tag:blogger.com,1999:blog-1513704378254120283.post4104428995140096085..comments2024-01-23T13:58:48.688-08:00Comments on The Trenches of Discovery: Comparing Planck's noise and dust to BICEP2Shaun Hotchkisshttp://www.blogger.com/profile/04832423210563130467noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-1513704378254120283.post-9218276798569603222014-10-15T10:06:28.948-07:002014-10-15T10:06:28.948-07:00Thanks for the feedback. Sorry for the late reply ...Thanks for the feedback. Sorry for the late reply from me (I guess you'll miss it). Work is definitely going on behind the scenes. You might have missed that on the day you wrote your comment there was a paper by Planck about the amplitude of polarisation from dust in the sky, and in particular in BICEP2's field of vision.<br /><br />What's more, there are numerous B-mode polarisation experiments going on right now measuring this stuff, so it definitely hasn't gone away for good. <br /><br />Either a detection will be made and confirmed, or the upper limits on the possible size of this signal will start to drop considerably over the next five or so years.Shaun Hotchkisshttps://www.blogger.com/profile/04832423210563130467noreply@blogger.comtag:blogger.com,1999:blog-1513704378254120283.post-23463798013365234522014-10-15T10:04:00.987-07:002014-10-15T10:04:00.987-07:00Heh, thanks Torbjörn. I unfortunately had my week ...Heh, thanks Torbjörn. I unfortunately had my week of free evenings in the wrong week it seems, so I was able to blog about the non-mainstream paper and not the main Planck result.<br /><br />Having said that, the Planck result didn't really say anything we didn't already know from the work in <a href="http://arxiv.org/abs/1405.7351" rel="nofollow">this paper by Flauger, Hill and Spergel</a>, so I wasn't super motivated to write about it.<br /><br />As we knew then, the dust does seem to have a comparable amplitude to BICEP2's signal. We now need to know whether it has the same shape, which is the next step.Shaun Hotchkisshttps://www.blogger.com/profile/04832423210563130467noreply@blogger.comtag:blogger.com,1999:blog-1513704378254120283.post-87138145469010072952014-10-15T09:58:52.531-07:002014-10-15T09:58:52.531-07:00For the record, I agree with Sesh regarding the pr...For the record, I agree with Sesh regarding the protectiveness of physicists with their data. I think this is just a consequence of people using data before the experiment considered the data "ready", rather than because the experiment was hoarding the data. This wasn't even data taken from an unpublished, but ready for public dissemination pre-print; it was from a slide at a conference!<br /><br />Regarding whether digitising someone's slide is good or bad science I kind of disagree with Sesh. People should be willing to use as much information as they can. The talk slide was additional information and digitising it was the best way for people outside Planck to extract data from it. And, in fact, it wasn't the digitisation procedure that BICEP2 got wrong, it was knowledge about what was actually in the slide! They digitised it fine.<br /><br />I think the boundary for whether something should be publishable or not (though publishing seems to me personally to be an outdated 20th century or earlier method of doing science) I would just want it to add considerable insight. If BICEP2 hadn't digitised this slide, the best dust models would have predicted dust that wasn't of the right magnitude to mimic BICEP2's signal. So BICEP2's result would have looked just as strong. If another group had then come along, having been the first to digitise this slide and had correctly interpreted what it was showing and had thus said "hey hang on, maybe dust can explain this signal" I would say that is definitely "publishable", and would have a significant impact.<br /><br />All results have caveats and approximations. those obtained from digitised slides would have their own, but so do even purely theoretical results. Over time the caveats are ironed out, the same has and will happen with these digitised images.Shaun Hotchkisshttps://www.blogger.com/profile/04832423210563130467noreply@blogger.comtag:blogger.com,1999:blog-1513704378254120283.post-72545818717871749402014-09-22T16:32:38.419-07:002014-09-22T16:32:38.419-07:00Thanks for this update Shaun. I have to admit that...Thanks for this update Shaun. I have to admit that it is a little complex for this lay person, however I did understand 60% of it <br />Have to admit I was wondering why everything had gone so quiet on this so it is interesting to know it is being worked on in the background.