1 Nicolaas Vroom  The behaviour of a clock in a linear accelerator versus a centrifuge  Sunday 9 September 2018 
2 Tom Roberts  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Tuesday 18 September 2018 
3 Nicolaas Vroom  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Sunday 23 September 2018 
4 Tom Roberts  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Wednesday 26 September 2018 
5 richali...@gmail.com  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Sunday 30 September 2018 
6 Nicolaas Vroom  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Sunday 30 September 2018 
7 Tom Roberts  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Tuesday 2 October 2018 
8 Tom Roberts  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Tuesday 2 October 2018 
9 Nicolaas Vroom  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Monday 8 October 2018 
10 Nicolaas Vroom  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Monday 8 October 2018 
11 Phillip Helbig  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Monday 8 October 2018 
12 Roland Franzius  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Tuesday 9 October 2018 
13 Nicolaas Vroom  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Tuesday 9 October 2018 
14 Tom Roberts  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Tuesday 9 October 2018 
15 Nicolaas Vroom  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Saturday 20 October 2018 
16 Phillip Helbig  Re :The behaviour of a clock in a linear accelerator versus a centrifuge  Saturday 20 October 2018 
The behaviour of a clock in a linear accelerator versus a centrifuge
16 posts by 5 authors
https://groups.google.com/forum/?fromgroups#!topic/sci.physics.research/IpIag7Im82w
In Sci.Physics.Relativity In the thread "A suggested time dilation experiment"
> 
Yes, within limits. Here we meet those limits and can consider the
rotating centrifuge to be "generating" an equivalent gravitational field
in its rotating frame. Note that in these coordinates the centrifuge
clock is not moving; let's place the lab clock at the center of
rotation, so it is also not moving relative to these coordinates
(and is also not moving relative to the lab).
Here are three calculations of the difference in elapsed proper time between the centrifuge and lab clocks:
1. Centrifuge clock's "time dilation" relative to the lab frame:
sqrt(1v^2/c^2), with v the clock's speed relative to the lab, measured
in the lab. Integrate this over 22 hours and one gets 0.93 ns
over 22 hours. 2. Centrifuge clock's "equivalent gravit... 
The question is if the behaviour of a clock in a centrifuge can be
described by means of the equation: sqrt(1v^2/c^2).
For certain clocks: Yes. For other clocks: NO.
To challenge the behaviour I have written a document:
See https://www.nicvroom.be/Clock%20and%20Centrifuge.htm
The document describes the behaviour of a clock in a linear accelerator
and in a centrifuge.
The clock used comes from the book "SpaceTime Physics"
which uses lightflashes.
The clock used actual consists of 4 mirrors.
1) Two mirrors parallel in the direction of movement
2) Two mirrors perpendicular in the direction of movement.
In any actual simulation only 2 are used.
In case #1 the light flash with v=0 moves in the vertical direction.
In case #2 the light flash with any speed moves in the horizontal direction.
What the simulation shows is that a clock with parallel mirrors
is in agreement with lotentz transformation. In case #2 not.
The simulation also shows that the behaviour of boths clocks in a centrifuge is rather complex.
In the document the train experiment is also extensive discussed. Specific the difference between the Observer at the plaform versus the Observer at the moving train. The true question to answer is if both Observers can call them self at rest.
Nioclaas Vroom https://www.nicvroom.be
>  The question is if the behaviour of a clock in a centrifuge can be described by means of the equation: sqrt(1v^2/c^2). 
In SR, "time dilation" does not depend on the type of clock  it is a geometrical projection caused by the fact that clocks in relative motion have nonparallel 4velocities. This is pure geometry and simply CANNOT depend on the type of clock.
The actual equation is:
>  For certain clocks: Yes. For other clocks: NO. 
Nope. Somewhere you goofed. The above equation holds for all types of clocks.
>  What the simulation shows is that a clock with parallel mirrors is in agreement with lotentz transformation. In case #2 not. 
Your simulation is wrong.
Tom Roberts
>  On 9/8/18 5:43 PM, Nicolaas Vroom wrote: 
> >  The question is if the behaviour of a clock in a centrifuge can be described by means of the equation: sqrt(1v^2/c^2). 
> 
The actual equation is:

> >  For certain clocks: Yes. For other clocks: NO. 
