Press Conference on Major Discovery - primordial B modes?

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Press Conference on Major Discovery -- primordial B modes?

Anyone have more information on this? Any speculation?

The Harvard-Smithsonian Center for Astrophysics (CfA) will host a press conference at 12:00 noon EDT (16:00 UTC) on Monday, March 17th, to announce a major discovery.

http://www.spaceref.com/news/viewpr.html?pid=42751
 
Space news on Phys.org
I'm betting on extraterrestrial life. Go big or go home, right?
 
I'm guessing it is related to work by a Harvard researcher.
 
As always though, rumours run beyond the available facts, starting with the claim that the discovery was made by BICEP2, a telescope at the South Pole. BICEP2 is one of a number of instruments around the world that are dedicated to observations of the microwave background, the afterglow of the Big Bang. The word is that the BICEP team will announce evidence for a primordial B-mode – a delicate twist in the polarisation-pattern of the microwave sky,

http://excursionset.com/blog/2014/3/15/the-smoking-gnu
 
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Looks like this may be the big announcement at SAO on Monday.
 
So I am guessing theyv'e found evidence for the b mode polarisation of the CMb.
If so , how much can we learn from a ground based detector? Do we need a space based project like CORE, PRISM or EPIC?
 
Two threads on the same topic have been merged. Note that this is still speculation and rumor -- we will have to wait for Monday to find out.

skydivephil said:
So I am guessing theyv'e found evidence for the b mode polarisation of the CMb.
If so , how much can we learn from a ground based detector? Do we need a space based project like CORE, PRISM or EPIC?

I think the answer to that is yes (cue quote from a biased source http://arxiv.org/abs/1310.1554):

Only from space can one reliably detect the very low-l B-modes due to the re-ionization bump. Because of its broad frequency coverage and extreme stability, PRISM will be able to detect B-modes at 5sigma for r = 5 exp -4;even under pessimistic assumptions concerning the complexity of the astrophysical foreground emissions that must be reliably removed. Moreover, PRISM will be able to separate and filter out the majority of the lensing signal due to gravitational deflections. Hence PRISM will perform the best possible measurement of primordial CMB B-mode polarization, and hence the best possible measurement of the corresponding inflationary tensor perturbations achievable through CMB observations.
 
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What would evidence for B mode polarization of the CMB indicate?
 
  • #10
Drakkith said:
What would evidence for B mode polarization of the CMB indicate?

A detection will indicate several things, as touched upon in the above blog post:

(i) it will be the first detection of gravitational waves, in itself a big milestone
(ii) the B mode is often called the 'smoking gun' test of inflation, since other mechanisms predict a very small signal
(iii) it's also evidence for quantum gravity, through the quantum fluctuations of the tensor gravitational mode during inflation
(iv) the size of the signal (called the tensor to scalar ratio for the inflationary model) will help rule out different classes on inflation models.
 
  • #11
cristo said:
A detection will indicate several things, as touched upon in the above blog post:

(i) it will be the first detection of gravitational waves, in itself a big milestone
(ii) the B mode is often called the 'smoking gun' test of inflation, since other mechanisms predict a very small signal
(iii) it's also evidence for quantum gravity, through the quantum fluctuations of the tensor gravitational mode during inflation
(iv) the size of the signal (called the tensor to scalar ratio for the inflationary model) will help rule out different classes on inflation models.

Thanks, Cristo. I know it mentioned some of these things, but I wasn't sure if that was the whole story.
 
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  • #13
A prior paper from BICEP giving a preview here:
https://www.cfa.harvard.edu/~cbischoff/bischoff_iaus288.pdf
 
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  • #14
Skydive:
Here's an alternative link to the IOPScience paper
http://iopscience.iop.org/1742-6596/484/1/012060
I see it is by Julien Grain
Loop quantum cosmology in the cosmic microwave background
The primordial universe can be used as a laboratory to set constraints on quantum gravity. In the framework of Loop Quantum Cosmology, we show that such a proposal for quantum gravity, not only solves for the big bang singularity issue, but also naturally generates inflation. Thanks to a quantitative computation of the amount of gravity waves produced in the loopy early universe, we show that future cosmological data on the polarized anisotropies of the Cosmic Microwave Background can be used to probe LQC model of the universe.

