back to article 'Cat-flap' pendulum offers 7x improvement for grav-wave detectors

A University of Western Australia (UWA) boffin who played a major part in Australia's contribution to finding gravitational waves reckons detectors can get a lot more sensitive. UWA Professor David Blair, who discussed how quantum noise can interfere with gravitational wave detection with Vulture South in 2011, has supervised …

  1. RIBrsiq

    See...? Everything is improved by adding cats!

    1. allthecoolshortnamesweretaken Silver badge

      No, it's the other way round - the cat flap is for getting the cat out of the LIGO setup so it won't paw at the shiny mirrors all the time.

      Anyway, mind-boggling top-notch boffinry.

      1. Stoneshop Silver badge

        getting the cat out of the LIGO setup

        They should switch the lasers off as well, or at least aim the dot at the exit flap.

  2. Anonymous Coward
    Anonymous Coward

    For schroedinger's cat

    Is it in or is it out?

    1. Swarthy Silver badge

      Re: For schroedinger's cat


  3. cray74

    Noise Filtering

    I wonder how they sort out all the noise. At sensitivity equal to 1/10,000th the diameter a proton, stray atoms in a vacuum chamber bumping the apparatus must be an issue.

    Do they shock isolate the bathrooms? One office chili cookoff at the LIGO facility could seriously pollute (har) the data.

    1. phuzz Silver badge

      Re: Noise Filtering

      They isolate the apparatus from the rest of the facility, so yes, it is isolated from the toilets (and aircon, and stairs, and that one guy who always bangs his fist on the desk when he's trying to make a point).

    2. John Mangan

      Re: Noise Filtering

      There are a whole array of isolation mechanisms. There are passive items like lead/rubber stacks, the mirrors are suspended on fine 'wires' to filter higher frequency noise. There are feedback mechanisms using laser beam sidebands to further reduce noise.

      On top of that although the impression given is that a laser beam enters the arm, reflects at the end and then exits these arms are actually Fabry-Perot cavities and the light bounces back and forth 'a lot'. The reflectivity of the mirrors define the 'finesse' of the cavity and the 'finesse' also defines the frequency response to gravitational waves. So one photon hitting a bump isn't going to be a big deal.

      There are also baffles along the tubes to ensure that scattered light doesn't get to re-enter the beam and (almost certainly) a whole host of other enhancements that weren't even thought of when I left the field nearly three decades ago.

    3. JeffyPoooh Silver badge

      Re: Noise Filtering

      cray74 "I wonder how they sort out all the noise?"

      There are some very nice audio samples of the raw Advanced LIGO audio signal available on-line. The raw signals are dominated by all sorts of artifacts, such as the 'Violin Mode' oscillation of the suspension strings. They do a lot of filtering with the usual Signal Processing tricks. That's after spending millions on the isolation hardware.

  4. Elmer Phud Silver badge

    'Ion Beam Etcher'

    Tends to put home 3D printers in thier place.

  5. Anonymous Coward
    Anonymous Coward

    1/7th of a "tsunami-like wave" is almost certainly a "tsunami-like wave". Is this ratio dumbed down for media consumption or is this merely a PR puff piece over a tiny tweak?

    1. cray74

      1/7th of a "tsunami-like wave" is almost certainly a "tsunami-like wave".

      Or you could say, "It's almost an order of magnitude improvement."

      But more to the point, not every large engineering improvement is accomplished in single giant leaps. Incrementalism works, too. A few percent here, a few percent there, and then the next generation of runners has shaved off a minute from the mile, or an hour from a marathon, or LIGO's watching the gravity waves of binary neutron stars rather than just spotting super giant black holes colliding.

  6. ma1010 Silver badge
    Paris Hilton


    But if the "tsunami-like wave" were water instead of gravity, how many Olympic swimming pools or Rose Bowl stadiums would it fill? Perhaps we need a new unit for gravity waves?

    Inquiring minds want to know.

    1. Stoneshop Silver badge

      Re: Units?

      Well, the gravitational force* between two bodies** is proportional to the product of their masses*** over the square of their distance****. So it would require two stadiums, the matter they are filled with, and also depends on the distance between them. A gravitational wave, as I understand it*****, is the variation in force due to matter shifting and/or being destroyed.

      This suggests the Roundhouse Kick as the preferred unit.

      * So, Norrises

      ** Say, Fred Astaire and Ginger Rogers

      *** Jubs squared

      **** Brontosauruses squared

      ***** BIANAGFE

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