tag:blogger.com,1999:blog-2846514233477399562.post2073598882860092360..comments2021-08-21T05:27:55.808+01:00Comments on RÉSONAANCES: Curly impressions Jesterhttp://www.blogger.com/profile/08947218566941608850noreply@blogger.comBlogger49125tag:blogger.com,1999:blog-2846514233477399562.post-83128106083404842552014-03-24T21:37:16.822+01:002014-03-24T21:37:16.822+01:00After reviewing the Planck "Cosmological Para...After reviewing the Planck "Cosmological Parameters" paper, I see why BICEP2 put in the varying A_L analysis. This seems to be the key tension between BICEP and Planck, meaning that LCDM has trouble reconciling them but A_L around 1.2 seems to work (with r then around 1.7). Does this support CCC instead? That's a tricky question, because CCC does not do a 'full early universe' scenario. Marni Dee Sheppeardhttps://www.blogger.com/profile/08188528831432604162noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-79178241829171593262014-03-22T20:28:34.726+01:002014-03-22T20:28:34.726+01:00Now it seems that the concept of inflaton field is...Now it seems that the concept of inflaton field is getting a strong support. Just as a crazy speculation (!): is it possible that after inflation is over, the inflaton field has a remnant CC or Lambda which remains constant for most of the history of our universe? Or is this completely absurd? If that is true it would be very economical. One would not need two independent fields for repulsive expansion. Both would contribute to expansion, in one case very rapid exponential expansion and in the other case lot slower but nevertheless an accelerated expansion.kashyap vasavadahttps://www.blogger.com/profile/10732897306667764590noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-73098791450364301962014-03-20T23:56:11.275+01:002014-03-20T23:56:11.275+01:00Gee, that didn' take long. Arxiv paper on Higg...Gee, that didn' take long. Arxiv paper on Higgs-inflaton plus sterile neutrino DM, to explain BICEP2:<br />http://arxiv.org/abs/1403.4132Marni Dee Sheppeardhttps://www.blogger.com/profile/08188528831432604162noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-75265320716857103022014-03-20T02:54:52.425+01:002014-03-20T02:54:52.425+01:00For those who have maintained a semblance of scien...For those who have maintained a semblance of scientific objectivity in the rapture over the BICEP2 results, please check out this well-informed warning from Dr. Peter Coles, a theoretical cosmologist who knows the details.<br /><br />http://telescoper.wordpress.com/2014/03/19/time-for-a-cosmological-reality-check/ <br /><br />Hold your bets, my friends!<br /><br />Robert L. Oldershaw<br />http://www3.amherst.edu/~rloldershaw <br />Robert L. Oldershawhttps://www.blogger.com/profile/15396555790655312393noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-92230110741136251102014-03-20T00:59:07.675+01:002014-03-20T00:59:07.675+01:00"After the BICEP2 results, we now know that ...."After the BICEP2 results, we now know that . . . r=0.2."<br /><br />No. This is not what we know. <br /><br />What we know that BICEP2 reported that r=0.2+0.07/-0.05 and that Planck has combined its data to date and prior results to report that r<0.11 at the two sigma level and is not inconsistent with zero (which is basically r=0.01 +0.05/-0.01).<br /><br />The best fit to all available data is roughly r=0.10 to r=0.11, which is in roughly two sigma tension with both the Planck data and the BICEP2 data. But, we will need more data points before we can comfortably reconcile those estimates. It is entirely possible that one of these two data points is flawed.<br /><br />Fortunately, we have the Planck polarization data coming later this year, and several other experiments also trying to measure r so we shouldn't have to wait too long to have a better estimate of the scalar-tensor ratio than we do today.<br /><br />andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-44715275473380538772014-03-19T20:46:17.975+01:002014-03-19T20:46:17.975+01:00So interesting that this results constrains CDM ax...So interesting that this results constrains CDM axions which are now in severe tension with data and had their parameter space massively reduced.<br /><br />There is also interesting ongoing work on the stability of our vacuum, and the implication of a UV completion.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-83549889815631574042014-03-19T19:57:40.832+01:002014-03-19T19:57:40.832+01:00With regards to the decay of massive particles pro...With regards to the decay of massive particles producing gravitational waves (1109.0542), this claim was further investigated and shown to very unlikely (1209.3848).<br /><br />Particle production during inflation corresponds to a Bogoliubov transformation of the field mode function with occupation number equal to n_k=|beta_k|^2.