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BICEP 2 wrong?

  1. May 13, 2014 #1
  2. jcsd
  3. May 13, 2014 #2

    wolram

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    http://physicsworld.com/cws/article/news/2014/mar/18/neil-turok-urges-caution-on-bicep2-results

    Yesterday, researchers from the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) telescope at the South Pole revealed that they have detected the first evidence for the primordial B-mode polarization of the cosmic microwave background (CMB). The astronomers claimed that the primordial B-mode polarization signal – which is related to primordial gravitational waves that flowed through the early universe – is the first direct evidence for cosmic inflation and has been measured to a statistical certainty of 3σ. Now, cosmologist and Perimeter Institute director Neil Turok, who worked on an inflationary model of his own with Stephen Hawking in the 1990s, urges caution and says that extensive experimental confirmation is necessary before BICEP2's results can be considered as evidence for inflation

    It seems untimely to jump on the bicep2 bandwagon.
     
  4. May 13, 2014 #3
    Well, Turok doesn't really like inflation in the first place. He and Steinhardt have their cyclic models. So I would also take his skepticism with a pinch of the same. I'm not saying that we should just believe the BICEP result either, mind you. Still, it will be decided soon enough I think.
     
  5. May 13, 2014 #4

    wolram

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    I agree on both accounts, but here is an explanation from Not Even Wrong as to why we should be skeptical.

    http://www.math.columbia.edu/~woit/wordpress/?p=6865

    However, it seems they misinterpreted the Planck results: that map shows the polarization fraction for all foregrounds, not for the galactic dust only (see the “not CIB subtracted” caveat in the slide). Once you correct for that and rescale the Planck results appropriately, some experts claim that the polarized galactic dust emission can account for most of the BICEP signal.....more.
     
  6. Jun 1, 2014 #5

    Dotini

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    ESA Planck researchers have explained polarized galactic dust emissions in a new NASA Sciencecast video:
    http://m.space.com/26036-milky-way-s-magnetic-fingerprint-mapped-by-probe-video.html

    http://www.allreadable.com/vid/scie...s-not-just-a-refrigerator-magnet-3554539.html <----readable format

    http://www.iau.org/science/meetings/proposals/loi/2015/218/ [Broken] <---related upcoming researches
     
    Last edited by a moderator: May 6, 2017
  7. Jun 2, 2014 #6

    Chronos

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    I view this as a competition and suspect both groups will end up feeling embarrassed.
     
  8. Jun 3, 2014 #7

    Dotini

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  9. Jun 3, 2014 #8

    George Jones

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  10. Jun 4, 2014 #9

    Dotini

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  11. Jun 4, 2014 #10

    bapowell

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    Yeah, Steinhardt's take is odd. The question is whether inflation is falsifiable, not whether it is uniquely corroborate-able. B-modes simply cannot be used for falsification because they depend on the energy scale of inflation, which can be tuned to below detectable levels. So what? How does not detecting something a theory does not definitely predict weaken the case for this theory?

    If not B-modes, how might we falsify inflation? I would think the lack of superhorizon polarization correlations in the CMB, or strongly non-adiabatic density perturbations would do it. Anybody have anything else?

    To me, Steinhardt is arguing from his heart, not his head. He's long been an opponent of inflation and this articles smacks of this bias.
     
  12. Jun 5, 2014 #11

    Dotini

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    See also "A joint analysis of Planck and BICEP2 B modes including dust polarization uncertainty",
    Authors: Michael J. Mortonson, Uroš Seljak
    http://arxiv.org/abs/1405.7351


    See also ‘No evidence for or against gravitational waves’
    http://www.nature.com/news/no-evidence-for-or-against-gravitational-waves-1.15322

    I had thought that the result was very secure,” Alan Guth, the cosmologist who first proposed the concept of cosmic inflation in 1980, and who is at the Massachusetts Institute of Technology in Cambridge, told Nature after learning about Flauger's talk. “Now the situation has changed.”
     
  13. Jun 7, 2014 #12
    If someone understands both sides of an argument without agreeing with either side are they an opponent? Neutral perhaps.
     
  14. Jun 7, 2014 #13

    bapowell

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    But he's securely on the other side, as a champion of ekpyrotic/cyclic models.
     
  15. Jun 7, 2014 #14
    ok thanks. Like the profile pic! Liked Bridges in K-Pax also, a truly wonderful movie.
     
    Last edited: Jun 7, 2014
  16. Jun 20, 2014 #15

    Dotini

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    http://www.bbc.com/news/science-environment-27935479

    On Thursday, the BICEP2 collaboration formally published its research in a peer reviewed journal - Physical Review Letters (PRL).

    "I'm feeling like I'm at the eye of the storm”, said Prof Clem Pryke of the BICEP2 Collaboration.

    In the paper, the US-led group stands by its work but accepts some big questions remain outstanding.

    And addressing a public lecture in London, one of BICEP2's principal investigators acknowledged that circumstances had changed.

    "Has my confidence gone down? Yes," Prof Clem Pryke, from the University of Minnesota, told his audience.

    --------------------

    'Data trumps models'

    At his lecture at University College London, Prof Pryke explained his team's lowered confidence: "Real data from Planck are indicating that our dust models are underestimates. So the prior knowledge on the level of dust at these latitudes, in our field, has gone up; and so the confidence that there is a gravitational wave component has gone down. Quantifying that is a very hard thing to do. But data trumps models."

    Prof Pryke spoke of the pressure he and his colleagues had been under since March. He said he never expected there would be such interest in their work, especially from mainstream media.

    "I'm feeling like I'm at the eye of the storm," he told me.

    "Look, the scientific debate has come down to this - we need more data. With the existing data that's out there, you can generate a lot of farce, a lot of blog posts, a lot of excitement and controversy, but you can't really answer the question scientifically. So, what you need is more data, and that's coming from Planck and it's coming from us."

    Prof Marc Kamionkowski, from Johns Hopkins University, commented that what we were witnessing currently was "science in action".
     
  17. Jun 22, 2014 #16

    bcrowell

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  18. Jun 22, 2014 #17

    marcus

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    Dearly Missed

  19. Sep 22, 2014 #18

    Dotini

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    September 22, 2014 BBC article with news on the BICEP underestimated dust problem. Includes link to latest ESA paper.

    http://www.bbc.com/news/science-environment-29305985#
    One of the biggest scientific claims of the year has received another set-back.

    In March, the US BICEP team said it had found a pattern on the sky left by the rapid expansion of space just fractions of a second after the Big Bang.

    The astonishing assertion was countered quickly by others who thought the group may have underestimated the confounding effects of dust in our own galaxy.

    That explanation has now been boosted by a new analysis from the European Space Agency's (Esa) Planck satellite.

    In a paper published on the arXiv pre-print server, Planck's researchers find that the part of the sky being observed by the BICEP team contained significantly more dust than it had assumed.
     
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