Notion of Absolute Clock Synchronization in SR
in [Relativity]
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From: PD on 7 Apr 2010 16:28 On Apr 7, 3:14 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > On Apr 7, 3:35 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > On Apr 7, 1:56 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > On Apr 7, 2:52 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Apr 7, 1:49 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > > On Apr 7, 2:36 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > On Apr 7, 9:43 am, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > > > > On Apr 7, 9:45 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > On Apr 7, 1:32 am, Tom Adams <tadams...(a)yahoo.com> wrote: > > > > > > > > > > On Mar 11, 11:35 am, GSS <gurcharn_san...(a)yahoo.com> wrote: > > > > > > > > > > > As per Newtonian notion of absolute space and time, clocks can be > > > > > > > > > > synchronized in absolute terms such that identical precision atomic > > > > > > > > > > clocks located anywhere within the solar system and in any state of > > > > > > > > > > motion, will read the same time t1 when a standard master clock reads > > > > > > > > > > t1. This notion of absolute clock synchronization implies the notion > > > > > > > > > > of absolute simultaneity. > > > > > > > > > > > However, as per SR, spatial distance and time measurements have been > > > > > > > > > > rendered 'relative' and cannot be the same value for different > > > > > > > > > > observers in different states of motion. As per SR the notion of > > > > > > > > > > global 'absolute simultaneity' is fundamentally invalid for different > > > > > > > > > > observers in different states of motion. Therefore, the notion of > > > > > > > > > > global 'absolute clock synchronization' (in contrast to e- > > > > > > > > > > synchronization) is no longer valid in SR. > > > > > > > > > > > Since the term 'absolute clock synchronization' is often used in > > > > > > > > > > discussions, I would like to request some Relativity experts to kindly > > > > > > > > > > clarify the precise definition of absolute clock synchronization in > > > > > > > > > > SR. Kindly illustrate the procedure, through some 'thought experiment' > > > > > > > > > > or 'gedanken', to achieve absolute clock synchronization for all > > > > > > > > > > observers in different states of motion within our solar system. > > > > > > > > > > > Further, I also need some expert opinion on the following situation, > > > > > > > > > > involving clock synchronization. > > > > > > > > > > > Two identical precision atomic clocks are positioned side by side at > > > > > > > > > > point A on the surface of earth and mutually synchronized to ensure > > > > > > > > > > that > > > > > > > > > > (a) their clock rates or frequencies are exactly matched or > > > > > > > > > > synchronized > > > > > > > > > > (b) their instantaneous timing offsets are eliminated to ensure that a > > > > > > > > > > common trigger pulse yields the same timing reading t1 from both > > > > > > > > > > clocks. > > > > > > > > > > > Assuming the inherent drift of the two atomic clocks is identical and > > > > > > > > > > well within 100 ps per day, it can be demonstrated that while the two > > > > > > > > > > clocks remain side by side, their synchronization, after a period of > > > > > > > > > > one day, is retained at well within one ns accuracy. > > > > > > > > > > > Let us shift one of the synchronized atomic clocks to a position B > > > > > > > > > > such that distance AB is about 30 km. > > > > > > > > > > Stop right there. You are outside of the scope of SR. All acceleration > > > > > > > > > is outside the scope. SR cannot address your question. > > > > > > > > ================== > > > > > > > > > This is a mistake on two fronts. SR can and does routinely handle > > > > > > > > accelerations. > > > > > > > > Secondly, the resolution of the twin paradox is a straightforward > > > > > > > > implication of the fact that straight world lines have longer proper > > > > > > > > time integrated along the path, compared to bent world lines. This is > > > > > > > > something that can be seen in a spacetime diagram from basic SR. > > > > > > > > Penrose makes this point very succinctly, for example. > > > > > > > > Can you show us a four-vector proof that the final term > > > > > > > of that exercise, "elapsed proper time" > > > > > > > preserves the relevant symmetries? > > > > > >http://en.wikipedia.org/wiki/Noether%27s_theorem#Applications > > > > > > > What "relevant symmetries" do you think a measurable physical quantity > > > > > > should preserve? > > > > > > Time and energy might be a good for a start. > > > > > Time and energy are not symmetries. > > > > << Application of Noether's theorem allows physicists to > > > gain powerful insights into any general theory in physics, > > > by just analyzing the various transformations that would > > > make the form of the laws involved invariant. For example: > > > > * the invariance of physical systems with respect > > > to spatial translation (in other words, that the laws > > > of physics do not vary with locations in space) gives > > > the law of conservation of linear momentum; > > > * invariance with respect to rotation gives the law > > > of conservation of angular momentum; > > * invariance with respect to time translation gives > the well-known law of conservation of