The clock I'm simulating is described at page 12 in the book SpaceTime
Phyisics.
The clock consists of two parallel mirrors in horizontal direction.
The eye piece is towards the right side in horizontal direction.
You can also depict the eye piece at the center between the two
parallel mirrors.
There are two ways to move this clock:
1) in veritical direction. That is done at page 69 of the book, inside
a rocket. However 90 degrees rotated.
The equation that describe this movement is the same as above mentioned.
From the rocket point of view, in the direction of movement, the signal is
reflected against the ceiling and the floor.
My simulation shows exactly the same in a linear acceleration.
2) in horizontal direction.
The equation that describes this behaviour is:
> 
Nope. Somewhere you goofed. The above equation holds for all types of
clocks.
Note that t and v MUST be associated with an INERTIAL FRAME. That could be your mistake. etc. Note that no rotating system is an inertial frame, so if you ever used rotating coordinates in any way you almost surely introduced an error. 
I fully agree. Any clock in a centrifuge is not in an inertial frame. My point is to simulate the behaviour of a clock undergoing acceleration. What the simulation shows is that the behaviour is very complex using the clock as described on page 12 (as a function of v) My point is also that allmost all clocks in principle have this problem. This is the case When for a clock in front of you on a table. For a clock in circular motion around the earth, around the Sun or around in our Galaxy. In the simulation this is done for one revolution. My point is also that accelaration is the primary influence of the behaviour of a clock.
> 
Your simulation is wrong.
Tom Roberts 
Nicolaas Vroom.
>  Any clock in a centrifuge is not in an inertial frame. My point is to simulate the behaviour of a clock undergoing acceleration. What the simulation shows is that the behaviour is very complex using the clock as described on page 12 (as a function of v) 
IIRC that is a light clock with a light pulse bouncing between two mirrors. Remember that the mirrors are accelerated but the light is not  the light pulse moves in straight lines between bounces (relative to any INERTIAL frame).
[#] This is a gedanken; I know of no way to actually implement it; I do not think these assumptions are unreasonable.
>  My point is also that allmost all clocks in principle have this problem. 
I doubt it: SR predicts that NO clock has this "problem", and I see no reason to doubt that prediction. For instance, muons in a "relativistic centrifuge" (aka storage ring), undergoing the enormous proper acceleration of 10^18 g, are observed to decay at the rate SR predicts; that prediction depends on only their speed relative to the lab and their proper lifetime (see equation given earlier in this thread); in particular it is completely independent of their acceleration.
>  My point is also that accelaration is the primary influence of the behaviour of a clock. 
Not in SR. (Also not in GR.) And apparently not in the world we inhabit.
As I said before: your simulation is wrong.
Tom Roberts
> 
Tom Roberts 
Tom,
Unless I am misinterpreting your argument, I believe the last statements about acceleration not affecting the period of the clocks is incorrect. Let me describe a counter example that I believe makes this clear:
Consider the two mirrors to be at the same radius in the centrifuge, but displaced along the axis of the centrifuge so the light pulses are describing a zigzag along a cylinder at that radius. There is also a slight radial component, which gets larger as the centrifuge spins faster. At very low speeds the distance the light travels between reflections is basically the axial separation of the mirrors. At very high speeds there is a substantial circumferential component to the light path and it is significantly extended. This happens when the mirrors are experiencing a very high acceleration. This the ticking of this light clock slows down with high accelerations. Certainly much, if not most, of this slowing can be attributed to the tangential velocity of the mirrors. However because of the increase in radial motion of the light paths with increasing acceleration/velocity there will also be a component of the slowing that is due to the radial acceleration.
HOWEVER, I do agree with your basic position that acceleration itself does not affect the "rate of clocks" because this affect of acceleration can be recognized by the local observer. He can make clocks with shorter and longer paths between the mirrors and will see that these clocks run at different rates (even after compensating for the longer light paths). As the mirrors are put closer and closer together the rate will asymptotically approach the "normal" rate of time for that observer. Thus the observer could use this set of clocks to measure his acceleration. This puts this effect in a completely different category from the SR and GR time dilation effects.
Rich L.
