Notion of Absolute Clock Synchronization in SR
in [Relativity]
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From: Androcles on 8 Apr 2010 15:26 "Tom Adams" <tadamsmar(a)yahoo.com> wrote in message news:90f361ab-8793-45de-9ac6-29c3a030eb64(a)v20g2000yqv.googlegroups.com... On Apr 8, 11:37 am, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > news:bd7d58e3-eac1-4128-aeb5-d4c4cefdc10f(a)z3g2000yqz.googlegroups.com... > On Apr 7, 3:32 am, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > > > > > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > >news:d48f740f-4aa9-4fc2-ad2f-41a59f23816f(a)w42g2000yqm.googlegroups.com... > > On Mar 12, 9:31 am, GSS <gurcharn_san...(a)yahoo.com> wrote: > > > > On Mar 11, 10:58 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Mar 11, 9:35 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 synchronization) is no longer valid in SR.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. > > > > > Sure. One such procedure is as follows. > > > > 1. Start at clock A and note the time T1. > > > > 2. Proceed to clock B by any method of travel that is guaranteed to > > > > be > > > > at constant speed. > > > > 3. At arrival at clock B, note the time T2. > > > > 4. Proceed back to clock A by the same method of travel, and at the > > > > same speed. > > > > 5. At arrival at clock A, note the time T3. > > > > 6. If T3-T2 = T2 - T1, then the clocks are synchronized. If T3-T2 > > > > > T2- > > > > T1, then clock B is running slow and should be set forward by half > > > > the > > > > difference noted. If T3-T2 < T2-T1, then clock B is running fast and > > > > should be set back by half the difference noted. > > > > >> 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. > > > > >> 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. 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. > > > > > No, this is not what SR says. The clocks are still synchronized in > > > > the > > > > frame in which they are at rest. However, they are not synchronized > > > > in > > > > any frame where the two clocks are moving. > > > > You say that two clocks 'synchronized' in their rest frame, are 'not > > > synchronized' in any other frame where the clocks are moving. Let us > > > examine the plausibility of this statement. When two identical > > > precision atomic clocks are said to be 'synchronized' in their rest > > > frame, essentially their clock frequencies are supposed to have been > > > perfectly matched. > > > The matching of the two frequencies is a physical > > > phenomenon, controlled through their hardware circuitry and > > > sophisticated components. > > > In SR, physical phenomena are defined in 4D space-time. They are > > all systems of events. They have no fixed defintion for all reference > > frames. > > > > But when the same two clocks are 'viewed' by > > > different observers in different states of motion, they appear to be > > > out of synchronization. That is their clock frequencies 'appear' to be > > > mismatched by different amount to different observers in different > > > states of motion. > > > > However, creating a mismatch in the clock frequencies of two clocks is > > > a physical phenomenon controlled through their hardware circuitry and > > > sophisticated components. How do you think different observers in > > > different states of motion actually manage to physically influence the > > > hardware circuitry and sophisticated components of the two clocks to > > > create different amounts of mismatch in their frequencies, through the > > > mere act of 'viewing' from a distance? Do you think there is some > > > 'magic' involved in creating this phenomenon, which ordinary humans > > > cannot understand? > > > The observers don't influence the system of events I referred to > > earlier. Each reference frame uses the operational definition of > > simultaneity and comes up with a different subset of events that thay > > consider to be simultaneous. So they disagree on whether the clocks > > are synchronous. > > > Physical objects are systems of events in space-time. The objects > > viewed from a reference frame are projections into space and time, > > they are like shadows that change based on the angle of projection. > > > > GSS- Hide quoted text - > > > > - Show quoted text - > > > You are a physical object that does not change as the angle of the sun > > changes. So how can your shadow be so different with different > > angles. That's what you are asking, you seem to think that is a > > paradox. > > > ============================================ > > A sundial is a physical object and is a clock. A twin sundial goes > > on an accelerated relativistic journey and returns beside the sundial > > that remained at rest. The sundial that travelled is now younger than > > the sundial that remained. > > So how can its shadow be so different with different angles? > > That's what I am asking, I seem to think that is a paradox. > > -- Androcles.