curve shows the B-mode polarization that’s expected to be generated not by primordial gravitational waves but by gravitational lensing; this signal is already known. There’s a slight hint of an excess over the red curve at multipoles of order 200, but it is not statistically significant. Note that the error bars are larger when proper uncertainties are folded in.

Here’s a quasi-official statement of the result (orginall issued in French) that has been floating around on Twitter:

BICEP_null

To be blunt, therefore, the BICEP2 measurement is a null result for primordial gravitational waves. It’s by no means a proof that there are no gravitational waves at all, but it isn’t a detection. In fact, for the experts, the upper limit on the tensor-to-scalar ratio  R from this analysis is R<0.13 at 95% confidences there’s actually till room for a sizeable contribution from gravitational waves, but we haven’t found it yet.

The search goes on…

UPDATE: As noted below in the comments, the actual paper has now been posted online here along with supplementary materials. I’m not surprised as the cat is already well and truly out of the bag, with considerable press interest, some of it driving traffic here!

UPDATE TO THE UPDATE: There’s a news item in Physics World and another in Nature News about this, both with comments from me and others.

43 Responses to “The BICEP2 Bubble Bursts…”

  1. Reblogged this on thecuriousastronomer and commented:
    Very interesting update on the BICEP2 primordial gravitational waves story. The results of their collaboration with Planck will be officially released next week.

  2. […] In The Dark: The BICEP2 Bubble Bursts… […]

  3. […] [3:25 MEZ] Das französische Statement ist verschwunden aber z.B. hier archiviert – und es wussten eh alle Bescheid. [17:35 […]

  4. Reblogged this on jauntytraveller and commented:
    I voted for this scenario on Peter’s poll 😉

  5. […] ESA, Planck (offline docs), BBC News, In the Dark (Peter Coles), h/t […]

  6. […] ESA, Planck (offline docs), BBC News, In the Dark (Peter Coles), h/t […]

  7. I would submit that after the faster-than-light neutrinos saga,
    the “nightmare scenario” that unfolded at the LHC, 40 years of
    “WIMP” false-positives and the latest BICEP-2 fiasco, there is most certainly cause for abundant concern about the state of theoretical physics.

    It is time to question fundamental assumptions in theoretical
    physics that have led us into this cul-de-sac.

    This does not mean seeking new epicycles for the old standard paradigms of particle physics/cosmology. It means considering entirely new and different paradigms for understanding the cosmos.

    Robert L. Oldershaw
    http://www3.amherst.edu/~rloldershaw

    • telescoper Says:

      This comment is just silly. The faster than light neutrino debacle was an experimental error, not a theoretical one. The failure to detect GWs was a consequence of a very difficult measurement being made even more difficult by unexpectedly high levels of foreground emission. Theory has made a prediction and we wait for experimental confirmation or refutation. That’s how science works despite the occasional false start.

      • 1. Many feel that the last 40-50 years have been a disappointing era for theoretical physics, in contrast to the assessment of those whose status is based on the limited progress of that period.

        2. What good is a “steel trap mind” if it is closed. A closed mind can never grasp a new idea.

      • telescoper Says:

        Many people feel many things, but whether there’s any rational basis for those feelings is another matter. Fortunately, theoretical physics can be judged by a rigorous standard: how well it can explain observed phenomena. By that standard, theoretical physics has been an amazing success over the last 50 years. There are glaring gaps, of course, and the journey is very far from complete but there has been clear progress.

        As for your second point, it makes no sense. Theoretical physicists are very open to new ideas, as they have always been, and I hope hope always will be, but it gets harder to be radically inventive when the experimental constraints are so strong.

        It seems to me that what you dislike about modern theoretical physics is that it has been too successful. I admit it would be much more fun if there were less data, but it’s hardly the attitude of a proper scientist to bemoan this state of affairs.

      • No.

        I strongly question the liturgies of strict reductionism and absolute scale.

        I think a discrete (“broken”) global conformal geometry offers a much better paradigm and can potentially answer some of the major enigmas of our era.

        The problem is that giving up absolute scale and strict reduction is far too radical a change for most theoretical physicists.

      • telescoper Says:

        I strongly question people who claim they have a better paradigm but can’t use it to make testable predictions. That’d not unscientific it’s antiscientific.

      • Here is a link to 15 definitive predictions and references to the published observational evidence that has either verified or supports those predictions.

        http://www.academia.edu/2917630/Predictions_of_Discrete_Scale_Relativity

        By definitive predictions I mean that they are prior, feasibly testable, quantitative, NON-ADJUSTABLE, and unique to the paradigm being tested.

        You might want to educate yourself on the potential of discrete fractal models to offer a better way to model and understand nature.

      • telescoper Says:

        Gabing trouble accessing your site. Pleade paste a list if peer-reviewed papers here. Alternatively please provide, for example, a plot of your predictions for the angular power spectrum of the CMB snd galaxy clustering.

        If you are claiming fractal behaviour of the latter then your model has already been falsified.