>  On 9/23/18 4:57 PM, Nicolaas Vroom wrote: 
> >  My point is to simulate the behaviour of a clock undergoing acceleration. 
> 
IIRC that is a light clock with a light pulse bouncing between two mirrors. Remember that the mirrors are accelerated but the light is not  the light pulse moves in straight lines between bounces. 
In principle my clock consists of 6 mirrors (3 pairs of parallel mirrors) The center of the clock is the most important point. This is point where a light flash is emitted. This is also the point where the photon is observed or 'measured' and where a new flash is created after one cycle. The light flash is a sphere of photons emitted in all directions. If the clock is at rest then a photon emitted in vertical direction upwards, will be reflected at the ceiling, move downwards, is reflected at the bottom and is measured at the center. This is one cylce. Next a new flash will be emitted in all directions. etc. etc. The same can be done in all 6 directions.
Now what happens when this clock is linear accelerated. The simulation shows that the behaviour is not the same in the all directions. This link: https://www.nicvroom.be/la_par3.jpg shows the behaviour (4 cycles) of a clock moving in the x direction with the flash in the vertical direction (y or z), at 4 different speeds: 0.1, 0.3, 0.5 and 0.7 times c. This behaviour is in agreement with SR. Cycle 1 is indicated with the numbers 1,2,3 and 4. Cycle 2 with the numbers 4,5,6 and 7 and finally Cycle 4 with the numbers 10,11,12 and 13
This link: https://www.nicvroom.be/la_per4.jpg shows the behaviour (4 cycles) of a clock moving in the x direction with the flash also in the horizontal x direction, at 4 different speeds: 0.1, 0.3, 0.5 and 0.7 times c. The behaviour is not in agreement with SR. Cycle 1 is indicated with the numbers 1,2,3 and 4. The cycle start with the clock at position 1. The flash is emitted towards the left and bounces back when the clock is at position 2. Now the flash moves towards the right until the clock is at position 3. Again a bounch. The flash moves towards the left until it reaches the center of the clock at point 4. This terminates cycle 1. Cycle 2 is identical except that the distances are larger. etc etc. For more detail see:
https://www.nicvroom.be/Clock%20and%20Centrifuge.htm The important point is that the time to perform the 4 cycles in the second clock (tc= 432.249) is longer then for the first clock (tc=277.128). That means the first clock runs faster then the second clock.
>  For instance, while they are being accelerated you must tilt the mirrors so the light pulse continues to bounce between them. Parallel mirrors work only when they are moving inertially. 
I definitive do not want to change anything inside the clock as part of the experiment. The whole clock functions as a fixed box, all the angles are 90 degrees.
>  Let me assume a light clock in a centrifuge, and [#]: a) the center of the centrifuge is at rest in the lab b) the lab is at rest in an inertial frame c) we can ignore the size of the light pulse d) the light clock is constructed so at every bounce its mirrors' centers are at rest in the same instantaneously comoving inertial frame, and the distance between their centers remains fixed in each of those frames (i.e. the mirrors adjust themselves to make this so, independent of any strains in their support structures) 
How is this self adjustement performed in reality? For more detail see: https://en.wikipedia.org/wiki/John_Harrison The clock I use (simulate) is very simple. Identical as discussed in the book: "SpaceTime Physics" If SR requires a much more complex construction, with some self adjustment then ofcourse my simulation is wrong.
>  e) the light clock is constructed so the light pulse always bounces from the exact center of each mirror (i.e. the mirrors adjust themselves to make this so) 
What is science? Do you adjust an experiment to fit the mathematics or Do you adjust the mathematics to fit the experiment?
>  f) all bounces are perfect, with no light loss Then it is straightforward to see that the trajectory of the light pulse relative to the lab is a series of straight lines with corners at the 
>  successive locations of the mirrors' centers when it bounces. This is just basic geometry, and if your simulation does not show this then it is wrong. 
My simulation shows that with parallel mirrors and in a linear accelerator that when the parallel mirrors move in the direction of motion and the flash is perpendicular than its behaviour is accordingly to SR. When the mirrors are perpendicular to the direction of movement and the flash is horizontal its behaviour does not.
> 
Independence of acceleration is obvious, but it is not so
obvious that for a given clock speed relative to the lab that
the bounce rate is independent of the orientation of the
clock  a detailed calculation MUST show that it is (because
we are using SR as the basis of the calculation, and SR
clearly predicts independence of clock orientation).
