tag:blogger.com,1999:blog-2846514233477399562.post3121589542826526040..comments2024-01-08T09:37:04.406+01:00Comments on RÉSONAANCES: The universe after Planck Jesterhttp://www.blogger.com/profile/08947218566941608850noreply@blogger.comBlogger36125tag:blogger.com,1999:blog-2846514233477399562.post-11074344222188822592013-03-30T19:40:12.015+01:002013-03-30T19:40:12.015+01:00@ nicholas suntzeff - It may have been a poor choi...@ nicholas suntzeff - It may have been a poor choice of words on my part - Other than NGC 4258 (with a 5% error in distance) many other extragalactic distance measurements can have errors of up to 20%; when you consider the statistical and possible systematic errors, it's remarkable that the direct H0 measurements are as close to Planck's - Looking at the published history of H0 measurements over the last 5 to 10 years it averages 67 (pretty good!) with an error of +16/-8<br /><br />Cepheid distances have improved quite a bit but there's still somewhat of an issue with the values to the LMC Cepheids, for example.<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-83506957772801333012013-03-29T20:35:18.146+01:002013-03-29T20:35:18.146+01:00@crappy - If you're a String Theorist or Deepl...@crappy - If you're a String Theorist or Deeply Truly in love with SUSY, then yeah, I can see how the recent Planck and LHC results are a bit like "The Crying Game" (you know, THAT scene...). This is especially true if you've devoted a career to the above (or worse, just got or are about to get a PhD in the above.) <br /><br />I'm an Astronomer; if I'd chosen Physics, I would have picked an area where I would have a job for life - something like Plasma Physics - and worked on magnetic confinement fusion. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-77611711720792202832013-03-29T16:30:33.539+01:002013-03-29T16:30:33.539+01:00My goodness. Anonymous states that the SN distance...My goodness. Anonymous states that the SN distances are rickety? Please try to read the papers rather than dismiss 23 years since the first modern Hubble diagram from SNe. We are very careful in accounting for the errors in our measurements. Maser distances to NGC 4258, eclipsing binaries, two different types of Cepheid distance measurments, Pop II distance scales all have Hubble constants not consistent at 2 sigma from Planck/WMAP. Remember, the Hubble constant is the *local* expansion of the universe, and the local methods, with their real errors, are direct measurements of H0, whereas Planck is a multicomponent fit to data in the distant Universe. Planck may be right! But unless you have specific objections to the local methods, your simple dismissal is uninformed.nicholas suntzeffnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-78956048959274582652013-03-29T09:48:29.329+01:002013-03-29T09:48:29.329+01:00"I don't get the Sturm und Drang over the..."I don't get the Sturm und Drang over the LHC and Planck results; it's Science - crappy theories get thrown in the trash or modified."<br /><br />Yeah? So science is all about crappy theories? What about non-crappy theories -- how many of those can draw comfort from the LHC or Planck? Nobody is upset about the death of crappy theories, what we are upset about is the new version of the Second Law -- Boredom either remains constant or increases.Crappy Theoristhttp://www.crappy.comnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-52517142115773887922013-03-28T17:31:59.866+01:002013-03-28T17:31:59.866+01:00AMS will show their positron results on April 3, b...AMS will show their positron results on April 3, but they don't have anything we didn't know before. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-46128341799903727862013-03-28T17:13:23.351+01:002013-03-28T17:13:23.351+01:00It'll be great if AMS-02 detected something si...It'll be great if AMS-02 detected something significant, especially if you can squint at their data and see something similar to the Fermi results (which also requires some squinting...)<br /> It could still be an unusual astronomical process (not DM related), but if it is DM, it'll be great news. <br />You would still have to deal with the conflicting mess of results from DAMA/LIBRA, Pamela and ANTARE, but that's another battle.<br /><br />All DM models really need to work on the galaxy problem; IF DM depended on the data from galactic rotation curves, satellite galaxies, dwarf galaxies and low surface brightness galaxies the theory would have been thrown out years ago, because current DM theories fail miserably at explaining them (DM defenders - please take an honest, dispassionate view at the galaxy data...)<br /><br />Obviously there IS some form of DM in the Universe. Current theories work great at galaxy cluster and larger scales; they're probably far too simplistic to explain its "fine grained" behavior. <br /><br />This is why Physics and Astrophysics is still extremely exciting. I don't get the Sturm und Drang over the LHC and Planck results; it's Science - crappy theories get thrown in the trash or modified. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-75853778369157730382013-03-28T01:18:38.772+01:002013-03-28T01:18:38.772+01:00What of ams-02?What of ams-02?