A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Peter Webb on 3 Mar 2010 21:53 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:df834005-0692-42ba-88c7-b462ad4cd0b2(a)i25g2000yqm.googlegroups.com... > On 3 Mar, 12:30, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >> You say you are here to learn about SR. >> >> > I am here to learn more about the *conceptual basis* of SR. >> >> Minkowksi space time? > > No. > Well, that is the conceptual basis of SR for most people who understand it fully. > >> >> Do you believe SR is true? >> >> > I accept it's mathematical form has some obvious truth, yes. >> >> Do you believe that it correctly predicts the results of every experiment >> that it claims to? That clocks run slower, > > No. In SR, clocks *appear* to run slower as you are increasing your > distance from the clock. The effect is entirely apparent in SR. > > > >> and 80 foot ladders can fit through 40 feet barns, > > It remains slightly unclear, but I'm inclined to say no, although it > can certainly be made to appear to happen in certain circumstances. > So you do or don't believe? > > >> and that the speed of light is measured the same in >> every intertial frame of reference and this speed is independent of the >> speed of the emitter, receiver, and underlying medium of transmission? > > Yes. I think I've been able to reconcile this partially, but only > vaguely and within a definitely non-standard conceptual framework, and > it is forced to completely dispense with any corpuscular form of > matter, and instead relies wholly on fields. Unfortunately it's > probably the sort of thing that physicists spend their lives thinking > about and never quite put their finger on. > > > >> If you believe all of those things, then you are saying more than "SR has >> some obvious truths in its mathematical form" you are saying it is an >> accurate portrayal of reality - ie, what happens when you conduct those >> experiments, what physically and actually happens, is exactly as >> predicted >> by Relativity. > > I think we all agree that SR portrays reality, but none of us seem to > be able to agree on what kind of reality it portrays. > > > >> If, on the other hand, you do not believe in the twin "paradox" actually >> happening, you don't believe in SR. > > We resolved the twins paradox months ago. The astronaut twin undergoes > asymmetrical acceleration, and that is why he returns younger. > No, its because of SR, not due to acceleration. Time dilation deriving from acceleration at 1 g is absolutely microscopic. > > >> If you do believe the predictions of SR >> that one twin is older, then you believe that time dilation is more than >> some mathematical fiction, its what actually happens in the real world. > > On the contrary. The involvement of acceleration, which is the domain > of GR, makes me wonder why this is held to be a paradox in SR at all. > And yes, the acceleration causes real effects for the astronaut twin. > Its not an effect of acceleration. Even if the period of acceleration is eliminated, then the twins will not age at the same rate. If you do not believe this, you do not believe SR. > > >> So, when relativity predicts that one twin will age more than the other, >> is >> this just some mathematical truth, or is it what really happens as well? > > It really happens, due to acceleration. > No, you don't understand. The time dilation due to acceleration is microscopic and can be made as small as desired. SR predicts teh differential aging even in the absence of acceleration. If you do not believe it occurs, then you do not believe in SR. > > >> So, do you believe that SR is correct in its prediction (for example) >> that >> if one twin were to be sent off into space at 0.9c for 10 years they >> would >> have aged less on their return than the twin that stayed at home? > > I'm not sure SR does predict this. As I understand it, GR is required > to predict this effect. The problem for SR was, as I understand it, > explaining why SR *doesn't* predict that effect. > Wrong on both counts: GR is *not* required to explain the effect. SR *does* predict this result. Buy a book. > > >> Do you agree its correct when it says that an 80 foot ladder could fit >> inside a 40 foot barn? > > No, I'm not confident about that prediction. I think it's more likely > to be an apparent effect. > So you don't believe in SR. OK. > > >> You seem to agree they are "mathematical truths". Do you also agree those >> equations correctly predict the outcomes of real world experiments, which >> means they are far more than simply "mathematical truths"? > > The question is of interpreting the mathematical predictions. As I say > above, there is a difference between what is real and what is merely > apparent. And that is ... ???? It appears you do not believe the predictions of SR, eg the twins paradox and the barn door paradox. Yet you said before that you do believe the predictions of SR. Make up your mind.