[#] This is a gedanken; I know of no way to actually implement it; I do not think these assumptions are unreasonable. 
When all your points ef are only thoughts (I'm not claiming that they are wrong) how can you be sure that my simulation, which simulate the working of a running clock using light signals, is wrong?
> 
Tom Roberts 
Nicolaas Vroom
>  On Wednesday, September 26, 2018 at 1:42:05 PM UTC5, Tom Roberts wrote: ... 
>>  [description of] a light clock with a light pulse bouncing between two mirrors. [...] Then it is straightforward to see that the trajectory of the light pulse relative to the lab is a series of straight lines with corners at the successive locations of the mirrors' centers when it bounces. It is quite clear that the rate of bouncing measured in the lab depends ONLY on the size of the clock and how fast the mirrors move relative to the lab (i.e. how far apart the corners/bounces are); the mirrors' acceleration DOES NOT MATTER (i.e. it does not matter how they get to successive positions of the bounces/corners). This is just basic geometry, and if your simulation does not show this then it is wrong. 
> 
Unless I am misinterpreting your argument, I believe the last statements about acceleration not affecting the period of the clocks is incorrect. 
For a centrifuge with a fixed radius, the speed of the mirrors relative to the lab is directly related to their acceleration, making it easy to confuse the dependence.
That said, a more careful analysis shows my statements are indeed wrong:
Consider two centrifuges with vertical axes and different radii, but the same tangential speed relative to the lab; they have different accelerations. Let each have a light clock with mirrors separated vertically (along the axis of rotation). Plot the bounce points (in 3d) in the lab for each centrifuge, and project them onto a single horizontal plane  each centrifuge's points all lie on a circle, and the tangential speed of the centrifuge is related to the arc of the circle between the projected points (which is equal for the two centrifuges). Since the radii are different, the chords of the circle between projected points are different, and Pythagoras' theorem (applied to the chord and the vertical separation of the mirrors) implies the light path lengths are different  the two light clocks tick at (slightly) different rates.
This leads us to a rather different lesson: in relativity, clocks are considered to be pointlike [#]. These light clocks are pointlike, and behave as relativity predicts, ONLY when their internal light path is much smaller than their acceleration between bounces (i.e. only when the two chords above differ by a negligible amount). They do, of course, behave as relativity predicts for all INERTIAL motions, even when they are not really pointlike.
In retrospect, this should have been obvious, especially for a light clock in a centrifuge oriented with its mirrors along the radius (i.e. at different "heights" in the equivalent "gravitational field").
>  Consider the two mirrors to be at the same radius in the centrifuge, but displaced along the axis of the centrifuge so the light pulses are describing a zigzag along a cylinder at that radius. 
NO! In the lab, the points of the bounces are all on that cylinder, but the light rays follow STRAIGHT LINES between the bounce points. You sort of talk around this, but it OUGHT to be clear that the light follows straightline paths between bounces (i.e. on the faces of a manysided polygon, not a cylinder).
>  [... description of what appears to be similar, using very different words] 
Bottom line: clocks must be pointlike or their behavior can differ from what relativity predicts.
Tom Roberts
>  [...] 
See my recent post in this thread, which shows an effect  my earlier claims were wrong and a light clock can deviate from the predictions of relativity when it is not pointlike. That is, when its movement between bounces due to acceleration is not very much smaller than its internal lightpath length.
>>  For instance, while they are being accelerated you must tilt the mirrors so the light pulse continues to bounce between them. Parallel mirrors work only when they are moving inertially. 
> 
I definitive do not want to change anything inside the clock as part of the experiment. The whole clock functions as a fixed box, all the angles are 90 degrees. 
Then it won't work when accelerated.
For instance, in a centrifuge with a vertical axis and a light clock having a light path along the vertical axis and parallel mirrors, the light pulse will remain at a fixed azimuth in the lab, and the clock will rotate away from it. That is, motion of a mirror parallel to its surface does not affect light bouncing from it.
You MUST tilt the mirrors when the clock is accelerated, or the light pulse won't remain inside the clock. This applies to all orientations except when the acceleration is parallel to the clock's internal light path.
