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Thread: Simultaneity

  1. #1 Simultaneity 
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    Imagine a very long row of clocks fastened to cameras. Each camera/clock unit faces a similarly equipped rocket. We now have two very long parallel lines of stationary clocks which can all be synchronized. When the clocks reach 01:00:00 the cameras start recording and the rockets accelerate rapidly for 1 second along the line of the stationary clocks. We now have a situation akin to clocks on a train moving alongside clocks on a platform.

    Special relativity predicts that the two sets of clocks will no longer be synchronized and the time differences will increase along the lines of clocks. So if the lines are sufficiently long the leading clock will be delayed to before 01:00:00. Such a time cannot be filmed before the start of the experiment. If one says the leading clock does not jump back to before 01:00:00 then all the other moving clocks will need to show correspondingly later times. The moving clocks will, on average, move into the future compared with the stationary clocks. This does not seem to be predicted. We also have the problem of knowing how the leading clock, assuming it knows it faces a logical problem, is able to tell all the other clocks to adjust their times into the future.

    In reality I think clocks that are considered to be moving would not variously leap backwards and forwards in time. I believe this to be the case because identical clocks under identical conditions must behave identically. If there is a plausible physical mechanism by which identical clocks can jump to different times, despite undergoing identical accelerations, please will someone explain it. (SRs assumptions, and the cognate assumptions of Minkowski space, do not constitute a physical mechanism.)

    An assumption underlying SRs predictions is that objects are fundamentally changed by observation. Distant observers having different speeds relative to clocks, or to the Earth, are able to produce differing clock times and rates and different physical sizes of the Earth. But there is no logical or experimental reason to think this is the case. Clocks slow down as a result of acceleration but this involves a change in kinetic energy; observations do not. Again, if there is a plausible physical mechanism by which an observer can compress the Earth, please will someone explain it. I can find no experimental support for non-simultaneity (or symmetrical time dilation or distance contraction).

    P.S. By symmetrical time dilation I mean SR's predicted dilation effects are necessarily always equal. The slowing effect just depends on relative speed and this must be the same for both observers. For me, the speed must arise from accelerations involving a change in kinetic energy. It does not depend on the speed between the observers per se. So whilst observers may be accelerated to equal speeds, this is not the case in general.


    Last edited by Andrew?; August 15th, 2017 at 12:29 PM. Reason: PS added
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    Quote Originally Posted by Andrew? View Post
    The moving clocks will, on average, move into the future compared with the stationary clocks. This does not seem to be predicted. We also have the problem of knowing how the leading clock, assuming it knows it faces a logical problem, is able to tell all the other clocks to adjust their times into the future.
    Your question is quite difficult to understand. Do you mean that speed makes the clocks perception of time go slower, thus making it go less fast. So the rocket that goes the fastest will show an earlier time than the rocket that goes the slowest?

    Did i understand you correctly?


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    Thanks for your reply, and apologies for the lack of clarity. Unfortunately I didn't really understand your question either!

    Ignoring SR's predictions, the clocks immediately after the 1 second acceleration would show the following elapsed times:

    1 1 1 1 1 1 1
    1 1 1 1 1 1 1

    SR's non-simultaneity would show something like this, except I am hugely exaggerating the effect:

    1 1 1 1 1 1 1
    -2 -1 0 1 2 3 4

    To avoid showing a time from before the experiment started we could then have the following:

    1 1 1 1 1 1 1
    0 1 2 3 4 5 6

    This is why I spoke of one set of times shifting into the future of the other observer, but as I say, how could the clocks work this solution out or implement it?

    I wouldn't bother too much about the details. I am interested in your comments on my reasons for rejecting SR's non-simultaneity in general.
    Last edited by Andrew?; August 15th, 2017 at 09:43 AM. Reason: Tried the tab key, this sent unfinished reply
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  5. #4  
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    You are ignoring a number of things in your example. First, you have to include the effects of length contraction and time dilation in the problem.
    Assuming that you have two parallel lines of clocks each spaced 1 light sec apart and synchronized in their own frames. The lines of clocks are moving at 0.6 c relative to each other.(for now we will ignore how they got to this relative speed) This means that each line will measure the distance between the clocks in the other line as being only 0.8 light sec apart and running 0.8 as fast as their own clocks. They will also note that each successive clock in the other line will be 0.6 sec out of sync with its neighboring clocks(even though the clock in that other line would say that they are in sync with each other).

