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From: glird on 22 Dec 2009 16:16 On Dec 22, mpc755 wrote: > glird wrote: ><< M' measures to A' (because that's where the lightning struck) and to B' (because that's where the lightning struck). >> mpc wrote: >< And the Observer at M' would be incorrect. The light from the lightning strike at A/A' and B/B' travels with respect to the water which is at rest with respect to the embankment. The light from the lightning strikes DO NOT travel from A' and B' to M', the light from the lightning strikes travels from A and B to M'. Is this your response, or is this my response? > Yours! >< I just went back through the posts and see the above post is mine. If you think you understand the point I am trying to make, then you need to understand the above. The light travels with respect to the medium it propagates through. If the water, glass, luminiferous stuff, is at rest with respect to the embankment, the light propagates outward at the same speed in all directions from A and B. When the light, propagating through the medium which is at rest with respect to the embankment reaches ANY Observer, the light has traveled from A and B to the Observer, in nature. > I am beginning to see your point. I think this is what you mean: The light from the lightning strike at A/A' and B/B' travels at w with respect to the water which is at rest with respect to the embankment. The light from the lightning strikes DO NOT travel from A' and B' to M' at w, however, it travels from AA' to M' at w-v, and from BB' to M' at w+v, where v is the velocity of M' wrt THE WATER. Pleae correct me if my c-at and mowse game is wrong. Either way, here is what I think you meant in your next statement: The light travels at a given speed with respect to the medium it propagates through. If the water, glass, luminiferous stuff, is at rest with respect to the embankment, the light propagates outward at the same speed in all directions from A and B. When the light, propagating at w through the medium which is at rest with respect to the embankment, reaches ANY Observer, the light has traveled from A &/ or A' and B &/or B' to the Observer at a relative speed that depends on that of the Oberver, in nature though not in STR. glird
From: glird on 22 Dec 2009 12:31 On Dec 22, 5:53 am, "papar...(a)gmail.com" wrote: > > You {mpc} should complete your citing!!! It goes like > follows: Rather than presenting the entire quoted portion that followed, here is a significant bit that Miguel skipped past: "If we denote the velocity of the light relative to the tube by W, then this is given by the equation (A) or (B), according as the Galilei transformation or the Lorentz transformation corresponds to the facts. Experiment decides in favour of equation (B) derived from the theory of relativity, and the agreement is, indeed, very exact." Although the data is indeed in agreement with equation (B), the Lorentz transformations were not "derived from the theory of relativity" or anywhere else. They were written by Poincare' in a paper published in June of 1905 and read by Einstein the following summer, after which he spent a month or so frantically revising the proof copy of his own paper -- which was published in the fall of 1905 -- in order to incorporate into it Poincare's LTE. glird
From: glird on 22 Dec 2009 13:06 On Dec 22, 9:38 am, PD wrote: > mpc755 <mpc...(a)gmail.com> wrote: > ><< M' measures to A' (because that's where the lightning struck) and to B' (because that's where the lightning struck). And the Observer at M' would be incorrect. The light from the lightning strike at A/A' and B/B' travels with respect to the water which is at rest with respect to the embankment. The light from the lightning strikes DO NOT travel from A' and B' to M', the light from the lightning strikes travels from A and B to M'. > >< At the time of the lightning strike, A and A' are at the same location. Then the light leaves that common spot before A and A' separate. Therefore to say that the light comes from A and not A', when A and A' were at the SAME PLACE at the moment of the strike, is not just stupid, it is spectacularly stupid. > ><< The water is at rest with respect to the embankment. A pebble is dropped into the water when A and A' are at the same location. The wave the pebble creates propagates outward in all directions at the same speed WITH RESPECT TO THE WATER. The wave the pebble creates propagates outward in all directions at the same speed WITH RESPECT TO A. >> > >< That's true for water. What's true for light is this experimental observation: The speed of light approaching M from either direction is the same: c. The speed of light approaching M' from either direction is the same: c. The fact that what you say about water is true does not mean that the experimental facts about light I just listed are disputable. They aren't. >> What PD listed aren't experimental FACTS; they are interpretations -- by physicists -- of experimental data. The data is indisputable, but the interpretations are off the wall. Even the smartest physicist of them all, Einstein, knew that it is impossible for anything to move at a given velocity relative to two differently moving objects. That's why he invented a novel method of setting clocks of a given system. (As Einstein showed, at least one of PD's two indisputable facts would be experimentally false without it.) glird