Open access, too, thanks for spotting it!

Here's an arxiv preprint version of Julien's paper:
http://arxiv.org/abs/1206.1511
 
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  • #15
Very interesting! I will try to tune in on Monday for this. According to the spaceref page the conference will be streamed here: http://www.cfa.harvard.edu/news/news_conferences.html
 
  • #16
cristo said:
A detection will indicate several things, as touched upon in the above blog post:

(i) it will be the first detection of gravitational waves, in itself a big milestone
(ii) the B mode is often called the 'smoking gun' test of inflation, since other mechanisms predict a very small signal
(iii) it's also evidence for quantum gravity, through the quantum fluctuations of the tensor gravitational mode during inflation
(iv) the size of the signal (called the tensor to scalar ratio for the inflationary model) will help rule out different classes on inflation models.
Perhaps most interestingly, though it's somewhat model-dependent, the level of primordial B modes serves as a measurement of the energy scale of inflation.

If the rumor is true, and if the detection is a solid one, this is a seriously big deal.
 
  • #17
One blog is saying Alan Guth and Andrei Linde are rumoured to be at the press conference, didnt mention a source for this
http://cosmobruce.wordpress.com/2014/03/14/108/
the blog also doubts the "detection" will have a sufficiently high sigma.
 
  • #18
re Monday pres conference. The day after Andei Linde one of the fathers of inflationary theory is giving a talk athe joint MIT/Tufts seminar. I don't think this was on their schedule previously . The title of the talk is "Inflation News and Persepective. The poster is below and has no other details: http://cosmos2.phy.tufts.edu/joint-seminar/poster-7.pdf
 
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  • #19
An interesting paper claiming that the detection of the B mode is not enough to rule in favour of inflation but the tilt of the spectral slope needs to be red, others models give a blue tilt but still detectable gravity waves:

http://arxiv.org/pdf/1104.3581.pdf

What will it take to measure this? Cant be done from the ground?
 
  • #20
Yes, now we need to measure the tilt of the tensor spectrum. Shameless plug, but a while back I studied how well we can expect future experiments to distinguish between the competing models:

http://arxiv.org/abs/arXiv:1106.5059
 
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  • #21
DennisN said:
Very interesting! I will try to tune in on Monday for this. According to the spaceref page the conference will be streamed here: http://www.cfa.harvard.edu/news/news_conferences.html

It was scheduled for noon Eastern, so should have started 20 minutes ago. I tried your link, but could not get connection (may be overloaded).

Anybody have another suggestion? Some other link to try later, for summary report or written statement?
 
  • #22
Here are the results:
http://bicepkeck.org/
for a news story see here:
http://www.nature.com/news/b-mode-1.14884
A lot of stories running this as proof of inflation if confirmed. However as I understood it discovering the b Mode was not enough, we need to know if the gravity wave spectrum is red or blue tilted. I am basing this on the following paper:
http://arxiv.org/pdf/1104.3581.pdf
am I right, if so can we answer this with today's data or will it take a space based mission or...?
 
  • #23
marcus said:
It was scheduled for noon Eastern, so should have started 20 minutes ago. I tried your link, but could not get connection (may be overloaded).

Anybody have another suggestion? Some other link to try later, for summary report or written statement?
I think it started closer to 11:00 Eastern. I caught the latter half. Bottom line: r=0.20+0.07-0.05, r=0 disfavored at 7.0/5.9 sigma. This implies GUT-scale inflation, too. Far out.

Oh, and this video of Linde hearing the news has been circulating: https://www.youtube.com/watch?feature=player_embedded&v=ZlfIVEy_YOA
 
  • #24
Here is an alternative livestream: http://www.ustream.tv/channel/aagie?#astronomy

The viewing angle is a bit odd, but now they are at questions anyway.
 
  • #25
DennisN said:
Very interesting! I will try to tune in on Monday for this. According to the spaceref page the conference will be streamed here: http://www.cfa.harvard.edu/news/news_conferences.html

I actually got connected on that link and was able to watch. It just took a while. They also said that the news conference would be archived at the harvard website, so could be watched later.