    The point is that when you take all three effects into account, If you take any two clocks, one from each line, and ask them or anyone else what their respective readings were when they passed each other, they would all be in agreement. (you'll never get someone saying that when clock 3 in line A passed clock 5 in line B the clock in line A read 2.3 sec and the clock in line B read 3.2 sec, while someone else would say that the readings on the clocks were 1.2 and 2.1 secs respectively. ) The conditions of all events (such as clocks passing each other) are the same for everyone. There are none of the physical contradictions that would occur if you did not take all three effects into account.

    The second problem is that you introduced acceleration into the mix. Once you apply acceleration to either line of clocks you have a new ball of wax. If you accelerate a line of clocks, the clocks in that line will go out of sync with each other [i]according to the clocks in that line[i], no matter how carefully you make sure to accelerate them so that the distance between them as measured by the clocks themselves remains constant. While under acceleration, the clock in the direction of the acceleration will run faster than the one in the other direction, with the difference in clock rate increasing with the distance between the clocks. So after the acceleration is complete the clock will be all out of sync with each other.

    This statement:
    We also have the problem of knowing how the leading clock, assuming it knows it faces a logical problem, is able to tell all the other clocks to adjust their times into the future.
    and this statement
    Clocks slow down as a result of acceleration but this involves a change in kinetic energy; observations do not. Again, if there is a plausible physical mechanism by which an observer can compress the Earth, please will someone explain it. I can find no experimental support for non-simultaneity (or symmetrical time dilation or distance contraction).
    display the fundamental misconception you are struggling with when it comes to Relativity.
    The first one, about the clock "needing to know" how to "adjust" the readings of other clocks is like asking how do you "know" that a lamp to left must move to being in front of you when you turn towards it, or how does the lamp "know" that it needs to move in front of you when you turn towards it.

    The second statement starts with a misstatement. Clocks are not slowed by acceleration. Acceleration, in of itself, has no local effect on a clock. While separated clock in an accelerating frame do run t different rates, it has nothing to do with any difference in the acceleration they are experiencing, but is due to their relative positions in that frame.

    Then you go on to talk about a "physical mechanism".

    This is where the real stumbling block is. By insisting on looking for physical mechanisms that effect clocks and the length of objects, you are missing the fundamentals behind Relativity, which is that it deals with the very nature of "time" and "space" and how we measure them.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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    Thanks for your reply Janus.

    I agree I didn't mention length contraction or time dilation, but according to a physics book of mine the non-simultaneity still increases along the line of clocks. Assuming the book is correct, it is still legitimate to consider the implications of the progressive change in clocks times at the extremes. I am not questioning the mathematical consistency of SR's handling of the various effects, just the consequences.

    I don't doubt that acceleration is predicted to produce different clock times along the line. My question of course is how this can physically happen when the clocks undergo the same accelerations.

    I know that the relative velocity of observers is all that matters in SR's prediction of time dilation, but I take a different view. If a rocket is launched from the Earth and eventually achieves a relative speed of v, then SR predicts that observers in the rocket and on the Earth will measure equal time dilations of the other body. I though would consider the acceleration experienced by each body. As the mass of the rocket is negligible, so is the acceleration and resulting velocity of the Earth. So I would say that changes to the Earth's clocks can be ignored, thus giving an asymmetric dilation. I have explained this to try to dispel the impression that I am completely clueless about relativity. As far as I can tell, my own way of looking at things fits the experimental findings better and doesn't create the difficulties that result in physicists being perpetually plagued by sceptics. However, there's no need to say any more about this.

    I agree entirely with your last comment about the stumbling block. I have mention a number of areas where I think SR lacks experimental support but no one seems to thinks it is reasonable to question SR, so I will resort to using an analogy. Physicists are happy to dismiss homeopathy as complete rubbish on the grounds that there is no plausible physical mechanism to explain its predicted effects. Homeopaths may say they don't need one, the problem being that physicists don't understand the fundamentals of the spiritual energy involved. Physicists would again dismiss this as rubbish. Given that non-simultaneity, for example, seems to lack experimental support, I don't see why it is unreasonable to ask for the mechanism behind this prediction. If all of SR's predictions were experimentally supported then I wouldn't be asking. Physicists rightly ask others for mechanisms, why can't others ask physicists?
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    SR is fundamentally about how events in flat spacetime are related to one another; it's a purely geometrical model. When you want to define the separation between points on a manifold, you use a generalised version of the Pythagorean theorem - the squared distance being a sum of squares in each direction. It's just like the triangles you'd be used to from high school maths, just in more dimensions. That's the meaning of the line element, I.e. the metric. The only difference is that Minkowski spacetime is hyperbolic in nature instead of Euclidean - hence the time and space parts in the sum of squares carry opposite signs. This is the key to all the physics, and the reason why SR works where Newton fails. It all comes down to a single sign, and the difference that makes to the resulting geometry.

