A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
|
From: Peter Webb on 25 Feb 2010 04:16 > And on this point, I've repeatedly maintained that it isn't. All > you've offered in the converse is a quote by Einstein that it is. No, I've also referred you to the works of Kuhn and Lakatos. And indeed, the very method that you describe involves formulating a theory and then testing its predictions - in other words, the tests that are carried out are constrained by the predictions made by the theory. One would be unlikely to test for something that the theory does not predict in the first place. ____________________________ Thus demonstrating you also have no understanding whatsoever of the scientific method or these philosophers. The whole point of testing through experiment is to look for places where the theory might break down, not places where you have tested similar things in the past. The idea is to try and disprove the theory, and through failure, demonstrate it is true. This is the complete opposite to what you say. The sad fact that even you must acknowledge - and tell us if you don't - is that SR is routinely tested every day of the year in wildly diverse environments such as particle accelerators, GPS units, astronomy, and space exploration. All completely independent ways of testing, and some giving very highg precision indeed. Like it or not, the equations of SR are obviously correct. So the only thing that you can bring to the table is some philosophical interpretation of what is "really" going on. This is a task you are poorly prepared to do, as you don't understand the current (dominant) interpretation of what is really going on, which is Minkowski space-time. It is (when you understand it) a very simple model which explains a great deal of the physics very simply - in particular the Energy and Momentum of a particle. Frankly, you are not going to find a mental model of SR which is better or simpler than Minkowski space-time, I very much doubt one exists at all. Your disbelief of SR stems from the fact that you don't understand it. That's because you are lazy; you seem intelligent enough to learn it if you wanted. However, jumping from you don't understand SR to therefore physicists are all wrong shows an almighty conceit on your part. Just because you are an idiot doesn't mean every physicist in the world is as well. If you really don't believe that SR has been massively and overwhelmingly been "proved" by experimental evidence, just say so, and I will dig up a list of experimental proofs for you. If you accept that the equations of SR are correct, then your point in all this is ..... ?
From: Peter Webb on 25 Feb 2010 04:18 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:ab0ad038-f849-4d36-a73d-8bbb7bf7e366(a)t23g2000yqt.googlegroups.com... On 24 Feb, 17:37, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 24, 2:56 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > Of course, I don't pretend to even have a > > speculative account for what this variable may be. I will finish > > however by saying that surely you accept that clocks that actually > > exist must have some common principles at a fundamental level, and > > that if the time dilation phenomenon operates at that level then it's > > quite plausible that they would all react in the same way to time > > dilation. > > On this last point, I will simply conclude that, yes, indeed all > clocks operate with a common principle at some level, and that time > dilation operates at that level. That principle and that operation of > dilation are PRECISELY what is described by special relativity, as far > as we can tell from the evidence we have in hand. Congratulations. > > Now, at this point, I imagine you might say, "But I don't BELIEVE in > special relativity and hold faith that there is some OTHER principle > and operation of dilation that is responsible for what is going on." > That is, of course, a possibility. Anything is possible. However, > among those models that have been tested and which do purport to > account for the principle that drives dilation, special relativity is > the demonstrated winner. You are free to put forward a new candidate > to add to the race. There are others who are doing exactly the same > thing this very day. As I say, I don't necessarily disbelieve SR. I just don't think it is conceptually very clear. _____________________________ Have you tried? Found a simple link or book explaining Minkowski space time and tried to go through it? Where do you get stuck?