Statements by Mark Kamionkowski and Clem Pryke were especially clear and articulate. The questions from the audience were worthwhile (I thought) and so some of the responses were enlightening. Alan Guth and Andrei Linde were in the audience and took the mike several times to talk up the "multiverse". Their argument was essentially that it was possible to make models of inflation that do NOT lead to eternal inflation and that kind of multiverse, but that it was HARD to construct models in which adequate inflation occurred and stopped in some cases without generating a lot of unsatisfactory cases as well. Thanks to the other posters who just now provided what look like very helpful links! I'll be checking some out this morning.

Just glanced at the main BICEP release paper that Skydive linked to
http://bicepkeck.org/b2_respap_arxiv_v1.pdf
full of technical detail, very thorough, see Figure 13 on page 17, which kind of sums it up. r is the strength of the signal confirming direct evidence of gravitational waves have been seen. The find r = 0.2 and they regard that as very strong, higher than they thought could be the case based on rough back-of-envelope estimates.
They say they now have a handle on the energy density of the very early universe, and with further observations will be able to plot how it changed.
 
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  • #27
marcus said:
I actually got connected on that link and was able to watch. It just took a while. They also said that the news conference would be archived at the harvard website, so could be watched later.

Statements by Mark Kamionkowski and Clem Pryke were especially clear and articulate. The questions from the audience were worthwhile (I thought) and so some of the responses were enlightening. Alan Guth and Andrei Linde were in the audience and took the mike several times to talk up the "multiverse". Their argument was essentially that it was possible to make models of inflation that do NOT lead to eternal inflation and that kind of multiverse, but that it was HARD to construct models in which adequate inflation occurred and stopped in some cases without generating a lot of unsatisfactory cases as well. Thanks to the other posters who just now provided what look like very helpful links! I'll be checking some out this morning.

Just glanced at the main BICEP release paper that Skydive linked to
http://bicepkeck.org/b2_respap_arxiv_v1.pdf
full of technical detail, very thorough, see Figure 13 on page 17, which kind of sums it up. r is the strength of the signal confirming direct evidence of gravitational waves have been seen. The find r = 0.2 and they regard that as very strong, higher than they thought could be the case based on rough back-of-envelope estimates.
They say they now have a handle on the energy density of the very early universe, and with further observations will be able to plot how it changed.

Thanks MArcus , can't wait to get a chance to watch the video. Sorry to keep bugging, but what about the issue of red tilt versus blue tilt in the primordial gravity wave spectrum? Can that/has that been addressed by BICEP 2 data or not?
 
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  • #29
bapowell said:
Yes, now we need to measure the tilt of the tensor spectrum. Shameless plug, but a while back I studied how well we can expect future experiments to distinguish between the competing models:

http://arxiv.org/abs/arXiv:1106.5059

Hi Bapowell, I missed your post sorry. But thanks, your paper was very interesting. Can I confirm that given the results today it is still the case that current data cannot tell us the tilt of the spectrum and only a future space mission will do be bale to do so?
Planck polarisation data should be out by November , would you say that it will not give us the relevant information?
A lot of press reports are saying this is proof of inflation but this seems premature to me , do you agree?
 
  • #30
skydivephil said:
..., but what about the issue of red tilt versus blue tilt in the primordial gravity wave spectrum? Can that/has that been addressed by BICEP 2 data or not?

I had better pass and let someone like Brian Powell respond to that. they did say something in the press conference about the need for more observation to confirm something about a tilt in a spectrum. I'm not sure it was the primordial g-wave spectrum that they were talking about. It may be that their analysis depended on making some reasonable assumptions about the overall CMB anisotropy power spectrum. So to increase their confidence in their findings they wanted a better grip on that. Its a case where I'm not quite sure how to interpret what I heard the people on the news conference panel say. So I'll have to pass on that.
 
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  • #32
I was under the impression the Planck polarization data release was scheduled for the first half of 2014, but, may be mistaken. Perhaps getting scooped by BICEP relieves the scheduling pressure. The power of the r [tensor to scalar] signal was so strong that Clem Pryke [U of Minn] characterized it as finding a crowbar in a haystack while looking for a needle. Some [e.g., Matt Strassler and David Spergel] believe the 0.2 signal is overstated and a lower value will be agreed upon after more data is examined - re: http://profmattstrassler.com/2014/03/17/bicep2-new-evidence-of-cosmic-inflation/.
 