From: paparios on 22 Dec 2009 13:30 On 22 dic, 14:31, glird <gl...(a)aol.com> wrote: > On Dec 22, 5:53 am, "papar...(a)gmail.com" wrote: > > > > > You {mpc} should complete your citing!!! It goes like > > follows: > > Rather than presenting the entire quoted portion that followed, here > is a significant bit that Miguel skipped past: > "If we denote the velocity of the light relative to the tube by W, > then this is given by the equation (A) or (B), according as the > Galilei transformation or the Lorentz transformation corresponds to > the facts. Experiment decides in favour of equation (B) derived from > the theory of relativity, and the agreement is, indeed, very exact." > > Although the data is indeed in agreement with equation (B), the > Lorentz transformations were not "derived from the theory of > relativity" or anywhere else. They were written by Poincare' in a > paper published in June of 1905 and read by Einstein the following > summer, after which he spent a month or so frantically revising the > proof copy of his own paper -- which was published in the fall of 1905 > -- in order to incorporate into it Poincare's LTE. > > glird Nobody, less Einstein, is affirming that the Lorentz equations were derived from the theory of relativity, as you say. The paper of Einstein was published on June 30, 1905 and it contains a complete different derivation of those equations (which Poincare had already published on June 5, 1905, so it is most probably that Einstein did not know of its existence before the publication of his own paper). On the other hand, when Einstein writes "Experiment decides in favour of equation (B) derived from the theory of relativity" he is correctly referring to the theorem of addition for velocities in one direction, which it was indeed derived on his June 30, 1905 relativity paper, on section $5. Miguel Rios
From: PD on 22 Dec 2009 13:41
On Dec 22, 12:06 pm, glird <gl...(a)aol.com> wrote: > On Dec 22, 9:38 am, PD wrote:> mpc755 <mpc...(a)gmail.com> wrote: > > ><< M' measures to A' (because that's where the lightning struck) and to B' (because that's where the lightning struck). > > And the Observer at M' would be incorrect. The light from the > lightning strike at A/A' and B/B' travels with respect to the water > which is at rest with respect to the embankment. The light from the > lightning strikes DO NOT travel from A' and B' to M', the light from > the lightning strikes travels from A and B to M'. > > >< At the time of the lightning strike, A and A' are at the same location.. Then the light leaves that common spot before A and A' separate. Therefore to say that the light comes from A and not A', when A and A' were at the SAME PLACE at the moment of the strike, is not just stupid, it is spectacularly stupid. > > ><< The water is at rest with respect to the embankment. A pebble is dropped into the water when A and A' are at the same location. The wave the pebble creates propagates outward in all directions at the same speed WITH RESPECT TO THE WATER. The wave the pebble creates propagates outward in all directions at the same speed WITH RESPECT TO A. >> > > >< That's true for water. > > What's true for light is this experimental observation: > The speed of light approaching M from either direction is the same: > c. > The speed of light approaching M' from either direction is the same: > c. > The fact that what you say about water is true does not mean that the > experimental facts about light I just listed are disputable. They > aren't. >> > > What PD listed aren't experimental FACTS; they are interpretations -- > by physicists -- of experimental data. No, they're facts. Do you need references to the experiments that directly measure the isotropy of the speed of light, and the independence of the speed of light upon the motion of the source? > The data is indisputable, but the interpretations are off the wall. > Even the smartest physicist of them all, Einstein, knew that it is > impossible for anything to move at a given velocity relative to two > differently moving objects. It can't be impossible if that's what's actually observed in experiment. If you pretend to think scientifically, but then look at an experimental result and announce that it's impossible, then your pretense is uncovered. > That's why he invented a novel method of setting clocks of a given > system. (As Einstein showed, at least one of PD's two indisputable > facts would be experimentally false without it.) > > glird |