BLAMING SPECIAL RELATIVITY?
in [Physics]
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From: Greg Hansen on 15 Jul 2008 06:28 theauthor wrote: > On Sun, 13 Jul 2008 06:33:00 -0500, Greg Hansen <greg> wrote: >> Here's a case in point. Another is that if you consider what a >> approaching and receding trains "look like", the approaching train would >> appear shorter because of the difference in signal propagation times >>from the front of the train and the back, and a receding train would >> longer. > > No, you got that the wrong way round. Differential signal propagation > delays cause the approaching train to look longer, and the receding > train to look shorter. Thanks. I guess I got a sign error there in my thought experiment.
From: Eric on 19 Jul 2008 21:21 On Sun, 13 Jul 2008 00:58:59 -0500, Tom Roberts <tjroberts137(a)sbcglobal.net> wrote: >Danny Milano wrote: >> [... quote from Einstein] >> From this Eric Baird built an entire theoretical structure >> about GR without SR ... > >Which is completely and utterly wrong. GR inherently and intrinsically >includes SR: > A) as the local limit of any manifold at any point > B) as the unique solution to the field equation for a world without > any contents and the topology of R^4. Basing the core physical relationships for how matter interacts with other matter by exchanging EM signals ... by presupposing a universe in which matter doesn't exist //as a point of principle// ... is a bit of a stretch. It's a neat trick if you can get away with it, but there's no guarantee that the results are definitely going to be real physics. The "empty universe" argument is a bit like asking, what sound does a tree make when it falls in the forest ... if there's nobody there to hear it ... and also no tree ... and also no forest. And from the perspective of "acoustic metric" physics, the "local limit" argument is like asking what sound a tree makes when it falls in a region that's too small to actually contain a tree in the first place. Both approaches have the //mathematical// advantage that they allow a mathematician to quickly generate a single unambiguous set of equations (those of special relativity). But if we wanted to be able to say that those equations were mathematically //proven// to be the equations that describe the interactions of real matter, we'd need to do a bit more work than this. We'd need to demonstrate that the form of the equations doesn't change when we introduce real matter into our "empty universe" model, or when we allow the possibility that real moving matter might be associated with local spacetime distortions. If you try that exercise, you should find that when we "switch off" the extreme idealisations of SR, the equations seem to change -- the exercise suggests that the particular form of special relativity might be specific to a set of conditions that depend on the absence of real matter in the region being modeled. >> Baird said: >> Almost all of the problems and potential problems that >> we've identified here with Einstein general theory seem >> to be consequences of the theory's incorporation of >> special relativity, and its assumption that the >> relationships of SR have to apply as a limiting case of >> the theory. > >This is complete nonsense. Without SR there would be no GR; there COULD >be no GR. Wolfgang Rindler:: :: "General relativity before special relativity: An unconventional :: overview of relativity theory" :: American Journal of Physics, Volume 62, Issue 10, 887-893 (1994) :: ABSTRACT: It is suggested how Bernhard Riemann might have :: discovered General Relativity soon after 1854 and how today's :: undergraduate students can be given a glimpse of this before, :: or independently of, their study of Special Relativity. At the :: same time, the whole field of relativity theory is briefly :: surveyed from the space-time point of view. Rindler finishes his paper by pointing out that once we'd put together the basics of a general theory based on spacetime curvature (without assuming or knowing anything about special relativity), we'd then naturally be able to get Einstein's special theory as a flat-spacetime limit of it. Which is correct. But if such a theory //had// been proposed in the C19th, it's not obvious that the C19th mindset would have decided that it was a good idea to try to develop an offshoot theory that didn't use the new curved-spacetime geometry. :EXTRAPOLATING FORWARD IN RINDLER'S ALTERNATIVE TIMELINE: In real life, the guys that attempted to construct curved-space models in the C19th were eventually crushed by their collective inability to get the damned things to work (because they didn't realise that they needed curvature to be applied in four dimensions rather then three). Their failure left open the problem of how to reconcile lightspeed constancy with inertial mechanics, which ended up being addressed instead as a flat-spacetime problem by Poincare, Lorentz and Einstein. But if the curved-spacetime solution had arrived //first//, it would have caught the first wave of "curvature" enthusiasts like William Kingdon Clifford (1845-1879, the "Clifford algebra" guy): : http://en.wikipedia.org/wiki/William_Kingdon_Clifford , who was already arguing that ==all== physics was curvature. The curved-spacetime model would have suggested velocity-dependent gravitomagnetic effects between moving gravitational sources, Clifford's approach would then have suggested that we try to apply the same rules to particles (considered as "micro-sources") and the resulting local lightdragging prediction would have chimed nicely with experimental verifications in the 1850's that moving bodies dragged light. The C19th aether theorists could then have gotten onboard and helped thrash out the geometrical details of a relativistic acoustic metric, and the model could then have snowballed, sucking in C19th experts from a range of disciplines. The operating characteristics of acoustic metrics would probably have been more familiar to aether theorists than to "modern" physicists, and the new model would have fixed the arbitrariness of C19th dragged-aether models by giving them a geometrically-derivable foundation. The new model could also have been claimed by the surviving emission-theory guys as a success for //their// subject, since it'd have finally reconciled Newtonian optics with wave theory. Finally, when the "Ultraviolet Catastrophe" came along, http://en.wikipedia.org/wiki/Ultraviolet_catastrophe and people were forced to consider quantum effects, the QM guys, desperate for some sort of physical model to attach their statistics to, would probably have realised that some of the "craziness" of QM seemed to correspond suspiciously well to the analogous "craziness" that you get when you try to project the contents of an acoustic metric onto a simpler surface. So we'd have had a convergence of the C19th geometers, the C19th aether theorists, the C19th emission theory guys and the other C19th Newtonian guys, and we'd have had the pioneers of quantum mechanics also coming onboard a few years later. Now, set against that lumbering juggernaut, I'm not sure how any poor soul subsequently discovering special relativity would have had a snowball's chance in hell of getting SR accepted as anything other than an interesting partial group-theory "echo" of what would have been considered to be the "proper" physics. ==== Note that although it probably seems inconceivable to a modern physicist that a general theory could work without SR, in the alternative scenario it would probably appear at least as inconceivable that a general theory could work satisfactorily //with// SR. Since moving to SR-based physics would break the alternative timeline's default compatibility between GR and QM, that timeline's physicists might take this as proof positive that SR-based physics wasn't workable. Since they'd already have c-constancy licked as a local effect, it wouldn't have been immediately obvious why they should further complicate their system by introducing SR. How could we convince that timeline's physicists that they'd totally misunderstood the basic nature of physics? Perhaps we could suggest that they study the properties of both versions of physics, work out where the two sets of physical predictions diverge, and then carry out some comparative tests that would (hopefully) tell them that we were right and they were wrong. If they hadn't already tried these tests, we could point to this as evidence that their science was sloppy, and their physics probably inferior to ours. But unfortunately, they'd be able to point out that =we= hadn't conducted a proper comparative study of the two paths either, and that =we= hadn't conducted tests designed to distinguish between them. They'd also have the advantage over us that they'd be able to say that their versions of QM and GR had worked well together almost from the beginning, whereas our "SR-based" GR still wasn't compatible with quantum theory after ninety-something years. === Note also that the split between the two alternative histories doesn't depend on any physical experimental data: It seems to be a sheer historical accident that we ended up on this theoretical path rather than the other one. It's a small step from gravitational shifts (predicted by John Michell way back in the //Eighteenth// Century, http://en.wikipedia.org/wiki/John_Michell 1784) to gravitational time dilation (and curved spacetime). If anything, it seems rather odd that GR //didn't// appear until the C20th, given the brilliant guys who were trying to get spatial curvature to work in the C19th. If they'd just experimented with applying curvature in one extra dimension, they might have hit the jackpot. So although we're currently convinced of the inevitable correctness of the SR-based approach, that degree of conviction doesn't seem to carry any deeper significance. If history had played out slightly differently, we might now be just as deeply convinced that the SR-based approach was obviously wrong, without any of our experiments having turned out differently. Human nature's a funny thing. >While there are indeed POTENTIAL problems with GR, at present there are >NONE related to SR. Actually, most of them do seem to relate to SR (at least, on the list that I drew up). Once you've looked at how the properties of a general theory based