energy >> > > http://en.wikipedia.org/wiki/Noether%27s_theorem#Applications > > > > > > What symmetries did you have in > > > > > mind? > > > > And do you understand the difference between a measurable physical > > > > quantity and a physical law? > > > Right. Do you know the difference between a physical law (which is > > what your web blurb is referring to) and a measurable physical > > quantity (such as proper time)? > > > So far, you show no ability to distinguish them at all. So I take it you can't. > > Remember... You have given up LET for SR > so rulers are not dependent on inertial frames. > Minkowski Spacehttp://www.bartleby.com/173/17.html > > I can tape a metre stick to a gun barrel and > that is a proper clock. > > K.E. = 1/2 mv^2 > > The hijackers of the world would be interested > to hear from you which inertial frame most > slows the clock and weakens the lawmam's > bullet. > > Sue... > > > > > > > [rest of nonsequiturs ignored] > > > > > > What does the space-time curvature tell > > > > > us about the muzzle velocity of a gun: > > > > > > A) In a gravitational potenetal. > > > > > > B) When signs are wrong converting from coordinate time. > > > > > > ;-) > > > > > > Sue... > > > > > > > Note your link talks about how *laws of physics* preserve certain > > > > > > symmetries, but measurable physical quantities are not laws of > > > > > > physics. I hope you don't get the two confused. > > > > > > > > Sue... > > > > > > > > > > Strictly speaking, the twin paradox is not part of SR since in > > > > > > > > > involves acceleration. The space-time paths that the twins take do > > > > > > > > > involve different elapsed times in a reference frame, but taking one > > > > > > > > > of the paths involves acceleration. > > > > > > > > > > > As per Newtonian notion of > > > > > > > > > > absolute space and time, the mutual synchronization of the two clocks, > > > > > > > > > > positioned at points A and B, will be retained in tact and this > > > > > > > > > > synchronization can be referred as 'absolute synchronization'. But > > > > > > > > > > according to SR, the mutual synchronization of the two clocks will > > > > > > > > > > 'breakdown' during the shifting of one of the clocks from point A to > > > > > > > > > > point B. Since 'after' shifting of one clock to point B on the surface > > > > > > > > > > of earth, there is no relative motion between the two clocks, their > > > > > > > > > > time rates or frequencies will again 'become' synchronized. Therefore, > > > > > > > > > > the only persisting effect of the 'synchronization breakdown' during > > > > > > > > > > shifting or repositioning of the two clocks, will be a motion induced > > > > > > > > > > constant time offset, say dT, in the instantaneous readings of the two > > > > > > > > > > clocks. > > > > > > > > > > > My question to the learned Relativity experts is: > > > > > > > > > > What is the order of magnitude of this 'relative motion induced' > > > > > > > > > > timing offset dT between the two clocks? > > > > > > > > > > Can it be precisely calculated in SR? Is it likely to be within a few > > > > > > > > > > nanoseconds or less? > > > > > > > > > > > Suppose we now shift the clock at point B to bring it back to point A, > > > > > > > > > > (with an identical speed and acceleration profile), will this timing > > > > > > > > > > offset dT now increase to 2.dT or reduce to zero? > > > > > > > > > > > I shall be thankful to the Relativity experts for their valuable > > > > > > > > > > opinions and clarifications. > > > > > > > > > > > GSS > >
From: Da Do Ron Ron on 7 Apr 2010 16:37 On Mar 12, 7:27 pm, "Inertial" <relativ...(a)rest.com> wrote: > "Da Do Ron Ron" <ron_ai...(a)hotmail.com> wrote in messagenews:cf5a6f3a-22e3-4ca6-8e8c-592fc3c45cbf(a)15g2000yqi.googlegroups.com... > > > > > On Mar 11, 5:20 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> "Da Do Ron Ron" <ron_ai...(a)hotmail.com> wrote in > >> messagenews:0df07b16-99d7-4f22-9342-c63357088dc0(a)upsg2000gro.googlegroups.com... > > >> > On Mar 11, 12:58 pm, PD <thedraperfam...(a)gmail.com> wrote: > >> >> On Mar 11, 9:35 am, GSS <gurcharn_san...(a)yahoo.com> wrote: > > >> >> > Kindly illustrate the procedure, through some 'thought experiment' > >> >> > or 'gedanken', to achieve absolute clock synchronization for all > >> >> > observers in different states of motion within our solar system. > > >> >> This cannot be done, given what we know about the laws of physics. > > >> > Careful, PD, ol' boy, you know that a negative can't be proved. > > >> Yes it can .. because we know that we can have three clocks where A and B > >> are in sync (in one frame), and B and C are in sync (in another), but A > >> and > >> C are not (in either). That proves there is no such thing as absolute > >> clock > >> sync. > > > You did not prove that A and B were actually in synch, > > I don't have to *prove* that they are .. I am describing a scenario, and in > that scenario we have synced the clocks .. that means they are in sync. > By what process were they synch'd? > > so your > > argument is no good. > > Yes it is > > > Besides, absolute synch can exist in a single frame between a > > pair of clocks, and you cannot prove that this cannot happen. > > That is not ABSOLUTE sync. That is frame-dependent sync, because in OTHER > frames those same clocks are NOT in sync > > Really .. this isn't that hard a concept to grasp Why are they not in synch per other frames?