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-21485712165624934572014-03-19T05:37:49.571+01:002014-03-19T05:37:49.571+01:00Thanks, Jester! After grabbing the paper, I saw th...Thanks, Jester! After grabbing the paper, I saw that <a href="http://www.preposterousuniverse.com/blog/2011/09/06/arxiv-find-new-sources-of-gravitational-waves-during-inflation/" rel="nofollow">Sean Carroll</a> mentioned that paper. There are a couple of related papers in the comments section of that posting.Marty Tysannerhttps://www.blogger.com/profile/18113481752481566995noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-9271082898872845012014-03-19T04:05:44.587+01:002014-03-19T04:05:44.587+01:00I learned this from 1109.0542. I learned this from 1109.0542. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-46617172201174336342014-03-19T03:07:09.903+01:002014-03-19T03:07:09.903+01:00For example, an early phase transition or decay o...<i>For example, an early phase transition or decay of massive particles during inflation may also generate tensor perturbations.</i><br /><br />Is there a decent reference that discusses tensor modes generated by the decay of massive particles during inflation?Marty Tysannerhttps://www.blogger.com/profile/18113481752481566995noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-91815478074318836192014-03-19T00:58:23.806+01:002014-03-19T00:58:23.806+01:00"But I think the mass larger than 10^16 GeV w... "But I think the mass larger than 10^16 GeV would be inconsistent with the measured V(inflaton)~[10^16 GeV]^4 plus the slow-roll conditions. Maybe there's a loophole for the latter argument but I'm not aware of one."<br /><br />No need to pick up a model. The energy scale we observed V~Mp^2H^2, solve for H ~ 10^14GeV. This is the energy scale of the 'experiment' at which the tensor and scalar exit the horizon. (This changes a bit if cs \neq 1. However, from today we learned it cannot be too far from 1, unless we truly buy this running...) <br /><br />Incidentally, Mp^2\dot H is also a very important scale ("\dot\phi^2") and that one is much closer to V^(1/4) for such "large" \eps ~ \dot H/H^2 (again with cs ~ 1).Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-77052684140284901142014-03-18T21:20:00.641+01:002014-03-18T21:20:00.641+01:00Of course there is no QG in the vanilla gravitatio...Of course there is no QG in the vanilla gravitational wave idea. QG should show up quantitatively in new constraints on LCDM, CCC etc., starting with the GUT scale. Marni Dee Sheppeardhttps://www.blogger.com/profile/08188528831432604162noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-1464063322103599922014-03-18T19:23:55.545+01:002014-03-18T19:23:55.545+01:00That's metaphysics. All we care for and all we...That's metaphysics. All we care for and all we can probe is the last ~60 e-folds. If you wait another 10 billion years you'll see the e-fold no.61 ;) Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-78186588817969515752014-03-18T18:03:56.816+01:002014-03-18T18:03:56.816+01:00Ok, some context for the question. I've seen s...Ok, some context for the question. I've seen several claims by Linde that inflation resulted in around 10^12 e-foldings. He had an article at Scientific American based on this number - I dont know if its a lower or upper bound.<br /> I recall vaguely that this follows from assuming a quadratic potential and using the fact that density fluctuations have amplitude 10^ -5 <br />Was wondering what happens if you repeat the calculation for quartic potentials, because I dont remember the detailssenanindyahttps://www.blogger.com/profile/04275136786127034360noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-89407167660896945202014-03-18T17:15:21.073+01:002014-03-18T17:15:21.073+01:00We had known before that we need at least around ...We had known before that we need at least around 60 e-folds to explain the uniformity of the CMB. I don't think anything changed in this respect after BICEP2. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-401301366538594472014-03-18T16:57:28.309+01:002014-03-18T16:57:28.309+01:00After the BICEP2 results, we now know that ns=0.96...After the BICEP2 results, we now know that ns=0.96 and r=0.2.<br /><br />From what I understand, this fits extremely well with the basic chaotic inflation model given by V(Φ)=λΦ4.<br /><br />We also know that amplitude of density fluctuations is ≈10−5 and Energy scale of inflation is around 1016 GeV.<br /><br />My question: Given also this information, can we now make an educated guess for how many e-foldings happened during inflation ? Or at least a theoretical lower (upper ?) bound ?