Is Length Contraction in SR physical??
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From: Inertial on 11 Feb 2010 16:39 "kenseto" <kenseto(a)erinet.com> wrote in message news:84da8267-49eb-4f5c-af12-ca20121119c8(a)q16g2000yqq.googlegroups.com... > On Feb 10, 10:32 pm, "Inertial" <relativ...(a)rest.com> wrote: >> "Tom Roberts" <tjroberts...(a)sbcglobal.net> wrote in message >> >> news:kvSdnQR4g8u56O7W4p2dnAA(a)giganews.com... >> >> > Nor does the rod get "physically shorter" by any measure we take in any >> > other frame, either. Making a measurement of its length does NOT affect >> > the length of the rod itself, regardless of how the measurement is >> > made. >> >> Just using 'length' is also a linguistic problem (similar to that of >> using >> 'physical'). >> >> Does it mean 'proper length' / 'intrinsic length' / 'rest length' ... or >> does it mean the 'measured length' (ie the distance between the >> coordinates >> of two points at a given time in a given inertial frame) (or is there a >> better term for that 'length' that I can't think of atm :)) ??? > > There is no such thing as measured length of a moving rod. Of course there is > There is a > predicted length or geometric projected length of a moving rod. And that is a prediction of WHAT YOU WOULD MEASURE WHEN YOU MEASURE IT > I > don't understand why you physicists keep on using the word *measured* Everything a theory says is a prediction .. It would be silly to say SR predicts a prediction. It doesn't .. it says what the MEASURED LENGTH would be. > instead of *predicted*. Is it to give your SR theory more credence? That you don't understand physics (let alone SR) is very clear
From: Inertial on 11 Feb 2010 16:42 "JT" <jonas.thornvall(a)hotmail.com> wrote in message news:a72cef7f-8dc3-4205-a8d1-aa61a695dac0(a)r24g2000yqd.googlegroups.com... > On 11 Feb, 15:39, kenseto <kens...(a)erinet.com> wrote: >> On Feb 10, 10:32 pm, "Inertial" <relativ...(a)rest.com> wrote: >> >> > "Tom Roberts" <tjroberts...(a)sbcglobal.net> wrote in message >> >> >news:kvSdnQR4g8u56O7W4p2dnAA(a)giganews.com... >> >> > > Nor does the rod get "physically shorter" by any measure we take in >> > > any >> > > other frame, either. Making a measurement of its length does NOT >> > > affect >> > > the length of the rod itself, regardless of how the measurement is >> > > made. >> >> > Just using 'length' is also a linguistic problem (similar to that of >> > using >> > 'physical'). >> >> > Does it mean 'proper length' / 'intrinsic length' / 'rest length' ... >> > or >> > does it mean the 'measured length' (ie the distance between the >> > coordinates >> > of two points at a given time in a given inertial frame) (or is there a >> > better term for that 'length' that I can't think of atm :)) ??? >> >> There is no such thing as measured length of a moving rod. There is a >> predicted length or geometric projected length of a moving rod. I >> don't understand why you physicists keep on using the word *measured* >> instead of *predicted*. Is it to give your SR theory more credence? > > Of courese you are right Ken they are not measured they are only > projections of the applied Lorentz > transform. Predictions of WHAT WOULD BE MEASURED. What do *you* think they are predictions of? > I just wanted to point out that even if the Lorentz transform should > turn out to be a realworld event and not a projection, It IS a real world event. We observe it happening experimentally. > the logical > standpoint of using the same unit with different magnitudes is still > simply wrong. We don't > The use of length units must of course be invariant > between frames, It is .. every frame has the same size length unit. > a meter is not a turd of certain degree of > contraction, It isn't > because then a meter is a flattened turd. A meter is not > a physical entity it is a comparisson tool and must be invariant > between frames to even have a function. It is > So they are wrong in so many ways it is hard to really know where to > start critisize the theory. So stop .. you're embarrassing yourself > Maybe you just can not make them > understand that the Lorentz transfomr is a mathematical projection That corresponds to a real world projection. > where the world simultaneous lost all meaning, afterall they think > already the values is measured when only applying the formula. > > But you can and must stess the invalid use of units where they lack > purpose, a unit is not a measure that can be compressed or contracted > a material with a volume can be compressed to have another volume. But > the unit liter can not be compressed it is so confusing even imaging > such idiocy, but still it falls perfectly natural for them to state > that lengths is framedependent. > > So how you even confront such idiocy, i simply do noit i only talk > with others who have enough brain to see the idiocy in what is going > on. Although i can see signs that SR today is more a brick holding > back the cold reality from surface, i think many SRIANS todays > understand the faulthy methodology that lead the theory, but they can > just not state outfront that they and Einstein was wrong so they keep > on juggling turds like nothing happened. You're an idiot like ken.