- Hide quoted text - > > > - Show quoted text - > > One of the sundials just took a space-time path to the future that > took less time. > > ============================================ > That's handwaving. If it took less time it should record less time. > Prove your case. I will try. You are correct that the sundial will be younger. But sundials are curious kinds of clocks. The are really just transcribing the oscillations of the earth. If I look at a clock in a mirror, I can tell time with a mirror, is the mirror a clock? ================================================= A clock in a regular oscillator (almost perfect) and a perfect counter. A mirror is not a clock. ================================================= Suppose I had two identical mirrors. I sent one of them on a journey away and back at high speeds. It is still almost new, but the one that remained in an inertial frame is old. Now I reflect the dial of a clock in both mirrors, and the reflected clocks read the same time. If I understand your example correctly, both sundials are reflecting the oscillations of the same Earth. Correct? ================================================== Not correct, sundials measure a fraction of an oscillation, unless the sundial is near a pole when a human being is needed to count the full oscillations for half a year (it will be in shadow for the other half). But what you are saying is the sundial is part of a system. I'll accept that, but you have yet to show that the travelled object is younger without the handwaving assertion. > > It's a paradox in the sense that it seems impossible from our everyday > way of thinking, but it's not a contradiction. > ========================================== > More handwaving. How can its shadow angle be different from the > shadow angle of the sundial that is beside it? > Let's talk about a balance clock as the bozo Einstein does. > The hands count oscillations of the balance wheel, they are merely a > divider gear train. A digital watch counts oscillations of a quartz > crystal > electronically. > If they record more or less time then the count of the oscillations is > greater or less. Prove that the count changes because the clock moves. > > The seeds of this possiblilty was already in our everyday idioms. > ========================================== > We are not discussing vague possibilities, Einstein ASSERTS that > the count of the balance wheel's oscillations is different, some counts > have been lost because the clock moved. Einstein ASSERTS that time > itself changes, but a sundial doesn't show it. Produce an experiment > that supports Einstein's ridiculous claim. > > You > can meet and old friend and say "It's seems like only yesterday when > we were last together" and it won't raise a eyebrow. But try saying > "It seems like only tomorrow..." > ========================================== > Doesn't matter how subjectively you record time, a clock is an > objective instrument and when I wake up I look at the clock, not > listen to my own impressions of what time it is. > The clock is always in agreement with the sun, I know when to expect > sunrise and sunset. Quite handwaving and PROVE the clock lost > some oscillations because it moved. In particular, show an atomic > clock lost some oscillations because it moved, i.e. the moving clock > has less than 9 192 631 770 "ticks" per second of the > stationary clock. > Ref: > http://physics.nist.gov/cuu/Units/second.html- Hide quoted text - > > - Show quoted text -
From: Androcles on 8 Apr 2010 16:04 "Tom Adams" <tadamsmar(a)yahoo.com> wrote in message news:a779de06-faa9-4cd0-85df-8ee04f9aedf7(a)r18g2000yqd.googlegroups.com... On Apr 8, 12:06 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > news:4512a6c4-1d93-40b6-bc7e-84b200f3c1fb(a)u31g2000yqb.googlegroups.com... > On Apr 7, 10:05 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > > > > > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > >news:3cfbbdd8-1c7e-4113-9ea9-d9ee6a4cf187(a)g30g2000yqc.googlegroups.com... > > 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. > > ====================================== > > Not relevant, v is squared in tau = t * sqrt(1-v^2/c^2), > > so (-v)^2 = v^2. Cars go around oval race tracks without > > changing speed all the time, reversing their velocity. > > ====================================== > > > > "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. > > ======================================= > > If there were then its duration and distance would be pertinent. > > Unless you can state their relevance then acceleration is just so > > much hand-waving, like Gordon Brown dog-paddling the economy > > as he sinks, flapping his paws up and