  • #33
skydivephil said:
Hi Bapowell, I missed your post sorry. But thanks, your paper was very interesting. Can I confirm that given the results today it is still the case that current data cannot tell us the tilt of the spectrum and only a future space mission will do be bale to do so?
Planck polarisation data should be out by November , would you say that it will not give us the relevant information?
A lot of press reports are saying this is proof of inflation but this seems premature to me , do you agree?
Not a problem. Yes, I believe it is still the case that we need more results. The slope of the tensor spectrum is key to determining whether the seeds of structure formation were inflationary, the result of a contracting phase, string gases, etc.
 
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  • #34
bapowell said:
Not a problem. Yes, I believe it is still the case that we need more results. The slope of the tensor spectrum is key to determining whether the seeds of structure formation were inflationary, the result of a contracting phase, string gases, etc.

Thanks and can this be done from the ground or does it need a space based mission?
 
  • #35
http://www.astro.caltech.edu/people/faculty/Jamie_Bock.html at Caltech is one of the members in the Caltech Observational Cosmology Group that today has released the 17Mar2014: Detection of B-mode Polarization at Degree Scales with BICEP2, and here is http://bicepkeck.org/b2_respap_arxiv_v1.pdf.

2014-05.jpg


Jamie_Bock.jpg

Jamie Bock

BICEP2 Technical Presentation Part 1
https://www.youtube.com/watch?v=H-hJ78o1Y2c
http://www.youtube.com/embed/H-hJ78o1Y2c

BICEP2 Technical Presentation Part 2
https://www.youtube.com/watch?v=UP7rncdR9Jw
http://www.youtube.com/embed/UP7rncdR9Jw
 
  • #36
Andrei Linde is happy and hopes he is not tricked. :smile:

https://www.youtube.com/watch?v=ZlfIVEy_YOA
http://www.youtube.com/embed/ZlfIVEy_YOA

And now it's all over the news...

https://www.youtube.com/watch?v=UWEAtRrRLsg

https://www.youtube.com/watch?v=qun1L3HfQ7M

BBC Radio 4
Scientists 'expect' echoes of Big Bang

TELEGRAPH.CO.UK
http://www.telegraph.co.uk/science/space/10703721/Big-Bang-echo-scientists-find-signal-from-dawn-of-time.html
 
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  • #37
This is indeed a very important discovery, with far ranging implications that are (imo) quite a bit more important than anything that we have learned from Planck.

If true (and that's a big if and already being challenged by a number of colleagues) we will have essentially confirmed a number of remarkable properties about the early universe.

Moreover, the constraints on model building are absolutely staggering, with all sorts of popular models being ruled out. I recommend the following blog posts on the theoretical aspects of this discovery:

http://resonaances.blogspot.com/2014/03/curly-impressions.html

http://motls.blogspot.com/2014/03/bicep2-primordial-gravitational-waves.html
 
  • #38
skydivephil said:
Thanks and can this be done from the ground or does it need a space based mission?
It depends on how big n_T ends up being. If we are looking at inflation, then from the consistency condition r=-8n_T, n_T will be sufficiently small to require a high-precision experiment. I'm not sure whether there is a preference for space- vs. ground-based observations, but either one would need to be close to cosmic variance-limited in order to conclude with strong evidence (with a Bayes factor satisfying 2.5 < ln|B| < 5) that the tensor spectrum is red.
 
  • #39
Maybe someone can explain a little what the B-mode polarization is as opposed to the E-mode, and how it relates to the usual EM polarization, is the difference just the handedness(like in linear vs. elliptical EM polarization)?.
 
  • #41
Watched the YouTube part 1, could hear fine but video taken from too far from screen so slides not clearly visible.
Maybe if one had the downloaded paper, and or supplemental material in front of one , to consult, it would substitute for not being able to see the slides. Clem Pryke gave the second half of Part 1, on data analysis
 
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  • #42
In some places I am reading things like the following:

So, granting the context of inflation, the BICEP measurement tells us that inflation occurred around the GUT scale, just two orders of magnitude below the Planck scale. This is on the doorstep of quantum gravity. I will say more about this below.