    When you say that there is no evidence of relativity of simultaneity, then what you are really saying is that there is no evidence that the sides in a triangle are related via sums of squares; it is hardly surprising that people ( not just scientists ) will shake their heads at this, because you are essentially saying that a fundamental tenet of elementary geometry is wrong.

    This should also answer your question as to mechanisms - what is the "mechanism" behind the sides of triangles being related by sums of squares ? It's not a very meaningful question, because it's simply geometry. Same for SR - it's just geometric relationships between events, there is no mechanism going on.
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    Quote Originally Posted by Markus Hanke View Post
    When you say that there is no evidence of relativity of simultaneity, then what you are really saying is that there is no evidence that the sides in a triangle are related via sums of squares; it is hardly surprising that people ( not just scientists ) will shake their heads at this, because you are essentially saying that a fundamental tenet of elementary geometry is wrong.
    By evidence of non-simultaneity I mean experiments that demonstrate that a line of clocks that were synchronized whilst at rest are seen to move backwards and forwards in time, depending on their positions along the line, when the observer is moving.

    Minkowski geometry is not elementary geometry, it incorporates the assumptions of SR. As SR's assumption about relativity and some of its predictions cannot be demonstrated (and I would say they've been disproved) then Minkowski geometry cannot be relied on.

    Humans cannot know the true nature of spacetime, for one thing our one-way experience of time differs from how time appears in equations. We can only infer what spacetime is by means of experiments. If the Einstein/Minkowski version of spacetime were correct then distance contraction and the inherent symmetry of SR's time dilation could be demonstrated by experiment. They can't, so Minkowski space doesn't work.

    I am very grateful for your patient explanations of Minkowski space, but physics must rest on experimental results.
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    I'll try to explain why I think Minkowski geometry is fundamentally flawed - it ignores mass and hence energy. This means it can be applied equally to a muon and to the Earth. It conforms to Einstein's idea that the frames of both bodies are equivalent.

    The way I look at it is to say that the muon has been accelerated, and its KE explains why its time rate is slowed, and quite possibly its length has shrunk. The muon has time to reach the Earth's surface and that's all there is to it. It is invalid to apply any transformations to the Earth because its change in KE is negligible. I insisted on some sort of plausible mechanism or reason for SR's predictions because there isn't one. There is no way the muon can shrink the Earth. No shrinkage of the Earth due to a moving observer can ever be measured because this is impossible.

    It seems to me that all the problems of simultaneity etc. can then be avoided. A line of accelerated clocks will slow down equally, but nothing changes for the clocks that do not gain any KE, and no distances contract. This is why I asked for experimental evidence. This would show which prediction is correct, but it seems that physicists' belief in SR means that physics no longer needs to be supported by experiments.

    The failure of SR's prediction of distance contraction is also then explained. The distance between particles that are spread around a circular accelerator cannot contract as predicted because the ring of particles would shrink inside the circumference of the accelerator. Individual particles can shrink because of their KE, but the distances between the particles do not acquire KE and so they do not shrink. Changes in KE also explain asymmetric time dilation whereas SR cannot.

    The Earth has one size and one mass and we can all share the same reality. The universe starts to make sense without SR.
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    By evidence of non-simultaneity I mean experiments that demonstrate that a line of clocks that were synchronized whilst at rest are seen to move backwards and forwards in time, depending on their positions along the line, when the observer is moving.
    You mean like Satellites with on-board clocks ? Like the GPS network ? This is why relativistic effects have to be accounted for when calculating position from a satellite's time signal.

    I'll try to explain why I think Minkowski geometry is fundamentally flawed - it ignores mass and hence energy.
    Usually the mass of a small object is negligible to the geometry of spacetime, but if you want you can of course accounts for its effects, and go to a more general Riemannian spacetime instead. That's what we have GR for. SR with its Minkowski geometry is only a special case of that.

