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Gravity Wave Detector Ready For Business

Posted by timothy on from the very-expensive-ripples dept.

Arthur Embleton writes "The BBC has an article about a Gravity Wave Detector. There are two L shaped set-ups. One in Washington, the other in Louisiana. They've got a Laser pointing at a mirror 4km away, watching for the reflection and if it is distorted then it shows that there has been a gravitational pulse, possibly by two Black Holes colliding. The detectors are apparently so accurate they can measure to one-thousandth of the width of a proton! How did they test that it works?"

6 of 53 comments (clear)

  1. Really.. by NegativeK · · Score: 4, Insightful

    How did they test that it works?

    I think that's the problem. These detectors should work in theory, but gravitation waves are so minute when they get to us that it's _really_ hard to be able to get a reading on them. My bet is the first to provide fairly solid evidence of gravitational waves gets a Nobel.

    --
    This statement is false.
  2. "This week's finds" on LIGO by mike_stay · · Score: 4, Informative

    John Baez has some really good info about LIGO in several of his "This Week's Finds in Mathematical Physics" columns. week198 is the most recent to mention it. Baez is a great place to start if you like understanding connections between all kinds of different areas of math & physics (which, of course, includes everything else :)

  3. Re:Doesn't matter by Mt._Honkey · · Score: 4, Interesting
    Millions of dollars in federal grant money later, do you think anyone gives a rat's ass?
    Don't bother us with details like "how do you verify that it's calibrated?". There's a board of directors who have pensions! Nice little retirement nesteggs!
    I know that this is a troll, but I am going to respond anyway. I know/work with physicists at Fermilab, and I can vouch for how hard these people work to make sure that everything works perfectly and that data generated is valid. They have teams of people checking to make sure that every assumption made is correct (I'm involved in one such group). Physicists like those at Fermilab, or LIGO, or other such facilities are among the most dedicated, competent people you will ever meet. They aren't there for the money, they are there for the science. Even after they "retire", many continue to work for decades for free. Physicists are there to get shit done, and I'm sure that their retirement benefit packages are not their primary motives.

    If that were the case, I doubt that they would have gone through 4 hard years of painful undergraduate courses, followed by even harder grad school, then working through a post-doc position... all to secure a good pension. People like that just go into business.

    They're in it for the hunt, the dream, the achievement... the advancement.

    --

    Don't Bogart the fish sticks
  4. More info by crapulent · · Score: 5, Informative

    Here are the slides [pdf] from the Oct 2002 NSF review. Lots of pictures, graphs, technical details, etc. for anyone interested. In a nutshell they are aiming to measure strain on the order of 10^-21 over the frequency range of 100Hz - 1kHz. Using two facilities separated by 3000km allows them to search for correlated events and weed out localized noise. IANAP.

    More slides here.

    LIGO home page.

    HTH.

  5. Re:Insulation from vibrations noise... by Frans+Faase · · Score: 4, Interesting

    The idea is to find a place where there are not many fibrations and to make the system rigid. Movements parallel to the detector axis are (theoretically) not noticed. The remaining vibrations will simply make the instrument temporarily blind. That is no problem as long as they do not occur continiously. It is possible to distinguis between vibrations and changes in lenght. Using multiple instruments all over the world also helps distinquishing between local vibration events and globally caused changes in length due to gravational waves.

  6. Re:Insulation from vibrations noise... by stevelinton · · Score: 4, Informative
    I wonder how exactly they are doing this - what kind of technology can be used to hold two things 4km away at precisely (give or take a few thousandths of the width of a proton) the same relative position all the time.


    They don't. They damp out a certain amount of vibration via clever mountings, etc.
    Then they make sure that all the rest happens at very specific frequencies. You can think of a guitar string. When you jolt a guitar, the string will "sing" at its tuned note. I think the LIGO mirror supports are incredibly precisely tuned.

    Now they only look for gravity waves at other frequencies, mainly ones away from where seismic noise mostly is.

    Finally, they compare respoonses from two remote detectors and look for "matching" events separated by the speed of light, instead of the speed of seismic waves.