On 6 Jan 2014 at 16:51, Ray Tayek wrote:

http://science.slashdot.org/story/14/01/06/236245/experiments-reveal-tha t-deformed-rubber-sheet-is-not-like-spacetime

Interesting -- I don't understand this stuff and can't visualize it at all, but <http://science.nasa.gov/science-news/science-at-nasa/2011/04may_epic/> May 4, 2011: Einstein was right again. There is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity. Researchers confirmed these points at a press conference today at NASA headquarters where they announced the long-awaited results of Gravity Probe B (GP-B). "The space-time around Earth appears to be distorted just as general relativity predicts," says Stanford University physicist Francis Everitt, principal investigator of the Gravity Probe B mission. /Bernie\ -- Bernie Cosell Fantasy Farm Fibers mailto:bernie@fantasyfarm.com Pearisburg, VA --> Too many people, too few sheep <--

Um, isn't this well known? Grapefruits on trampolines are (and always were) part of popular science, not science proper. In fact, one defect of explaining gravity this way is that it begs the question of what is pulling the grapefruit down to begin with. Attributing gravitational attraction in n dimensions to a downward pull in the n+1st dimension is just stacking elephants. Einstein once quipped: “Put your hand on a hot stove for minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. THAT'S relativity.” Is someone going to write an article explaining that this analogy ignores the fundamental role played by the motion (as opposed to mental state) of an observer, and contending that Einstein didn't understand his own theory? Jim Propp On Monday, January 6, 2014, Ray Tayek wrote:

http://science.slashdot.org/story/14/01/06/236245/experiments-reveal-that- deformed-rubber-sheet-is-not-like-spacetime

Posted by <http://unknownlamer.org/>Unknown Lamer on Monday January 06, 2014 @06:59PM from the deformed-example dept. KentuckyFC writes "<http://en.wikipedia.org/wiki/General_relativity>General relativity is mathematically challenging and yet widely appreciated by the public. This state of affairs is almost entirely the result of one the most famous analogies in science: that the warping of spacetime to produce gravity is like the deformation of a rubber sheet by a central mass. Now physicists have tested this idea theoretically and experimentally and say it doesn't hold water. It turns out that a marble rolling on deformed rubber sheet does not follow the same trajectory as a planet orbiting a star and that <https://medium.com/the-physics-arxiv-blog/b8566ba5a110>the marble's equations of motion lead to a strangely twisted version of Kepler's third law of planetary motion. And experiments with a real marble rolling on a spandex sheet show that the mass of the sheet itself creates a distortion that further complicates matters. Indeed, < http://arxiv.org/abs/1312.3893>the physicists say that a rubber sheet deformed by a central mass can never produce the same motion of planet orbiting a star in spacetime. So the analogy is fundamentally flawed. Shame!"

--- co-chair http://ocjug.org/

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