    The way I look at it is to say that the muon has been accelerated, and its KE explains why its time rate is slowed
    In the frame of the muon, there is no KE, no time dilation, and no acceleration either. Also, kinematic time dilation in general does not depend on anything other but relative velocity - KE does not come into it.
    Btw, the muon is not accelerated, it moves inertially, even within the atmosphere.

    The muon has time to reach the Earth's surface and that's all there is to it
    Exactly. In the earth frame, that's because the muon is time dilated; in the muon frame, it's because the earth's atmosphere is length contracted. Both frames agree how far the muon can travel before it decays, and that distance depends on relative velocity, but not on mass of the muon. Time dilation and length contraction are two aspects of the same effect, which is why the frames always agree.

    The universe starts to make sense without SR.
    Without SR, the muon would not exist in the first place, because the particle is an excitation of a relativistic quantum field. Even if it did, it couldn't be a muon, since leptons are spin- particles, and spin is a relativistic phenomenon. In fact, no particle could exist at all, since all quantum fields in the Standard Model are relativistic; without SR, there would be no particles.
    The earth would also not exist, since without SR there would be no electromagnetism, and hence atoms could not form.
    Lastly, in a universe without SR there would be no gravity. It is debatable that such a universe could exist at all; even if it can, it would be a cold, dark and desolate place.

    Minkowski geometry is not elementary geometry, it incorporates the assumptions of SR
    Minkowski manifolds are special, very simple, cases of more general Riemann manifolds. Such manifolds were known and had been extensively studied in the 1850s, long before Einstein was even born. The knowledge that such manifolds exist dates back even further than that, all the way to Gauss.
    it is true, however, that Minkowski was the first person who applied ( not: invented ) this mathematical model to physics - the discipline of differential geometry already existed at that time, and is quite independent from Einstein's SR.
    And due to its very simple metric, it is indeed elementary; it's the same as Euclidean geometry, just with a reversed sign in the metric.

    If the Einstein/Minkowski version of spacetime were correct then distance contraction and the inherent symmetry of SR's time dilation could be demonstrated by experiment
    Which they have - extensively and repeatedly. You and the computer you type on only exist, because relativity applies.

    I am very grateful for your patient explanations of Minkowski space, but physics must rest on experimental results.
    Yes, like these :

    Modern Tests of Relativity

    And thousands more.
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    Quote Originally Posted by Markus Hanke View Post
    By evidence of non-simultaneity I mean experiments that demonstrate that a line of clocks that were synchronized whilst at rest are seen to move backwards and forwards in time, depending on their positions along the line, when the observer is moving.
    You mean like Satellites with on-board clocks ? Like the GPS network ?
    No, I mean a test of simultaneity exactly as I described it.

    Quote Originally Posted by Markus Hanke View Post
    The way I look at it is to say that the muon has been accelerated, and its KE explains why its time rate is slowed
    In the frame of the muon, there is no KE, no time dilation, and no acceleration either. Also, kinematic time dilation in general does not depend on anything other but relative velocity - KE does not come into it.
    Btw, the muon is not accelerated, it moves inertially, even within the atmosphere.
    You seem to think I'm describing my understanding of SR. Instead I'm describing a simpler way to understand events which avoids the problems of SR. I am analysing the situation from the frame of the Earth's centre of gravity. The frame of the muon is irrelevant. The relative speed between observers is irrelevant. What matters is the KE of the object (per unit mass) because this determines the object's time dilation. The muon has a lot of KE because it was accelerated to a high speed and hence it is markedly dilated. Nothing happens to the Earth as its KE is basically unchanged.

    Quote Originally Posted by Markus Hanke View Post
    If the Einstein/Minkowski version of spacetime were correct then distance contraction and the inherent symmetry of SR's time dilation could be demonstrated by experiment
    Which they have - extensively and repeatedly. You and the computer you type on only exist, because relativity applies.
    I looked at your list but found no evidence of distance contraction or symmetrical time dilation. Neither have I found any using Google. Please will you provide a specific example. Nothing exists by virtue of relativity, the first postulate has been disproved.
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  12. #11  
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    Quote Originally Posted by Andrew? View Post
    The frame of the muon is irrelevant.
    Are you saying that there can't be an observer travelling with the muon? An observer travelling with the muon can make measurements, and those measurements are just as valid as the measurement made by anyone else.


    Quote Originally Posted by Andrew? View Post
    I am analysing the situation from the frame of the Earth's centre of gravity
    Why not from the frame of the Sun's centre, or the galaxy's centre?