down and saying "No", > > and "Should" without answering any questions. > > > Einstein claims his result is proved for a polygonal line and a > > continuous curved line, there is no change in SPEED (not velocity) > > as the ship swings around the back of the star and returns to Earth. > > He contradicts his own xi = x'/sqrt(1-v^2/c^2), eta = y, zeta = z, > > but that's normal for his nonsense. > > ======================================= > > > > 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. > > ==================================================== > > Oh yes there is, > >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 > > > As the ship goes around turns 2 and 3 it travels at v = 0 when u = > > <unchanged speed>, > > so > > eta = y'/sqrt(1-u^2/c^2) > > and NOT > > eta = y > > Einstein wasn't bright enough to know the difference between speed > > and velocity, he was too busy reading sci-fi in school. > > ==================================================== > > > One twin accelerated and the other did not. You can't just reverse A > > and B. > > =================================================== > > > Einstein can! He can do as he likes, He's a god. He can defy the laws of > > physics. He's holy, a genius. > > The important thing is that *you* can't reverse A and B because they > took > different paths in space-time. No inertial frame will consider these > two paths to be equivalent. > > Einstein did not reverse them either. > ================================================== > > The important thing is > "Take, for example, the reciprocal electrodynamic action of a magnet and a > conductor. The observable phenomenon here depends only on the relative > motion of the conductor and the magnet... > Examples of this sort, yada, yada, yada... will hereafter be called the > ``Principle of Relativity'' > Ref: > ON THE ELECTRODYNAMICS > OF MOVING BODIES > by A. Einstein > June 30, 1905 > Einstein does reverse A and B (when it suits him). > > The important thing is Humpty Roberts has just told you SR can handle > acceleration > just fine and you've agreed with him, and here you claim acceleration is > required. That's a paradox, and the PoR requires that A and B can be > reversed. No, the PoR makes speed relative. It does not make acceleration relative. ==================================================== Yes, the PoR makes speed relative. No, it does make acceleration relative since acceleration is rate of change of velocity and velocity is relative. If the Earth goes away from the ship and then returns to the ship, which is exactly what those aboard the ship see, then the Earth changed its velocity and therefore accelerated. The PoR requires the station to come to the train. ==================================================== I agreed that SR calculations might be able to handle acceleration. I meant that it might be able to handle some calculations or inferences about acceleration. ==================================================== No, "Might be" is handwaving. Humpty Roberts is very good at it but hopeless at mathematics. No, I do not agree that SR calculations might be able to handle acceleration, so where does that leave us? No, We should agree to differ? No, Not at all, you have the burden of proof, its your claim. No, This is physics and mathematics, not religion where faith applies. ==================================================== I was not agreeing that the PoR applies to acceleration. It clearly does not apply to acceleration. ==================================================== No, CLEARLY it DOES, as I've proven above. No, Acceleration is rate of change of velocity and velocity is relative. No, The station comes to the train. No, Do not confuse force with rate of change of velocity, in case you are thinking of doing so. No, In the frame of reference of the train, the station accelerates. ==================================================== All inertial frames will agree about which clocks have accelerated and which clocks have not accelerated, the PoR does not apply. ==================================================== No, A team of scientists working under the direction of researchers from the University of Sussex have recently discovered that Einstein did not say "inertial". No, Here is a copy of their experimental results. http://www.androcles01.pwp.blueyonder.co.uk/inertial.JPG "If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B by 1/2 tv^2/c^2 (up to magnitudes of fourth and higher order), t being the time occupied in the journey from A to B. It is at once apparent that this result still holds good if the clock moves from A to B in any polygonal line, and also when the points A and B coincide. 