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Last Week's Announcement About Gravitational Waves and Inflation May Be Wrong 194

Posted by samzenpus
from the not-so-fast dept.
KentuckyFC (1144503) writes "If you've been living under a stone, you might not have heard last week's announcement that astrophysicists from the BICEP2 experiment have found the first evidence of two extraordinary things. The first is primordial gravitational waves--ripples in spacetime from the very first moments after the Big Bang. The second is that these waves are evidence of inflation, the theory that the universe expanded rapidly, by twenty orders of magnitude in the blink of an eye after the Big Bang. But that can only be possible if the gravitational waves formed before inflation occurred. Now critics have begun to mutter that the waves might have formed later and so provide no evidence of inflation. The new thinking is that as the universe cooled down after inflation, various phase changes occurred in the Universe which generated the laws of physics we see today. These phase changes would have been violent events that generated their own ripples in space time, which would look very much like the primordial gravitational waves that the BICEP2 team claims to have found. So the BICEP2 team must rule out this possibility before they can claim evidence of inflation. But the critics say the data does not yet allow this to be done. That doesn't mean inflation didn't occur. Indeed, the critics say this is still the most likely explanation. But until the phase change possibility is ruled out, the result must be considered ambiguous. So put the champagne back in the fridge."
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Last Week's Announcement About Gravitational Waves and Inflation May Be Wrong

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  • by wcrowe (94389) on Monday March 24, 2014 @10:11AM (#46563337)

    What really happened was that Wolowitz and Koothrappali rigged the electric can opener to create false postitive results for Sheldon's test equipment. He shouldn't have announced his findings so soon.

  • Re:Jumping the gun (Score:4, Informative)

    by photonic (584757) on Monday March 24, 2014 @10:30AM (#46563467)
    Scientist are still analyzing the data of ESA's Planck satellite [wikipedia.org], with first results expected in October this year. This instrument is supposedly sensitive enough to confirm or reject BICEP's results. I guess Planck's team must feel pretty depressed that the potential big discovery of their 700 MEuro instrument is scooped by the relatively small-scale BICEP experiment.
  • Re:No confirmation (Score:5, Informative)

    by interkin3tic (1469267) on Monday March 24, 2014 @12:03PM (#46564407)
    It sounds like this is actually sort of the confirmation.

    Last year, another telescope in Antarctica — the South Pole Telescope (SPT) — became the first observatory to detect a B-mode polarization in the CMB (see Nature http://doi.org/rwt [doi.org]; 2013). That signal, however, was over angular scales of less than one degree (about twice the apparent size of the Moon in the sky), and was attributed to how galaxies in the foreground curve the space through which the CMB travels (D. Hanson et al. Phys. Rev. Lett. 111, 141301; 2013). But the signal from primordial gravitational waves is expected to peak at angular scales between one and five degrees...

    Furthermore, data taken with a newer, more sensitive polarization experiment, the Keck array, which the team finished installing at the South Pole in 2012 and will continue operating for two more years, showed the same characteristics. “To see this same signal emerge from two other, different telescopes was for us very convincing,” says Kovac.

    Nature [nature.com]

    So it's not just one experiment, there are multiple other readings that support it, though I guess a complete experiment duplication is not yet complete. That nature article mentions that the SPT is a competitor to BICEP2, which published the findings, and they were literally a few meters away at the south pole. So I'd assume that SPT and maybe some other competitor is most of the way to confirming the findings, enough that they were confident in publishing.

    That said, I'm totally not a physicist. It just sounds like this isn't a single experiment.

  • by MightyMartian (840721) on Monday March 24, 2014 @12:03PM (#46564409) Journal

    I urge anyone interested in these questions to go to Professor Matt Strassler's blog: http://profmattstrassler.com/ [profmattstrassler.com] . In particular he goes to some length to describe what BICEP2's data might mean.

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