Press Conference on Major Discovery - primordial B modes?

In summary, a Harvard researcher announced that they have found evidence for a primordial B mode in the microwave background. This would be a significant discovery, as it would suggest that the universe went through an inflationary period. It is still unclear if this discovery requires a space-based mission, but it is an exciting prospect nonetheless.
  • #1
Greg Bernhardt
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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
 
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  • #2
I'm betting on extraterrestrial life. Go big or go home, right?
 
  • #3
I'm guessing it is related to work by a Harvard researcher.
 
  • #4
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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  • #6
Looks like this may be the big announcement at SAO on Monday.
 
  • #7
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?
 
  • #8
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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  • #9
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
 

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