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 tv^2/c^2 second slow. Thence we conclude that a balance-clock at the equator must go more slowly, by a very small amount, than a precisely similar clock situated at one of the poles under otherwise identical conditions." No, A continuous curve is not inertial by any stretch of the imagination. No, "Inertial" isn't relevant, and Einstein did not mean inertial. No, You are handwaving. =================================================== That is, given any curve or piecewise line in space-time, all inertial frames will agree on whether that line represents acceleration or not. Acceleration = the line is not straight in space-time. Simple as that. ============================================= No, Einstein did not say "space-time" either. No, The "space-time curve" of the station is reflected in the frame of the train. No, In any event, a "spacetime diagram" is a distance/time graph with the axes reversed to promote bullshit. No, Simple as that. No, You are handwaving. > > > > =================================================== > > 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. > > ==================================================== > > That's what I said, B meets A before A meets B. It's a whole lot > > harder to do than mere instant acceleration in zero time. > > > >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. > > > > ================================================
From: Tom Roberts on 8 Apr 2010 16:24 GSS wrote: > [...] Bottom line: while one can take two clocks at rest on earth's geoid and synchronize them in an inertial frame (e.g. the ECI), one CANNOT treat them as if they were at rest in that inertial frame. Because they aren't. The method used by the GPS to synchronize clocks in the ECI works in a way that relies on each clock moving at a constant speed wrt the frame, and at a constant gravitational potential. For a set of clocks at rest on the geoid, those conditions hold for the ECI frame. They do NOT hold for the BCRF frame, which is why it is not possible to synchronize them in that frame. The other thing you are missing is the fact that neither the ECI nor the BCRF is an inertial frame in the sense of SR -- they are LOCALLY inertial frames in the sense of GR, in which the effects of gravitation have been approximately canceled. In particular, the relative velocity between them is NOT constant -- the ECI revolves around the origin of the BCRF. This is what invalidates your attempts to apply notions of synchronization in SR to this different situation. > (i) When two clocks under consideration are mutually synchronized, > they represent a physical phenomenon which must not change with our > arbitrary choice of a reference frame. This is just plain not true. Synchronization INHERENTLY depends on the frame used. This is not "to protect the validity of [the] second postulate of SR", this is OBSERVED FOR REAL CLOCKS (specifically, the GPS). There cannot possibly be a "physical phenomenon" that represents a human's ARBITRARY decision of how to set the offsets of clocks. > [... Further nonsense based on mis-reading what I wrote and a warped > insistence on "how the world must work" that is inconsistent with > itself and with experiments.] Tom Roberts
From: Sue... on 8 Apr 2010 17:28 On Apr 8, 9:43 am, GSS <gurcharn_san...(a)yahoo.com> wrote: > On Apr 7, 1:15 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > > > > GSS wrote: > >> On Apr 6, 8:13 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > >>> GSS wrote: > >>>> On Apr 3, 9:12 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > >>>>> By saying "inertial frame" you imply the context is SR -- in SR one could set > >>>>> the offsets of two clocks such that they are synchronized in any inertial frame > >>>>> you choose. They would be synchronized with each other in that frame, but not > >>>>> with coordinate clocks of the selected frame (these two would "tick at a > >>>>> different rate" than those coordinate clocks). > >>>> You have made a very important statement which I would like to repeat > >>>> with some emphasis. "In SR one could set the *offsets* of two clocks > >>>> such that they are *synchronized* in *any* inertial frame you choose.. > >>>> They would be synchronized with each other in *that* frame." > >>>> Let us extend the analogy of two clocks fixed on earth's geoid to a > >>>> million (or more) clocks fixed on earth's geoid. Let us synchronize > >>>> all these clocks in ECI frame by synchronizing their time to UTC by > >>>> using GPS service. In this state, each and every adjoining pair of > >>>> clocks can be considered as mutually synchronized with zero time > >>>> offset between them. > ... > >>> But, of course, each pair is synchronized in the ECI frame. The concept > >>> "synchronized" is ALWAYS qualified with a frame. > > >>>> Let us *adjust* the offsets of all these clocks such that they are now > >>>> synchronized in BCRF. > >>> It is not