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-91802521646395480342013-03-27T19:57:46.260+01:002013-03-27T19:57:46.260+01:00@Rex - Astronomy & Physics still has gravity a...@Rex - Astronomy & Physics still has gravity and dark matter to explore. I think that's where the some of the most exciting research will be in the next 10 - 20 years. <br /><br />While Planck has done a great job of supporting LCDM, the number of dark matter particles detected is still zero. With the death of sterile neutrinos, the potential zoo is becoming even more exotic.<br /><br /> Most dark matter models do a marginal job of describing the rotational curves in normal galaxies and a miserable job of doing the same with dwarf and low surface brightness galaxies (without invoking uncomfortably unrealistic explanations.)Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-73702267488798682772013-03-25T17:36:51.661+01:002013-03-25T17:36:51.661+01:00Sigh! So this is where we're at. Adding decim...Sigh! So this is where we're at. Adding decimal places to existing paradigms in both cosmology and particle physics. BSM physics anyone....please!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-42852479663098646062013-03-24T12:54:24.932+01:002013-03-24T12:54:24.932+01:00A bit clumsy sentence but it's correct. ns=1 d...A bit clumsy sentence but it's correct. ns=1 denotes the scale-invariant spectrum. Inflation predicts ns slightly different than one. Planck definitively proved that ns minus 1 is different from zero, which is what I wrote. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-13561040706006350002013-03-24T12:45:32.001+01:002013-03-24T12:45:32.001+01:00The density fluctuations are not decaying, on the ...The density fluctuations are not decaying, on the contrary. Small primordial fluctuations were seeded by inflation, after which they grow due to the force of gravity. However, the pressure of photons in the plasma provides a counteracting force, hence oscillations. I never studied CMB physics in detail, but if I understand this correctly, the 1st peak at 1 degree corresponds to a half-oscillation, the 2nd to one full oscillations, and so on. <br />I don't know exactly how big a detector you'd need to study the neutrino background, but I guess bigger than the Earth. People have some other ideas how to detect the presence of the neutrino background (e.g. Z bursts), but that won't happen anytime soon. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-6407461140829616392013-03-24T12:39:21.635+01:002013-03-24T12:39:21.635+01:00Hi Jester,
I'm an economist so I'm probab...Hi Jester,<br /><br />I'm an economist so I'm probably wrong but in your sentence "pushes the departure of ns-1 from zero past the magic 5 sigma significance." be one rather than zero?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-49635047684954689592013-03-24T00:51:55.598+01:002013-03-24T00:51:55.598+01:00Yes, that was a good link as starting point for th...Yes, that was a good link as starting point for the lost in the early Universe, and particularly for interpreting the latest CMB power spectrum. I guess I was off by a few dozen orders of magnitude in my futile attempts at mapping cosmology to more mundane physics intuition...<br /><br />Inevitably I have now other silly questions like "Are the density fluctuations apparent in the CMB the decaying waves of earlier excitations, say a cymbal (without boundaries) struck long ago but still ringing, or travelling waves driven by some more continuous energy releasing process ?" or "How many times a patch that is now, say, seen at 1° angular scale, did significantly oscillate in average density between end of inflation (if any) and recombination ? 10^0 ? 10^40 ?" or <br />"How impossibly huge and cold and exotic a cosmic neutrino background detector would need to be to achieve the same resolution and precision as Planck observatory ?"<br /><br />But I will keep those questions secret and not dare ridiculing myself again. This is only about the Universe, I shouldn't feel so personally concerned %)<br />Thanks.Robinhttps://www.blogger.com/profile/15659302378568144828noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-28185608829554163882013-03-23T19:31:55.220+01:002013-03-23T19:31:55.220+01:00"I'm better in ridiculing than explaining..."<i>I'm better in ridiculing than explaining</i>"<br />Not so!<br /><br />Yours is not my remotely field, but I've learned a ton, while being entertained. (Meanwhile gigatons have passsed over my head, but they passed amusingly also.)<br /><br />Besides which, providing that useful link demonstrates excellence in exposition. If the backup careers in bioinformatics, gambling, press releations, comedy and HEP don't work out, there's always teaching secondary school.<br /><br />Thanks for your years of effort.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-7564673874790435812013-03-23T06:10:24.760+01:002013-03-23T06:10:24.760+01:00There are measurements of H_0 which don't invo...There are measurements of H_0 which don't involve local calibration at all (see p.31 of Planck paper 16) and they are equally discordant with Planck or more so.5371noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-84840299343310947112013-03-23T01:17:00.507+01:002013-03-23T01:17:00.507+01:00so LCDM is confirmed again.