>  What is science? Do you adjust an experiment to fit the mathematics or Do you adjust the mathematics to fit the experiment? 
Neither. In this case, PHYSICS (geometrical optics) requires that one tilt the mirrors when the light clock is accelerated, or it does not remain a light clock.
This is, of course, a GEDANKEN, not a real experiment. The conditions required are not achievable in the real world.
Tom Roberts
>  On 9/30/18 11:59 AM, Nicolaas Vroom wrote: 
> >  [...] 
> 
See my recent post in this thread, which shows an effect  my earlier claims were wrong and a light clock can deviate from the predictions of relativity when it is not pointlike. That is, when its movement between bounces due to acceleration is not very much smaller than its internal lightpath length. 
In physics nothing physically can be treated as a point. It always has a size. Under Newtons Law a physical object can be treated as a point in the sense that all its mass is 'contracted' in a point. As such a distance between two objects is the distance between the center of each object. Following that reasoning the behaviour of a clock can not be explained when the clock is considered pointlike. In the book SpaceTime physics all the clocks have a 3D Dimension. Nothing is considered pointlike.
My whole point is that when a clock (Using lightsignals) undergoes acceleration (its speeds increases) its behaviour changes. These changes are different, and are a function, of how the clock is build. (This difference depents about the direction of the mirrors relatif to the direction of movement of the clock)
>  You MUST tilt the mirrors when the clock is accelerated, or the light pulse won't remain inside the clock. This applies to all orientations except when the acceleration is parallel to the clock's internal light path. 
My simulation shows that when the lightsignal follows a continuous path and is reflected against the mirrors of the clock than the light signal will not stay inside a clock. This is what I call a Long simulation. Such a simultion needs an initial angle.
A different type of simulation is what I call a short simulation.
A short simultion consists of cycles (or ticks) and each cycle consists
of two reflections. After each cycle a lightflash is generated in all
directions and the flash that reaches the center of the clock is used
to define the next cycle.
See https://www.nicvroom.be/Clock%20and%20Centrifuge.htm
for more details.
The clock discussed at page 37 (Latticework of meter sticks and clocks)
works the same way. It sends out a flash of light that spreads out as
a spherical wave in all directions (page 38)
The whole point is when you use such a clock in a linear accelerator it functions accordingly to SR. In a centrifuge it does not. It is a function of radius and size of clock
> >  What is science? Do you adjust an experiment to fit the mathematics or Do you adjust the mathematics to fit the experiment? 
> 
Neither. In this case, PHYSICS (geometrical optics) requires that one tilt the mirrors when the light clock is accelerated, or it does not remain a light clock. 
That means you adjust the experiment.
>  This is, of course, a GEDANKEN, not a real experiment. The conditions required are not achievable in the real world. 
What is the value of a clock (an experiment) when it can not be build (performed) or when it only functions under specific conditions?
The simulation is more or less the same as a snooker table with only
one ball. There is no friction. v=constant.
First you build a subroutine 2 with as input a position and an angle
The purpose of that subroutine is to calculate the trajectory of one
stroke against the ball.
Subroutine 2 uses subroutine 3 which function is to calculate the
straight trajectory from one reflection to the next reflection.
This routine initial has a fixed long step size. This step size is
decreased the smaller the distance to the reflection point is.
What makes subroutine 3 more complex is that the snooker table
either moves in a straight line or rotate. That means the borders move.
In fact this means at the beginning of the trajectory you do not
know which border the ball is going to hit.
A simulation in which the ball follows its path continuous is called
Long. What you can also do is try to calculate the initial angle
such that the ball reaches the center of the clock after one cycle.
This type of simulation is called short.
Such a simulation starts from subroutine 1. Subroutine 1 calls subroutine 2
four times and stores the initial angle and the result in an array.
The result is the distance from the center after one cycle (2 reflections)
Next it removes the worst result and calculates a new intial angle based
on the three historical saved values. This is repeated until the final
distance between the ball and the center is small enough.
Using the final result the next cycle can be simulated. etc. etc.
See the above mentioned link for more detail.
The power of this simulation is that it does not use the strict concept of a rest frame. In the simulation the linear accelerator or (the center of) the centrifuge are considered at rest. But that is not a strict requirement.