possible to make such an "adjustment". They all have essentially the > >>> same gravitational potential, but they have different speeds relative to the > >>> BCRF -- the earth both rotates and revolves around the sun. > > >> As per your statement above, "They would be synchronized with each > >> other in that [BCRF] frame, but not with coordinate clocks of the > >> selected [BCRF] frame (these two would "tick at a different rate" than > >> those coordinate clocks)." > > > That was for two clocks AT REST IN SOME INERTIAL FRAME, being synchronized in > > some other inertial frame. > > No. I had pointed out to you earlier too that the two clocks under > consideration in this thread (clocks A and B fixed on earth's geoid > and separated by distance S), CAN NEVER BE AT REST IN ANY INERTIAL > FRAME. Your statement above reads, "But, of course, each pair is > synchronized in the ECI frame. The concept "synchronized" is ALWAYS > qualified with a frame." There is no mention of *at rest* in your > statement. > > > Here the clocks on the geoid are NOT at rest in ANY > > inertial frame, and my "statement above" does not apply. > > > Remember that the context in which statements are made is important, and you > > cannot take a statement from one context, apply it in a different context, and > > expect it to remain valid. > > Wrong, I have not changed the context. Throughout this thread I have > consistently used the context of 'two identical precision atomic > clocks A and B, fixed on the surface of earth (implying geoid) and > separated by finite distance S (or D) of the order of 30 km. The only > reference frames considered in these discussions are, > > (a) The local or Lab frame of the clocks, fixed on the surface of > earth, in which the clocks under consideration are at rest. But you > have refused to consider it an 'inertial reference frame' for the > purpose of clock synchronization. You have repeatedly emphasized that > as per SR, the term 'synchronization of clocks' is only valid when the > synchronization is done in *some inertial reference frame*. > > (b) The ECI reference frame, which you have accepted as an 'inertial' > reference frame in SR. In this reference frame your stand has often > been contradictory. In one post you accept that the pair of clocks > under consideration when synchronized to UTC time through GPS, can be > regarded as mutually synchronized in the ECI inertial frame. In the > next post you assert that a pair of clocks under consideration can be > synchronized in *any inertial reference frame* only when the two > clocks are *at rest* in that (or *some inertial*) reference frame. > Here there is a vagueness in your stand. It is not clear whether by > referring to the *AT REST IN SOME INERTIAL FRAME* requirement, you are > accepting the local or lab frame (a) of the clocks, as the *inertial > reference frame*, or whether you are denying the mutual > synchronization of the two clocks under consideration, in the ECI > frame. > > (c) The BCRF inertial reference frame. At one stage you declared that > if the two clocks under consideration are mutually synchronized in one > (say ECI) inertial reference frame, they can be mutually synchronized > in another (say BCRF) inertial reference frame simply by *setting* the > offsets of the clocks accordingly. Later on you retracted your > position and stated that the clock pair under consideration cannot be > mutually synchronized in BCRF because of their changing speed in that > frame. On second thoughts you declared, "in SR one could set the > offsets of two clocks (under consideration) such that they are > synchronized in *BCRF* inertial frame (you choose). They would be > synchronized with each other in that (BCRF) frame, but not with > coordinate clocks of the selected (BCRF) frame (these two would "tick > at a different rate" than those coordinate clocks)." However, in the > latest post you have again changed your stand and now demand that the > two clocks under consideration must be AT REST IN SOME INERTIAL FRAME > to enable their mutual synchronization in BCRF. > > (d) The Galactic reference frame. Of course, the discussions were > invariably scuttled before reaching this frame. ============= > > Finally, let me sum up your SR dominated viewpoint which I am unable > to agree with. LOL Particle accelerators are a better place to play with SR. Aparently without mention of SR, This <<... paper summarizes the most important effects in Einsteinian gravitomagnetic fields related to propagating light rays, moving clocks and atoms, orbiting objects, and precessing spins. Emphasis is put onto the gravitational interaction of spinning objects. The gravitomagnetic field lines of a rotating or spinning object are given in analytic form. >> --G. Schaefer http://arxiv.org/abs/gr-qc/0407116 No doubt you have N.Ashby's