Is Length Contraction in SR physical??
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From: Inertial on 12 Feb 2010 18:09 "kenseto" <kenseto(a)erinet.com> wrote in message news:bc26ba47-6e5f-4202-aa13-97ebbb1e9bf0(a)a5g2000yqi.googlegroups.com... > On Feb 11, 7:59 pm, "Inertial" <relativ...(a)rest.com> wrote: >> "kenseto" <kens...(a)erinet.com> wrote in message >> >> news:3ab08ba8-abb2-4ba6-9fb6-d4ae8b396b69(a)z26g2000yqm.googlegroups.com... >> >> >> >> >> >> > On Feb 11, 10:32 am, PD <thedraperfam...(a)gmail.com> wrote: >> >> That is not so, Ken. You see, that is the only way YOU can think of >> >> this happening, and so you assume it IS the only way it can happen. In >> >> this way, you prevent yourself from learning anything new. >> >> >> Things can be physically contracted without being materially >> >> contracted. >> >> However, YOU can only think of one way something can be physically >> >> contracted, and that's if it's materially contracted. That's YOUR >> >> limitation, and yours only. >> >> > No things cannot be physically contracted without materially >> > contracted. The word physical has the meaning of "of matter; material" >> > in the dictionary. I don't understand why you insist to give the word >> > physical a new meaning that is not associated with material. >> > Furthermore in SR there is geometric contraction effect....why don't >> > you use that instead of "physical contraction"? >> >> So you are using 'physical' as a synonym for 'material' .. why not just >> say >> 'material' and then we'll all agree with you. As is evident, the word >> 'physical' is a term that causes confusion. > > In the dictionary physical is defined as (matter, material). The > confusion is on your part when you tried to hijack the word physical > to give it a completely different meaning than what is defined in the > dictionary. So you are claiming that fields (which are immaterial) are not physical ?? If they are not physical, what are they? And how can they affect physical things? >> So a ladder tilting over is (by your use of the word) physically >> unchanged, >> but it is also true that it is not as tall, and so can it fit through >> doorway gap that is shorter than the ladder's length. > > This is not the same as the longer material pole can fit into a > shorter material barn with both doors close simultaneously. But a longer ladder fits thru a shorter doorway > This > requires real physical or material contraction. So you must then claim a ladder gets physically shorter when you tilt it. So a 6 foot ladder is physically contracted when you tilt it ?? How long is a six foot ladder when you tilt it. >> Would *you* describe the tilted ladder passing through the shorter >> doorway >> as something 'physical'? Does the ladder physically get to the other >> side >> of the doorway? Is the a rotation of a ladder something physical? > > No it is not physicsl contraction; it is a geometric projection. I didn't ask if it was a physical contraction .. I asked if it something physical happened. Surely you would agree that the rotation of the ladder changes something physical about the combination of ladder and doorway (the combined system of two objects). Even though individually there was no physical intrinsic change to either of them. That physical change to the system allows the ladder to fit thru the doorway and pass to the other side. That is the same with the pole and barn. There is no physical intrinsic change to either the pole or the barn in SR. However, there is a physical change to the combination of pole and barn. This allows the barn doors to close simultaneously with the pole between them. Do you see now?