on SR compare to those of a general theory //not// based on SR, it's easier to see which aspects of current theory are consequences of the SR-based approach, and which aren't. But in order to see the dependencies between SR and various aspects of current GR, you have to actually do that exercise (or know the results of someone else doing it). >The experimental support of SR in essentially all non-gravitational >contexts is solid and unassailable (except in certain ways by experts >blazing a trail toward quantum gravity -- look up "doubly special >relativity", but be prepared for advanced math). SR is one of the >best-tested theories we have, and within its domain of applicability >there is not a single reliable and reproducible experiment which >contradicts its predictions. SR and GR are also inflexible >theoretically: attempting to modify SR and/or GR is like being "a little >bit pregnant" -- there are no simple modifications possible (the experts >know this, and take it into account in pursuing QG). Cranks like Baird >(and many others around here) simply do not have a clue about how to do >physics, or what physics really is. > >> What do you think? I can't find other researchers working >> on GR without SR. How many relativists or even anti-relativists >> attempt this? > >It does not matter what various people think, and it does not matter how >many people attempt "this" -- GR inherently and intrinsically includes >SR. We agree that the current default implementation of a general theory (Einstein's) explicitly reduces to the physics of special relativity. Where we seem to disagree is about whether an alternative implementation of the general principle of relativity -- an alternative general theory of relativity -- would necessarily have to reduce to the physics of SR. Most GR people seem to genuinely believe that the argument of "SR as a geometrical limit to GR" means that any variation on GR has to reduce to the //physics// of SR as a geometrical necessity ... but Clifford's idea of "all physics as curvature" provides a logical counterexample -- a conceivable system of physics in which a flat-spacetime limit doesn't represent a physical solution. One counterexample is sufficient to destroy a mathematical proof, so the "reduction to SR" argument isn't a general one until we can find some way of proving that a Cliffordian system of physics can't work. (And by "proving that it can't work", I mean more than just "proving that it's not compatible with special relativity". Of course a curvature-based model isn't compatible with special relativity -- that's what makes the idea important) >The structure of a theory is utterly independent of what people >might "think". In the case of a new or unfamiliar theory, a certain amount of thinking is often necessary in order to explore what the structure of that new system ought to be. Sometimes you arrive at a structure by successive approximation or by the progressive elimination of alternatives, with the theory's "logical derivation" only being produced afterwards for public consumption. To someone who is "taught" a theory, the final polished version of the theory will tend to appear as an unavoidable result of a set of definitions and starting assumptions that lead inevitably to it, and to nothing else. To someone else whose interest is the construction of theories, they may look at the same theory and see not an inevitable path from known principles to a single outcome, but a branching range of alternative half-possibilities that the theorist has managed to rule out by using particular wordings or syntax. Most of those combinations of alternative meanings won't work together, but sometimes there'll be enough ambiguity in a general principle to allow you to branch off in a different direction, or sometimes when you break a theory into its component parts, you'll find that by adding or removing a part, the rest of the pieces can be fitted together in a different way. So yes, for a given specified theory, the structure should (ideally) be completely defined and non-negotiable. But for a ==class== of theory there can sometimes be suggestions of possible alternative implementations. Most of them probably won't work, or will be considered "bad" in context because they conflict with some feature that a theory requires, but occasionally you might find enough leeway in the choices that were originally available to the author to allow a different choice and a different structure. >As I have said before: it is amazing how persistent and prolific some >cranks are, without much understanding of the basic physics underlying >what they attempt to write about. Eric Baird is one of them. > >Tom Roberts I find that people who've spent a lot of time in the educational system tend to be taught to expect only one solution to a given problem ("first-answer syndrome"). Once they've been taught the "standard" answer, "A", they tend to fixate on it and assume that it's the //only// answer, and if you come up with a more subtle solution, "B", they'll tend to tell you that you're dumb for not recognising the obvious correctness of the first answer, "A", which everybody who knows anything about the subject knows is The Right Answer. You can try to explain to them that yes, you //do// understand "A", but you're more interested in this other, more obscure thing, "B" ... specifically //because// it doesn't correspond to what's in the books .... and they'll reply, no, no, the correct answer is "A", so there can't be another answer "B", by definition ... you clearly haven't understood answer "A", let me repeat the arguments for "A" once more, so that you understand them ... =Erk= (Eric Baird) http://www.youtube.com/user/ErkDemon : " You are not thinking. You are merely being logical. " : -- Niels Bohr