>  Tom Roberts 
Nicolaas Vroom
>  On 9/30/18 1:15 AM, richalivingston.AT.gmail.com wrote: 
> >  On Wednesday, September 26, 2018 at 1:42:05 PM UTC5, Tom Roberts wrote: 
> >>  Then it is straightforward to see that the trajectory of the light pulse relative to the lab is a series of straight lines etc. It is quite clear that the rate of bouncing measured in the lab depends ONLY on the size of the clock and how fast the mirrors move relative to the lab (i.e. how far apart the corners/bounces are); the mirrors' acceleration DOES NOT MATTER (i.e. it does not matter how they get to successive positions of the bounces/corners). etc. and if your simulation does not show this then it is wrong. 
Here the clock is clearly not treated as pointlike i.e. it has a size. My simulation calculates the bounces at the exact moment (event) when the lightflash reaches a mirror. The speed of the mirror is of no importance. The position (direction) is important.
> >  Unless I am misinterpreting your argument, I believe the last statements about acceleration not affecting the period of the clocks is incorrect. 
> 
For a centrifuge with a fixed radius, the speed of the mirrors relative to the lab is directly related to their acceleration, making it easy to confuse the dependence. That said, a more careful analysis shows my statements are indeed wrong: Consider two centrifuges with vertical axes and different radii, but the same tangential speed relative to the lab; they have different accelerations. 
In my simulations I'm primarlily considering clocks of the same size with different speeds. See https://www.nicvroom.be/Clock%20and%20Centrifuge.htm Figure 7 and Figure 11 different radii are considered.
> 
Let each have a light clock with mirrors separated vertically
(along the axis of rotation). Plot the bounce points (in 3d) etc
and the vertical separation of the mirrors) implies the light path lengths
are different  the two light clocks tick at (slightly) different rates.
This leads us to a rather different lesson: in relativity, clocks are considered to be pointlike [#]. 
We are not discussing here GR but SR. We are discussing the internal behaviour of a clock. We are discussing the Lorentz Transformations.
>  These light clocks are pointlike, and behave as relativity predicts, ONLY when their internal light path is much smaller than their acceleration between bounces (i.e. only when the two chords above differ by a negligible amount). They do, of course, behave as relativity predicts for all INERTIAL motions, even when they are not really pointlike. 
That is part of the problem. Are we trully discussion INERTIAL motions. What we are discussing is the behaviour of a clock with different speeds. In some sense we are discussing: What is the most acurate clock under all circumstances.
> 
[#] E.g. atomic clocks are pointlike compared to GPS orbits.
In retrospect, this should have been obvious, especially for a light clock in a centrifuge oriented with its mirrors along the radius (i.e. at different "heights" in the equivalent "gravitational field"). 
I doubt if the behaviour of a clock is obvious.
In the book Gravitation at page 393 we can read:
"Alternative, one can analyze the clock in its own "proper reference frame"
with FermiWalker transported basis vector, using the standard local
Lorentz laws of quantum mechanics as adapted to accelerated frames
(local Lorentz laws plus an "inertial force" which can be treated as due
to a potential with a uniform gradient.
Ofcourse any clock has a "breaking point" beyond which it will cease to
function properly. But that breaking point depends entirely on the
construction of the clock  and not at all on any "universal influence of acceleration on the march of time."
Nowhere the word pointlike is mentioned
In short the behaviour of a clock is complex and to describe an accelerated
clock by means of Lorentz transformation (t' = \integral (1v^2/c^2) dt)
is too simple. Not to mention that an accelerated clock has its limmits.
>  Bottom line: clocks must be pointlike or their behavior can differ from what relativity predicts. 
There are two complete different situations:
In GR or Newtons Law, clocks used to simulate (predict) the movement
of planets around the Sun, are pointlike. They show the time of a point
in space.
When you want to study the internal behaviour of a clock, clocks
ofcourse are not point like. The issue is that some clocks (dependent
how they are used) are in agreement with SR others (often) are not.
This behaviour becomes more complex when gravitation has to considered.
For example for mechanical clocks.
>  Tom Roberts 
Nicolaas Vroom
>  My whole point is that when a clock (Using lightsignals) undergoes acceleration (its speeds increases) its behaviour changes. These changes are different, and are a function, of how the clock is build. 