      • For peer-reviewed papers see list of publications (~ 70) on my website: http://www3.amherst.edu/~rloldershaw
        Many are in peer-reviewed physics/astronomy journals.

        For 15 definitive predictions search on:
        Predictions of Discrete Scale Relativity

        The website contains a very large amount of material that introduces the discrete fractal paradigm, demonstrates its potential for much greater unification of our balkanized theoretical physics, and presents a large amount of empirical and theoretical support for this new paradigm. It would radically change our understanding of nature’s fundamental geometry, principles and structure.

        If you think an unbounded discrete fractal model has been ruled out empirically on astrophysical (or any other) grounds, it is you who are in error. You continue to ignore Mandelbrot’s cogent discussion of this topic because it involves thinking outside of your preferred box. You do not want what, to you, represents a highly disruptive new paradigm, and so you accept hand-waving theory and a very dubious paper out of Australia to summarily dismiss the uncomfortable truth.

        The cosmic web is blatantly fractal, and “homogeneity” is a Platonic fiction to make the math simpler.

      • telescoper Says:

        You are simply wrong. Mandelbrot’s ideas were quite interesting in the 70s but have been refuted by clear statistical evidence of departures from fractal behaviour. See my posts on this if you want to educate yourself. I suspect you do not.

        You are doing precisely what you wrongly accuse others of doing. It’s very sad.

      • Anton Garrett Says:

        Might I sharpen Peter’s request for a testable prediction from RLO by requesting one or two *quantitative* predictions of observables whose value is not known today? These can be phrased in one or two sentences.

      • Anton,

        I gave the correct link to 15 definitive predictions and defined what I mean by definitive: prior, feasible, QUANTITATIVE, non-adjustable, and unique to the paradigm in question.

        This site cut off the link. I will try one more time.
        http://www.academia.edu/2917630/Predictions_of_Discrete_Scale_Relativity

        The end = Predictions_of_Discrete_Scale_Relativity

        If the link gets sliced and diced again, SEARCH ON “PREDICTIONS OF DISCRETE SCALE RELATIVITY” with GOOGLE. That will get you to my page at Academia.com and various papers are posted there.

        Sigh

      • I was wondering when master Helbig’s little muzzle would come off.

        We have been through the electron substructure issue many times and the discussions are in the public record. If you bother to read “Predictions of Discrete Scale Relativity” prediction #10 discusses the electron substructure issue.

        You repeatedly misconstrue the 1987 prediction by ignoring the caveat stated (IN PRINT IN THE PAPER) that the prediction would have to be reassessed if the electron corresponded to a naked singularity. DSR has now verified that the electron should be modeled as a nearly naked singularity with a very low-density plasma shell extending to ~ 10^-17 cm. The shell is not yet detectable with present methods.

        Will you continue to pretend you are ignorant of this information, after it has been presented to you 4-6 times? Probably, because scientific discussion is not your real goal.

        But more generally, I do not spend much time discussing science with a poster boy for dogmatism, for the same reason that I do not argue scientific matters with a Jehovah’s witness.

    • Also, at
      http://www3.amherst.edu/~rloldershaw/
      there is a page entitled “Successful Predictions and Retrodictions” which lists 40 items.

      Or search on:

      Discrete Scale Relativity

      Predictions of Discrete Scale Relativity

      Also see papers on arXiv.org
      http://arxiv.org/a/oldershaw_r_1

    • This is how Faraday was treated when he proposed his new field paradigm for electromagnetic fields.

      Polite physicists shook their heads and said Faraday had descended into questionable speculation.

      The more typical and dogmatic physicists considered his ideas quackery.

      All agreed that what Faraday was proposing was contradicted by all reliable physical theories and all observational evidence (at least the evidence they chose to back up their bias). He, in their opinion, was obviously wrong and foolish to persist.

      Fortunately Maxwell and Heaviside and a small number of true natural philosophers eventually saw what Faraday saw, and what the overwhelming majority was blind to, because they could not see outside of their paradigmatic box.

      So it goes and same as it ever was.

      • telescoper Says:

        Now you have the appaling arrogance to compare yourself with Faraday!

        You are the one stuck in a paradigmitic box and you’re either too stupid or too deluded to realise it.

        I suggest you find some other website to troll.

      • This is a shabby debating trick that I expect of master Helbig, but not of you.

        See if you can grasp this: citing this well-known example from the history of physics does not imply that I am comparing myself to Faraday.

        What I am comparing is closed-minded attitude of the theoretical physics community towards Faraday’s new paradigm, and the present closed-minded attitude of the theoretical physics community towards new paradigms that seek to replace the stagnant paradigms of particle physics/cosmology.

        Of special interest in both cases is the insistence of the Platonists that their model-building paradigms are the only viable ones.

        Well, spin your wheels for all eternity, but until the theoretical physics community is willing to question strict reductionism, absolute scale, and a host of other dubious and untested assumptions, you will only champion mediocre and unnatural model-building.