From: JT on 12 Feb 2010 18:29 On 13 Feb, 00:09, "Inertial" <relativ...(a)rest.com> wrote: > "kenseto" <kens...(a)erinet.com> wrote in message > > news:bc26ba47-6e5f-4202-aa13-97ebbb1e9bf0(a)a5g2000yqi.googlegroups.com... > > > > > > > On Feb 11, 7:59 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> "kenseto" <kens...(a)erinet.com> wrote in message > > >>news:3ab08ba8-abb2-4ba6-9fb6-d4ae8b396b69(a)z26g2000yqm.googlegroups.com.... > > >> > On Feb 11, 10:32 am, PD <thedraperfam...(a)gmail.com> wrote: > >> >> That is not so, Ken. You see, that is the only way YOU can think of > >> >> this happening, and so you assume it IS the only way it can happen. In > >> >> this way, you prevent yourself from learning anything new. > > >> >> Things can be physically contracted without being materially > >> >> contracted. > >> >> However, YOU can only think of one way something can be physically > >> >> contracted, and that's if it's materially contracted. That's YOUR > >> >> limitation, and yours only. > > >> > No things cannot be physically contracted without materially > >> > contracted. The word physical has the meaning of "of matter; material" > >> > in the dictionary. I don't understand why you insist to give the word > >> > physical a new meaning that is not associated with material. > >> > Furthermore in SR there is geometric contraction effect....why don't > >> > you use that instead of "physical contraction"? > > >> So you are using 'physical' as a synonym for 'material' .. why not just > >> say > >> 'material' and then we'll all agree with you. As is evident, the word > >> 'physical' is a term that causes confusion. > > > In the dictionary physical is defined as (matter, material). The > > confusion is on your part when you tried to hijack the word physical > > to give it a completely different meaning than what is defined in the > > dictionary. > > So you are claiming that fields (which are immaterial) are not physical ?? > If they are not physical, what are they? And how can they affect physical > things? > > >> So a ladder tilting over is (by your use of the word) physically > >> unchanged, > >> but it is also true that it is not as tall, and so can it fit through > >> doorway gap that is shorter than the ladder's length. > > > This is not the same as the longer material pole can fit into a > > shorter material barn with both doors close simultaneously. > > But a longer ladder fits thru a shorter doorway > > > This > > requires real physical or material contraction. > > So you must then claim a ladder gets physically shorter when you tilt it. So > a 6 foot ladder is physically contracted when you tilt it ?? How long is a > six foot ladder when you tilt it. > > >> Would *you* describe the tilted ladder passing through the shorter > >> doorway > >> as something 'physical'? Does the ladder physically get to the other > >> side > >> of the doorway? Is the a rotation of a ladder something physical? > > > No it is not physicsl contraction; it is a geometric projection. > > I didn't ask if it was a physical contraction .. I asked if it something > physical happened. Surely you would agree that the rotation of the ladder > changes something physical about the combination of ladder and doorway (the > combined system of two objects). Even though individually there was no > physical intrinsic change to either of them. That physical change to the > system allows the ladder to fit thru the doorway and pass to the other side. > > That is the same with the pole and barn. There is no physical intrinsic > change to either the pole or the barn in SR. However, there is a physical > change to the combination of pole and barn. This allows the barn doors to > close simultaneously with the pole between them. Your analogy is hilarious there is no rotation of the pole into another dimension what is even more hilarious is that you seem to miss the point that the Lorentz transformed meters is variant between the frames thus what you really says is looky looky my 3 meters banana fit in my two meters cucumber see the amazing properties of spacetime........... Well i never was that impressed by *the use* of variant units... Especially not when some less gifted try to compare them and show big eyes when you fit more shorter meter units into fewer longer units. For me that is no suprise it is due to the fucked up meter system due to projection and have nothing soever to do with reality. JT > Do you see now?- Dölj citerad text - > > - Visa citerad text -