From: Eric on 19 Jul 2008 21:25 On Sun, 13 Jul 2008 23:34:26 -0700 (PDT), "hhc314(a)yahoo.com" <hhc314(a)yahoo.com> wrote: >On Jul 12, 10:51�pm, Danny Milano <milanoda...(a)yahoo.com> wrote: >> Albert Einstein said in Scientific American April 1950: >> >> "I do not see any reason to assume that.. the principle >> of general relativity is restricted to gravitation and >> that the rest of physics can be dealt with separately >> on the basis of special relativity... I do not think >> that such an attitude, although historically >> understandable, can be objectively justified. ... In >> other words, I do not believe that it is justifiable to >> ask: what would physics look like without gravitation?" >Danny, I don't know where you get your information, but it appears >seriously flawed. > >First of all, Albert Einstein was already on or near his deathbed in >1950 (He was born in 1879 and died in 1955 after being hospitalilized >for for a number of years.) At the time of his death, he was 76. Do >you really believe that while undergoing medication and lying in bed >in severe pain, he could even remember the basis of his theories >publishes at least 40 years previously. Harry, it sounds to me as if you don't like the direction of the quote, can't think of any way to counter it, and are therefore inventing a scenario in which Einstein was supposedly soft in the head at the time that he wrote the article ... because you can't come up with a proper counter-argument. That's not very nice behaviour. ==== Einstein's April 1950 article for Scientific American was a review piece on the history and development of relativity theory (and its foundations), leading up to his (then) current view of the subject. It was for a special issue of Scientific American, with Einstein on the cover. It's been republished in the "Ideas and Opinions" compilation (pp.341-356), where it takes up about 14-15 pages, and for those with an aversion to visiting libraries or buying books, it's also available online, on the Encarta website: : On the Generalized Theory of Gravitation : (An account of the newly published extension of the general theory : of relativity against its historical and philosophical background) http://encarta.msn.com/sidebar_761599216/einstein_on_gravitation.html This article was presumably written on a commercial basis for Scientific American, making SciAm the commissioning body and copyright holder, so it's not available on //my// website, but Encarta seem to have gotten permission from SciAm to use the entire article on theirs. The full paragraph in question (here lifted from Encarta) says: :: " The first observation is that the principle of general relativity :: imposes exceedingly strong restrictions on the theoretical :: possibilities. Without this restrictive principle it would be :: practically impossible for anybody to hit on the gravitational :: equations, not even by using the principle of special relativity, :: even though one knows that the field has to be described by a :: symmetrical tensor. No amount of collection of facts could lead :: to these equations unless the principle of general relativity :: were used. This is the reason why all attempts to obtain a deeper :: knowledge of the foundations of physics seem doomed to me unless :: the basic concepts are in accordance with general relativity from :: the beginning. This situation makes it difficult to use our :: empirical knowledge, however comprehensive, in looking for the :: fundamental concepts and relations of physics, and it forces us :: to apply free speculation to a much greater extent than is :: presently assumed by most physicists. I do not see any reason to :: assume that the heuristic significance of the principle of general :: relativity is restricted to gravitation and that the rest of :: physics can be dealt with separately on the basis of special :: relativity, with the hope that later on the whole may be fitted :: consistently into a general relativistic scheme. I do not think :: that such an attitude, although historically understandable, can :: be objectively justified. The comparative smallness of what we :: know today as gravitational effects is not a conclusive reason for :: ignoring the principle of general relativity in theoretical :: investigations of a fundamental character. In other words, I do :: not believe that it is justifiable to ask: What would physics look :: like without gravitation? " I think that most people who've read the full piece would agree that it doesn't come across as something written by a feeble-minded