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A Penrose: Noise in LIGO signal implies CCC

  1. Jul 19, 2017 #1
    Roger Penrose, July 2017. Correlated "noise" in LIGO gravitational wave signals: an implication of Conformal Cyclic Cosmology
  2. jcsd
  3. Jul 19, 2017 #2
    Dark Matter particle around 10^-5g? Are you talking Planck mass?
  4. Jul 20, 2017 #3
    Penrose sure is. A particular model of DM in Penrose' CCC scheme is proposed to be of the order of the Planck mass meaning oscillations of these particles have Planck frequency order and thus constitute a cosmological noise source when measuring pretty much all gravitational waves.
  5. Jul 20, 2017 #4
    Yes, a Planck mass, or a simple multiple of that mass. He said.
  6. Jul 20, 2017 #5
    Yeah, however I'd say that's almost the least interesting aspect of the new paper. Much more interesting is that this erebon theory possibly kills two birds with one stone (noise in gravitational wave signals and DM) and is easily testable without requiring copious amounts of effort, funding or both.

    As Penrose says:
  7. Jul 20, 2017 #6
    Are you so content? I was looking for hints of DM contributions to the universe density, but no direct message was found. Maybe you can help me.
  8. Jul 20, 2017 #7
    Correct me if I'm wrong, that would be n times Planck masses (DM's) every 10^19 m^3. Also very few in space.
    What was the size of the BH's merged? Was supposed to be 49 x Sun's mass, 49 x Sun's Schwartzschild Radius = 72353 km. How many of DM's were within the range affected by the BH merger? Maybe not many.
  9. Aug 4, 2017 #8

    Ken G

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    I agree this is potentially quite significant, Penrose is proposing a simple test that could falsify both CCC and his model for dark matter. A pass of that test would be most interesting indeed! And how ironic would it be if the most important result from LIGO comes not from sources but rather from background noise. It would be akin to the detection of the CMB.
  10. Aug 5, 2017 #9
    Exactly my point. Being a theorist however, Penrose seems to have presented his test as easier than it actually seems to be. For his test to work two things are needed, namely 1) the ability for LIGO to focus on a particular point in the sky and 2) the possibilty to rotate LIGO's detectors such that they can focus on any other point in the sky.

    The first isn't possible yet, at least not with only two detectors. The regions identified as possible locations for detected BH sources are immense gigaparsec bands of the sky instead of crisp galaxies. With three or more detectors active however the precision should improve alot.

    As for the second point, rotating LIGO like a telescope or satellite seems out of the question, given that we are talking about a stationary 4 km Michelson-Morley setup. What would be needed for this to work are LIGO detectors in space, i.e. something akin to the planned LISA experiment.
  11. Aug 5, 2017 #10

    Ken G

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    Penrose knows you can't rotate LIGO, he is saying that the noise, unlike the CMB, would not be isotropic. So even with just two detectors, you could look for a background signal in the data that would always correspond to the time delay associated with Andromeda, where the dark matter will be. I agree this gets to be a more convincing test when more LIGO-type apparatuses are online in the future, or when LISA flies. Indeed, I've always been a little skeptical that we really are looking at a "new window" onto the universe with just LIGO-type instruments (how much is there really to learn about stellar black-hole mergers anyway?), but if Penrose's test gets a pass, then we have a new window indeed-- the best possible window into dark matter.
  12. Aug 5, 2017 #11


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    We have three now.

    The Earth rotates the detectors daily. LISA will only rotate once per year.
  13. Aug 5, 2017 #12
    I'm pretty sure he knows we can't rotate LIGO, but he does clearly state in the paper that all it would take is "to point the detector in some direction". Locating sources without being able to voluntarily rotate the detector is a far less clean route, involving far more statistics than a theorist usually bargains for.

    Don't get me wrong, I'm very enthusiastic about Penrose' proposal, but it's because of its potential magnitude that I want to make sure as certain as possible that we aren't fooling ourselves.
    Of course, but the rotation of the Earth is involuntary motion, where we are being rotated for the test hopefully in such a way as to get a good signal of some point, instead of choosing and rotating a telescope towards some specific point. This doesn't make things impossible but significantly constrains us in our possibilities.

    In any case, it is wonderful news to hear that VIRGO has finally gone online. The accurate localisation of sources should improve immensely using the ability to triangulate. Its too bad we can't retroactively locate any of the BH mergers though since their GWs have already passed. Now just to wait for another detection...
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