From: Peter Webb on 25 Feb 2010 04:46 And indeed, I said openly that I couldn't make that work, once I'd been able to construct a graphic where I could see the proof with my own eyes, and clearly the physical understanding on which that was based is untenable. As it stands, I don't really have any workable physical model for light under relativity. _________________________________ Relativity does not provide a workable physical model for light, in fact it says nothing about it at all. The workable physical model for light is provided by Maxwell's eqns, which tell us *exactly* what light is; it is two out of phase electric and magnetic fields, and this uses the same maths and mechanisms as explain radio broadcasting, transformers, generators etc. You would be well off learning this before you attempt SR, as much of the experimentation and theory was motivated by physicists knowing that Maxwell's equations - used a billion times a day - used a Lorentz transform, and this would allow an absolute frame of reference to be established. In practice, the mathematics of Maxwell are harder than SR, but I will try and explain some key concepts. Most importantly, Maxwell's eqns are said to give rise to light waves, but these are fundamentally different what you think of as a wave. In water waves, there is a single variable - water height - and the wave exchanges energy with the medium through which it travels. Similarly with sound waves, where it is air pressure. In Maxwell, there are two waves always generated, the electric and the magnetic. The electric increases, it draws energy from the magnetic, the magnetic runs out, the electric collapses which feed energy into the magnetic, and so on ... multiply this by about 10^20 in speed and you have light. The total energy of the photon/wave is constant, it simply exchanges energy between its electric and magnetic fields. If you ask what the electric wave is "waving through" - what is storing its energy as it goes up and down like a water wave - its the waves magnetic field, and the waves magnetic field is similarly beating against the electric field. This means there is no connection to any underlying medium which is waving, like in a water wave, it is self contained. This is ultimately why it has a Lorentz transform, and if you do the maths on Maxwell's equations you actually get the Lorentz contraction popping out automatically. The Michelson Morley experiment was specifically designed to compare the transforms for light and a physical object, and contrary to your opinion that physicists don't know how to design tests, was deliberately testing to the limits the prevailing understanding at that time, and found it to be wrong. The rest is now over 100 years of history; you are a little late to find a problem.
From: Jerry on 25 Feb 2010 06:06 On Feb 25, 1:53 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Jerry" <Cephalobus_alie...(a)comcast.net> wrote in message > > For the speed of light c not to equal the universal speed limit d > > would mean only that Maxwell's equations need to be replaced by > > Proca's equations, which allow for the possibility of a massive > > photon. > > And there is the rub. > > You cannot use 'd' instead of 'c' in SR without breaking either Maxwell or > Galilean Relativity. Maxwell's equations are not sacred. They constitute a theory that must match observation, and are already known to break down at the quantum level, where light is well-described by QED, which represents the successful merger of SR with quantum theory. SR is a deeper theory than Maxwell's equations. It is a statement that the universe is described by a certain particular geometry (in regions of sufficiently low gravity). We seem to be using different understandings of the term "Galilean relativity". To me, Galilean Relativity requires that c = infinity, and imply the validity of the Galilean transforms, rather than the Lorentz transforms. This would be the meaning understood by the great majority of (legitimate) posters on these newsgroups. http://en.wikipedia.org/wiki/Galilean_transformation > Using 'c' as the speed limit in SR is the only choice that doesn't break > something else; its not simply based on observation or wishful thinking. Einstein originally explored an axiomatic system comprising the two postulates plus several common notions. Minkowski demonstrated a powerful alternate formalization of Einstein's theory which was essential to Einstein's later development of GR. Later researchers have developed other derivations of Einstein's theory starting from other assumptions. For instance, you may have seen mentioned on these newsgroups the group theory derivation of SR, which uses -only- the first postulate plus a single experimental data point: "Is c finite or infinite?" Minkowski stands in somewhat the same relation to Einstein as Descartes stands in relation to Euclid. In Minkowski spacetime, "c" is the proportionality constant that relates the time axis with the space axes. It happens to have the same numerical value as the speed of light, but that is not the primary importance of "c" in this alternate formulation of SR. > > Fortunately, the speed of light c DOES seem to equal the > > universal speed limit d to an accuracy of at least 10^-16. > > http://www.skyandtelescope.com/news/39867717.html > > > The minor discrepancy noted in the Fermi Gamma Ray Telescope > > measurements could simply be a reflection of our ignorance > > concerning the mechanism of gamma ray bursts, or (more exciting) > > could be indicative of quantum foam effects. Even if confirmed, > > these results should not be misconstrued as any