Notion of Absolute Clock Synchronization in SR
in [Relativity]
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From: Tom Adams on 9 Apr 2010 20:37 On Apr 9, 5:19 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > news:ea4bfd46-651f-403f-ad98-773f446e40e1(a)q15g2000yqj.googlegroups.com... > On Apr 8, 11:53 am, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > > > > > "Tom Adams" <tadams...(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. > > You *can* say which clock was and which clock was not either > stationary or uniformly moving from departure to arrival. > ============================================== > Isaac Asimov wrote in "Quasar, Quasar, Burning Bright" , > ISBN 0-380-44610-3 > (concerning life after death) > [ If you want to argue the point, present the evidence. > I must warn you, though, that there are some arguments I will not > accept. > I won't accept any argument from authority. ("The Bible says so") > I won't accept any argument from internal conviction ("I have faith it > is so") > I won't accept any argument from personal abuse ("What are you, an > atheist?") > I won't accept any argument from irrelevance ("Do you think you have > been put on this Earth just to exist for a moment of time?) > I won't accept any argument from anecdote ("My cousin has a friend who > went to a medium and talked to her dead husband") > And when all that, and other varieties of non-evidence are eliminated, > there turns out to be nothing.] > > Present the evidence; all you need do is argue your case logically, > based on acceptable axioms, and I'll accept what you say. > When one teaches, two learn. > I'm quite willing to listen, but I'll jump down your throat and rip your > lungs out (metaphorically, of course) if you try to bullshit me. > ============================================ Are Newton's laws of motion are the axioms. The clock that takes a polygonal path had to change direction, F=ma and all that that implies. Other clock remains at rest or has uniform motion. No F, no a. Newton, Galileo, and Einstein all agree that an observer at rest or in uniform motion can tell these clocks apart (as long as you leave gravity out of the picture, at least.) > > > > > 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?- Hide > > quoted text - > > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: BURT on 9 Apr 2010 20:57 On Apr 9, 5:37 pm, Tom Adams <tadams...(a)yahoo.com> wrote: > On Apr 9, 5:19 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > > > > > "Tom Adams" <tadams...(a)yahoo.com> wrote in message > > >news:ea4bfd46-651f-403f-ad98-773f446e40e1(a)q15g2000yqj.googlegroups.com.... > > On Apr 8, 11:53 am, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > > "Tom Adams" <tadams...(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. > > > You *can* say which clock was and which clock was not either > > stationary or uniformly moving from departure to arrival. > > ============================================== > > Isaac Asimov wrote in "Quasar, Quasar, Burning Bright" , > > ISBN 0-380-44610-3 > > (concerning life after death) > > [ If you want to argue the point, present the evidence. > > I must warn you, though, that there are some arguments I will not > > accept. > > I won't accept any argument from authority. ("The Bible says so") > > I won't accept any argument from internal conviction ("I have faith it > > is so") > > I won't accept any argument from personal abuse ("What are you, an > > atheist?") > > I won't accept any argument from irrelevance ("Do you think you have > > been put on this Earth just to exist for a moment of time?) > > I won't accept any argument from anecdote ("My cousin has a friend who > > went to a medium and talked to her dead husband") > > And when all that, and other varieties of non-evidence are eliminated, > > there turns out to be nothing.] > > > Present the evidence; all you need do is argue your case logically, > > based on acceptable axioms, and I'll accept what you say. > > When one teaches, two learn. > > I'm quite willing to listen, but I'll jump down your throat and rip your > > lungs out (metaphorically, of course) if you try to bullshit me. > > ============================================ > > Are Newton's laws of motion are the axioms. > > The clock that takes a polygonal path had to change direction, F=ma > and all that > that implies. > > Other clock remains at rest or has uniform motion. No F, no a. > > Newton, Galileo, and Einstein all agree that an observer at rest or in > uniform > motion can tell these clocks apart (as long as you leave gravity out > of the picture, at least.) > > > > > > > > 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?- Hide > > > quoted text - > > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text - The strength of gravity slows time down. Speeding up energy in space causes that energy's clock to decelerate from a faster beginning rate. There is fastest time for the least motion of energy and least strength of gravity for the energy. The two clocks must be brought together to synchronize in both slowdown of rates. Mitch Raemsch
From: Tom Adams on 9 Apr 2010 21:14 On Apr 9, 5:19 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > I won't accept any argument from irrelevance ("Do you think you have > been put on this Earth just to exist for a moment of time?) That seems a version of the Anthropic Principle. It quite respectable (or notorious, at least :-)
