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LIGO Fails To Detect Gravity Waves

Posted by kdawson on from the listen-harder dept.

planckscale writes "Last weekend, LIGO (the Laser Interferometer Gravitational-Wave Observatory) did not detect gravitational radiation in association with a gamma ray burst (GRB). The non-detection was actually a valuable contribution, as it helped to distinguish between competing models for what powers GRBs. The detector is due to be upgraded this year for even more accurate measurements. The interferometer is constructed in such a way that it can detect a change in the lengths of the two arms relative to each other of less than a thousandth the diameter of an atomic nucleus."

5 of 357 comments (clear)

  1. diameter? by bwd234 · · Score: 3, Insightful

    "...of less than a thousandth the diameter of an atomic nucleus."

    Would that be a hydrogen nucleus... a uranium nucleus? Please be more specific.

  2. Re:Fails? by bluFox · · Score: 4, Insightful

    Any instrument needs to be calibrated before it can be used for detection. Which means that it has to detect gravitational waves *directly* on some event that is known to produce gravity waves. Apparently LIGO has not been able to detect *any* waves directly until now. Until it does that I think the grandparents question (If the gravity waves exist at all) holds good. Since LIGO has not been able to detect any waves, I do not understand how they can claim tha non-detection is a major event.

    --
    ~561
  3. Re:As a matter of interest... by master_p · · Score: 3, Insightful

    Other types of waves (e.g. sound waves, energy waves etc) are composed of particles. What is a gravitational wave composed of? of gravitons? gravitons are not proven to exist. If a gravitational wave has energy (as well as momentum and angular momentum) then what kind of energy is contained in the wave? where does this energy come from?

  4. Re:Of couse, they could *both* have it wrong... by dlevitan · · Score: 4, Insightful

    Maybe it's just the skeptic in me, but did you just claim that it's a very clear and well understood prediction? Doesn't that imply hypothesis phase? Isn't LIGO part of the observation phase? I have a hard time swallowing the idea that it's a solid theory when we haven't even been able to create any reliable, reproducible scientific observations. There are "clear and well understood" theories and there are not clear and poorly understood theories. GR has made several correct predictions that have been tested. The same theory has also predicted gravitational waves of which there is indirect observation (merging binaries). We haven't made any direct observations but that's only a matter of time and money.

    Looking at not clear and poorly understood theories, there is string theory, which has changed so many times that its not even close to the original anymore. The latest on string theory is that certain parts of it mimic what we know already, but exactly how it operates no one has any idea of. Another example is quantum gravity. Again, we have a general idea, but nothing concrete. However, just because we don't know the more correct theory doesn't mean we can't use the initial theory. Newtonian mechanics did not become wrong after QM and GR. Its just not as accurate.
  5. No one has detected gravitational waves... Yet by mbone · · Score: 5, Insightful

    There have been no direct detections of gravitational waves so far. There have been indirect detections (most robustly with the various binary millisecond pulsars, whose orbits slowly decay due to their radiating energy away in gravitational waves), but no direct detections. However, this was not really seen as an issue, as gravitational wave searches before LIGO suffered from the problem that there were no known sources strong enough for them to detect with good probability. You have to start somewhere, and there is always the chance of either good luck, say a close supernova, or some unknown source that is stronger than expected, but I believe that this is the first actual event whose gravitational waves, by a reasonable model, had a chance of being detected with existing equipment. One such non-detection means nothing - maybe the Gamma Ray Burst occurred way behind the Andromeda Galaxy, for example. If this is consistently repeated, we will eventually conclude that there is something wrong with our physics or our astrophysics, but it is much too soon for that.