bhoughto@cmdnfs.intel.com (Blair P. Houghton) (11/03/90)
In article <5847@ptsfa.PacBell.COM> dmt@PacBell.COM (Dave Turner) writes: >In article <1990Oct31.233529.25251@cbnewsj.att.com> asd@cbnewsj.att.com (Adam S. Denton) writes: >>A long time ago ('82?) in Radio-Electronics, there was a construction article >>to build a "gravity-wave" detector! This simple circuit, the author >>claimed, detected `gravity waves' which travel throughout the universe >>instantaneously (much faster than the the speed of light)!! > >It was in the April, 1986 issue (p. 53) but it didn't have the usual reference >to April 1 at the end. [First of all, I can't believe I'm thinking seriously about this crufty old net.canard, but we all have hangovers, eventually, right?] If gravity is bound by the speed of light, then it must produce waves. (Check out any text re propagation of energy). If gravity is not bound to the speed of light, then we should be able to map the universe ***as it exists "now"*** (modulo relativity), rather than as it existed at time now- minus-distance-divided-by-c. This depends on building focussable gravity detectors with detecting sensitivity comparable to early photon detectors (i.e., eyes, which are ridiculously sensitive when they choose to be). Unfortunately, the gravitational intensity of a star's-worth of matter is nothing compared to its electromagnetic intensity (I mean, we're talking a 10^lots kg of fusion reactor per star...). This means the sensitivity will have to be correspondingly increased. (I know! Let's strap all the astrologers to a big, flat mountain and ask them to infer the universe's constitution! A phased-array-astrolabe! :-) :-) :-) ] [note: don't think of gravity lenses in terms of light lenses; light bends because it's limited by Fermat's principle, which depends inexorably on the existance of a speed of light; further, the bending is proportional to the frequency of the light, and gravity has no as-yet-defined frequency (unless I'm missing something about 'gravitons' -- outside of Dr. Who, that is :-).] This is getting interesting. Anyone know of any credible research into gravity's propagating properties? It should be easy to measure the speed-of-gravity; I remember an experiment one Dr. Park did at the U. of Md. using SQUIDS to measure the non-divergence of gravity. He suspended the SQUID device a few meters from a swinging pendulum, measuring the force on the SQUIDS, which were arranged as the faces of a cube; he showed that the gravitational displacement summed to (the neighborhood of) zero over the faces of the closed surface of the cube, proving the gravitational field to be solenoidal. (The aim was to verify the inverse-square- law by getting a better precision for the '2.000...' in F = GmM/(r^2.000...). He proved that there were at least six zeroes following the decimal point, where previous researchers had only been able to verify four; these extra two zeroes earned Dr. Park his tenure in a special award from the UMd Physics dept.) One only need attach some reflectors, lasers, and photo- sensors to the setup to compare the variation in the transit time of light with the variation in the intensity of the gravity (which is considerable at a mean distance of ~5m with a variation of +- ~1m). BTW, the pendulum was a steel ball a meter in diameter weighing something like 1500kg. Part of the fun of the video (we watched this in 1st-semester physics) was watching Dr. Park get pushed around by the thing as he tried to demonstrate the most efficient method of stopping it manually by timing one's contact with it. --Blair "You're never too old and successful for simpleton physics."