<br /><br />PS: I am only referring to inflation of the patch of space that now contains our observable universe, not inflation of Universe as a whole.senanindyahttps://www.blogger.com/profile/04275136786127034360noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-37002426475775222272014-03-18T16:53:52.548+01:002014-03-18T16:53:52.548+01:00Anon 08:22, actually in simplest models with a qua...Anon 08:22, actually in simplest models with a quadratic inflaton potential the inflaton mass will be of the order of the Hubble scale during inflation: m~Sqrt[V]/M_Planck~10^14 GeV.<br />Right Anupam, i had single field in mind for the sake of this argument. But I guess even multi-field inflation will happen along a direction in the field space where the mass is much smaller than Planck? Or is there a counterexample? Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-73802934202677326562014-03-18T16:37:04.604+01:002014-03-18T16:37:04.604+01:00I also don't understand the fuzz about `quantu...I also don't understand the fuzz about `quantum gravity'. True, these are quantum fluctuations of the metric propagating from inflation to the last scattering surface . And yes, it's amazing that we can observe quantum effects happening in the early universe. But gravity and the scalar field mix during inflation, and previously we have seen quantum fluctuations of the scalar mode. So it's little surprise that all parts of a single system behave in the same quantum way. <br /><br />Also, the energy density during inflation is well below the Planck scale. So we're in the regime where Einstein gravity is a good effective theory, and we don't see what people usually call `quantum gravity', that is the gravitational physics above the Planck scale. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-89364708573749883832014-03-18T16:18:26.334+01:002014-03-18T16:18:26.334+01:00Large tensor mode is clearly anthropic. Without it...Large tensor mode is clearly anthropic. Without it we would die of boredom. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-89777506870634741282014-03-18T15:52:27.620+01:002014-03-18T15:52:27.620+01:00Jester,
Just a few weeks ago you were despondent ...Jester,<br /><br />Just a few weeks ago you were despondent and depressed and look at the gift nature gave you! 2014 turns out to be awesome...<br />I think the lesson here is you should never stop blogging<br />-TBAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-47064415994250101642014-03-18T13:40:21.847+01:002014-03-18T13:40:21.847+01:00What are the implications if these results from th...What are the implications if these results from the perspective of multiverse ?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-10918895734063168002014-03-18T12:19:57.830+01:002014-03-18T12:19:57.830+01:00Quote by Marni Dee Sheppeard: "Penrose won...Quote by Marni Dee Sheppeard: "Penrose won't know what to do about this, I suspect."<br /><br />Penrose's theory actually predicts CMB distortions by gravitational waves, only here they originate in the previous cosmic aeon (massive black hole collisions). But from what I remember he, Gurzadyan and others only looked at large scale structures in the CMB, not at the B-modes. It'll be interesting to see if these new observations can be explained by CCC.Jay Brownnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-44776363890782810632014-03-18T11:45:55.912+01:002014-03-18T11:45:55.912+01:00@vmarko,
but where do they come from@vmarko,<br /><br />but where do they come fromAlexnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-86026906810453416582014-03-18T10:29:43.739+01:002014-03-18T10:29:43.739+01:00Folks, I fail to understand the comments regarding...Folks, I fail to understand the comments regarding quantum gravity. AFAIK, the nonzero tensor mode says there are gravitational waves, which is an effect that can be described by classical GR (and we knew about the existence of those for a long time now).<br /><br />So where is anything "quantum" here? I would expect to see quantum gravity effects on the Planck scale (10^19 GeV), while the discussed inflaton scale is 10^16 GeV (a thousand times smaller). Am I missing something here?<br /><br />Best, :-)<br />Marko<br /><br />vmarkohttps://www.blogger.com/profile/12660488689205445871noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-43865785310727558962014-03-18T09:04:05.559+01:002014-03-18T09:04:05.559+01:00Hi, Ervin,
The large B-mode signal is unambiguo...Hi, Ervin,<br /> The large B-mode signal is unambiguous result of the fact that we cannot treat gravity classically, even at the linearized level it has to be quantised. This is sooooo amazing -- can't sleep over the results of BICEP at all.<br /><br /><br />For a simple one parameter mass model, indeed it fixes the mass, but more involved potentials, no -mass cannot be constrained.<br /><br />But guys - this is a major breakthrough, nature has given us - Planck mass, 10^{16} GeV, Electroweak scale and the scale of CC. everything can be built on these scales to understand the broad features of nature...Anupam Mazumdarnoreply@blogger.com