    The point is that one can't dismiss frames of reference. The reason for considering other frames of reference is because in principle there can be observers in those frames of reference making measurements and those measurements are as valid as measurements made from other frames of reference (actually, in the case of general relativity, one considers all possible coordinate systems simply because they exist, even if they don't correspond to any observer). The point of relativity is to be able to determine the result of one observer's measurements given the result of another observer's measurements.


    Quote Originally Posted by Andrew? View Post
    What matters is the KE of the object (per unit mass) because this determines the object's time dilation.
    How does kinetic energy cause time dilation?


    Quote Originally Posted by Andrew? View Post
    the first postulate has been disproved.
    By what experiment?
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Some very good questions, thanks.

    Quote Originally Posted by KJW View Post
    Are you saying that there can't be an observer travelling with the muon? An observer travelling with the muon can make measurements, and those measurements are just as valid as the measurement made by anyone else.
    I mean an observer moving with the muon needs to accept that events should be analysed from the frame of the centre of gravity. Obviously this departs from SR. An analogy would be that when a moving observer hears a siren, they need to accept that their measurement of its pitch is not as valid as everyone else's. The true pitch obviously does not include a Doppler shift.

    Quote Originally Posted by KJW View Post
    Why not from the frame of the Sun's centre, or the galaxy's centre?
    I could answer your question, but I hadn't intended to detail my own ideas. I posted a question about extended lines of clocks and I'm still hoping someone will answer it.

    Quote Originally Posted by KJW View Post
    The point is that one can't dismiss frames of reference. The reason for considering other frames of reference is because in principle there can be observers in those frames of reference making measurements and those measurements are as valid as measurements made from other frames of reference (actually, in the case of general relativity, one considers all possible coordinate systems simply because they exist, even if they don't correspond to any observer). The point of relativity is to be able to determine the result of one observer's measurements given the result of another observer's measurements.
    I obviously agree that this is what SR aims to do, but I do not agree that all frames are equivalent, as in the Doppler example.

    Quote Originally Posted by KJW View Post
    How does kinetic energy cause time dilation?
    This is fundamental to the way I look at things, but there would be no point discussing it as physicists see no problems with SR.

    Quote Originally Posted by KJW View Post
    By what experiment?
    I'm referring to Hubble's observation and Hubble's law.

    Thanks again for your time.
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  14. #13  
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    One needs to be exercise care when describing a relativity thought experiment as well as how relativity is applied to its analysis. So:

    Quote Originally Posted by Andrew? View Post
    I posted a question about extended lines of clocks and I'm still hoping someone will answer it.
    Consider two long lines of clocks which are initially at rest and synchronised with each other in this rest frame. Each clock of one line can accelerate independently of the others with motion that is controlled by the time value of the clock. All clocks in this line are now identically accelerated with motion that is synchronised in the rest frame. The result is that all the clocks of the moving line will remain synchronised with each other in the frame of the non-moving clocks. But due to time dilation, they will lag behind the non-moving clocks (both lines of clocks advance forward in time). Note that this means that in the frame of the moving clocks, the moving clocks are no longer synchronised, with the front (in terms of the direction of acceleration) clocks lagging behind the rear clocks.

    You appear to expect that the clocks themselves would indicate the notion of simultaneity of the moving clocks, but this is not the case as the manner in which the clocks are set in motion guarantee that they remain synchronised in the frame of the non-moving clocks. It should also be noted that if springs are used to connect adjacent clocks, then the springs will stretch as the clocks accelerate, indicating that the line of clocks in motion are not equivalent to the same line of clocks at rest. Again, this is because the manner in which the clocks are set in motion guarantee that in the frame of the non-moving clocks, the clocks have the same separation while moving as they did at rest, whereas length-contraction would shorten the distance between the clocks of a moving line that is equivalent to the same line at rest.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Quote Originally Posted by KJW View Post
    Note that this means that in the frame of the moving clocks, the moving clocks are no longer synchronised,
    You have provided a clear restatement of SR's predictions (though the above seems to be a typo - easily done when discussing SR) but not addressed the logical problem that these predictions appear to lead to. How could the clocks calculate what their displays need to show in order to avoid a negative time?

    Quote Originally Posted by KJW View Post
    It should also be noted that if springs are used to connect adjacent clocks, then the springs will stretch as the clocks accelerate,
    Exactly, but a measurement of the energy required to accelerate one line of clocks would show that no energy could have gone into compressing the springs in the other line. This is what I mean by saying SR ignores the essential principle of energy conservation.