From: Tom Adams on 7 Apr 2010 16:41 On Apr 7, 3:21 am, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > news:827aa470-d686-4b02-a943-ada1caebe193(a)g30g2000yqc.googlegroups.com... > On Mar 11, 11:35 am, GSS <gurcharn_san...(a)yahoo.com> wrote: > > > > > > > As per Newtonian notion of absolute space and time, clocks can be > > synchronized in absolute terms such that identical precision atomic > > clocks located anywhere within the solar system and in any state of > > motion, will read the same time t1 when a standard master clock reads > > t1. This notion of absolute clock synchronization implies the notion > > of absolute simultaneity. > > > However, as per SR, spatial distance and time measurements have been > > rendered 'relative' and cannot be the same value for different > > observers in different states of motion. As per SR the notion of > > global 'absolute simultaneity' is fundamentally invalid for different > > observers in different states of motion. Therefore, the notion of > > global 'absolute clock synchronization' (in contrast to e- > > synchronization) is no longer valid in SR. > > > Since the term 'absolute clock synchronization' is often used in > > discussions, I would like to request some Relativity experts to kindly > > clarify the precise definition of absolute clock synchronization in > > SR. Kindly illustrate the procedure, through some 'thought experiment' > > or 'gedanken', to achieve absolute clock synchronization for all > > observers in different states of motion within our solar system. > > > Further, I also need some expert opinion on the following situation, > > involving clock synchronization. > > > Two identical precision atomic clocks are positioned side by side at > > point A on the surface of earth and mutually synchronized to ensure > > that > > (a) their clock rates or frequencies are exactly matched or > > synchronized > > (b) their instantaneous timing offsets are eliminated to ensure that a > > common trigger pulse yields the same timing reading t1 from both > > clocks. > > > Assuming the inherent drift of the two atomic clocks is identical and > > well within 100 ps per day, it can be demonstrated that while the two > > clocks remain side by side, their synchronization, after a period of > > one day, is retained at well within one ns accuracy. > > > Let us shift one of the synchronized atomic clocks to a position B > > such that distance AB is about 30 km. > > Stop right there. You are outside of the scope of SR. All acceleration > is outside the scope. SR cannot address your question. > > Strictly speaking, the twin paradox is not part of SR since in > involves acceleration. The space-time paths that the twins take do > involve different elapsed times in a reference frame, but taking one > of the paths involves acceleration. > =========================================== > Stop right there. > Strictly speaking, the twin paradox is very much part of SR since it does > NOT involve acceleration. > The outbound journey is at velocity v and the inbound is at velocity -v, the > path is a two-sided polygon. Yes, but the twin has to go from v to -v. > > "If we assume that the result proved for a polygonal line is also valid for > a continuously curved line, we arrive at this result: If one of two > synchronous clocks at A is moved in a closed curve with constant velocity > until it returns to A, the journey lasting t seconds, then by the clock > which has remained at rest the travelled clock on its arrival at A will be > 1/2 t v^2/c^2 second slow." -- Einstein, 1905, "On the Electrodynamics of > Moving Bodies". Yeah, it's in the paper. But there is acceleration. > Thence we conclude that clock B (having travelled and being younger than > clock A) meets clock A before clock A meets clock B. The clock are twin > clocks, and in real physics A meets B when B meets A. That's the paradox. No, there is no real paradox. One twin accelerated and the other did not. You can't just reverse A and B. You can demonstrate the so-called "paradox" within SR by having the clock traveling at v pass close to another clock traveling back at - v. When they are close together they can synchronize. But when the clock traveling at -v gets back to the clock at rest, it will now be "younger" (less time ticked off) demonstrating that one path through space-time gets to the future faster than the other. > > http://www.merriam-webster.com/dictionary/paradox > > 2 a : a statement that is seemingly contradictory or opposed to common sense > and yet is perhaps true > > b : a self-contradictory statement that at first seems true > > c : an argument that apparently derives self-contradictory conclusions by > valid deduction