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LIGO Fails To Detect Gravity Waves
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."
This is another failiure in the long history of trying to detect gravity waves.
As a matter of interest what would be the consequences to modern physics if Gravity waves do not exist?
Choose your allies carefully, it is highly unlikely you will be held accountable for the actions of your enemies
"...of less than a thousandth the diameter of an atomic nucleus."
Would that be a hydrogen nucleus... a uranium nucleus? Please be more specific.
"I like to lick butts!" by MobileTatsu-NJG (#32700246) (Score:5, Informative)
I'll spell it out for you. This is not a failure of gravitational wave detection technology.
What you apparently do not understand is that this device can detect gravitational waves. However, it did not detect gravitational waves that correlated with a gamma wave burst originating in Andromeda. Normally such bursts arise from well known phenomena, such as a collision of black holes. But in this case, the collision could not have been from one of these well known phenomena.
What the article suffers from is bad writing. It should have been put in the positive--something like "the gamma-ray burst originated from a novel mechanism". Now, because astrophysicists can not account for the burst, they must go back and (1) study other similar phenomena and/or (2) revise astrophysical theory to explain the heretofore inexplicable gamma ray burst. Why is this burst inexplicable at this point? Because they did not detect gravitational waves that correlated with the burst.
Just callin' it like I see it.
They're little plastic blocks that kids build things with. Granted, you can make things like the Millenium Falcon with them but it can't actually fly.
Oh wait, you said LIGO, nevermind.
Summation 2
There is no gravity - Earth sucks!
In Murphy We Turst
1) General Relativity as formulated by Einstein (and a lot of other similar derivates - are there many?) would be in serious doubt. An exam question I had was take GR and show gravity waves exist - you basically show how the wave equation falls out of the formulas and these things carry momentum out of a system.
2) You then need to explain stuff such as Mercury's orbit precession and observed effects of double Neutron stars slowing down - the FSM stirring his planetary meatball lunch slower?
The Singularity is closer than you think
Quant
licet differant, aequabitur
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
For all the people arguing over whether or not this is a failure of LIGO or not...it doesn't really say much at all. Initial LIGO (which is currently running) is more of a proof of concept sold as a viable project. But if you look at the expected rates of detection, the absolute high end for all binary sources is less than one event/year. The low end is between 4 events every 10000 years and 4 events every 100 years. The other source types are not any better.
This article basically says that because LIGO is known to not be sensitive enough to measure past a certain distance from Earth (which encompasses the Andromeda galaxy, in whose direction this burst occurred) and because no detection was seen, the burst was not caused from a source in the Andromeda Galaxy.
I suppose that after spending all this money its not a bad thing that LIGO can actually produce some useful results (though I doubt they were amazingly useful). Advanced LIGO should be able to do the job - but not for another 5-6 years. At that point, the minimum event rate is supposed to be around 1/year and we should finally get some sort of positive detection.
Personally I'm hoping Advanced LIGO does work, because otherwise all this money will have gone to waste and the field of gravitational wave astronomy will be even more damaged than it already is. The thing is, many people in astronomy who are not affiliated with LIGO are not excited by it. Maybe that interest will be rekindled when Adv LIGO actually works, since right now its more of an engineering problem than an astronomy or physics problem. More people are interested in LISA which (if it ever launches) should have many more interesting sources. Its amusing seeing LIGO people try to point out the flaws of LISA while trying to explain why LIGO doesn't work, but then maybe I'm biased since I am working on LISA (though I have worked on LIGO in the past).
... but I would call this simply "bad" science - You can't use one poorly-understood phenomenon to explore another. You are incorrect. Gravitational waves (the phenomenon) are a very clear and very well understood prediction of the theory of General Relativity. So I would say that this is as far from "bad" science as you can get. If, ultimately, gravitational waves are not detected by LIGO and its successors that would prove GR was incorrect. And that would be a huge scientific advance.I looked at the Wikipedia article about LIGO and noticed this interesting question in the discussion. No one has answered it there. Apparently it's from some forum somewhere. Maybe someone here can explain the solution to this "conundrum" for me?
I'd be fascinated to see what's wrong with the reasoning here!
From the wiki GW and here : The gravitational wave has been indirectly shown to exist by showing that the evolution of orbit of the binary system is in precise agreement with the loss of energy predicted by gravitational waves. Note that this was not done by LIGO. It was observed using convensional Radio telescopes. More over the LIGO is a *direct* detector of Gravitational waves. So I would like to know if LIGO has ever detected gravitational waves. If not the claim is questionable.
~561
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.
Yes. This is no failure in the dectection technology. People at LIGO have estimated what they can detect and what they cannot. This puts an upper bound in the energy of the gravitational waves that were emitted by the GRB source. If it emitted more they would have detected them. This shows GRBs theories have a long way to go. We dont even know the total intrinsic amount of energy of a GRB source. If the source radiates in a polar pattern (like a lighthouse) we only see a small fraction of the GRB sources that exists (when the beam is directed toward the earth), in this case the intrinsic amount of energy is much smaller. If the GRB radiates like a star in all directions the intrinsic amount of energy is MUCH bigger. We can estimate the maximum size of the source bases in the timing of the event (if it has very fast variations it must be smaller because the information to coordinate this variation cannot propagate faster than light). But we dont know much more. This "failed" experiment is as important fot GRBs theory as the "failed" experiment in detecting the aether wind by Michelson and Morley was for the birth of Relativity. It shows we must review our theories. Airton da Fonseca Granero
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.