    Describing my question as an alternative theory is no way to answer it.
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    Quote Originally Posted by Andrew? View Post
    Quote Originally Posted by KJW View Post
    Note that this means that in the frame of the moving clocks, the moving clocks are no longer synchronised
    (though the above seems to be a typo - easily done when discussing SR)
    Where is the typo?


    Quote Originally Posted by Andrew? View Post
    How could the clocks calculate what their displays need to show in order to avoid a negative time?
    So you didn't understand what I wrote?


    Quote Originally Posted by Andrew? View Post
    a measurement of the energy required to accelerate one line of clocks would show that no energy could have gone into compressing the springs in the other line.
    The springs between the non-moving clocks do not compress even in the frame of reference of the moving clocks. Relativistic length contraction is not a physical compression.


    Quote Originally Posted by Andrew? View Post
    This is what I mean by saying SR ignores the essential principle of energy conservation.
    Not true. Conservation of energy-momentum was used in the derivation of the relativistic mass expression. But energy-momentum conservation does require that one stay in the same frame of reference. One can't expect quantities to be conserved across different frames of reference.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Quote Originally Posted by Andrew? View Post
    Quote Originally Posted by KJW View Post
    Note that this means that in the frame of the moving clocks, the moving clocks are no longer synchronised
    (though the above seems to be a typo - easily done when discussing SR)
    Where is the typo?


    Quote Originally Posted by Andrew? View Post
    How could the clocks calculate what their displays need to show in order to avoid a negative time?
    So you didn't understand what I wrote?


    Quote Originally Posted by Andrew? View Post
    a measurement of the energy required to accelerate one line of clocks would show that no energy could have gone into compressing the springs in the other line.
    The springs between the non-moving clocks do not compress even in the frame of reference of the moving clocks. Relativistic length contraction is not a physical compression.


    Quote Originally Posted by Andrew? View Post
    This is what I mean by saying SR ignores the essential principle of energy conservation.
    Not true. Conservation of energy-momentum was used in the derivation of the relativistic mass expression. But energy-momentum conservation does require that one stay in the same frame of reference. One can't expect quantities to be conserved across different frames of reference.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Quote Originally Posted by KJW View Post
    Where is the typo?
    I see what you mean now, but in the frame where one defines which clocks are moving, the moving clocks are moving clocks. What we both mean is that the clocks stay synchronized in their own frame.

    It may help to restate the problem more clearly:

    Imagine a very long row of clocks fixed on cameras. Each camera/clock unit faces a similarly equipped rocket. This gives us two very long parallel lines of stationary clocks which can all be synchronized. When the clocks reach 00:00:00 the cameras start recording and the rockets rapidly accelerate for 1 second parallel to the line of stationary clocks. The cameras record the times seen then the rockets take 1 second to turn round and a further second to decelerate to a halt.

    Ignoring SR, immediately after the acceleration some of the clocks would show the following elapsed times:

    1 1 1 1 1 1 1
    1 1 1 1 1 1 1

    SR predicts that the two sets of clocks will no longer be synchronized and the time differences will increase along the lines of clocks. If the lines are sufficiently long, SR predicts the following:

    1 1 1 1 1 1 1 as seen within a frame.
    -2 -1 0 1 2 3 4 as seen in the other frame.

    How can times be observed from before the experiment began in either frame, as well as after it ended? No shifts in clock times were then occurring.


    Quote Originally Posted by KJW View Post
    The springs between the non-moving clocks do not compress even in the frame of reference of the moving clocks. Relativistic length contraction is not a physical compression.
    I agree this is how it is defined, but I was making a fundamental point about the relativity of frames. When observers start from a common frame and then some are accelerated, their frames are no longer equivalent. Suppose we have two rockets with full fuel tanks. One accelerates away from the other then cruises for a while before returning to the stationary rocket. Whilst they were in inertial relative motion, the observers were in no doubt as to who was moving and who was stationary. Telemetry from the rockets’ fuel tanks would establish which rocket had accelerated since the experiment began. It is patently wrong to say observations cannot distinguish between the states of motion of these two frames, so the principle of relativity is false.

    The principles of conserving energy and momentum clearly show which rocket’s fuel is converted into KE. This is why SR must abandon these fundamental principles.

