A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Paul Stowe on 28 Feb 2010 17:59 On Feb 25, 11:21 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 26 Feb, 06:37, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: > > > Some more work has been done on the concept. About a 150 years worth. Its > > exactly how radio and TV transmitters work. You do concede that they do > > work, right? And that radio is a form of light? And radio waves can be made > > by simply oscillating electric and magnetic fields? > > > Just because you *nothing* about Maxwells eqns doesn't mean they need more > > work. It means you need to do more work, to bring your knowledge of physics > > up to where it was in the mid 19th Century. > > I think you misunderstand. I concede that light comprises some kind of > oscillation, and that many of its manifestations are well-understood, > but it seems to me (from what I've read) that it's conceptual basis is > a bit suspect. Hi, I'll try this again. SR like the equivalent theories of Lorentz & Poincare that preceded it does represent actual reality. The short answer to the thread's question is, light speed is the result of the density and compressibility of the substance of space. You can call that substance quantum foam, zero point field, dark stuff, quintessence, or whatever but it is independent of any movement of emitters/receivers. It is 'measured' as the same value in all 'inertial' reference frames solely because matter isn't rigid and consists of perturbative fields with remain internally consistent when moving. These fields 'resist' changes in motion because such changes result in reconfiguration of said fields. This is the likely root of the property we call inertia. The Lorentz contraction is the result. Because of the contraction all round trip paths remain equal under all states of uniform motion. Therefore a moving system and the paths light signals must travel is illustrated below. Definition of terms used P -> Path of light L -> Measured (Local) Length x -> velociy Displacement c -> Light Speed c'-> Local Light Speed v -> velocity b -> Lorentz Beta Factor g -> Einstein's Gamma Factor (inverse Beta) = y axis /^ | / | | / | | (P) c c' (L) | / | | / (x) | | ---v---> -----------+----------- = x axis c^2 = c'^2 + v^2 => c'^2 - v^2 = c'^2 Therefore, c' = c[Sqrt(1 - {v/c}^2)] Divide both sides by c, c'/c = Sqrt(1 - {v/c}^2) = b = 1/g Thus the ratio c'/c is the Lorentz beta factor (b) and, in SR, the inverse gamma factor (g). It relates the (L)ocal component of speed c (c') to the total propagation speed c, if, and only if, speed c is some finite value independent of any speed v. P = ct L = c't = ct/g x = vt Thus, P = Lg = L/b L = Pb = P/g and, t = P/c = Lg/c = L/c' = x/v Finally, dP/dt = c dL/dt = c' and therefore as long as for any round trip path the physical length (L) is invariant, for 0 < v < c the actual path (P) light takes must result in invariant speed measurements. Now why is that? Let's aay we don't know know the system is moving along the x axis at v. We do know that we define speed as dx/dt and assume light speed c is not altered by v, so what is the speed of a light pulse across distance L? Well, because we are actually traveling at v while we have 'assumed' instead v = 0 the actual path the light takes is P, not L. Thus what we 'think' is simply dL/dt is, in actuality, dP/dt. Clearly dP/dt = c and the path of our light ray is, in fact Lg, with a transit time of Lg/c. Thus what we has defined as dL/dt is, in actuality Lg/ (Lg/c) which, by mathematical definition, will always return a value of c. So, while it looked like light traveled path L it actually takes path P -> Lg and the time it took to transit is not L/c it was actually Lg/ c. So, if any system is moving at some dv relative to our reference and we assume that, for them, L is the same as ours, then 'relative' to us there must exist a g' (1/Sqrt(1 - {dv/c}^2)) and again, relative to us, an increase in transit time and increase in travel length of Lg' - L and the increase in travel time Lg'/c - L/c. Further, knowing that for them, they can assume their v = 0 and will also measure speed c as P/P/c or the same as ours, these actual physical differences of g' must be assigned to distortions in length and time between the two systems. In reality however, it should be rather obvious by now that the actual speed of transit is L/Lg/c = c'. Given the above derivation actual differental velocities would result in measurements which uniquely fit this specific mathematical form and the necessity of this form constitute proof that, while measurements in any frame returns an invariant value for light speed c, the reason isn't that the value hasn't physically changed. On the other hand, since only differental speeds are necessary to properly account for perspective changes, using the invariant measured value of c as a base for any local base is both mathematically sound, and in the absence of a common backdrop, logical. However, not so much for understanding if you do not know, or realize the reasons behind it. As illustrated above the physics behind it is that, in fact, the local speed of light in any moving system is actually slows to c' (c/g = cb) which results in longer transit times of L. Without a universal framework however one can readily assign this slowing in speed to distortion of length and time. This universal rest frame problem has, up until recently, been ambigious. Luckily we discovered that the universe illuminates it for us, its called the Cosmic background radiation. For it there exists one, and only one frame of reference where this radiation is isotropic. Thus any motion in respect to it is both detectable and quantifiable, as an anisotropic dipole Doppler shift, all one has to do is look at this background to and make the measurement. With this backdrop we can now sort all of this out and see the system Lorentz proposed in his 1904 paper along with all of the associated elements, local times, proper times, as as local light speed c' and proper light speed c. Regards, Paul Stowe
From: spudnik on 28 Feb 2010 18:26 I'd pen-intimately agree about Newton's dog-gone calculus; the original motivating problem was the brachistochrone of Bernoulli and Liebniz and Huyghens, apparently also solved by Sir Mintminder. remeber, that the speeed of light will be affected by the slowdown of your time-base (more or less frozen, "at" lightspeed, so....). > In the next sentence, answer the first two questions and then > answer, if you can, the third and most significant one. > In his equation tau = a(t - vx'/{c^2 - v^2}), > where did the "a" come from and what does it signify; and IF it IS "a > function phi{v) at present unknown" WHAT is its value if, as he later > said, "phi(v) = 1"? --les OEuvres! http://wlym.com --Weber's electron! http://www.21stcenturysciencetech.com/edit.html --Moon's atom! http://www.21stcenturysciencetech.com/articles/Fall02/Moon.html --Stop Cheeny, Rice, Waxman and the ICC's 3rd British invasion! http://www.larouchepub.com/pr/2010/100204rice-ists_sudan.html