work. http://relativity.livingreviews.org/Articles/lrr-2003-1/ Sue... > > (i) When two clocks under consideration are mutually synchronized, > they represent a physical phenomenon which must not change with our > arbitrary choice of a reference frame. But you refuse to accept it as > a physical phenomenon, essentially to protect the validity of second > postulate of SR. > > (ii) When two clocks under consideration are mutually synchronized on > earth's geoid, you refuse to call them 'synchronized' because in your > opinion the term 'synchronization' has been reserved for use in > conjunction with 'inertial reference frames' and the earth's geoid > does not represent an inertial reference frame. > > (iii) You believe that the two clocks under consideration can be > mutually synchronized in any inertial reference frame only if the pair > of clocks are AT REST IN SOME INERTIAL FRAME. Since the pair of clocks > under consideration cannot practically be at rest in any *inertial > reference frame*, it obviously implies that the given pair of atomic > clocks cannot be physically synchronized in any inertial reference > frame whatsoever. This awkward position or belief too is ultimately > aimed at protecting the validity of the second postulate of SR. > > Well, if you don't consider it necessary to clarify your position, let > us agree to close these discussions here. > > GSS
From: Tom Adams on 8 Apr 2010 20:04
On Apr 8, 4:04 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > news:a779de06-faa9-4cd0-85df-8ee04f9aedf7(a)r18g2000yqd.googlegroups.com... > On Apr 8, 12:06 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > >news:4512a6c4-1d93-40b6-bc7e-84b200f3c1fb(a)u31g2000yqb.googlegroups.com.... > > On Apr 7, 10:05 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > > >news:3cfbbdd8-1c7e-4113-9ea9-d9ee6a4cf187(a)g30g2000yqc.googlegroups.com.... > > > 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. > > > ====================================== > > > Not relevant, v is squared in tau = t * sqrt(1-v^2/c^2), > > > so (-v)^2 = v^2. Cars go around oval race tracks without > > > changing speed all the time, reversing their velocity. > > > ====================================== > > > > > "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. > > > ======================================= > > > If there were then its duration and distance would be pertinent. > > > Unless you can state their relevance then acceleration is just so > > > much hand-waving, like Gordon Brown dog-paddling the economy > > > as he sinks, flapping his paws up and down and saying "No", > > > and "Should" without answering any questions. > > > > Einstein claims his result is proved for a polygonal line and a > > > continuous curved line, there is no change in SPEED (not velocity) > > > as the ship swings around the back of the star and returns to Earth. > > > He contradicts his own xi = x'/sqrt(1-v^2/c^2), eta = y, zeta = z, > > > but that's normal for his nonsense. > > > ======================================= > > > > > 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. > > > ==================================================== > > > Oh yes there is, > > >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 > > > > As the ship goes around turns 2 and 3 it travels at v = 0 when u = > > > <unchanged speed>, > > > so > > > eta = y'/sqrt(1-u^2/c^2) > > > and NOT > > > eta = y > > > Einstein wasn't bright enough to know the difference between speed > > > and velocity, he was too busy reading sci-fi in school. > > > ==================================================== > > > > One twin accelerated and the other did not. You can't just reverse A > > > and B. > > > =================================================== > > > > Einstein can! He can do as he likes, He's a god. He can defy the laws of > > > physics. He's holy, a genius. > > > The important thing is that *you* can't reverse A and B because they > > took > > different paths in space-time. No inertial frame will consider these > > two paths to be equivalent. > > > Einstein did not reverse them either. > > ================================================== > > > The important thing is > > "Take, for example, the reciprocal electrodynamic action of a magnet and a > > conductor. The observable phenomenon here depends only on the relative > > motion of the conductor and the magnet... > > Examples of this sort, yada, yada, yada... will hereafter be called the > > ``Principle of Relativity'' > > Ref: > > ON THE ELECTRODYNAMICS > > OF MOVING BODIES > > by A. Einstein > > June 30, 1905 > > Einstein does reverse A and B (when it suits him). > > > The important thing is Humpty Roberts has just told you SR can handle > > acceleration > > just fine and you've agreed with him, and here you claim acceleration is > > required. That's a paradox, and