    It is only physicists who refuse to consider the relevant facts when analysing a situation. Biologists, detectives, doctors, engineers, mechanics ,plumbers and in fact everyone else knows that previous information about a system is relevant. Relativists seek to ignore the past when they say that acceleration wipes the slate clean. An observer keeps having new reference frames, so past information is irrelevant.

    This comes unstuck when observing the Hubble expansion and the CMBR because these observations come from the past. They distinguish between different states of motion in the visible universe and thereby provide a “space speedometer”. If you deny that the visible universe provides a valid reference for measuring speed then you are saying SR’s first postulate is meaningless – all speeds are equivalent because all speeds are equivalent. It is scientifically meaningless to make a statement that is defined as being unprovable.

    The universe is the total motion of all bodies. What more obvious benchmark is there for measuring an individual value of speed or anything else other than all the other values? The universe is the context in which everything needs to be understood. It is ridiculous to say a muon’s frame is equivalent to the universe’s.


    Quote Originally Posted by KJW View Post
    One can't expect quantities to be conserved across different frames of reference.
    The conservation principles show that energy and momentum must be conserved across consecutive frames, as they are in Newtonian mechanics. SR’s myopic frames ignore both prior knowledge and the mass, momentum and KE of each body that it falsely presumes to be at rest. This is why SR violates the conservation principles.

    Although I cannot believe anything as absurd as relativity, it has been interesting to learn how people try to defend it. I do appreciate the time you have spent on this, but there seems no point discussing it further.
    Last edited by Andrew?; August 23rd, 2017 at 12:31 PM.
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    KJW
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    Quote Originally Posted by Andrew? View Post
    Quote Originally Posted by KJW View Post
    Where is the typo?
    I see what you mean now, but in the frame where one defines which clocks are moving, the moving clocks are moving clocks. What we both mean is that the clocks stay synchronized in their own frame.
    That isn't what I said, and isn't what I mean. The clocks do NOT stay synchronised in their own frame of reference. You are clearly fixated on the idea that the clocks determine simultaneity. In general, they do not.


    Quote Originally Posted by Andrew? View Post
    SR predicts that the two sets of clocks will no longer be synchronized and the time differences will increase along the lines of clocks. If the lines are sufficiently long, SR predicts the following:

    1 1 1 1 1 1 1 as seen within a frame.
    -2 -1 0 1 2 3 4 as seen in the other frame.
    Actually, it will be more like this:

    9 9 9 9 9 9 9 on the non-accelerated clocks.
    8 8 8 8 8 8 8 on the accelerated clocks.

    It should be noted that the readings on the clocks do not reflect the notion of simultaneity of the frames of reference.


    Quote Originally Posted by Andrew? View Post
    When observers start from a common frame and then some are accelerated, their frames are no longer equivalent. Suppose we have two rockets with full fuel tanks. One accelerates away from the other then cruises for a while before returning to the stationary rocket. Whilst they were in inertial relative motion, the observers were in no doubt as to who was moving and who was stationary. Telemetry from the rockets’ fuel tanks would establish which rocket had accelerated since the experiment began. It is patently wrong to say observations cannot distinguish between the states of motion of these two frames, so the principle of relativity is false.
    Special relativity doesn't treat accelerated frames as equivalent to inertial frames. In your example, any non-equivalence between the frames is due to the acceleration, even though both frames are currently inertial. Special relativity doesn't actually say that two inertial frames are equivalent if one of them had some prior acceleration within it. In other words, you are creating a straw man.


    Quote Originally Posted by Andrew? View Post
    Relativists seek to ignore the past
    Do you know why? Perhaps I should ask if you've ever done science. In constructing theories, scientists simplify the subject under consideration. Non-scientists tend to be critical of this aspect of science because they fail to understand the purpose of simplification. For special relativity, this means a Minkowskian spacetime. Minkowskian spacetime is devoid of anything. It is important to know how empty spacetime behaves so that one can get an idea of what to expect when things start to be included.


    Quote Originally Posted by Andrew? View Post
    If you deny that the visible universe provides a valid reference for measuring speed
    Relativity does not say that the frame of the symmetric CMBR isn't a valid frame of reference. It says that it is not a preferred frame of reference. That's an important distinction.


    Quote Originally Posted by Andrew? View Post
    This is why SR violates the conservation principles.
    No. Relativity derives the conservation principles in the refined form necessary to be applicable to all frames of reference.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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