somebody should cong...so LCDM is confirmed again. <br /><br />somebody should congratulate Mike Turner for being a leader of a field that is as dead as particle physics.<br /><br />by Turner's standard, Planck is also nothing but a dinosaur.<br /><br />Turner should tell us who is going to be the next dinosaur in cosmology.<br /><br />so much for the president of APS.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-90347360140677474962013-03-22T21:40:25.584+01:002013-03-22T21:40:25.584+01:00The answer to all your questions is no :-) I'm...The answer to all your questions is no :-) I'm better in ridiculing than explaining, but at this link you can find a very pedagogic explanation: http://galileospendulum.org/2013/02/28/c-is-for-cosmic-microwave-background-alphabet-of-cosmology/ Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-46693371305938669022013-03-22T21:22:11.901+01:002013-03-22T21:22:11.901+01:00I'm trying to grasp the big picture of this am...I'm trying to grasp the big picture of this amazing big picture (without proper year long studies in cosmology or even particle physics I'm afraid).<br /><br />Can the power spectrum be somehow read as a signature of a time evolution with larger angles/scales corresponding to early phases of inflation, and small angles to later times in inflation ? Or where the fluctuations at different scales already there at beginning of inflation (and just getting dilated by it) or still taking place simultaneously at all scales during inflation ? At what epoch (if any) are we "dilated away" from a thermal bath at equilibrium ? So many questions...<br /><br />Hope Jester or some knowledgeable commentator can answer. Anyhow thanks for sharing your insights.Robinhttps://www.blogger.com/profile/15659302378568144828noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-40942225965569081032013-03-22T20:50:13.091+01:002013-03-22T20:50:13.091+01:00There isn't "tension" in the Hubble ...There isn't "tension" in the Hubble constant from Planck vs "direct" measurement of supernova distances. <br /><br />Supernova measurements are just not all that accurate; they're based on a rickety tier of distance assumptions, composition assumptions and even basic Astronomy (not properly accounting for reddening). The error bars are optimistic, at best.<br /><br /> A small error in one or more of the tiers can more than compensate for the difference. Planck's Hubble "constant" value matches the BAO value pretty well; supernova (and other extra galactic distance measurements) just need to improve their game.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-67104052831533435532013-03-22T20:29:24.812+01:002013-03-22T20:29:24.812+01:00It's a 2sigma effect, so it's not statisti...It's a 2sigma effect, so it's not statistically significant. Plus the fact the quadrupole is aligned with the ecliptic. It's ok to keep it in mind, but I think it was not serious on the part of Planck to push it so much.Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-38326066186855430172013-03-22T17:23:30.675+01:002013-03-22T17:23:30.675+01:00Jester,
I read that the two anomalies being discu...Jester,<br /><br />I read that the two anomalies being discussed were hinted at by WMAP and haven't gone away with the (better) PLANCK experiment. I'm not an expert in cosmology or experimental physics, but if the effects haven't gone away, why do you dismiss it? I'm confused.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-66997251188173917902013-03-22T11:28:45.644+01:002013-03-22T11:28:45.644+01:00What you say on Neff isn't really correct and ...What you say on Neff isn't really correct and the situation has not actually changed that much. The CMB only measurements give a value about 1 sigma larger than 3 (this is the value you quote) - this was also true before. If this is combined with the astrophysically measured value of H0 (the Riess value of around 72 \pm 2)<br />then Planck finds 3.6 \pm .25, and 3.046 is excluded at 95% confidence level).<br /><br />So this story continues, and boils down to the approx 2.5 sigma inconsistency between Planck's value of H0 and the astrophysical estimates. (cf Doddy's comment)piscatornoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-72246664988751408722013-03-22T11:08:00.809+01:002013-03-22T11:08:00.809+01:00Thanks, that's right, a good question to ask a...Thanks, that's right, a good question to ask at the next Planck seminarJesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-59971789443508573352013-03-22T10:42:31.182+01:002013-03-22T10:42:31.182+01:00Hi, concerning the bound on Sum(m_nu), giving a cl...Hi, concerning the bound on Sum(m_nu), giving a closer look to the XVI Planck paper (sect.6.3.1), I got the impression that the 0.23eV result is far from being a "conservative bound" (and seems to be largely driven by BAO, not by CMB). Actually I don't understand why the disregard the lensing, that favor non-zero values.<br /><br />Anyway, in their conclusion they prefer to quote 0.66eV from CMB data only.Gino Isidorinoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-38334478547945836932013-03-22T10:19:21.983+01:002013-03-22T10:19:21.983+01:00I think the fact that Planck would pay more attent...I think the fact that Planck would pay more attention to the "anomalies" than WMAP could always have been predicted, given the names in the author list.<br /><br />For instance, off the top of my head: Martinez-Gonzalez, Vielva, McEwen, Cruz etc. from the original papers that pointed out the Cold Spot, Eriksen, Hansen, Górski etc. from the hemispherical asymmetry papers, Räth and others from phase correlations, Kim and Naselsky from parity asymmetry and so on. (Apologies to any authors reading this whose names I may have forgotten.) Sesh Nadathurhttps://www.blogger.com/profile/07155102110438904961noreply@blogger.com