From: Ste on 28 Feb 2010 23:40 On 28 Feb, 06:25, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > How on Earth have you drawn that conclusion? On the contrary, I hold > > that it *is* a problem that there is no apparent physical explanation > > for gravity (in terms of what it is, how it is mediated, how it > > relates to other forces, etc). > > I am demonstrating that you are inconsistent in your requirement that > explanations be physical. > > You claimed that you had a physical model "in your head" of how the solar > system rotates - involving orbits, masses and "gravity". But your model has > no physical explanation for gravity. It is no more a physical description of > the solar system than Minkowski is of SR - both models contain things which > have no physical explanation (according to you, anyway). Yet you accept > these in your model of the solar system (as did Newton in his model), but > reject them for SR. I certainly accept that, in the model I have of gravity, gravity is simply assumed to be a fundamental manifestation of reality. And the obvious truth of its existence and apparent simplicity does not make that hard to believe. However, I fully accept that there is a question as to what gravity actually is, but when that question is answered my physical conception of the solar system will not really need to be retailored. As to the question of what defines a "physical model", as I've said, even I concede that it's very difficult to conceive of any particular explicit specification, even though I (and apparently many others) can identify intuitively what does and does not meet this specification. As I said, in the case of Minkowski, it clearly fails the test of having any meaningful physical form. The defining elements of Minkowski spacetime are all mathematical. It clearly requires interpretation to give it any meaning that would be amenable to our senses, and yet this interpretation layer seems to be implicit and adhoc. The prime example was the "rotating into time" explanation for length contraction.
From: Ste on 1 Mar 2010 00:08 On 28 Feb, 07:07, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > On 27 Feb, 15:44, PD <thedraperfam...(a)gmail.com> wrote: > > > I think you're attributing an absurd definition to "science". Paul > > > Draper probably had a more tenable argument when he said that string > > > theorists are scientists doing science, but that they do not yet have > > > a "scientific theory". But I know from talking to him that he > > > attributes a very contorted meaning to the phrase "scientific theory", > > > that would condemn a lot of scientific knowledge, both historical and > > > current, as being "unscientific". > > > Examples, please. > > In physics I would raise the same old example: string theory . But > there are certainly more. We have things like "dark matter". Or even > Newton. Or Galileo. And more broadly, in biology we have evolution, > and in economics, rational choice theory. > > __________________________________ > All of these things are falsifiable, or they are not scientific theories. I > don't know much about string theory, but the rest are certainly falsifiable. > Newton's theory was in fact falsified by observation. In another part of the > thread, I gave you half a dozen ways evolution could have been falsified. Not true. > All managed to fail your previously stated requirement of a > "scientific theory", which (amongst other things) is being falsifiable > (in a practical rather than just notional sense), not ad-hoc, and > predicting observations that are not already accounted for. > > _______________________________ > I didn't state any of these requirements other than it was falsifiable. Well I was replying to Paul. > All > of those theories are, at least as I understand them, with the proviso I > know zero about string theory and not a lot about some of the others. I have > already demonstrated how many of them in fact could be falsified. String theory is *not* falsifiable. Dark matter is resistent to falsification, because it "does not interact except through gravity and inertia". Both Newton and Galileo were falsified a number of times by their contemporaries, and they were forced to revise (of course, this was before Popper). We've dealt with evolution elsewhere. Rational choice theory is either falsified when it makes express claims as to what people want, or it becomes unfalsifiable when it makes no express claim as to what people want.
From: Ste on 1 Mar 2010 00:12
On 28 Feb, 07:45, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > I'm confused, because I thought we previously agreed that two > observers travelling along the same axis, maintaining equidistance > from both events at all times, would both report each event as > simultaneous with the other event. And moreover, if they not only both > maintained equidistance from both events, but if they maintained a > separation which was equal for both observers (which, if both > observers are moving relative to each other, requires either a > collision course between observers, or travel in diametrically > opposite directions), then there is no question that the signals are > received simultaneously. > > Illustration: > > E1 > > -------- > > E2 > > The line represents the line between events E1 and E2, along which the > observers may move while always reporting both events to be > simultaneous. > > _________________________________ > You still don't get it. You can say two events appeared to simultaneous or > "were" simultaneous in *some* inertial reference frame. That does *not* mean > they appeared simultaneous or "were" simultaneous in some *other* reference > frame. The concept that is lost is "absolute simultaneity", not > "simultaneity within a particular reference frame". But clearly if the two *observers* are moving relative to each other, then this is the definitive proof that events can be simultaneous when measured from more than one reference frame. And in some circumstances, the simultaneity also aquires an "absolute" character, in that the events would be observed to be simultaneous if the two observers were able to synchronise their clocks by a form of instantaneous communication. |