A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: mpalenik on 14 Feb 2010 18:46 On Feb 14, 2:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 14 Feb, 05:27, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > > > > > > Ste wrote: > > > I've been absolutely racking my brain (to the point of getting a > > > headache) for the last few days about this issue, and it's clear that > > > the speed of light (where light is either considered in the form of a > > > ballistic photon, or a wave-cycle) cannot, physically, be constant in > > > all relative frames, and at the same time be constant when travelling > > > between two objects in two different frames. It's a physical and > > > logical impossibility. > > > Not true. You are making implicit assumptions that are not valid in the world we > > inhabit. > > > At base, this is GEOMETRY, not any properties of light itself. And the only way > > to understand it is to study SR and its underlying geometry, Minkowski spacetime. > > > The primary invalid assumption you make appears to me to be Euclidean geometry. > > But you also implicitly assume that speeds add like vectors; they don't.. > > > Indeed, even this is wrong: "I mean the alternatives are that > > a object's velocity must cause either an increase or a decrease > > in the speed of light in a particular direction relative to > > something." > > > One does not "reconcile this physically", one reconciles it GEOMETRICALLY. > > > Speaking VERY LOOSELY, one could say that there are "grooves" > > in spacetime that go in every direction at every point, with > > the speed of light. And light "just happens" to always travel > > in these grooves. The actual geometry is MUCH more interesting, > > but as I keep saying, you must STUDY this -- your "20 questions" > > approach on the internet is woefully inadequate. > > > Tom Roberts > > I'm afraid you're easily satisifed Tom. As I say, I'm not really > interested in learning geometry, or talking about completely > hypothetical "grooves in spacetime". > And as many people have repeatedly tried to explain to you, the answer simply is geometry. When you accellerate, you rotate in spacetime. Why? Because that's what accelleration means. That's what it means to be travelling with a certain velocity with respect to something else. It means that you're both "facing different directions". Every effect predicted by relativity can be explained simply by the fact that two different observers at different speeds are "facing different directions" in spacetime--because that's what it means to be moving with respect to something else. It means that you have a different t and x axis.
From: mpalenik on 14 Feb 2010 18:48 On Feb 14, 2:09 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 13 Feb, 20:28, mpalenik <markpale...(a)gmail.com> wrote: > > > > > > > On Feb 13, 2:11 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > I'm afraid I do not accept that my "choice of mathematical coordinate > > > system" is the explanation for this.- Hide quoted text - > > > Think of it as your orientation in spacetime. For example, if you're > > facing north, a natural coordinate system is that north is foward and > > east is right. If you walk in a straight line, you'll end up going > > north. > > > Now, turn 45 degrees. A natural choice of coordinate system is > > northeast is forward and southeast is right. If you walk forward, > > you'll go northeast. > > > Are you going to tell me that you won't accept that your natural > > choice of coordinate systems is responsible for you ending up in > > different places when you walk forward? It has to do with your > > orientation, whether it's your orientation on the surface of the earth > > or your orientation in spacetime--your orientation depends on what > > happens when you move forward. > > Of course I accept that your orientation affects your direction. But > there is nothing magic about perspective.- Hide quoted text - > Who said anything about magic? Your orientation in Minkowski spacetime is what is responsible for everything predicted by relativity. There's no need to invoke magic. If you acknowledge that a moving observer is rotated in spacetime with respect to the "stationary" observer and do the math, every observation the moving observer akes matches the predictions of relativity. There is no magic involved.