If I enclose a springdriven pocket watch, an atomic clock, a quartzbattery clock, a grandfather clock and so on in a box and accelerate it, the decelerate it and examine them (or accelerate myself to catch up to it and enter it while moving), do you expect them to read differently, assuming that they were synchronized at the beginning (and, as per a Gedankenexperiment, all completely accurate when at rest)? One could argue that a grandfather clock is driven by gravity and thus, due to the equivalence principle, would be affected by acceleration, but what about the other three? What about two partiallysilvered mirrors with a light pulse bouncing between them which beeps when a photomultiplier behind one of the mirrors is activated?
Rather, any accelerated system may be viewed as disturbed somehow with particle and fields constituting it as a seemingly solid state device, not following their time evolution at rest or at constant velocity.
In the extreme case the atomic clock at the head and tail of an accelerated rocket will not show the same time, if they were synchronized before accelearation at rest.
What happens to the Hatom at constant acceleration is long known as gravitational shift of the sstate
http://iopscience.iop.org/article/10.1088/02536102/13/4/533/pdf
The reason is easy to see: The hard core of the electronic state is coupled to the accelerated environment. The nucleus in its center is hovering in the center of the electinic cloud by minimization of its potential energy. In the gravitational field the position of the nucleus is shifted out of the center resulting in an overall dipole correction to the effictive Hamiltonian in the relative coordinate of the twoparticle space. If accelaration is not constant, the nucleus will begin to expose an oscillator spectrum in the fine structure range.
As always in atomic and subatomic physics: There are conserved or nearly constant momentum and spectrum observables, that yield macroscopic measurable numbers. Coordinates and time are merely parameters of the theory. There is no way to physically fix a set of canonically "true" coordinates and time, they simply do not exist.
Clocks more relibale with respect to the measurement of proper time on curved paths in spacetime do not exist. There is no clock available on the length scale of nucleons and there do not exist any form of a clock in a hot plasma whatosever.
So spcetime coordinates are a definition in a concept of theoretical physics. One hase to use sets of stationary synchronised clocks and sticks in inertial frames of a system of laboratories and interpret the Lorentzpath length of a small enough volume of space under observation traveling through spacetime as its proper time.
If observation and transformation to the local rest system of the accelerated volume of space results in a consistent approximation of classical/quantum physics at small velocities up to squares of the momentum variables, the theory seems to be relativistically correct if expanded relativistically to noninertial systems.

Roland Franzius
> 
In article 
> > 
My whole point is that when a clock (Using lightsignals) undergoes acceleration (its speeds increases) its behaviour changes. These changes are different, and are a function, of how the clock is build. 
> 
If I enclose a springdriven pocket watch, an atomic clock, a quartzbattery clock, a grandfather clock and so on in a box and accelerate it, the decelerate it and examine them (or accelerate myself to catch up to it and enter it while moving), do you expect them to read differently, assuming that they were synchronized at the beginning (and, as per a Gedankenexperiment, all completely accurate when at rest)? 
The only way to find out is by performing an experiment. The results of my simulations show that not all clocks behave the same.
>  One could argue that a grandfather clock is driven by gravity and thus, due to the equivalence principle, would be affected by acceleration, 
Also this should part the experiment. As you expect such a clock will read differently and if that is the case you find the reason by investigation how this clock is build and operates.
>  (but what about the other three?) What about two partiallysilvered mirrors with a light pulse bouncing between them which beeps when a photomultiplier behind one of the mirrors is activated? 
This behaviour differences when you put the clock in a linear accelerator
depending about the direction of the bouncing light pulse versus the direction
of movement.
This behaviour is not the same if the direction of the bouncing light pulse
is thesame as the direction of movement versus if the two directions are
different i.e. perpendicular. In the last case the behaviour is described
by the Lotentz transformation.
If you put such a clock in an centrifuge you have a high chance that
the clock will not operate. This is specific described as this link:
https://www.nicvroom.be/Clock%20and%20Centrifuge%20part2.htm
>  but what about the other two? 
General speaking you have to study how they both operates. You can not do that by performing a Gedankenexperiment. Studying the reply by Roland Franzius you can see how complicated this is.
