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any comments on astro-ph/0509230
the title does look intriguing. at least the claims are very
extraordinary. maybe the GR experts on this forum can shed light on whether any of this makes sense Melroy |
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In message , jacob navia
writes wrote: the title does look intriguing. at least the claims are very extraordinary. maybe the GR experts on this forum can shed light on whether any of this makes sense Melroy I am no expert but... WHERE would the universe rotate ???????? I mean the universe is everything. To rotate it would have to have a limit, and an enclosing body where this "rotation" could be measured. Then the universe would not be the universe but a part of it, since it would be enclosed in a bigger body. Q.E.D. Rotation makes just NO SENSE when applied to the universe, excuse me. But I am happy that it does not rotate, of course :-) There's no problem with the idea of the universe rotating, and according to George Smoot in "Wrinkles in Time" you don't have to ask "relative to what ?" (no, I don't understand that. I'm no expert either :-) Godel found that a rotating universe allows time travel. And while COBE found evidence that the universe doesn't rotate, didn't someone look at asymmetries in galactic magnetic fields and claimed that it does, or at least a very large part of the observable universe does? -- Boycott Yahoo! Mail to jsilverlight AT merseia DOT fsnet DOT co DOT co DOT uk is welcome. |
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In sci.astro.research wrote:
[[about Chapline's astro-ph/0509230]] the title does look intriguing. at least the claims are very extraordinary. maybe the GR experts on this forum can shed light on whether any of this makes sense I would describe Chapline's work as "highly speculative", to say the least. Lubos Motol has written a strong critique of Chapline's work at http://motls.blogspot.com/2005/03/ch...ont-exist.html Apart from the many technical points where Chapline is way out on some pretty thin ice, I found it remarkable that Chapline claims that negative heat capacity is impossible. (It's actually ubiquituous in large-N Newtonian N-body self-gravitating systems, eg globular clusters and suchlike.) This passage (of Motol's, reporting on a Chapline seminar at MIT) # Someone asked whether Chapline's new picture of the black hole also # requires one to alter the membrane paradigm by Kip Thorne, in which the # horizon is viewed as a superconducting membrane, and the answer was that # the speaker did not know what the paradigm was. suggests that Chapline is seriusly uninformed about GR -- Thorne's "membrane paradigm" is a _very_ standard concept in GR, and there's a well-known textbook on it by Thorn, Price, and MacDonald, which I'd expect any serious researcher to at least be aware of. ciao, -- -- "Jonathan Thornburg -- remove -animal to reply" Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Golm, Germany, "Old Europe" http://www.aei.mpg.de/~jthorn/home.html "Washing one's hands of the conflict between the powerful and the powerless means to side with the powerful, not to be neutral." -- quote by Freire / poster by Oxfam |
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Jonathan Silverlight wrote:
There's no problem with the idea of the universe rotating, and according to George Smoot in "Wrinkles in Time" you don't have to ask "relative to what ?" (no, I don't understand that. I'm no expert either :-) Godel found that a rotating universe allows time travel. And while COBE found evidence that the universe doesn't rotate, didn't someone look at asymmetries in galactic magnetic fields and claimed that it does, or at least a very large part of the observable universe does? There are other conceptual problems. Rotation implies a center where the rotation is zero. The Universe would have to have a center, what would make some point in the universe VERY special and easy to spot... Everything in a rotating body points to its center of rotation. It is a point that is easy to spot. What the book of Smoot is concerned ("Wrinkles in Time") I found only one sentence (p 182) about this: "Also, the absence of rotation of the universe, which we noted during our U2 observations, becomes less of a puzzle in an inflationary universe". Strangely, in the chapter about the U2 observations he writes about a lot of things (The U2 pilots, Lima in Peru, etc etc) but I did not find anything about the rotation of the universe. There is also the talk of Mrs Rubin, that held a conference in december 1950 about "The rotation of the universe". I cite Smoot again (page 143) "Her talk had originally been titled "Rotation of the Universe" but the meeting organizer thought that sounded odd, and so he had changed it to "Rotation of the Metagalaxy". " I would share the feeling of the meeting organizer. A "rotating" universe is completely ridiculous. And note that there is a HUGE difference between a "rotating universe" and a "very large part of the observable universe". I am ready to accept the second if there is data supporting that. But the first is just NONSENSE, and I am sure there will be never any data to support it! Nowhere however, I find any mention of this elementary questions in the book of Smoot. He just writes that he doesn't have any data about the rotation without discussing in detail how could he even consider such an absurdity. jacob |
