LIGO Black Hole Echoes Hint at GR Breakdown:

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Dec 16, 2016.

  1. paddoboy Valued Senior Member

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    I sometimes need to grit my teeth before I post articles such as this, as it seems to draw cockroaches out of the woodwork metaphorically speaking that is.

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    But anyway......
    https://www.scientificamerican.com/...echoes-hint-at-general-relativity-breakdown1/

    Scientific American

    LIGO Black Hole Echoes Hint at General Relativity Breakdown
    Gravitational wave data show tentative signs of firewalls or other exotic physics


    It was hailed as an elegant confirmation of Einstein’s general theory of relativity — but ironically the discovery of gravitational waves earlier this year could herald the first evidence that the theory breaks down at the edge of black holes. Physicists have analysed the publicly released data from the Laser Interferometer Gravitational-Wave Observatory (LIGO), and claim to have found “echoes” of the waves that seem to contradict general relativity’s predictions1.

    The echoes could yet disappear with more data. If they persist, the finding would be extraordinary. Physicists have predicted that Einstein’s hugely successful theory could break down in extreme scenarios, such as at the centre of black holes. The echoes would indicate the even more dramatic possibility that relativity fails at the black hole’s edge, far from its core.

    If the echoes go away, then general relativity will have withstood a test of its power — previously, it wasn’t clear that physicists would be able to test their non-standard predictions.

    “The LIGO detections, and the prospect of many more, offer an exciting opportunity to investigate a new physical regime,” says Steve Giddings, a black-hole researcher at the University of California, Santa Barbara. The LIGO team says that it is aware of the prediction and searching its data for echoes.
    more at link.....
     
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  3. paddoboy Valued Senior Member

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    The preprint on arxiv:

    https://arxiv.org/pdf/1612.00266.pdf

    Echoes from the Abyss: Evidence for Planck-scale structure at black hole horizons:

    In classical General Relativity (GR), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. However, tentative resolutions to problems in quantum gravity, such as the cosmological constant problem, or the black hole information paradox, invoke significant departures from classicality in the vicinity of the horizon. It was recently pointed out that such near-horizon structures can lead to late-time echoes in the black hole merger gravitational wave signals that are otherwise indistinguishable from GR. We search for observational signatures of these echoes in the gravitational wave data released by advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), following the three black hole merger events GW150914, GW151226, and LVT151012. In particular, we look for repeating damped echoes with time-delays of 8M log M (+spin corrections, in Planck units), corresponding to Planck-scale departures from GR near their respective horizons. Accounting for the “look elsewhere” effect due to uncertainty in the echo template, we find tentative evidence for Planck-scale structure near black hole horizons at 2.9σ significance level (corresponding to false detection probability of 1 in 270). Future data releases from LIGO collaboration, along with more physical echo templates, will definitively confirm (or rule out) this finding, providing possible empirical evidence for alternatives to classical black holes, such as in firewall or fuzzball paradigms.
     
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  5. paddoboy Valued Senior Member

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    So no jumping to conclusions as we still only have a small sample size and of course any data so far is tentative with far more research needed to be done.

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  7. paddoboy Valued Senior Member

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    I find it interesting that they have included the LVT151012 event as data, when aLIGO are as far as I know, still researching with no firm decision either way.
     
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