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Press Conference on Major Discovery - primordial B modes?

  1. Mar 14, 2014 #1
    Press Conference on Major Discovery -- primordial B modes?

    Anyone have more information on this? Any speculation?

    http://www.spaceref.com/news/viewpr.html?pid=42751
     
  2. jcsd
  3. Mar 14, 2014 #2

    Drakkith

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    I'm betting on extraterrestrial life. Go big or go home, right?
     
  4. Mar 14, 2014 #3

    Chronos

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    I'm guessing it is related to work by a Harvard researcher.
     
  5. Mar 14, 2014 #4

    cristo

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    http://excursionset.com/blog/2014/3/15/the-smoking-gnu
     
    Last edited by a moderator: Mar 14, 2014
  6. Mar 14, 2014 #5
  7. Mar 14, 2014 #6

    Chronos

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    Looks like this may be the big announcement at SAO on Monday.
     
  8. Mar 14, 2014 #7
    So im 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?
     
  9. Mar 14, 2014 #8

    cristo

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    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.

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

     
    Last edited by a moderator: May 6, 2017
  10. Mar 14, 2014 #9

    Drakkith

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    What would evidence for B mode polarization of the CMB indicate?
     
  11. Mar 14, 2014 #10

    cristo

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    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.
     
  12. Mar 14, 2014 #11

    Drakkith

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    Thanks, Cristo. I know it mentioned some of these things, but I wasn't sure if that was the whole story.
     
  13. Mar 14, 2014 #12
  14. Mar 14, 2014 #13
    A prior paper from BICEP giving a preview here:
    https://www.cfa.harvard.edu/~cbischoff/bischoff_iaus288.pdf [Broken]
     
    Last edited by a moderator: May 6, 2017
  15. Mar 14, 2014 #14

    marcus

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    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
     
    Last edited: Mar 14, 2014
  16. Mar 14, 2014 #15

    DennisN

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  17. Mar 15, 2014 #16

    Chalnoth

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    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.
     
  18. Mar 16, 2014 #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.
     
  19. Mar 16, 2014 #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 [Broken]
     
    Last edited by a moderator: May 6, 2017
  20. Mar 16, 2014 #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?
     
  21. Mar 17, 2014 #20

    bapowell

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    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
     
    Last edited: Mar 17, 2014
  22. Mar 17, 2014 #21

    marcus

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    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?
     
  23. Mar 17, 2014 #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...?
     
  24. Mar 17, 2014 #23

    bapowell

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    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
     
  25. Mar 17, 2014 #24

    mfb

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  26. Mar 17, 2014 #25

    marcus

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    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 [Broken]
    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.
     
    Last edited by a moderator: May 6, 2017
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