<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1513704378254120283.post-44891812844343177762014-09-22T07:55:01.213-07:002014-09-22T07:55:01.213-07:00"Planck intermediate results. XXX. The angula..."Planck intermediate results. XXX. The angular power spectrum of polarized dust emission at intermediate and high Galactic latitudes", "(Submitted on 19 Sep 2014)", "submitted to A&A":<br /><br />"... Extrapolation of the Planck 353GHz data to 150GHz gives a dust power ℓ(ℓ+1)CBBℓ/(2π) of 1.32×10−2μK2CMB over the 40<ℓ<120 range; the statistical uncertainty is ±0.29 and there is an additional uncertainty (+0.28,-0.24) from the extrapolation, both in the same units. This is the same magnitude as reported by BICEP2 over this ℓ range, which highlights the need for assessment of the polarized dust signal. The present uncertainties will be reduced through an ongoing, joint analysis of the Planck and BICEP2 data sets."<br /><br />[ http://arxiv-web3.library.cornell.edu/abs/1409.5738?context=astro-ph ]Torbjörn Larssonhttps://www.blogger.com/profile/13304729731231255545noreply@blogger.comtag:blogger.com,1999:blog-1513704378254120283.post-29803888641840632412014-09-20T07:51:48.387-07:002014-09-20T07:51:48.387-07:00Also, in general I don't think it is true that...Also, in general I don't think it is true that physicists are more protective of their data*. The reason the Planck dust/polarization data have not been made public yet is because they is not ready yet - there's a whole lot of validation and verification work going on in the collaboration to actually produce data that is fit for science. Which makes nicking preliminary versions of that data even worse.<br /><br />*Some major experiments do of course have a "first-use" embargo on the data until a certain date before it is made public, which is a precaution to ensure that they get the most bang for their rather considerable investment buck in acquiring it. But the data is always made public eventually. This isn't even that kind of a case.Sesh Nadathurhttps://www.blogger.com/profile/07155102110438904961noreply@blogger.comtag:blogger.com,1999:blog-1513704378254120283.post-77745433621835316302014-09-20T07:43:54.078-07:002014-09-20T07:43:54.078-07:00It's not that different a situation in physics...It's not that different a situation in physics really. Digitising somebody's pdf slide is really bad science and you will not get your result published anywhere. The BICEP2 result was of course published in a prestigious journal, but clearly they got slapped down a bit by the referees and the version that finally got published was much toned down from the pre-print version we saw in March.<br /><br />Anyone who is trying to publish a result entirely based on digitised slides without a BICEP2- level of ground-breaking science discovery to form the primary part of the paper is I think going to find it very hard to get a journal to accept it. The typical comment about this paper is "this kind of study is fine to satisfy your own curiosity, but why would you put it in a paper?" Which I mostly agree with (though Shaun's blog post about it is nice).<br /><br />On the other hand, peer review in physics is sometimes of a pretty lax standard and all sorts of rubbish gets published, so maybe I'm wrong.Sesh Nadathurhttp://www.blankonthemap.blogspot.comnoreply@blogger.comtag:blogger.com,1999:blog-1513704378254120283.post-1624351313098685302014-09-20T02:12:29.113-07:002014-09-20T02:12:29.113-07:00I find it fascinating how different are the public...I find it fascinating how different are the publication conventions in different branches of science. It seems crazy to me that anyone would extrapolate data from a pdf figure and then re analyse them in their own paper. If you tried to do that in life sciences you would never get it published! If I needed data from another paper I would just contact the authors and they would almost certainly send them to me, if they weren't included in the original paper to begin with. Is this kind of protectiveness common in physics/cosmology or is there something unique to this situation that demands it? I wonder whether it has to do with how physicists seem to be more open with their results before publication than life scientists, and therefore can't be as open with the raw data as they don't yet have the safety net of formal publication? Nonetheless, particularly given how cooperative and open the physics community appears to an outsider, this looks very strange indeed!<br /><br />On a separate note - I was wondering roughly how many major questions in cosmology (and physics in general) are in a similar boat to this BICEP2-Planck debate - i.e. you really just need better technology to get a definitive answer? James Felcehttps://www.blogger.com/profile/14031758835739415241noreply@blogger.com