the PoR requires that A and B can be > > reversed. > > No, the PoR makes speed relative. It does not make acceleration > relative. > ==================================================== > Yes, the PoR makes speed relative. No, it does make acceleration > relative since acceleration is rate of change of velocity and velocity is > relative. If the Earth goes away from the ship and then returns to > the ship, which is exactly what those aboard the ship see, then the > Earth changed its velocity and therefore accelerated. > The PoR requires the station to come to the train. > > ==================================================== > I agreed that SR calculations might be able to handle acceleration. I > meant that it might be able to handle some calculations or inferences > about acceleration. > > ==================================================== > No, "Might be" is handwaving. Humpty Roberts is very good at it but hopeless > at mathematics. No, I do not agree that SR calculations might be able to > handle > acceleration, so where does that leave us? No, We should agree to differ? > No, Not at all, you have the burden of proof, its your claim. No, This is > physics and mathematics, not religion where faith applies. > > ==================================================== > I was not agreeing that the PoR applies to acceleration. It clearly > does not > apply to acceleration. > ==================================================== > > No, CLEARLY it DOES, as I've proven above. No, Acceleration is rate of > change of velocity and velocity is relative. No, The station comes to the > train. > No, Do not confuse force with rate of change of velocity, in case you are > thinking of doing so. No, In the frame of reference of the train, the > station > accelerates. > ==================================================== > All inertial frames will agree about which > clocks have accelerated and which clocks have not accelerated, the PoR > does not apply. > ==================================================== > No, A team of scientists working under the direction of researchers from the > University of Sussex have recently discovered that Einstein did not say > "inertial". No, Here is a copy of their experimental results. > > http://www.androcles01.pwp.blueyonder.co.uk/inertial.JPG > > "If at the points A and B of K there are stationary clocks which, viewed in > the stationary system, are synchronous; and if the clock at A is moved with > the velocity v along the line AB to B, then on its arrival at B the two > clocks no longer synchronize, but the clock moved from A to B lags behind > the other which has remained at B by 1/2 tv^2/c^2 (up to magnitudes of > fourth and higher order), t being the time occupied in the journey from A to > B. > It is at once apparent that this result still holds good if the clock moves > from A to B in any polygonal line, and also when the points A and B > coincide. > > 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 tv^2/c^2 second slow. Thence we conclude that a balance-clock at the > equator must go more slowly, by a very small amount, than a precisely > similar clock situated at one of the poles under otherwise identical > conditions." > > No, A continuous curve is not inertial by any stretch of the imagination. > > No, "Inertial" isn't relevant, and Einstein did not mean inertial. > No, You are handwaving. > > =================================================== > > That is, given any curve or piecewise line in space-time, all inertial > frames > will agree on whether that line represents acceleration or not. > > Acceleration = the line is not straight in space-time. Simple as > that. > ============================================= > No, Einstein did not say "space-time" either. > No, The "space-time curve" of the station is reflected in the frame of the > train. > No, In any event, a "spacetime diagram" is a distance/time graph with the > axes reversed to promote bullshit. No, Simple as that. No, You are > handwaving. > > > > =================================================== > > > 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. > > > ==================================================== > > > That's what I said, B meets A before A meets B. It's a whole lot > > > harder to do than mere instant acceleration in zero time. > > > > >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. > > > > > ================================================ The inertial frames will not agree about the rate of acceleration, but the will agree that straight paths in space-time represent constant velocities and they will agree on which paths are straight. You need to start from scratch and try to figure out where you got off on the wrong path. You are starting to seem unteachable. I can't help you and dealing with you just spinning my wheels. |