individual with a faltering recollection of special relativity. Okay, so a lot of people didn't agree that he was on the right track with his unified field theory, but if you ask those people how far they've gotten since with //their// UFT's ... well ... Einstein continued publishing scientific papers and other articles all the way up to 1955. These included the fifth appendix to his "popular" relativity book (1952) and a second appendix to the republished Princeton Lectures, "The Meaning of Relativity", in about 1950 (revised 1954). He's supposed to have been offered the Presidency of Israel in 1952, and been smart enough to turn them down. Dismissing Einstein's 1950 writing on the grounds of age is a bit low, I think. Certainly some people sink into a rut as they age and lose the ability to take in new ideas, but the article shows Einstein doing the opposite, exploring new possibilities even if they seemed to be at odds with one of the theories that had made him famous. Einstein wrote in 1927 that the thing that impressed him about Isaac Newton was Newton's ability to see the problems with his own models better than his supposed critics could. I think Einstein was probably striving for the same thing: to be the guy who understood the potential problems in his own theories better than anyone else. It's a good discipline to have. .... =Erk= (Eric Baird) http://www.worldcat.org/oclc/181743934 : " What, then, impels us to devise theory after theory? Why do we : devise theories at all? The answer to the latter question is : simply: Because we enjoy 'comprehending,' i.e., reducing phenomena : by the process of logic to something already known or (apparently) : evident. New theories are first of all necessary when we encounter : new facts which cannot be 'explained' by existing theories. But : this motivation for setting up new theories is, so to speak, : trivial, imposed from without. There is another, more subtle motive : of no less importance. This is the striving toward unification and : simplification of the premises of the theory as a whole (i.e., : Mach's principle of economy, interpreted as a logical principle). " : -- "On the Generalized Theory of Gravitation", Albert Einstein, 1950
From: Androcles on 19 Jul 2008 21:44 <Eric Baird> wrote in message news:rn3584pa6b2u1pnv83e97l7kotb29qqc1d(a)4ax.com... | On Sun, 13 Jul 2008 00:58:59 -0500, Tom Roberts | <tjroberts137(a)sbcglobal.net> wrote: | | >Danny Milano wrote: | >> [... quote from Einstein] | >> From this Eric Baird built an entire theoretical structure | >> about GR without SR ... | > | >Which is completely and utterly wrong. GR inherently and intrinsically | >includes SR: | > A) as the local limit of any manifold at any point | > B) as the unique solution to the field equation for a world without | > any contents and the topology of R^4. | | Basing the core physical relationships for how matter interacts with | other matter by exchanging EM signals ... by presupposing a universe | in which matter doesn't exist //as a point of principle// ... is a bit | of a stretch. It's a neat trick if you can get away with it, but | there's no guarantee that the results are definitely going to be real | physics. You haven't adressed his point, Eric. The idiot Roberts is reciting the cretin Roberts. http://www.androcles01.pwp.blueyonder.co.uk/SR.GIF When one sheep says "baa" they all do, including the original.
From: Androcles on 19 Jul 2008 21:48
<Eric Baird> wrote in message news:nr4584tkfilv2rc53vn87agu8fo1fash5k(a)4ax.com... | On Sun, 13 Jul 2008 23:34:26 -0700 (PDT), "hhc314(a)yahoo.com" | <hhc314(a)yahoo.com> wrote: | | >On Jul 12, 10:51 pm, Danny Milano <milanoda...(a)yahoo.com> wrote: | >> Albert Einstein said in Scientific American April 1950: | >> | >> "I do not see any reason to assume that.. the principle | >> of general relativity is restricted to gravitation and | >> that the rest of physics can be dealt with separately | >> on the basis of special relativity... I do not think | >> that such an attitude, although historically | >> understandable, can be objectively justified. ... In | >> other words, I do not believe that it is justifiable to | >> ask: what would physics look like without gravitation?" | | | >Danny, I don't know where you get your information, but it appears | >seriously flawed. | > | >First of all, Albert Einstein was already on or near his deathbed in | >1950 (He was born in 1879 and died in 1955 after being hospitalilized | >for for a number of years.) At the time of his death, he was 76. Do | >you really believe that while undergoing medication and lying in bed | >in severe pain, he could even remember the basis of his theories | >publishes at least 40 years previously. | | Harry, it sounds to me as if you don't like the direction of the | quote, can't think of any way to counter it, and are therefore | inventing a scenario in which Einstein was supposedly soft in the head | at the time that he wrote the article ... because you can't come up | with a proper counter-argument. "Harry" is the same cretin that claimed the shuttle turns west over Buffalo, New York on its way to Florida. If that isn't "seriously flawed" nothing is. |