• Is LIGO just an illusion?

    From jacobnavia@21:1/5 to All on Thu Nov 8 23:36:51 2018
    The New Scientist magazine has published a review of LIGO results
    indicating that they are... just an illusion.

    To avoid the paywall, here is a link to the article in question:


    The arxiv article is here:

    The authors argue that they find correlations in the NOISE between the
    two detectors, what should never happen.

    I am unable to decide if this is OK or not, I have read several blogs,
    for instance here:


    where LIGO people try to argue that their results are OK, arguing that
    the noise correlation of the danish group is due to their way of using
    the FFT, and that using their FFT method they find correlations in
    simulated white noise.

    I was very skeptic until there was a correlation reported between a
    satellite measurement and a LIGO observation of just a few seconds. For
    me, that closed the case. But I did not know that LIGO events like that
    appear several times each hour (!!!!) so that the probability of a
    spurious correlation becomes quite high!

    What do you think?


    [[Mod. note --
    1. Jennifer Ouellette has a very nice (NON-PAYWALLED!!) discussion at
    Her closing paragraphs are a nice summary:
    > For all the sound and fury, the Danish group's position is a minority
    > opinion. Even those physicists who went on the record with New
    > Scientist in support of the Danish team's analysis still think that,
    > in the end, the LIGO results will hold up. Their emphasis is on the
    > need for independent confirmation of LIGO's analysis.
    > On that point, people seem to be in agreement. But Reitze counters
    > that the complete data from that first run is already available
    > online. According to Shoemaker, this includes the relevant time
    > series data and the programs used, but "it's not a trivial matter
    > to use them." Caltech even held a training workshop on how to deal
    > with gravitational-wave data. That's a pretty far cry from asking
    > the physics community to take its analysis on faith, as Jackson
    > claims in the New Scientist article.
    > And contrary to Jackson's assertion in the article, a technical
    > paper really is in the works at the LIGO collaboration detailing
    > how it has handled the noise in its data--noise just hasn't been a
    > top priority. Shoemaker concedes this has given LIGO a needed nudge
    > to complete it. "We've been careful to write a paper that is not a
    > rebuttal of Jackson et al., since I don't think that would be very
    > useful for the community," he says. "Instead, it will be more
    > didactic about the specific points where we see they had difficulties."

    2. Two other informative blog discussions are
    There's a brief statement from the LIGO-Virgo Collaboration (LVC) at

    3. Referring to the "several times each hour": figuring out the exact
    statistical significance of a coincident detection is quite tricky,
    because the noise is time-dependent, frequency-dependent, doesn't
    have a Gaussian distribution, and has various other messy statistical
    properties that render simplistic analyses invalid. The LIGO Science
    Collaboration has put a lot of work into this, including using several
    independent analyses.
    -- jt]]

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