Nicolaas Vroom
Given that all of the (other) clocks are pointlike, as well as the box [#], then GR certainly predicts they all read the same. I see no reason to doubt this prediction  after all, it is based purely on geometry, not on any construction details of the clocks.
As my earlier discussion showed, this applies only to the accuracy with which the clocks and box [#] can be considered to be pointlike (not being pointlike affects the geometry). And of course the gedanken is limited to accelerations that do not break any of the clocks.
(I'm willing to discuss the geometry of GR; I'm not interested in construction details of clocks.)
Tom Roberts
>  On 10/8/18 12:37 PM, Phillip Helbig (undress to reply) wrote: 
> > 
If I enclose a springdriven pocket watch, an atomic clock, a quartzbattery clock, a grandfather clock and so on in a box and accelerate it, etc 
> 
A grandfather clock is not really a clock, it is just a pendulum and a counter; the actual clock is that PLUS THE EARTH. So it cannot possibly be put into the box (and if you imagine a hugeenough box then it will not be pointlike). Given that all of the (other) clocks are pointlike, as well as the box [#], then GR certainly predicts they all read the same. I see no reason to doubt this prediction  after all, it is based purely on geometry, not on any construction details of the clocks. 
The clocks used in the book SpaceTime Physics are not pointlike and the reason that tick is also because they are not pointlike. The reason that they behave differently is because the mirrors can be parallel or pendicular to the direction of motion. My simulation assumes the same.
>  As my earlier discussion showed, this applies only to the accuracy with which the clocks and box [#] can be considered to be pointlike (not being pointlike affects the geometry). And of course the gedanken is limited to accelerations that do not break any of the clocks. 
How can I understand a thought experiment when in reality a clock has 3 dimensions and in the thought experiment not. (only 1)
>  [#] The box must be pointlike, or clocks higher in the acceleration's equivalent "gravitational field" will not remain in sync with clocks that are lower. This is also geometry. 
That clocks don't remain in sync is also because they can behave differently even when gravity is not considered.
>  Note that arguments about "nothing being truly pointlike" are valid MATHEMATICALLY, but in physics such approximations are used all the time, when the error involved is smaller than the measurement resolution. 
IMO it only makes sense to assume that a clock is pointlike when you consider the time of a pointlike object in space. My simulations of the movement of the planet mercury (using Newton's law) assume the same time at each iteration for all the planets considered. The position of the clock, in theory, is considered fixed.
>  (I'm willing to discuss the geometry of GR; I'm not interested in construction details of clocks.) 
Nicolaas Vroom.
>  On Tuesday, 9 October 2018 20:14:39 UTC+2, Tom Roberts wrote: 
> >  On 10/8/18 12:37 PM, Phillip Helbig (undress to reply) wrote: 
> > > 
If I enclose a springdriven pocket watch, an atomic clock, a quartzbattery clock, a grandfather clock and so on in a box and accelerate it, etc 
> > 
A grandfather clock is not really a clock, it is just a pendulum and a counter; the actual clock is that PLUS THE EARTH. So it cannot possibly be put into the box (and if you imagine a hugeenough box then it will not be pointlike). Given that all of the (other) clocks are pointlike, as well as the box [#], then GR certainly predicts they all read the same. I see no reason to doubt this prediction  after all, it is based purely on geometry, not on any construction details of the clocks. 
> 
The clocks used in the book SpaceTime Physics are not pointlike and the reason that tick is also because they are not pointlike. 
Of course no real clock is pointlike. The point (pun intended) is whether it can be thought of as pointlike, i.e. whether this is a valid approximation. This depends on its behaviour in the limit of an arbitrarily small clock.
> >  As my earlier discussion showed, this applies only to the accuracy with which the clocks and box [#] can be considered to be pointlike (not being pointlike affects the geometry). And of course the gedanken is limited to accelerations that do not break any of the clocks. 
> 
How can I understand a thought experiment when in reality a clock has 3 dimensions and in the thought experiment not. (only 1) 
Because it is a sufficiently good approximation.
>  What I want to know is why my simulations of clock in a linear accelerator or centrifuge are wrong. 
This is the question which should be addressed.
In general, while a simulation might visualize something which is otherwise difficult to grasp, in terms of physics one gets out only what one puts in.
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