From: Paul Stowe on 3 Mar 2010 22:18 On Mar 2, 8:14 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Paul Stowe" <theaether...(a)gmail.com> wrote in message > >> > > > Newton was 'smart enough' to realize that this gravitational force > > > equation was simply a quantifying correlation and not a physical model > > > or explanation for gravity. The famous quote "hypothesis non-fingo" > > > said it all! You don't seem to grasp the fact that both GR and > > > Newton's equations provide no physical model or basis for their > > > existence. In the case of Newton his equation is mute on many aspects > > > of gravity like its speed of propagation as one example, so-called > > > frame dragging for another. Einstein was also smart enough to realise > > > that GR also needed so physical framework. But what I call the modern > > > science blindness does not realize that equations ARE NOT! physical > > > explanations they are, instead, the way such physical model are > > > quantified. Yes, you can correlate observed behavior to equations and > > > have those equations match observation. You can even further predict > > > that future observation must match the form but still be totally > > > ignorant of proper physical basis, tolemy's system is a classic > > > example of this. I would put Minkowski equation in the Ptolemic > > > category, not wrong, but not useful to understanding the underlying > > > physical process either. It is neat mathematical format which takes > > > advantage of a physical property but without any knowledge or basis of > > > what brings about that property. > > > > _____________________________ > > > Like the E and M fields in Maxwell, or the force of gravity in Newton? > > > There exist physical models for both. > > > _________________________ > > OK, explain to me the physical model of the electric field in Maxwell. > > > Maxwell simply quantified Faraday;s model. You sure do seem ignorant of the > > history of science... > > ______________________________ > > I never claimed otherwise, so I am wondering why you think I am ignorant > > of the history of science. > > Because you seem clueless to even the existence of Maxwell's WELL > KNOWN physical model for E and M 'fields'. See, > > http://www.vacuum-physics.com/Maxwell/maxwell_oplf.pdf > > _________________________ > That doesn't provide a physical model for the E field. Why don't you just > tell us what Maxwell's physical model for the E field was, if you think he > had one? Or what Newton's physical mechanism for gravity was? Or Darwin's > physical model for inheritability? Or, even better, Maxwell's physical mode > for the E field, like I asked? Haven't actually got one? Didn't think so. > Maybe you should read Maxwell's paper again, see if you can find where he > explains the physical model for the E field. (ROFL). Maxwell's model was one of quantized vortices. The circulation (vorticity) is the magnetic and these interacting circulation, the electric. This was what lead him to the 'displacement current'. You could not have possibly read Maxwell's paper throughly in the time between posting... Read what I said above about Newton, he WAS smart enough to realize that the equation was not, and more importantly, could not be, a physical model or explanation for gravity. However there does exist such a physical model which, from it Newton equation is derived as the weak slow speed limit and its not GR although Newton's equation is also the weak slow speed limit for it. But, I doubt you're even aware of its existence. > > Can you actually point to anything that I have said > > regarding the history of science which is wrong, or is this simply wishful > > thinking on your part? > > http://www.archive.org/details/historyoftheorie00whitrich > > Whittaker's book both volumes is probably the very best historical > account of the developmental history of science from 1600 to 1930. > > _________________________ > I repeat my question, which you ignored. "Can you actually point to anything > that I have said regarding the history of science which is wrong, or is this > simply wishful thinking on your part?" You claim that there exists no physical models for gravity for one. E & M for another. Paul Stowe
From: Inertial on 3 Mar 2010 22:35 "Bruce Richmond" <bsr3997(a)my-deja.com> wrote in message news:343d01e1-98ec-4962-bade-eab3d250e48f(a)g26g2000yqn.googlegroups.com... > On Mar 3, 8:29 am, Jerry <Cephalobus_alie...(a)comcast.net> wrote: >> On Mar 3, 6:28 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote: >> >> > I understand it and think it is correct. >> >> > My position is that far more people would understand it if it was >> > explained differently. >> >> It is generally accepted by most legitimate posters on these >> newsgroups that Einstein's original two-postulates axiomatic >> approach to the development of relativity is somewhat archaic and >> difficult to follow, to judge by the numerous crackpots who >> stumble at the very first steps in his derivation. > > Oh, and the crackpots catch right on to the newer methods? ;) > >> You prefer Bondi's presentation of Milne's derivation, which >> goes "backwards" starting with the Doppler effect. I also like >> Bondi's approach which is quite intuitive, but after rederiving >> all of Einstein's famous results, the reader is left somewhat >> dangling. How does one proceed from there? Bondi's approach is >> still, at its core, a classic geometric development of the >> subject. > > Actually I do not prefer Bondi. I suggested him for Ste only to give > him a different perspective, and to steer him away from Taylor and > Wheeler. > >> By analogy: One does not design a skyscraper using Euclid's >> Elements, and one does not get to General Relativity through >> either Einstein's original or Milne's "inverted" axiomatic >> development of relativity. It's just too cumbersome a way to >> get there. > > Since you like analogies, for a starting pool player it is better to > go for the easy shot and make it than to try for a more difficult shot > with a better leave and miss. Few of the posters here will go on to > GR. I think the way Einstein presented SR in "Relativity" is probably > the easiest way to understand, with a few clarifications added. It > was the easiest way that he could see it. The new methods become > clear with hindsight, but the new student doesn't have hindsight. > >> Proceeding forward means presenting Minkowski spacetime. The >> Minkowski spacetime approach to relativity in essence replaces >> the two postulates with a single assertion: "The geometry of the >> universe is accurately described (in low gravity fields) by a >> four dimensional manifold with properties as follows..." > > It still keeps the speed of light a universal constant c. > >> Taylor and Wheeler, which I like and you hate, start with this >> single "postulate" and spend the rest of the book familiarizing >> the reader with the implications of this visualization of the >> universe. If the reader is diligent, by the time they finish the >> book, Minkowski spacetime will have gone beyond mere mathematical >> manipulation, but will have become a coherent, consistent, and >> best of all, highly intuitive mental construct by which the >> reader apprehends relativity. >> >> Your main objection seems to be that Taylor and Wheeler don't >> bother trying to justify relativity. T&W just want the reader >> to accept that the battle has been won. Relativity works, so >> the reader should just get on with learning the most efficient >> way to work with it, et cetera. >> >> You obviously don't like that attitude. >> >> Jerry > > No, I don't. That's just learning how to crunch numbers. I don't really see the point of arguing about it .. its just a matter of taste and horses-for-courses. Some approaches work better for some, and other approaches for others. With one approach you may quickly get that 'lightbulb moment' where it all makes sense, and in another that may not happen at all. For someone else it may be the other way around. As long as all roads are still leading to Rome, find the one that makes the journey easiest for you.
From: BURT on 3 Mar 2010 22:44 On Mar 3, 7:35 pm, "Inertial" <relativ...(a)rest.com> wrote: > "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message > > news:343d01e1-98ec-4962-bade-eab3d250e48f(a)g26g2000yqn.googlegroups.com... > > > > > > > On Mar 3, 8:29 am, Jerry <Cephalobus_alie...(a)comcast.net> wrote: > >> On Mar 3, 6:28 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > >> > I understand it and think it is correct. > > >> > My position is that far more people would understand it if it was > >> > explained differently. > > >> It is generally accepted by most legitimate posters on these > >> newsgroups that Einstein's original two-postulates axiomatic > >> approach to the development of relativity is somewhat archaic and > >> difficult to follow, to judge by the numerous crackpots who > >> stumble at the very first steps in his derivation. > > > Oh, and the crackpots catch right on to the newer methods? ;) > > >> You prefer Bondi's presentation of Milne's derivation, which > >> goes "backwards" starting with the Doppler effect. I also like > >> Bondi's approach which is quite intuitive, but after rederiving > >> all of Einstein's famous results, the reader is left somewhat > >> dangling. How does one proceed from there? Bondi's approach is > >> still, at its core, a classic geometric development of the > >> subject. > > > Actually I do not prefer Bondi. I suggested him for Ste only to give > > him a different perspective, and to steer him away from Taylor and > > Wheeler. > > >> By analogy: One does not design a skyscraper using Euclid's > >> Elements, and one does not get to General Relativity through > >> either Einstein's original or Milne's "inverted" axiomatic > >> development of relativity. It's just too cumbersome a way to > >> get there. > > > Since you like analogies, for a starting pool player it is better to > > go for the easy shot and make it than to try for a more difficult shot > > with a better leave and miss. Few of the posters here will go on to > > GR. I think the way Einstein presented SR in "Relativity" is probably > > the easiest way to understand, with a few clarifications added. It > > was the easiest way that he could see it. The new methods become > > clear with hindsight, but the new student doesn't have hindsight. > > >> Proceeding forward means presenting Minkowski spacetime. The > >> Minkowski spacetime approach to relativity in essence replaces > >> the two postulates with a single assertion: "The geometry of the > >> universe is accurately described (in low gravity fields) by a > >> four dimensional manifold with properties as follows..." > > > It still keeps the speed of light a universal constant c. > > >> Taylor and Wheeler, which I like and you hate, start with this > >> single "postulate" and spend the rest of the book familiarizing > >> the reader with the implications of this visualization of the > >> universe. If the reader is diligent, by the time they finish the > >> book, Minkowski spacetime will have gone beyond mere mathematical > >> manipulation, but will have become a coherent, consistent, and > >> best of all, highly intuitive mental construct by which the > >> reader apprehends relativity. > > >> Your main objection seems to be that Taylor and Wheeler don't > >> bother trying to justify relativity. T&W just want the reader > >> to accept that the battle has been won. Relativity works, so > >> the reader should just get on with learning the most efficient > >> way to work with it, et cetera. > > >> You obviously don't like that attitude. > > >> Jerry > > > No, I don't. That's just learning how to crunch numbers. > > I don't really see the point of arguing about it .. its just a matter of > taste and horses-for-courses. Some approaches work better for some, and > other approaches for others. With one approach you may quickly get that > 'lightbulb moment' where it all makes sense, and in another that may not > happen at all. For someone else it may be the other way around. As long as > all roads are still leading to Rome, find the one that makes the journey > easiest for you.- Hide quoted text - > > - Show quoted text - If all roads are leading to Rome then all roads exit Rome. Mitch Raemsch
