Wednesday, October 22, 2014

POLARBEAR announces detection of B-modes

Focus of the March paper is mostly orthogonal to the BICEP2-Planck dispute

You are often being told that polar bears love the chilling weather and thick ice but POLARBEAR is a CMB experiment located in a desert in Chile (although the altitude is over 5 kilometers). Californian cosmologists from Berkeley and San Diego are the main members of the collaboration.

A few hours ago, it announced a "breakthrough" that was reported in the media:
POLARBEAR detects B-modes in the cosmic microwave background: Mapping cosmic structure, finding neutrino masses (Science Daily, news)

A Measurement of the Cosmic Microwave Background B-mode Polarization Power Spectrum at Sub-degree Scales with POLARBEAR (Astrophysical Journal, arXiv)
A problem with the hype is that the paper producing the story is nothing else than the March 2014 preprint that many of us have seen a long time ago. But let me discuss this as if the story were really new because no blog post has been dedicated specifically to POLARBEAR yet.

They describe themselves as the most accurate ones, and so on.

Just to be sure, yes, it is a team of 70 experimenters that is potentially competing with BICEP2 and Planck. But if you expect that they already have their own verdict on inflation, you will be disappointed.

They have only focused on the spherical harmonics with\[

500\leq \ell \leq 2,100

\] which are finer than what BICEP2's remarkable claim was all about. At these sub-degree scales, gravitational lensing is the main effect contributing to the B-modes. And POLARBEAR has only ruled out the hypothesis that no gravitational lensing is needed at a 97%, i.e. slightly over 2-sigma, level.

In the recent 2 years, POLARBEAR has focused on the very fine angular scales. I don't quite understand why their already collected data don't immediately contain the information about the inflation-related scales \(\ell\sim 90\).

They seem obsessed with the gravitational lensing and choose to emphasize that even at \(\ell\sim 90\), there is some contribution from gravitational lensing and it's important to measure it (and subtract it, when looking for traces of inflation) and POLARBEAR is great to do so. I have some doubts about the importance of the gravitational lensing. You may see that each of the teams has their own focus of the interpretations. BICEP2 wasn't afraid to look for traces of "inflation", Planck loves to say the word "dust", and POLARBEAR loves to say "gravitational lensing".

We're also promised that detailed observations they will publish in the future will be sufficient to measure the neutrino masses out of the cosmological data which would be cool but it doesn't seem to me that this paper is close to this particular goal.

Aside from the Astrophysical Journal paper, two more papers by the collaboration were accepted to PRL. They could be really new but we will have to wait.


  1. Dear Lubos, this is completely off topic but I want to learn what do you thing.

    What do you think about Ron Maimon's answer here :

    I don't believe researchers intentionally hides knowledge of old articles but how much useful to read them ?

  2. Dear John, there are way too many things in Ron's reply. Unlike him, for example, think that Polchinski is spelled with an "I" at the end, not "Y", although "Ý" would be the most correct spelling in Czech LOL.

    He's wrong that N=8 SUGRA is "increasingly more clear to be finite". It's surely inconsistent non-perturbatively but even perturbatively, it's probably divergent at the 7-loop level.

    It's good for him to read the old articles but I think that much of it is only needed for one to get the history straight. Everything that has survived as important stuff *is* incorporated in the contemporary textbooks etc.

    If one reads a contemporary review or textbook, he may feel "how is that possible that people have found such a seemingly complicated set of rules and insights?" If one reads the whole history etc., he will understand that there was never an "impossibly huge jump" in the knowledge. But with studying history, one also learns lots of redundant things that aren't really needed for the science, including wrong and misleading interpretations of things that would later be clarified differently, and so on.

    It doesn't hurt to learn some "spirit" about the true history of science, to know how difficult things are, how far from the final form the proposals often are, and how accurate things are from the beginning in other cases, and so on. But if one wants to learn *too much* of these things, he is really doing a social science - the history of science - not the natural science itself.

  3. Off topic: I'm greatly looking forward to your review of the kip thorne / christopher nolan movie coming out next month, Interstellar.

  4. "have the potential to measure the sum of neutrino masses with an uncertainty comparable to the known mass splittings measured by flavor oscillation experiments"

    This doesn't sound like they would have a chance to affect the lower limit of the lightest neutrino mass. Am I correct in interpreting this as just limiting the max mass for the lightest to a few meV?

  5. I think so. Only the differences of squared masses are known now, from neutrino oscillations, and I guess that they have the capability to find the absolute masses i.e. show that they're low if they're low.