For example here: http://motls.blogspot.com.ar/2014/03/bicep2-primordial-gravitational-waves.html#more

Where in the whole discovery is seen a connection with the scale at which inflation operated (10^16 Gev from what I see in the reviews). Is this energy value another output of the discovery? Why? Where?

Thanks!
 
  • #43
Is there anything to suggest that this discovery favours or disfavours the eternal inflation variation on the inflation model?
 
  • #44
http://en.wikipedia.org/wiki/B-modes

In the reference above r the tensor-to-scalar ratio, can this be defined? Perhaps pictorially?

Could there by more than one stage of gravitational lensing on the cmbr at different distances which could explain this instead of inflation?

I am only aware of horizontal, vertical, and circular RF polarization. Does anyone have a pictorial description of b and e modes?

Useful links:
http://blankonthemap.blogspot.co.uk/2014/03/b-modes-rumours-and-inflation.html

http://blankonthemap.blogspot.co.uk/2014/03/first-direct-evidence-for-cosmic.html
 
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  • #45
marcus said:
I tried your link, but could not get connection (may be overloaded).
Yeah, same here :smile:.
Hopefully a nicely recorded conference will pop up here: http://www.cfa.harvard.edu/news/conferences (it isn't up yet).
And thanks to everybody else in this thread for all links!
 
  • #46
E-mode vs. B-mode is how the polarization direction is related to the fluctuation strength's gradients. E-mode is along the gradient or perpendicular to it, B-mode is 45d away from the gradient. This is an extension of the Stokes parameters for describing polarization.

I = overall intensity
Q = horizontal - vertical
U = one diagonal - other diagonal
V = circular

I and V are essentially scalars, and are thus easy to specify for an area. However, Q and U are not, but they can be expressed as components of a symmetric traceless tensor:

L11 = Q, L12 = U, L21 = U, L22 = -Q

That gives a hint as to how to find Q and U as functions of a scalar quantity:

Lij(E) = φ,ij - (1/2)δijφ,kk
is the E mode
and
Lij(B) = (1/2)(εikLjk(E) + εjkLik(E))
is the B mode

In components,

L(E) = {{(1/2)(φ,11 - φ,22), φ,12}, {φ,12, (1/2)(- φ,11 + φ,22)}}

L(B) = {{φ,12, (1/2)(- φ,11 + φ,22)}, {(1/2)(- φ,11 + φ,22), - φ,12}}

where φ is a scalar function.

I derived this for a flat surface, but one can extend it to a spherical one with the differential-geometry apparatus of general relativity.
 
  • #47
Thanks for the link and the explanation, skydivephil and Ipetrich.
 
  • #49
DennisN said:
Yeah, same here :smile:.
Hopefully a nicely recorded conference will pop up here: http://www.cfa.harvard.edu/news/conferences (it isn't up yet).
And thanks to everybody else in this thread for all links!

The conference is now up as a downloadable mp4 file (553 MB).
Page: http://www.cfa.harvard.edu/news/conferences
MP4 File:http://www.cfa.harvard.edu/pao/Bicep2_news_con.mp4

I'm downloading it right now, and will watch it later today :smile:.
EDIT: I looked at it briefly, and it seems it is excellent quality, both video, audio and slides.
 
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  • #50
Haelfix #37 said:
This is indeed a very important discovery, with far ranging implications ...
.
For me, these implications include correcting my poor understanding of quantum mechanics,
and of its ‘vacuum state’, which I imagine as a label for probabilistic chaos in a seething,
fluctuating, unobservable turmoil of zero-point mass/energy. Perhaps the ultra-energetic state of
the nascent universe can also only be described in such probabilistic quantum-mechanical terms.
But I’ve wrongly thought of vacuum fluctuations as having real, observable consequences ( Casimir
effect, Van der Waals forces), and of fluctuations as rather less real entities — conveniently
imagined but unobservable constructs. However the observations made with BICEP2 pretty much
confirm that inflation indeed promotes vacuum fluctuations into the realm of directly observable
entities, and therefore strongly supports the accepted history in which vacuum fluctuations act as
seeds for gravitational condensation, and all the amazing complications that follow.
Chalnoth#16 said:
...this is a seriously big deal.
Informs about quantum mechanics and the 'reality' of the wave function as well!
 
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