From: Paul Stowe on 13 Feb 2010 01:03 On Feb 11, 8:12 pm, "Inertial" <relativ...(a)rest.com> wrote: > "PaulStowe" <theaether...(a)gmail.com> wrote in message > > news:7c846ac6-1ab0-4a6b-b1fd-3b38936c6f90(a)u19g2000prh.googlegroups.com... > > > > > > > On Feb 11, 4:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> "PaulStowe" <theaether...(a)gmail.com> wrote in message > > >>news:3b3fb45b-8442-413c-bd96-df4dd57c8b50(a)m35g2000prh.googlegroups.com.... > > >> > On Feb 11, 1:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> >> "PaulStowe" <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: > >> >> >> "PaulStowe" <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? > > >> Why do you need to know the equation for a sphere? > > > Then the equation should be simple to present. Hint, > > >http://en.wikipedia.org/wiki/Wave_equation > > I don't need a wave equation for the equation for a sphere. > > > > > > >> >> 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. > > >> No need to be instantaneous > > >> > The disturbances must propagate from the source outward at finite > >> > speed. > > >> Yes .. in all directions at the same speed wrt the medium. Hence you get > >> a > >> sphere. > > > No, they don't It's not a cartoon, > > I didn't say it was > > > where the source stops for an > > instant, emits a pulse, then moves to the next position, stops and > > pulses. > > I didn't say it did > > > Both are continuous, > > Yes > > > thus the wavefronts cannot possibly be > > perfectly spherical. > > Why not > > > You might think it to be teardrop shaped... > > >> And as the source is going slower than the speed of propagation in the > >> medium, the overall bounds of the wavefront is always a sphere .. the > >> sphere > >> defined by the leading wavefront. > > > So, with v = 0.999c you still think it's spherical? > > Yes .. of course it is. > > >> > Thus for every dx the field propagates the source moves forward some > >> > ds... > > >> Pretty much what I said > > >> > 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. > > >> But a wave-front is spherical. What is a 'sound field', and what do > >> areas > >> of constant pressure have to do with SR? > > You didn't answer my question > > > How do you think that can be if c is independent of the speed of the > > source??? > > It is spherical in all frames of reference because the light travels at c in > all directions from the source. > > >> >> What has a surface of constant sound pressure got to do with anything > >> >> in > >> >> SR? > > >> > Think about it for awhile..... > > >> OK .. just did. No answer. So .. seeing it is your claim, what does > >> sound > >> pressure have to do with SR? > > > One can lead a person to information but cannot make'em think. > > So you don't know. Why not just admit it instead of bullshitting and > avoiding questions. No, but my interest wanes in attempting to explain to cynics. You might try looking at appendix C of http://eprints.soton.ac.uk/64784/01/bassett.pdf And looking at Ref 68 of this document. Good luck
From: BURT on 13 Feb 2010 01:12 On Feb 12, 10:03 pm, Paul Stowe <theaether...(a)gmail.com> wrote: > On Feb 11, 8:12 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > > > > > "PaulStowe" <theaether...(a)gmail.com> wrote in message > > >news:7c846ac6-1ab0-4a6b-b1fd-3b38936c6f90(a)u19g2000prh.googlegroups.com.... > > > > On Feb 11, 4:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > > >> "PaulStowe" <theaether...(a)gmail.com> wrote in message > > > >>news:3b3fb45b-8442-413c-bd96-df4dd57c8b50(a)m35g2000prh.googlegroups.com... > > > >> > On Feb 11, 1:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > > >> >> "PaulStowe" <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: > > >> >> >> "PaulStowe" <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? > > > >> Why do you need to know the equation for a sphere? > > > > Then the equation should be simple to present. Hint, > > > >http://en.wikipedia.org/wiki/Wave_equation > > > I don't need a wave equation for the equation for a sphere. > > > >> >> 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. > > > >> No need to be instantaneous > > > >> > The disturbances must propagate from the source outward at finite > > >> > speed. > > > >> Yes .. in all directions at the same speed wrt the medium. Hence you get > > >> a > > >> sphere. > > > > No, they don't It's not a cartoon, > > > I didn't say it was > > > > where the source stops for an > > > instant, emits a pulse, then moves to the next position, stops and > > > pulses. > > > I didn't say it did > > > > Both are continuous, > > > Yes > > > > thus the wavefronts cannot possibly be > > > perfectly spherical. > > > Why not > > > > You might think it to be teardrop shaped... > > > >> And as the source is going slower than the speed of propagation in the > > >> medium, the overall bounds of the wavefront is always a sphere .. the > > >> sphere > > >> defined by the leading wavefront. > > > > So, with v = 0.999c you still think it's spherical? > > > Yes .. of course it is. > > > >> > Thus for every dx the field propagates the