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In article ,
jacob navia wrote: There are other conceptual problems. Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at , as opposed to .] |
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In message , jacob navia
writes Jonathan Silverlight wrote: There's no problem with the idea of the universe rotating, and according to George Smoot in "Wrinkles in Time" you don't have to ask "relative to what ?" (no, I don't understand that. I'm no expert either :-) Godel found that a rotating universe allows time travel. And while COBE found evidence that the universe doesn't rotate, didn't someone look at asymmetries in galactic magnetic fields and claimed that it does, or at least a very large part of the observable universe does? There are other conceptual problems. Rotation implies a center where the rotation is zero. The Universe would have to have a center, what would make some point in the universe VERY special and easy to spot... Everything in a rotating body points to its center of rotation. It is a point that is easy to spot. What the book of Smoot is concerned ("Wrinkles in Time") I found only one sentence (p 182) about this: "Also, the absence of rotation of the universe, which we noted during our U2 observations, becomes less of a puzzle in an inflationary universe". Strangely, in the chapter about the U2 observations he writes about a lot of things (The U2 pilots, Lima in Peru, etc etc) but I did not find anything about the rotation of the universe. There is also the talk of Mrs Rubin, that held a conference in december 1950 about "The rotation of the universe". I cite Smoot again (page 143) "Her talk had originally been titled "Rotation of the Universe" but the meeting organizer thought that sounded odd, and so he had changed it to "Rotation of the Metagalaxy". " I would share the feeling of the meeting organizer. A "rotating" universe is completely ridiculous. And note that there is a HUGE difference between a "rotating universe" and a "very large part of the observable universe". I am ready to accept the second if there is data supporting that. But the first is just NONSENSE, and I am sure there will be never any data to support it! Nowhere however, I find any mention of this elementary questions in the book of Smoot. He just writes that he doesn't have any data about the rotation without discussing in detail how could he even consider such an absurdity. Au contraire :-) Looking at my copy (ISBN 0316905089) there are two entries in the index, pages 115 and 135. Page 115 is just about Kurt Godel's idea, but 135 says "it began to be all too clear to us that the DMR data contained no hint of rotation of the universe. This was a major surprise, because we can see that everything within the universe is rotating - planets, stars, and galaxies. I had convinced myself that the universe should be rotating.... I knew that general relativity allowed rotation in spite of the inevitable question: what does the universe rotate with respect to? From our results, we calculated that if the universe does rotate, it does so at lass than on hundred-millionth of a rotation in the last billion years". It's the most accessible account of this idea I found. Also, I found a web page about the asymmetry http://www.rochester.edu/pr/releases/phys/borge.htm, which was linked from Daniel Fischer's Cosmic Mirror page http://www.astro.uni-bonn.de/~dfischer/mirror41-50.html (Item "Physicists baffled: Is the Universe anisotropic?") Rereading it, I see they aren't saying that the universe is rotating but that it has a preferred orientation, which is probably just as heretical :-) |
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In article ,
wrote: In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. And in fact, just as there's a simple Newtonian/Euclidean proof that there is no centre in a universe that obeys Hubble's law, even though it appears that everything is receding from us, there's a simple proof in vector algebra (exercise for the reader) that there is no centre in a universe where it appears that all bodies are moving around us with constant angular speed. Thus this isn't, particularly, some peculiarity of general relativity. Martin -- Martin Hardcastle School of Physics, Astronomy and Mathematics, University of Hertfordshire, UK Please replace the xxx.xxx.xxx in the header with star.herts.ac.uk to mail me |
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