From: Tom Roberts on 14 Feb 2010 18:49 Ste wrote: > I want simple answers to what seem to me to be simple physical > questions. Just because they seem "simple physical questions" to you does not mean that they actually are such questions. Indeed, from understanding our current best models of the world we inhabit, it is incredibly likely that you are condemned to disappointment in this. > As I said on a previous occasion, few here seem to be able > to break out of the notion that something exists independent of > observation. Hmmm. It is quite clear to me that the world exists and proceeds in its evolution without any observers at all. But it is true that modern physics places an emphasis on observation, or more accurately, on measurements. That's because discussing measurements eliminates many ambiguities, and because the only information we have about the world we inhabit comes from observation (measurements). IOW I utterly reject the solipsism your statement here seems to espouse. > I want an explanation where, essentially, information travels > instantaneously, That's part of your problem. As best we know, that is impossible. If you insist on counterfactual properties, you are condemned to disappointment. > but from which I can derive the effects that any > particular observer would observe. It matters not that information > does not, really, travel instantaneously. The point is that I want an > explanation where it *does*, and I can then add on a layer of observer > effects to reconcile it with real observation. Almost surely hopeless. You need to LEARN what is currently known, because it implies your hopes and dreams can not be satisfied. Note this is essentially always true of people like you who insist on imposing their will on nature. Nature does not care what you think, wish, or desire. Live with it, because you have no choice -- you must take nature as she is, not as you wish her to be. [Don't expect me to continue, until and unless you decide to do science. Whatever it is you are trying to do is uninteresting.] Tom Roberts
From: Peter Webb on 14 Feb 2010 18:58 "mpc755" <mpc755(a)gmail.com> wrote in message news:13d31b2a-e1d4-4b1f-8c50-703bb52a09be(a)u15g2000prd.googlegroups.com... On Feb 14, 9:44 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "mpc755" <mpc...(a)gmail.com> wrote in message > > news:24b1dbfc-e19c-4c2e-a7f7-6a3601ea13da(a)q16g2000yqq.googlegroups.com... > On Feb 14, 1:31 am, "Peter Webb" > > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > "mpc755" <mpc...(a)gmail.com> wrote in message > > >news:49c69202-f525-4bba-bfa0-09b662433837(a)s33g2000prm.googlegroups.com... > > On Feb 14, 1:12 am, "Peter Webb" > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > Now, here's the kicker. If the Observers on the train know they are > > > moving relative to water at rest with respect to the embankment, the > > > Observers on the train will be able to factor in the trains motion > > > relative to the water and calculate back and determine the lightning > > > strikes were in fact, simultaneous with respect to the water > > > > _______________________________________ > > > Yes. > > > > and conclude the lightning strikes were simultaneous, in nature. > > > > __________________________________________ > > > No. Nowhere in the 200 lines that preceded this do you show that > > > reference > > > frame of the water is the reference frame of "nature". It doesn't even > > > make > > > any sense. > > > Light propagates at a constant speed with respect to the state of the > > medium in which it exists. > > > __________________________________________ > > No. > > > The Observers on the train know their state > > with respect to the state of the water and are able to conclude > > correctly the lightning strikes at A/A' and B/B' were simultaneous, in > > nature. > > > ________________________________ > > If by "in nature", you mean the "in the frame of reference of the earth > > considered as an inertial frame", then yes. If "in nature" means > > something > > else, perhaps you should explain exactly what "in nature" is supposed to > > mean. > > As long as any Observer is able to factor in their state with respect > to the state of the medium in which the light propagates being at rest > then the Observer is able to conclude when the lightning strikes > occurred in nature. > > ______________________________________ > > So the inertial reference frame of nature is the rest frame in which light > moves at a constant rate? > > What reference frame is that, relative to the Sun? The reference frame is the state of the aether the light propagates through. And this includes the state of the aether which exists in any and all mediums in which the light propagates. __________________________________ No, you misunderstood my question. If the aether defines a stationary reference frame, what is it exactly? The Sun and the planets are presumably moving through space, what is the Sun's speed relative to the ether? Is it stationary, moving at 1 kms/sec, what is its speed?
From: Inertial on 14 Feb 2010 19:08
"Ste" <ste_rose0(a)hotmail.com> wrote in message news:98a0590c-da07-42d9-afec-c26155be9744(a)w31g2000yqk.googlegroups.com... > I want an explanation where, essentially, information travels > instantaneously, but from which I can derive the effects that any > particular observer would observe. There is no need for that. When we talk about what would be observed in a given frame, it does NOT mean that there is just single observer at the origin of that frame whose measurements are affected by how long light takes to travel to him (unless we are explicitly talking about what a given observer would actually 'see'). We generally assume (in a gedanken) that one can place an 'observer' (ie some sort of appropriate measuring device) at any point in space and time required. One can take simultaneous readings with such devices without the need for information to travel instantaneously. So for the lightning strikes on a train scenario, we can place clocks at the appropriate places and detect the times the strikes occur. That we can do some of the analysis based on the time light takes to reach given points does not mean that the effect is purely some optical illusion. Of course, *some* things that SR will predict ARE predictions of what a single observer would 'see' .. and they are clearly described as such .. eg Terrel rotation. |