From: Androcles on 10 Apr 2010 01:59 "Tom Adams" <tadamsmar(a)yahoo.com> wrote in message news:786bf782-fd00-40d4-a7f9-f0c9a681792f(a)r18g2000yqd.googlegroups.com... On Apr 9, 5:19 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > I won't accept any argument from irrelevance ("Do you think you have > been put on this Earth just to exist for a moment of time?) That seems a version of the Anthropic Principle. It quite respectable (or notorious, at least :-) ================================================= Yes, but please do not attribute Asimov's words to me. These are my own words: http://www.androcles01.pwp.blueyonder.co.uk/
From: Tom Roberts on 10 Apr 2010 22:24
GSS wrote: > On Apr 9, 1:24 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: >> 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. >> > Agreed. That is fair enough. > >> 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. >> > That is if we 'set' or 'adjust' or 'synchronize' each of the two > clocks to the 'coordinate' time of that frame (BCRF) then the two > clocks will no longer remain mutually synchronized. Yes. Such clocks on the geoid will not be mutually synchronized IN ANY INERTIAL FRAME. You keep forgetting that "synchronized" must INHERENTLY be qualified with an inertial frame -- that is part of the definition. > After all, when the two clocks A and B under consideration, are > mutually synchronized to UTC time through GPS, these clocks are > actually, physically located in (a) their local or lab frame, (b) ECI > frame, (c) BCRF frame and the (d) Galactic reference frame. That is > these clocks are simultaneously located in ALL of these frames ALL the > time. Hmmm. "physically located in frame X" really makes no sense -- frames are merely a way of describing locations (via coordinates). Objects are "physically located" in the WORLD, not any particular frame; but the coordinates of any frame can be used to describe the location of a given object (relative to that frame, of course). This is sort of what you said, but the implications are quite different. Frames are a "point of view", and not any "physical" entity at all. They are, at base, an artifact of human minds, as are the coordinates of any frame. Nature herself uses no frames or coordinates; nature herself synchronizes no clocks -- these are all HUMAN ARTIFACTS. We often use a physical object, such as a lab, to define a frame. It is the physical object that is physical, not the frame. > Only when you have to force the application of the second > postulate of SR in different inertial frames, perforce you have to > bring in the notion of coordinate time and hence need to 'adjust' the > clocks accordingly in each frame. Not true. As I said before, the clocks are synchronized in ONE AND ONLY ONE inertial frame because THAT IS HOW THE WORLD WE INHABIT WORKS [#]. This has nothing directly to do with the second postulate of SR. But, of course, that postulate was formulated because it, too, reflects how the world we inhabit works [%]. I cannot help it if you do not understand this and refuse to accept it. You need to STUDY basic physics and LEARN what is known about the world we inhabit. [#] Actual measurements show this. [%] Actual measurements show this. But their accuracy is not perfect, and better data could force revisions in the theory. The difference in these two footnotes is that [#] is a statement about measurements, while [%] is a statement about a theory (i.e. a synthesis from imperfect measurements). > Let us suppose you have set the offsets of two precision clocks A and > B so as to mutually synchronize them in some inertial reference frame > say ECI. We can arrange to let their output in the form of 1PPS > recorded in the associated computers. This 1PPS data from both clocks > can be recorded for a 24 hour period for its detailed analysis later > on. This recorded data is a physical record which CANNOT CHANGE > whether we consider the clocks to be physically located in their lab > frame, or ECI frame or BCRF or even the Galactic reference frame. Sure. Except as I said before, we cannot "consider" them to be "physically located" in any frame, they are physically located in the WORLD. But the issue is about SYNCHRONIZATION, not any sort of historical record like this. That requires some method of comparison other than merely looking at a "record" of each clock's ticks. You'll necessarily find that whether they are "synchronized" or not depends INHERENTLY on the method of comparison. And for any approach you choose, you will necessarily have to select an inertial frame in which to perform it. If you don't perform the comparison in an inertial frame, nobody would call the result "synchronization". This is at base why qualification with an inertial frame is required. > Don't you agree that the digital recording of the clock outputs is a > physical phenomenon which is not influenced by the fact that the two > clocks are actually, physically located in ALL of the above mentioned > frames ALL the time. No. The record is a record, not any sort of "physical phenomenon". As I said before, we cannot "consider" them to be "physically located" in any frame, they are physically located in the WORLD; but yes, the record depends on the computers' relationships to the clocks, not any frame. Bottom line: that "record" is a HUMAN ARTIFACT of what was recorded. Nature herself uses no such artifacts, and the phrase "physical phenomenon" refers to Nature, not human artifacts. [This is getting overly repetitive. Don't expect me to continue until and unless you LEARN something, and recognize the inherently HUMAN nature of clock synchronization. Ask yourself: who is it that pushes the reset buttons on the clocks at specified times, in order to synchronize them? Who is it that determines WHEN to do so (for each)? How is that "when" determined (for each)? -- the answer to each involves humans and their rather arbitrary choices; nature does not care about any of this, and does whatever she does without regard to such human foibles.] Tom Roberts |