From: Peter Webb on 3 Mar 2010 22:54
"Paul Stowe" <theaetherist(a)gmail.com> wrote in message news:4aaecfd5-934f-4218-9d21-4f51996fd5c8(a)v20g2000prb.googlegroups.com... On Mar 2, 8:14 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Paul Stowe" <theaether...(a)gmail.com> wrote in message > >> > > > Newton was 'smart enough' to realize that this gravitational force > > > equation was simply a quantifying correlation and not a physical model > > > or explanation for gravity. The famous quote "hypothesis non-fingo" > > > said it all! You don't seem to grasp the fact that both GR and > > > Newton's equations provide no physical model or basis for their > > > existence. In the case of Newton his equation is mute on many aspects > > > of gravity like its speed of propagation as one example, so-called > > > frame dragging for another. Einstein was also smart enough to realise > > > that GR also needed so physical framework. But what I call the modern > > > science blindness does not realize that equations ARE NOT! physical > > > explanations they are, instead, the way such physical model are > > > quantified. Yes, you can correlate observed behavior to equations and > > > have those equations match observation. You can even further predict > > > that future observation must match the form but still be totally > > > ignorant of proper physical basis, tolemy's system is a classic > > > example of this. I would put Minkowski equation in the Ptolemic > > > category, not wrong, but not useful to understanding the underlying > > > physical process either. It is neat mathematical format which takes > > > advantage of a physical property but without any knowledge or basis of > > > what brings about that property. > > > > _____________________________ > > > Like the E and M fields in Maxwell, or the force of gravity in Newton? > > > There exist physical models for both. > > > _________________________ > > OK, explain to me the physical model of the electric field in Maxwell. > > > Maxwell simply quantified Faraday;s model. You sure do seem ignorant of > > the > > history of science... > > ______________________________ > > I never claimed otherwise, so I am wondering why you think I am ignorant > > of the history of science. > > Because you seem clueless to even the existence of Maxwell's WELL > KNOWN physical model for E and M 'fields'. See, > > http://www.vacuum-physics.com/Maxwell/maxwell_oplf.pdf > > _________________________ > That doesn't provide a physical model for the E field. Why don't you just > tell us what Maxwell's physical model for the E field was, if you think he > had one? Or what Newton's physical mechanism for gravity was? Or Darwin's > physical model for inheritability? Or, even better, Maxwell's physical > mode > for the E field, like I asked? Haven't actually got one? Didn't think so. > Maybe you should read Maxwell's paper again, see if you can find where he > explains the physical model for the E field. (ROFL). Maxwell's model was one of quantized vortices. The circulation (vorticity) is the magnetic and these interacting circulation, the electric. This was what lead him to the 'displacement current'. You could not have possibly read Maxwell's paper throughly in the time between posting... Read what I said above about Newton, he WAS smart enough to realize that the equation was not, and more importantly, could not be, a physical model or explanation for gravity. However there does exist such a physical model which, from it Newton equation is derived as the weak slow speed limit and its not GR although Newton's equation is also the weak slow speed limit for it. But, I doubt you're even aware of its existence. > > Can you actually point to anything that I have said > > regarding the history of science which is wrong, or is this simply > > wishful > > thinking on your part? > > http://www.archive.org/details/historyoftheorie00whitrich > > Whittaker's book both volumes is probably the very best historical > account of the developmental history of science from 1600 to 1930. > > _________________________ > I repeat my question, which you ignored. "Can you actually point to > anything > that I have said regarding the history of science which is wrong, or is > this > simply wishful thinking on your part?" You claim that there exists no physical models for gravity for one. __________________________ No, I said that Newton did not have one. And in fact he didn't. E & M for another. ____________________________ Maxwell did not supply a physical model for what an electric field really is. He characterised it purely in terms of its properties, not by a physical explanation of how charges attract and repel at distance. If you think he did, you should post it. I note that GR provides a physical explanantion of gravity, and QM provides a physical explanation (to some extent) of electric fields. Of course, neither Newton or Maxwell were aware of these, and neither had any physical explanation of why massive objects are attracted by gravity at distance, or why electric charges can attract or repel at a distance. |