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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."
And here I was always convinced they were Gravity Particles.
Then a decade later, the scientific community goes "oops, you were right".
Hm. But this raises an interesting question. Was he actually right?
Let's assume for the moment that TFA is correct, that higher-order terms can enhance gravity waves and that this is the case for SN1987A. So Weber's measurements in 1987 contained a valid signature of a gravity wave.
In a sense, then, he did detect gravity waves. And so he was right in saying "I detected gravity waves". However, he may have been right for the wrong reasons. Science works by interpreting data, and convincing others that your interpretation is correct. Weber was not able to do so. He was not able to convince others because he couldn't provide a way to connect the magnitude of the signal in his measurements to the available theory.
Now, if he had done what the present scientists have done, and demonstrate that the higher-order terms make gravity waves detectable in his apparatus, then he might have been able to convince his colleagues. Then he would really have been right (and for the right reasons). But he didn't (as far as I can tell). He incorrectly said "gravity waves, as described by these theories/equations, have been measured on my instrument"... which is wrong.
Some of you may think I'm just splitting hairs or something. But it's important because in science being right is not about randomly guessing the right answer... it's about providing a robust argument based on repeatable measurements. In science, happening upon the right answer using the wrong logic isn't really considered a good thing. As an extreme analogy, imagine that I am trying to predict when the next volcanic eruption will be, and I come up with a complicated theory based on tides. Then I correctly predict an eruption. A few years later some smarter guys come along and create a really great theory that predicts volcanic eruptions, and show that it is really based on magma flow... and that I was just lucky to have predicted the eruption. Was I "right" in my prediction?
No, science is supposed to be a process of observe, hypothesise, test, repeat. You can discard theories that don't fit hypotheses, but discarding observations because they don't fit theories is the exact opposite of science. This is the kind of behaviour I would expect from people preaching intelligent design, not from anyone who deserves the title of scientist.
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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.