from acceptable premises > > No need for any word salad about 'synchronized' or 'spacetime' or > 'acceleration', the paradox is: B meets A before A meets B, contradictory to > the acceptable premise that A meets B when B meets A. > > ================================================ > > > > > As per Newtonian notion of > > absolute space and time, the mutual synchronization of the two clocks, > > positioned at points A and B, will be retained in tact and this > > synchronization can be referred as 'absolute synchronization'. But > > according to SR, the mutual synchronization of the two clocks will > > 'breakdown' during the shifting of one of the clocks from point A to > > point B. Since 'after' shifting of one clock to point B on the surface > > of earth, there is no relative motion between the two clocks, their > > time rates or frequencies will again 'become' synchronized. Therefore, > > the only persisting effect of the 'synchronization breakdown' during > > shifting or repositioning of the two clocks, will be a motion induced > > constant time offset, say dT, in the instantaneous readings of the two > > clocks. > > > My question to the learned Relativity experts is: > > What is the order of magnitude of this 'relative motion induced' > > timing offset dT between the two clocks? > > Can it be precisely calculated in SR? Is it likely to be within a few > > nanoseconds or less? > > > Suppose we now shift the clock at point B to bring it back to point A, > > (with an identical speed and acceleration profile), will this timing > > offset dT now increase to 2.dT or reduce to zero? > > > I shall be thankful to the Relativity experts for their valuable > > opinions and clarifications. > > > GSS- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: Sue... on 7 Apr 2010 16:42 On Apr 7, 4:28 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 7, 3:14 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > On Apr 7, 3:35 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Apr 7, 1:56 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > On Apr 7, 2:52 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > On Apr 7, 1:49 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > > > On Apr 7, 2:36 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > On Apr 7, 9:43 am, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > > > > > On Apr 7, 9:45 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > > On Apr 7, 1:32 am, Tom Adams <tadams...(a)yahoo.com> wrote: > > > > > > > > > > > On Mar 11, 11:35 am, GSS <gurcharn_san...(a)yahoo.com> wrote: > > > > > > > > > > > > As per Newtonian notion of absolute space and time, clocks can be > > > > > > > > > > > synchronized in absolute terms such that identical precision atomic > > > > > > > > > > > clocks located anywhere within the solar system and in any state of > > > > > > > > > > > motion, will read the same time t1 when a standard master clock reads > > > > > > > > > > > t1. This notion of absolute clock synchronization implies the notion > > > > > > > > > > > of absolute simultaneity. > > > > > > > > > > > > However, as per SR, spatial distance and time measurements have been > > > > > > > > > > > rendered 'relative' and cannot be the same value for different > > > > > > > > > > > observers in different states of motion. As per SR the notion of > > > > > > > > > > > global 'absolute simultaneity' is fundamentally invalid for different > > > > > > > > > > > observers in different states of motion. Therefore, the notion of > > > > > > > > > > > global 'absolute clock synchronization' (in contrast to e- > > > > > > > > > > > synchronization) is no longer valid in SR. > > > > > > > > > > > > Since the term 'absolute clock synchronization' is often used in > > > > > > > > > > > discussions, I would like to request some Relativity experts to kindly > > > > > > > > > > > clarify the precise definition of absolute clock synchronization in > > > > > > > > > > > SR. Kindly illustrate the procedure, through some 'thought experiment' > > > > > > > > > > > or 'gedanken', to achieve absolute clock synchronization for all > > > > > > > > > > > observers in different states of motion within our solar system. > > > > > > > > > > > > Further, I also need some expert opinion on the following situation, > > > > > > > > > > > involving clock synchronization. > > > > > > > > > > > > Two identical precision atomic clocks are positioned side by side at > > > > > > > > > > > point A on the surface of earth and mutually synchronized to ensure > > > > > > > > > > > that > > > > > > > > > > > (a) their clock rates or frequencies are exactly matched or > > > > > > > > > > > synchronized > > > > > > > > > > > (b) their