Gravitational Waves May Have Been Detected In 1987 221
KentuckyFC writes "In 1987, a physicist called Joe Weber claimed to have detected gravitational waves at the same time that other scientists spotted a supernova called SN1987A. His claims were largely ignored because of calculations showing that gravitational waves could not be strong enough to be picked up by Weber's equipment, a set of giant aluminium cylinders designed to vibrate as the waves passed by. But these calculations were based on first order effects in the way spacetime can be distorted. Now a new analysis shows that second order effects can enhance gravitational waves by four orders of magnitude, but only when certain asymmetries are present. It turns out that SN1987A possesses just the right kind of asymmetries to make this enhancement possible because the supernova wasn't entirely spherical. Which means that Weber, who died in 2000, may have been the first to see gravitational waves after all."
Nobel prize (Score:5, Interesting)
Gravity model (Score:3, Interesting)
Isn't that like using gravity to explain the effect of gravity?
Re:Honor (Score:3, Interesting)
But if this Weber (Joe) detected the gravity waves at the same time as SN1987A lit up, the Honorverse has a major problem as that Weber (David) assumed that gravity waves would be FTL.
Re:How much (Score:3, Interesting)
Science should be a marathon, not a sprint.
Poor guy (Score:3, Interesting)
What are they going to name the gravity SI unit, Webers? Right...
Some more info (Score:5, Interesting)
As already mentioned in a previous comment, the article is somewhat speculative and it is a little bit late to verify the experiment. The standard accepted practice for claiming the detection of a GW is to observe the event with at least 2 detectors which are separated far enough to not measure the same external disturbances (but preferably 3 or more spread around the world so that you can do proper triangulation of the source). One single glitch might be a cosmic ray, lightning, dust falling before your detector, an earthquake, an instrumental error, anything. We see more of those than we like. One glitch measured at different observatories within the time it takes to travel at lightspeed (a few ms) at different observatories around the world might give you a nobel prize.
One book that is high on my 'to read' list is Gravity's shadow [amazon.com], which supposedly describes not only Weber's experiments, but also its reception by the scientific community and the eventual downfall of Weber's reputation.
Re:Gravity model (Score:4, Interesting)
Isn't that like using gravity to explain the effect of gravity?
Sure, but it's just an analogy. It's not supposed to explain why masses warp space-time, only to show how a mass causing space-time to warp gives rise to effect we call gravity. In the analogy, the curvature of the space-time sheet is caused by gravity pulling downward on a ball to create the curve. In the reality the analogy is supposed to represent, the curvature of space-time is gravity. The analogy just gives you an easy way to ignore the "why" that theory can't answer, so you can focus on understanding the effect.
If it makes you feel better, you can just ignore the gravity-pulling-the-balls-down part of the analogy, and replace it with a simple assumption that a ball on the sheet causes the sheet to bend, and that other balls tend to move towards "low" spots in the sheet, with no explanation for why this happens.
Re:Not really. (Score:4, Interesting)
Er, no, you don't "truly" see anything. Your brain forms a representation of reality based on sensory input. In the visual side of that, the spatial representation is 3D.
Furthermore, you don't "see" in 2 dimensions, in your understanding of the word (which is kinda meaningless, cf visual illusions, hallucinations etc), because of the parallax effect afforded by having two eyes.
Also, the complete internal representation of a thrown ball is fundamentally 4 dimensional (3 spatial + 1 temporal). But it's hard to visualize curvature of 4 dimensional spacetime.
Re:Honor (Score:3, Interesting)
For a start it means gravity affects itself in the same way it bends and affects light. As light travels away from a gravity well it's redshifted, bringing it down to a lower energy state. Light can also be focused by a gravity well (gravitational lensing). Since gravity arrived at the same time it can also do all these things to itself. So why aren't we seeing a whole lot of unpredicted gravitational anomolies if gravity affects itself?
It also raises the question: if light waves can't escape a black hole then why can gravitational waves?
It's not like a black holes gravity well remains in a static position in space once it forms. The gravity well of a black hole apparantly still moves around which would mean information in the form of gravity waves must be able to get out from inside the event horizon.
Lastly if gravity does to itself what it does to light. Wouldn't an increase in mass of an object bring about less gravitational pull than expected?
As the object gets a stronger and stronger gravity well the gravity escaping will have less an less energy (just like the light escaping as it gets redshifted has less and less energy).
So take an object with a 100Gs of gravity, double its mass and you shouldn't end up with 200Gs of gravity. As gravity affects itself in the same ways it affects light.
Re:Honor (Score:3, Interesting)
The theory that was used to reject the observations was the same one being tested. That's circular. God forbid anyone actually inject reality into that feedback loop of the purely theoretical.
Yes, except that same theory was the only thing that would have suggested that he did find a gravity wave. When you're dealing with this kind of fringe physics, where the things you're trying to measure are minute, poorly understood, and largely detectable only through inference, there's often a circular relationship between the theory and the experiment designed to test the theory. When the fundamental design of your experiment depends upon the calculations in the theory being correct, and then you get a result outside the bounds of what the theory allows, then what exactly can you say other than "null result"?
I mean, if his data was by itself compelling enough to be convincing evidence of a gravity wave, then he could have convinced others that this was the case. You can talk about "orthodoxy" all you want, fact is that physicists and astronomers regularly publish results that essentially say "this outcome does not match existing theory and our theory is probably wrong". We see it on slashdot itself on occasion. But the fact is that getting convincing evidence of a gravity wave is tough and nobody else could repeat his experiment or try to increase the accuracy. So without at least being able to say that the result fell within predicted results, what is to say that this was really a gravity wave and not a passing train or road construction or anything else, except assertion?
After all, is it not the fact that our newly updated theory (a very mercurial orthodoxy this is) says that his results were within the expected range that has caused you to look back and say that he was ignored due to orthodoxy? If it weren't for the new theory, there'd still be no reason to think he was right. Even if he was right!
So I guess my point is, he may have gotten a bum rap and been ignored, but it also isn't obvious that this implies that had he not been ignored, gravity waves would have been confirmed by his experiment at the time he conducted it.
I don't think so. (Score:4, Interesting)
I don't like to speak ill of the dead, so I will leave it at that.
I saw the setup (Score:5, Interesting)
I saw the setup in the winter of late 1986. It was deep (many levels) under the physics department's machine shop, deep underground, at the University of Maryland & you had to go down several ladders to get there. It was hanging from the ceiling, big giant (I thought hollow, but apparently solid) cylinders of what looked like aluminum, hanging from thin wires. Does anyone know if it is still there?
Joe Weber (Score:4, Interesting)
In 1980 I met with Joe Weber at the Jet Propulsion Lab.
He had been reducing the noise in his experiment over the decades was still confident that the disturbances he was recording were gravitational waves.
Rather that being bitter about the 20 years of skepticism concerning his experiment, he was upbeat and optimistic. He understood that the theorists claimed that he could not possibly being seeing gravitational waves, but, as he told me, "You are not going to see them if you don't look!"
The reason he was at JPL was that John Anderson, Frank Estabrook, and Hugo Walquist conducted searches for gravitational waves using high precision spacecraft tracking during the 1970s and continue to search to this day.