From: Inertial on 11 Feb 2010 16:46 "Paul Stowe" <theaetherist(a)gmail.com> wrote in message news:e197d580-e4c3-4afa-a4e6-2fbf404412e6(a)l12g2000prg.googlegroups.com... > On Feb 10, 11:16 pm, "Inertial" <relativ...(a)rest.com> wrote: >> "Paul Stowe" <theaether...(a)gmail.com> wrote in message >> >> news:0db4a675-2ae3-4b9d-af25-9b5f4fac9d55(a)a16g2000pre.googlegroups.com... >> >> >> >> >> >> > On Feb 10, 11:36 am, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > {Snip...} >> >> >> The question therefore remains, how can the speed of propagation >> >> possibly be measured to be constant in all frames. >> >> > The answer to your question is actually simple and 'intuitive' if you >> > think >> > about what must happen in a medium. The propagation of any type of >> > disturbance travels by 'conduction' from one entity to the next. This >> > is >> > set by the mean speed and spacing. If the medium is 'incompressible' >> > the >> > entities are all touching (spacing is zero) and the entities >> > 'infinitely >> > hard' In that case, the speed of propagation is infinite, and no >> > delta >> > 'pressures' are possible 'within the medium. OTOH, in any >> > compressible >> > medium there is spacing, and the entities have momentum and energy. >> > This >> > results a distinctive independent set speed by which any disturbances >> > (like wave propagation) will occur. This is designated as c for ANY! >> > medium >> >> > Now it should be obvious that in the case of a medium it is this >> > process >> > that always dominates... The speed of sources must, by that >> > constraint, >> > alter there emission/field profiles to conform to this limitation. >> >> > So now, start with a source of a omni-directional wave generator 'at >> > rest' >> > with respect to the medium. The resulting waves propagate outward 'at >> > c' >> > in all directions, resulting in a perfectly spherical field form. >> > Next, >> > give this source some speed v, obviously c hasn't changed so, in the >> > direction of motion the source is displacing forward at v so each >> > wave >> > front must be separating 'from the source' at c - v. In the >> > perpendicular >> > (transverse) direction the wave fronts are still separating from the >> > source at c. Thus, for the hemisphere in front of the moving source >> > the >> > wave field form is no longer spherical, but flatten into an >> > ellipsoid. >> > Now what happens to the back half??? >> >> The opposite >> >> > Intuitively you would think >> > that >> > the wave front would be separating 'from the source' at c + v. >> >> It does >> >> > However, remember that a wave is an oscillation (a back & forth >> > motion) so, >> >> Not for light. It is side-to-side >> >> > one cycle is c - v and c + v. >> >> Nonsense [snip rest] > > From the �Handbook of Physics� (Section 3, Chapter 8 - �Acoustics�, > Rev 2 1967), > > �The surfaces of constant sound pressure on the other hand > are given by R� = constant, which corresponds to the > ellipsoid x'^2 + y^2 + z^2 = constant = R�^2 as pictured > in Fig. 8.2. It is interesting to note that the field is > the same up and down wind and that the intensity is > larger in the directions at right angles to the flow.� Don't have that book Each wavefront (for sound), however, forms a sphere around the point from which it was emitted. The source continues to move, so successive wave cycles have the centre of their spherical wavefront at a different position What has a surface of constant sound pressure got to do with anything in SR? > Go check it out for yourself. As for using the words "back and forth" > I guess I should of said cyclic... Yes
From: Inertial on 11 Feb 2010 17:36 "kenseto" <kenseto(a)erinet.com> wrote in message news:a6c38944-11ee-4595-90f8-9da92c7c9f69(a)q27g2000yqn.googlegroups.com... > On Feb 11, 10:24 am, PD <thedraperfam...(a)gmail.com> wrote: >> On Feb 11, 8:39 am, kenseto <kens...(a)erinet.com> wrote: >> >> >> >> >> >> > On Feb 10, 10:32 pm, "Inertial" <relativ...(a)rest.com> wrote: >> >> > > "Tom Roberts" <tjroberts...(a)sbcglobal.net> wrote in message >> >> > >news:kvSdnQR4g8u56O7W4p2dnAA(a)giganews.com... >> >> > > > Nor does the rod get "physically shorter" by any measure we take in >> > > > any >> > > > other frame, either. Making a measurement of its length does NOT >> > > > affect >> > > > the length of the rod itself, regardless of how the measurement is >> > > > made. >> >> > > Just using 'length' is also a linguistic problem (similar to that of >> > > using >> > > 'physical'). >> >> > > Does it mean 'proper length' / 'intrinsic length' / 'rest length' >> > > ... or >> > > does it mean the 'measured length' (ie the distance between the >> > > coordinates >> > > of two points at a given time in a given inertial frame) (or is there >> > > a >> > > better term for that 'length' that I can't think of atm :)) ??? >> >> > There is no such thing as measured length of a moving rod. >> >> Of course there is, Ken. Even at horse races, horses are measured to >> win over second-place finishers by three and a half lengths. What >> makes you think it is impossible to measure the length of a moving >> rod? How to do it has been described to you dozens of times. > > But that's not a measurement of the length of a moving horse. Of course it is. Do you think they ask all the horses to stop so they can measure the distances, and then keep running?