  6. The whole reason for having textbooks is to eliminate the messy history and provide students with a clear, coherent presentation of the current science. As in any enterprise, there will always be variations in the quality of textbooks but there are, today, abundant reviews, which should be helpful in pointing students in the right direction direction.
    Reading the original papers can be very useful in understanding how things evolved, naturally, but I think that a good, basic understanding of the subject is more easily attained via textbooks.
    I have two favorites, Gilbert Newton Lewis’ textbook on thermodynamics and Dirac’s classic text on quantum mechanics. Both are simply wonderful and both provide that clear, coherent presentation that is so very helpful.

  7. Szczepan ChelkowskiOct 22, 2014, 8:24:00 PM

    Out of topic, you may like this:


  8. I just downloaded the mentioned texts in about 40 seconds :)

  9. I have an old friend, veteran, who was part of the military unit that was training Osama in Afghanistan. He agrees with me that we did a purdy fine job. All evidence points to that, after all. We spent untold billions on Iraq, all to extinguish the terrorism, only to end up arming even more dangerous new enemy. But nobody can really blame Congress or any politicians in DC because we will keep voting them in as long as we think they are managing rather well.

  10. Probably!

    Too busy today.

    Google and others are constantly trying to buy "really unusual" external - Google just annonunced purhcase of Magic Leap for 500 million

    Augmented virtual reality, elephants flying in front of you...

  11. My “rather well” comment dealt only with the unavoidable internal tradeoff of national security vs. personal freedom. I ought to have made that clear. Sorry.
    Our foreign policy actions have been, in some cases, catastrophic. Iraq, for instance, is a very costly disaster. Our 2003 invasion was a huge mistake and I thought so at the time. We will be living with the consequences of that folly for decades. My vote for Obama in 2008 was almost entirely due to his opposition to that stupidity.

  12. All legislation restricts someone’s freedom. We have to discuss details before condemning Congress or passing judgement on the benefits vs. costs of its actions.

  13. I understand that.

    But considering also


    As the four-star general in charge of U.S. digital defenses, Keith Alexander warned repeatedly that the financial industry was among the likely targets of a major attack. Now he’s selling the message directly to the banks.

    Joining a crowded field of cyber-consultants, the former National Security Agency chief is pitching his services for as much as $1 million a month."

    and you'll see one more reason for my skepticism towards our (ex in this case) 'public servants'.


  15. This is a crucially important interview since one of the last remaining demographics not already converted to climate alarm skepticism is the open minded hip and hipster urban tech crowd who worship big names in the startup capital and Silicon Valley world. So far their visceral urban hatred of Bible thumping Republicans had been enough to blind them to the STEM majors actually behind climate alarm debunking.

  16. I thought the primary founder of PayPal was Elon Musk,

  17. profanephysicistsOct 23, 2014, 5:15:00 PM

    from: Lee Smolin's, Sabine Hossenfelder's, Garret "Ed Witten is a Dick" Lisi's, and Peter Woit's Assault on Math, Physics, Honor, and Decency.
    Circa 2007, Lee Smolin, Sabine Hossenfelder, and Peter Woit ushered in the era of "science (pseudoscience) via press releases, lies, hype, sockpuppetry, suspect social media, and decrepit deceit." Today they are trying to take noble physics further down their dismal road by ushering in the era "physics via profanity" wherein the team of failed physicists call respected, award-winning, senior physicists such as Ed Witten "Dicks."

    The respected Dr. Leonard Susskind characterizes team fail with: "Well, for example, there’s one fellow who failed as a physicist, never made it as a physicist, became a computer programmer, has been angry all of his life that he never became a physicist and that physicists ignore him, so he’s now taking out his revenge by writing diatribes and polemics against string theory. . . There’s another fellow who has his own theory, I won’t tell you who his name is or what his theory is, but he writes lots and lots of theories and his theories go glub, glub, glub to the bottom of the sea before he even gets a chance to put them out there. Physicists don’t take him seriously, he’s angry and so he’s also writing a book complaining. "

    The failed psuedoscience of Lee Smolin, Garret "Ed Witten is a Dick" Lisi, Sabine Hossenfelder, and Peter Woit generally consists of the following stages whose goal is to instigate nuclear media firestorms so as to create an entirely hype-based wikipedia (Lisipedia) page to mislead the public, while engaging in profanity and calling Ed Witten "a Dick." As is well-documented, Lee Smolin, Sabine Hossenfelder, Garret "Ed Witten is a Dick" Lisi, and Peter Woit engage in the following behaviors.

    1. Hype a non-theory and asinine gibberish to the popular press as "fabulous," as Lee Smolin did repeatedly, while also financing said theory numerous times, in numerous manners.

    2. Fan the flames of the nuclear media assault in numerous follow-up comments, interviews, Sabine/Woit/Lisipedia blog posts, and hoax papers.

