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Gravitational Waves May Have Been Detected In 1987
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."
Gravity waves? I thought they'd never be observed! Impeller Drive, here we come! Now all we need is to prove hyperspace as a viable means of travel and invent Warshawski sails. :-P
(Joking aside, this is great news! Gravity waves have been one of the most difficult aspects of relativistic physics to pin down.)
Javascript + Nintendo DSi = DSiCade
...where's my surfboard ? I'm totally stoked, I want to be the first to ride a gravity wave, that'd be, like really heavy, man !
Can this be awarded posthumously ?
And here I was always convinced they were Gravity Particles.
How much does it have to suck to die, with your observations being discredited, and your claims laughed at? Then a decade later, the scientific community goes "oops, you were right".
And now, in Slashdot's infinite wisdom, I am required to wait five minutes between posts.
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
One thing I've never liked about the current popular gravity model, you know, the one they discuss on discovery channel, usually for a cosmology special, where they discuss how gravity distorts space-time, and then you get to see a CGI animation of a large ball on a rubber like grid -drawn as a 2 dimensional analogy- and the ball is pushing down on the grid, making an indentation in it, and another, smaller, ball starts circling the bigger ball, eventually falling in towards the larger ball..
Isn't that like using gravity to explain the effect of gravity?
Look back up at my post, now look back down, you're on the Internet. Now look back up. I'm a signature.
it was the pure amazement of my high school teachers that I was graduating. I was pretty shocked too.
It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
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, which supposedly describes not only Weber's experiments, but also its reception by the scientific community and the eventual downfall of Weber's reputation.
karma police: arrest this man, he talks in maths; he buzzes like a fridge, he's like a detuned radio. [radiohead]
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.
Azural - instrumentals
All we need to do is hire Malcom McDowell to destroy the Sun! Just tell him that it will get him into the Nexus, he'll do it for free!
Man is the animal that laughs.
And occasionally whores for Karma.
Since I work in gravitational wave physics, I read this article with great interest when I saw it. I'm afraid, the arguments are far from compelling. Some of the many problems:
1) The proposal for the calculation of the energy content of the gravitational wave is speculative at best. There is no agreed upon quantity for the energy of spacetime curvature, as the author himself points out.
2) The only calculation of the claimed non-linear enhancement seems to be in a paper which is cited by title and author only - there is no way to find and read the paper which this calculation was supposed to be in.
3) There seems to be some confusion between cylindrical gravitational waves and cylindrical gravitational wave sources. His method using approximate lie symmetries would correspond to the symmetry of the spacetime - ie the matter. I don't believe there is any way to produce cylindrical (or spherical) gravitational waves since you need a time-varying mass quadrupole to create them. Axisymmetric sources do not produce such waves. In short, there are exact (non-linear) solutions to the Einstein equations with no sources that have a gravitational wave-like nature, but they are not the solutions you get for (linear) gravitational waves from sources, and it is misleading to confuse them.
4) His supposition that 10% asphericity of the source is somehow related to a gravitational wave which is 90% spherical and 10% cylindrical is just bizarre. The gravitational waves from a rotating ellipsoid which has a 0.1 asphericity (assuming it is rotating about one of it's minor axes, since if it was rotating about the major axis it would be axisymmetric and give of no gravitational waves) is not really like an exact spherical wave or an exact cylindrical wave solution.
So, all told, this is still very early and very speculative. The safe money at this point is still that Weber (who had other irreproducable "detections") did not see a gravitational wave. While the non-linear nature of gravity would in principle allow for some sort of self-amplification, there has been to my knowledge no paper that claims to show this kind of amplification by four orders of magnitude available to view, let alone verified by other calculations or observations. Until something like that is available, this is at best speculation and hype, not science.
I remember because I was alive in 1987 and I felt it too when it happened. It was just as that star was exploding as a matter of fact. But it was hard to notice and you had to be paying really close attention. I take a lot of mind-altering drugs so I was able to sit still and concentrate on the physics.
Basically gravitational waves have a quadrupole moment so you feel your ears move apart slightly and your face contracting vertically. Then your face expands vertically as your ears move together. This happens a bunch of times and the effect is very slight- just a few femtometers- so you might not notice. But once you feel that cool wind of neutrinos flowing up from the floor and blowing through your hair, that should be a fairly obvious hint that a star is exploding somewhere and deserving of your attention.
I don't like to speak ill of the dead, so I will leave it at that.
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?
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.