source moves forward some > > >> > ds... > > > >> Pretty much what I said > > > >> > 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. > > > >> But a wave-front is spherical. What is a 'sound field', and what do > > >> areas > > >> of constant pressure have to do with SR? > > > You didn't answer my question > > > > How do you think that can be if c is independent of the speed of the > > > source??? > > > It is spherical in all frames of reference because the light travels at c in > > all directions from the source. > > > >> >> What has a surface of constant sound pressure got to do with anything > > >> >> in > > >> >> SR? > > > >> > Think about it for awhile..... > > > >> OK .. just did. No answer. So .. seeing it is your claim, what does > > >> sound > > >> pressure have to do with SR? > > > > One can lead a person to information but cannot make'em think. > > > So you don't know. Why not just admit it instead of bullshitting and > > avoiding questions. > > No, but my interest wanes in attempting to explain to cynics. You > might try looking at appendix C of > > http://eprints.soton.ac.uk/64784/01/bassett.pdf > > And looking at Ref 68 of this document. > > Good luck- Hide quoted text - > > - Show quoted text - Flatend atoms don't work in physics. Mitch Raemsch
From: Paul Stowe on 13 Feb 2010 01:13
On Feb 12, 10:03 pm, Paul Stowe <theaether...(a)gmail.com> wrote: > On Feb 11, 8:12 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > > > > > "PaulStowe" <theaether...(a)gmail.com> wrote in message > > >news:7c846ac6-1ab0-4a6b-b1fd-3b38936c6f90(a)u19g2000prh.googlegroups.com.... > > > > On Feb 11, 4:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > > >> "PaulStowe" <theaether...(a)gmail.com> wrote in message > > > >>news:3b3fb45b-8442-413c-bd96-df4dd57c8b50(a)m35g2000prh.googlegroups.com... > > > >> > On Feb 11, 1:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > > >> >> "PaulStowe" <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: > > >> >> >> "PaulStowe" <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? > > > >> Why do you need to know the equation for a sphere? > > > > Then the equation should be simple to present. Hint, > > > >http://en.wikipedia.org/wiki/Wave_equation > > > I don't need a wave equation for the equation for a sphere. > > > >> >> 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. > > > >> No need to be instantaneous > > > >> > The disturbances must propagate from the source outward at finite > > >> > speed. > > > >> Yes .. in all directions at the same speed wrt the medium. Hence you get > > >> a > > >> sphere. > > > > No, they don't It's not a cartoon, > > > I didn't say it was > > > > where the source stops for an > > > instant, emits a pulse, then moves to the next position, stops and > > > pulses. > > > I didn't say it did > > > > Both are continuous, > > > Yes > > > > thus the wavefronts cannot possibly be > > > perfectly spherical. > > > Why not > > > > You might think it to be teardrop shaped... > > > >> And as the source is going slower than the speed of propagation in the > > >> medium, the overall bounds of the wavefront is always a sphere .. the > > >> sphere > > >> defined by the leading wavefront. > > > > So, with v = 0.999c you still think it's spherical? > > > Yes .. of course it is. > > > >> > Thus for every dx the field propagates the source moves forward some > > >> > ds... > > > >> Pretty much what I said > > > >> > 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. > > > >> But a wave-front is spherical. What is a 'sound field', and what do > > >> areas > > >> of constant pressure have to do with SR? > > > You didn't answer my question > > > > How do you think that can be if c is independent of the speed of the > > > source??? > > > It is spherical in all frames of reference because the light travels at c in > > all directions from the source. > > > >> >> What has a surface of constant sound pressure got to do with anything > > >> >> in > > >> >> SR? > > > >> > Think about it for awhile..... > > > >> OK .. just did. No answer. So .. seeing it is your claim, what does > > >> sound > > >> pressure have to do with SR? > > > > One can lead a person to information but cannot make'em think. > > > So you don't know. Why not just admit it instead of bullshitting and > > avoiding questions. > > No, but my interest wanes in attempting to explain to cynics. You > might try looking at appendix C of > > http://eprints.soton.ac.uk/64784/01/bassett.pdf > > And looking at Ref 68 of this document. > > Good luck Also, http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PHESEM000022000003000318000001&idtype=cvips&gifs=yes&ref=no "... These findings are in line with the acoustic Lorentz invariance shown by linear acoustic fields from uniformly moving sound sources. ..." |