sort of disproof > > of SRT within its classical domain of applicability. > > > Jerry > > I was unaware of the finding, but am not impressed or surprised. > > What the article doesn't mention is that all light lags typo: "leads" > the neutrino flux, > which may or may not comprise particles that have mass at various times. If > shorter light wavelengths are slowed more than longer ones, it just means > space has a non-zero refractive index. typo: "dispersion" > In practice, all known materials have > non-zero refractive indexes, apparently now also including interstellar > space. > > Its a long way from "interstellar space has a non-zero refractive index" to > quantum foam. Even ignoring the fact that we don't actually know the high > and low energy photons were created at the same time. Agree. Although the results are real, the interpretations are quite controversial. Jerry
From: Peter Webb on 25 Feb 2010 08:25
"Jerry" <Cephalobus_alienus(a)comcast.net> wrote in message news:4b65e9b1-c2eb-445b-8eb8-206d78f0bc79(a)b30g2000yqd.googlegroups.com... On Feb 25, 1:53 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Jerry" <Cephalobus_alie...(a)comcast.net> wrote in message > > For the speed of light c not to equal the universal speed limit d > > would mean only that Maxwell's equations need to be replaced by > > Proca's equations, which allow for the possibility of a massive > > photon. > > And there is the rub. > > You cannot use 'd' instead of 'c' in SR without breaking either Maxwell or > Galilean Relativity. Maxwell's equations are not sacred. They constitute a theory that must match observation, and are already known to break down at the quantum level, where light is well-described by QED, which represents the successful merger of SR with quantum theory. SR is a deeper theory than Maxwell's equations. It is a statement that the universe is described by a certain particular geometry (in regions of sufficiently low gravity). We seem to be using different understandings of the term "Galilean relativity". To me, Galilean Relativity requires that c = infinity, and imply the validity of the Galilean transforms, rather than the Lorentz transforms. This would be the meaning understood by the great majority of (legitimate) posters on these newsgroups. http://en.wikipedia.org/wiki/Galilean_transformation _________________________ We do: By the term Galilean Relativity I am referring to the principle that dynamics looks the same in all inertial frames, first enunciated by Galileo using thought experiments involving dropping balls on moving ships. It still stands at the bedrock of physics. "The special principle of relativity was first explicitly enunciated by Galileo Galilei in 1632 in his Dialogue Concerning the Two Chief World Systems, using the metaphor of Galileo's ship. (http://en.wikipedia.org/wiki/Principle_of_relativity)." It is unfortunate his name also became attached to the Galilean Transform, which I don't think was his idea and turned out wrong in practice. > Using 'c' as the speed limit in SR is the only choice that doesn't break > something else; its not simply based on observation or wishful thinking. Einstein originally explored an axiomatic system comprising the two postulates plus several common notions. Minkowski demonstrated a powerful alternate formalization of Einstein's theory which was essential to Einstein's later development of GR. Later researchers have developed other derivations of Einstein's theory starting from other assumptions. For instance, you may have seen mentioned on these newsgroups the group theory derivation of SR, which uses -only- the first postulate plus a single experimental data point: "Is c finite or infinite?" Minkowski stands in somewhat the same relation to Einstein as Descartes stands in relation to Euclid. In Minkowski spacetime, "c" is the proportionality constant that relates the time axis with the space axes. It happens to have the same numerical value as the speed of light, but that is not the primary importance of "c" in this alternate formulation of SR. > > Fortunately, the speed of light c DOES seem to equal the > > universal speed limit d to an accuracy of at least 10^-16. > > http://www.skyandtelescope.com/news/39867717.html > > > The minor discrepancy noted in the Fermi Gamma Ray Telescope > > measurements could simply be a reflection of our ignorance > > concerning the mechanism of gamma ray bursts, or (more exciting) > > could be indicative of quantum foam effects. Even if confirmed, > > these results should not be misconstrued as any sort of disproof > > of SRT within its classical domain of applicability. > > > Jerry > > I was unaware of the finding, but am not impressed or surprised. > > What the article doesn't mention is that all light lags typo: "leads" ____________________ I stand partially corrected. The neutrino flux from distant supernova reach us before the light does, but that is because of delays getting through the star, not through space. > the neutrino flux, > which may or may not comprise particles that have mass at various times. > If > shorter light wavelengths are slowed more than longer ones, it just means > space has a non-zero refractive index. typo: "dispersion" > In practice, all known materials have > non-zero refractive indexes, apparently now also including interstellar > space. > > Its a long way from "interstellar space has a non-zero refractive index" > to > quantum foam. Even ignoring the fact that we don't actually know the high > and low energy photons were created at the same time. Agree. Although the results are real, the interpretations are quite controversial. Jerry |