    3. Violently attack and personally smear any detractors (or those who simply ignore the pseudoscience hype) in a profane, ad hominem manner, such as calling them names including "Dick" and other profane terms.

    4. Collect the nuclear media fallout for the hoax paper and stitch it together as anonymous sockpuppets in numerous massive, circular-referencing, wikipedia (Lisipedia) articles.

    5. Deny any involvement, even when the press (Fox/Discover MAgazine/et al.) has documented all the lying, hyping quotes straight from Smolin's mouth.

    6. Call Ed Witten "a Dick" in the pages of Scientific American, thusly further degrading Science and bringing it down to Smolin's debased level.

    7. Let the massive wikipedia page centered around a Smolin- financed hoax, filled with pure Smolin hype, mislead the public so as to feed the massive egoes of Woit/Smolin/Bee/Lisi.

    8. Call Ed Witten "a Dick" in the pages of Scientific American so as to garner more attention for Lisi/Smolin's failed-physicist egoes.

    Firstoff, all four--Woit/Smolin/Bee/Lisi--are utterly failed physicists. And that is why they have to engage in name-calling, ad hominem attacks (calling Ed Witten a "Dick"), and vile, base behavior--the sort of profane, hype-driven behavior that Scientific American and its favorite useful idiot John Horgan love and profit off of. Were it not for the blogosphere, we would have never known Lisi/Bee/Smolin/Woit's names, as they are naught but empty hype created to drive tweets and traffic to unscrupulous media companies which exalt in namecalling and profanity, and thus favor those who call others "Dicks." from:

  18. I am not sure if you are right. It is Xerox's managers' fault, certainly developers understood its value. In this case there were important innovations, just someone else sold it. And google is certainly a good example. You should check its history. Of course if you don't understand value of your innovation you can't become a great company but this is something different. Another example is happened between IBM and Microsoft for example.

  19. Gene, would you be prepared to condemn any of the 4 Alien and Sedition Acts? How about the Espionage Act of 1917? Probably not, but what about the Sedition Act of 1918? It's my own judgement that Congress' actions may sometimes be justified, but more often than not they are not. But the point is that Congress is not the best judge of whether their own policies have stepped over the line. Surely that is self evident! And surely it would be better not to have a body with this record as our *only* bulwark against Executive Overreach-it's all too easy for them to be *in on it.*

  20. There's still hope, Gene. Get a degree in Community Organizing and you'll be President some day.

  21. Just from the abstract it is not clear to me if they are proposing to subtract gravitational lensing due to large galactic structures and arrive at lensing due to neutrinos and dark matter. Also it seems that currently they may not be confident enough about small l (large angle analysis) to get into controversy between BICEP2 and Planck groups. Presumably, they are looking at a different patch of sky than Planck and BICEP2. Any thoughts on this? I admit these comments may be due to large amount of ignorance of their procedures!

  22. Lubos -

    You are usually a careful thinker, so I am surprised that you are not regarding “evolution”. What Lindzen and Thiel recognize is that the debates on “evolution” are marked by the same rhetorical dishonesty that characterize the debate on “climate change”.

    When one expresses skepticism about climate alarmism he is accused of being skeptical about the mechanism of
    CO2 warming. The former has almost no evidence behind it; the latter has a great deal of evidence behind it. The alarmists make this subtle equivocation (in the logic sense) constantly and wiggle out of it by changing the subject
    and resorting to ad homs when called out.

    Likewise, those who question that Darwinism is able to explain all aspects of life on earth get accused of denying the age of the earth and the fact that life emerged slowly. Darwinism has almost no evidence behind it; while the latter (which is really what is meant by “evolution”) has massive evidence behind it. Again, the Darwinists constantly confuse the two questions in the popular mind and resort to ad homs when called out.

    The fact that there are many young earth creationists does not help careful thinking on the matter, but
    that is no excuse for those who wish to engage with integrity and on a scientific basis.

    Gordon – I am not a particular advocate of the ID movement, but if you think there is a plausible explanation
    for blood clotting etc. that does not involve wild hand waving, you are very mistaken.

  23. I've removed this misleading exaggeration.

  24. Dear Tom, there is a huge nontrivial evidence - and also de facto a "physics-based proof from first principles" - for evolution. And yes, evolution is a major example that leads me to saying that Thiel's method of deciding about the answers is highly unreliable.

  25. I just find it surprising, since Elon is all aboard getting subsidies for the Tesla and SolarCity.

  26. Subsidies suck but I think that Musk has contributed lots ofadded value even if you subtract the subsidies... and yes, libertarians often have to team up with folks who are... less libertarian.

  27. Dear Lubos, I have seen another comment by Ron Maimon, and this is really interesting (at least to me):

    Of course, I don't know how much of these are true.