From: Paul Stowe on 11 Feb 2010 17:56
On Feb 11, 1:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > "Paul Stowe" <theaether...(a)gmail.com> wrote in message > > news:e197d580-e4c3-4afa-a4e6-2fbf404412e6(a)l12g2000prg.googlegroups.com... > > > > > > > On Feb 10, 11:16 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> "Paul Stowe" <theaether...(a)gmail.com> wrote in message > > >>news:0db4a675-2ae3-4b9d-af25-9b5f4fac9d55(a)a16g2000pre.googlegroups.com.... > > >> > On Feb 10, 11:36 am, Ste <ste_ro...(a)hotmail.com> wrote: > > >> > {Snip...} > > >> >> The question therefore remains, how can the speed of propagation > >> >> possibly be measured to be constant in all frames. > > >> > The answer to your question is actually simple and 'intuitive' if you > >> > think > >> > about what must happen in a medium. The propagation of any type of > >> > disturbance travels by 'conduction' from one entity to the next. This > >> > is > >> > set by the mean speed and spacing. If the medium is 'incompressible' > >> > the > >> > entities are all touching (spacing is zero) and the entities > >> > 'infinitely > >> > hard' In that case, the speed of propagation is infinite, and no > >> > delta > >> > 'pressures' are possible 'within the medium. OTOH, in any > >> > compressible > >> > medium there is spacing, and the entities have momentum and energy. > >> > This > >> > results a distinctive independent set speed by which any disturbances > >> > (like wave propagation) will occur. This is designated as c for ANY! > >> > medium > > >> > Now it should be obvious that in the case of a medium it is this > >> > process > >> > that always dominates... The speed of sources must, by that > >> > constraint, > >> > alter there emission/field profiles to conform to this limitation. > > >> > So now, start with a source of a omni-directional wave generator 'at > >> > rest' > >> > with respect to the medium. The resulting waves propagate outward 'at > >> > c' > >> > in all directions, resulting in a perfectly spherical field form. > >> > Next, > >> > give this source some speed v, obviously c hasn't changed so, in the > >> > direction of motion the source is displacing forward at v so each > >> > wave > >> > front must be separating 'from the source' at c - v. In the > >> > perpendicular > >> > (transverse) direction the wave fronts are still separating from the > >> > source at c. Thus, for the hemisphere in front of the moving source > >> > the > >> > wave field form is no longer spherical, but flatten into an > >> > ellipsoid. > >> > Now what happens to the back half??? > > >> The opposite > > >> > Intuitively you would think > >> > that > >> > the wave front would be separating 'from the source' at c + v. > > >> It does > > >> > However, remember that a wave is an oscillation (a back & forth > >> > motion) so, > > >> Not for light. It is side-to-side > > >> > one cycle is c - v and c + v. > > >> Nonsense [snip rest] > > > From the Handbook of Physics (Section 3, Chapter 8 - Acoustics, > > Rev 2 1967), > > > The surfaces of constant sound pressure on the other hand > > are given by R = constant, which corresponds to the > > ellipsoid x'^2 + y^2 + z^2 = constant = R^2 as pictured > > in Fig. 8.2. It is interesting to note that the field is > > the same up and down wind and that the intensity is > > larger in the directions at right angles to the flow. > > Don't have that book > > Each wavefront (for sound), however, forms a sphere around the point from > which it was emitted. Really? What's the general form of the wave equation for that? > The source continues to move, so successive wave cycles have the centre of > their spherical wavefront at a different position If the field for each source position (instant) could manifest itself instantaneously maybe, but the field doesn't/can't. The disturbances must propagate from the source outward at finite speed. Thus for every dx the field propagates the source moves forward some ds... The result of this is as described in the reference provided, and I described earlier. Namely, the resulting overall sound field is a flatten ellipsoid contracted along axis of motion by precisely Sqrt(1 - [v/c]^2), a.k.a. it undergoes a Lorentz contraction. > What has a surface of constant sound pressure got to do with anything in SR? Think about it for awhile..... > > Go check it out for yourself. As for using the words "back and forth" > > I guess I should of said cyclic... > > Yes Paul Stowe |