        We need theories of principle that can make and pass definitive predictions, not ad hoc Ptolemaic model-building with an endless succession of epicycles added to “save” the paradigms when they are contradicted by empirical evidence, which has occurred repeatedly over the last 40 years.

      • telescoper Says:

        “This is a shabby debating trick..”

        Your words are there for all to read. I will comment no further on them.

    • telescoper Says:

      I have looked at your so-called cosmological predictions, most of which are on stellar and substellar scales where the physics will be dominated by highly nonlinear astrophysical processes. How about making a prediction relating to extragalactic observations? What is your prediction of the cosmic microwave background temperature and polarization spectra, measured to high accuracy by Planck and other experiments? What about the galaxy clustering spectrum?

      And if the dark matter is not elementary particles, how do you account for the elemental abundances that are well fitted by the standard big bang theory?

      • Discrete Scale Relativity reinterprets the solid evidence for global expansion, large peculiar velocities, etc. in terms of a radically different paradigm.

        See my website: page is “Galactic Scale Self-Similarity”

        It also makes a definitive prediction for the dark matter, which you may remember constitutes something like 85% of all matter.

        Master Helbig repeats endlessly that the predicted stellar-mass and planetary-mass primordial ultracompacts have been ruled out. This is a false hope and prayer of Helbig’s. And note how he sycophantically makes excuses for popular (and totally AWOL) dark matter candidates, but will not countenance astrophysical dark matter. Talk about holes!

        You can cherry-pick papers that trash fractal cosmology and astrophysical dark matter and say the case is closed. But the truth is that the case for both is wide open and we have discovered 100s of billions (possibly many trillions!!!) of MACHOs, black holes, neutron stars, planetary-mass nomads, fast radio bursts, etc.

        Meanwhile we have discovered ZERO mythical dark matter particles. That’s ZERO as in Nature says NO!

      • One last thing.

        I have worked on Discrete Scale Relativity in semi-isolation at the fringes of academia.

        DSR has not had the benefit of 1000s of people with varied talents working their butts off for decades to improve DSR.

        Ask yourselves how far you would get without your colleagues to show you the way and validate your efforts.

        If Helbig could not memorize and parrot the work of others, he would be in low finance. Oh, wait! He is anyway.

      • telescoper Says:

        Perhaps nobody else wants to work on it because they can see that it’s garbage.

  8. The paper is now out at http://new.bicepkeck.org/bkp_2015_release.html, for what its worth.

  9. […] ESA, Planck (offline docs), BBC News, In the Dark (Peter Coles), h/t @cosmos4u [via Discovery […]

  10. […] ESA, Planck (offline docs), BBC News, In a Dark (Peter Coles), h/t […]

  11. […] ESA, Planck (offline docs), BBC News, In the Dark (Peter Coles), h/t […]

  12. @Peter: I am curious if you had sense of what was wrong with the foreground dust estimates used in the original BICEP2 paper (besides DDM1/2), particularly in light of the latest results. Was it that the models were just wrong or that the uncertainty in the mean power spectrum was badly underestimated?

    • telescoper Says:

      There simply wasn’t enough information at the time to make any reliable estimate of the foreground. When the BICEP2 result came out I was very impressed by the sensitivity they had reached but completely unimpressed by the discussion of foregrounds. It seemed to me thst that there was no way they could have any confidence that they had a primordial signal. Unfortunately the press machine kicked into action and theorists started a bandwagon, all based on very flimsy evidence. There’s egg on quite a few faces now.

      Do I get a prize for mixing do many metaphors?

  13. Peter Jackson Says:

    Great to see ‘joined up’ theory surviving the nonsense. A new source of redshift incorporating field interactions is now also identified (also joining up photonics and other findings), without accelerationg expansion. Much work is needed. I hope you’ll comment on this initial explanatory video; http://youtu.be/KPsCp_S4cUs

  14. Peter Jackson Says:

    I was considering a remake of Alice in Wonderland, but are we not all a little tired of fantasy worlds? lol. I suggest ‘joined up physics’ is the way ahead, not so much ‘new’ physics, but needing joined up thinking.
    We cant solely rely on the old foundations and old doctrine to advance understanding, though I well understand those still teaching have little choice.
    Though grounded in history of science I have some sympathy for RLO as I’ve seen no valid falsification of his hypotheses. Let’s remember only THAT is science!
    (You’ll note my own hypothesis predicts the CP Violations found, i.e. the approximation for pions was ~5%. All falsification of the analysis is invited, but scientifically please!).

  15. […] the new paper hasn’t yet been made public, its contents have been widely discussed on- as well as offline. It will describe results from the analysis to correlate the BICEP2 data […]

  16. […] had time to look at these in any detail myself, but my attention was drawn (in the light of the recently-released combined analysis of Planck and Bicpe2/Keck data) to the constraints on inflationary cosmological models shown in this […]

  17. […] it subsequently turned out that I was right to be […]

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