instantaneous timing offsets are eliminated to ensure that a > > > > > > > > > > > common trigger pulse yields the same timing reading t1 from both > > > > > > > > > > > clocks. > > > > > > > > > > > > Assuming the inherent drift of the two atomic clocks is identical and > > > > > > > > > > > well within 100 ps per day, it can be demonstrated that while the two > > > > > > > > > > > clocks remain side by side, their synchronization, after a period of > > > > > > > > > > > one day, is retained at well within one ns accuracy. > > > > > > > > > > > > Let us shift one of the synchronized atomic clocks to a position B > > > > > > > > > > > such that distance AB is about 30 km. > > > > > > > > > > > Stop right there. You are outside of the scope of SR. All acceleration > > > > > > > > > > is outside the scope. SR cannot address your question. > > > > > > > > > ================== > > > > > > > > > > This is a mistake on two fronts. SR can and does routinely handle > > > > > > > > > accelerations. > > > > > > > > > Secondly, the resolution of the twin paradox is a straightforward > > > > > > > > > implication of the fact that straight world lines have longer proper > > > > > > > > > time integrated along the path, compared to bent world lines. This is > > > > > > > > > something that can be seen in a spacetime diagram from basic SR. > > > > > > > > > Penrose makes this point very succinctly, for example. > > > > > > > > > Can you show us a four-vector proof that the final term > > > > > > > > of that exercise, "elapsed proper time" > > > > > > > > preserves the relevant symmetries? > > > > > > >http://en.wikipedia.org/wiki/Noether%27s_theorem#Applications > > > > > > > > What "relevant symmetries" do you think a measurable physical quantity > > > > > > > should preserve? > > > > > > > Time and energy might be a good for a start. > > > > > > Time and energy are not symmetries. > > > > > << Application of Noether's theorem allows physicists to > > > > gain powerful insights into any general theory in physics, > > > > by just analyzing the various transformations that would > > > > make the form of the laws involved invariant. For example: > > > > > * the invariance of physical systems with respect > > > > to spatial translation (in other words, that the laws > > > > of physics do not vary with locations in space) gives > > > > the law of conservation of linear momentum; > > > > * invariance with respect to rotation gives the law > > > > of conservation of angular momentum; > * invariance with respect to time translation gives the well-known law of conservation of energy >> > http://en.wikipedia.org/wiki/Noether%27s_theorem#Applications > > > > > What symmetries did you have in > > > > > > mind? > > > > > And do you understand the difference between a measurable physical > > > > > quantity and a physical law? > > > > Right. Do you know the difference between a physical law (which is > > > what your web blurb is referring to) and a measurable physical > > > quantity (such as proper time)? > > > > So far, you show no ability to distinguish them at all. > ================ > So I take it you can't. Pseudoscience appeals to false authority, to emotion, sentiment, or distrust of established fact. http://www.quackwatch.org/01QuackeryRelatedTopics/pseudo.html PD, That is so unlike you. Usually you have a story for everything. Give it another try: Remember... You have given up LET for SR so rulers are not dependent on inertial frames. Minkowski Space http://www.bartleby.com/173/17.html I can tape a metre stick to a gun barrel and that is a proper clock. K.E. = 1/2 mv^2 The hijackers of the world would be interested to hear from you which inertial frame most slows the clock and weakens the lawmam's bullet. Sue...
From: Tom Roberts on 7 Apr 2010 16:42
Tom Adams wrote: > Stop right there. You are outside of the scope of SR. All acceleration > is outside the scope. SR cannot address your question. This is just plain not true. SR can handle acceleration just fine. Of course an accelerated system is not an inertial frame, but the math is self-consistent, meaningful, and agrees with experiments. It is also complicated, so one must be careful. SR is used to model particle ACCELERATORS all the time. SR cannot handle gravitation -- in relativity that is modeled as a curved manifold, and the equations of SR require that the manifold be flat. Indeed, GR can be considered to be SR generalized to non-flat manifolds; the increase in complexity is enormous, and the change in ontology is significant.... > Strictly speaking, the twin paradox is not part of SR since in > involves acceleration. This is also not true, for the same reason. Tom Roberts |