Notion of Absolute Clock Synchronization in SR
in [Relativity]
|
From: Androcles on 8 Apr 2010 11:53 "Tom Adams" <tadamsmar(a)yahoo.com> wrote in message news:eb8a8b80-b069-45cd-a43b-ea3be0dcf897(a)g30g2000yqc.googlegroups.com... On Apr 7, 4:42 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > 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 You are probably right. Just a matter of calculus. ============================================== Einstein did not understand calculus. We establish by definition that Einstein got his knickers in a twist when he said "we establish by definition that the "time" required by a ray to travel from A to B equals the "time" it requires to travel from B to A" and claimed 1/2 [ tau(0,0,0,t) + tau(0,0,0,t+x'/(c+v)+x'/(c-v))] = tau(x',0,0, t+ x'/(c-v)) Ref: http://www.fourmilab.ch/etexts/einstein/specrel/www/figures/img22.gif (It would have been far easier to write tau(x',0,0, t+ x'/(c-v)) =tau(0,0,0, t+ x'/(c+v)) and then differentiate that, but then that would make Einstein's silly spoof rather too obvious.) Hence if x' be taken infinitesimally small, @tau/@x' + 1/(c-v) * @tau/@t = @tau/@0 + 1/(c+v)*@tau/@t Ref right-hand side of: http://www.fourmilab.ch/etexts/einstein/specrel/www/figures/img23.gif There is no derivative @tau/@0 or @tau/@x', Einstein confuse the coordinate (x',0,0) with the length x'. ============================================== There are SR effects and separate acceleration effects on the clocks. I learned something for once on this group. Anyway, it's possible to show the "paradox" without acceleration. You just have 2 clocks in 2 inertial frames pass each other close together and you synchronize them when they are close. You can get sufficient sychronization that way between a clock moving away from our clock and the clock returning to our clock. In the idealized version, the two clocks participate in the same event (somehow without colliding) and are perfectly synchronized. ================================================ Turning the hands is allowed at departure, not on arrival. The paradox is the PoR, you can't say which clock moved. That was how acceleration got into the act in the first place. So which is it? The clock that accelerated loses time or acceleration doesn't matter, each sees the other move away and come back again?
From: Androcles on 8 Apr 2010 12:06 "Tom Adams" <tadamsmar(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. > =================================================== > 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. > > > ================================================- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: Tom Adams on 8 Apr 2010 14:01 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? 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? > > 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: Tom Adams on 8 Apr 2010 14:18 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. 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. I was not agreeing that the PoR applies to acceleration. It clearly does not apply to acceleration. All inertial frames will agree about which clocks have accelerated and which clocks have not accelerated, the PoR does not apply. 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. > > > > > =================================================== > > 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. > > > > ================================================- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: Sue... on 8 Apr 2010 14:38
On Apr 8, 2:18 pm, Tom Adams <tadams...(a)yahoo.com> wrote: > 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. > > 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. > > I was not agreeing that the PoR applies to acceleration. It clearly > does not > apply to acceleration. ===================== > All inertial frames will agree about which > clocks have accelerated and which clocks have not accelerated, the PoR > does not apply. Which inertial frame could an aeroplane coast in such that a hijacker might benefit from a weakened lawman's bullet? K.E. = 1/2 mv^2 Sue... > > 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. > > > > > > =================================================== > > > 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. > > > > > ================================================- Hide quoted text - > > > > - Show quoted text -- Hide quoted text - > > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text - > > |