Discussion
Started 5th Mar, 2022

# Another Special Relativity thought experiment

Imagine a row of golf balls in a straight line with a distance of one metre between each golf ball. This we call row A. Then there is a second row of golf balls (row B) placed right next to the golf balls in row A. We can think of the row A of golf balls as marking of distance measurements within the inertial frame of reference corresponding to row A (frame A). Similarly the golf balls in row B mark the distance measurements in frame B. Both rows are lined up in the x direction.
Now simultaneously all the golf balls in row B start to accelerate in the x direction until they reach a steady velocity v at which point the golf balls in row B stop accelerating. It is clear that the golf balls in row B will all pass the individual golf balls of row A at exactly the same instant when viewed from frame A. It must also be the case that the golf balls in the rows pass each other simultaneously when viewed from frame B.
So we can see that the distance measurements in the frame of B are the same as the distance measurements in row A. The row of golf balls is in the x direction so this suggests that the coordinate transformation between frame A and frame B should be x - vt.
This contradicts the Lorentz transformation equation for the x direction which is part of the standard SR theory.
If we were to replace the golf balls in row B with measuring rods of length one metre then in order to match the observations of the Michelson Moreley experiment we would conclude that measuring rods must in general experience length contraction relative to a unique frame of reference. So this thought experiment suggests that we need to maintain distances as invariant between moving frames of reference while noting that moving objects experience length contraction.
This also implies the existence of a unique frame of reference against which the velocity v is measured.
I would be interested to see if the thought experiment can be explained within standard Special Relativity while retaining the Lorentz transformation equations.
Richard

22nd Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<SQ: two clocks which do not exchange em waves are linked by Lorentz Transformations as well according to SR, this I know quite well... in principle only with RDE you need radiation...
PG: The time it takes for an electron to buzz around a carbon atom in your body reacts on the same way as any clock. We need radiation of EM waves to keep our body together and our nerves communicating.>>
I'm talking about two atomic clocks with digital gauges, they do not exchange anything at all between eachother as the muon which is in motion, whose half lifetime is measured, with a clock at rest which just measure such time.
<<SQ: To say that a measurement has to be wrong because it does not comply with SR in a effect which has never been experimentally verified is just an ARISTOTELIAN ipse dixit, abandoned 400 years ago with Galielei...
PG:The measurement can be perfect, accurate, but according to rules that disagree with SRT. Then they are invalid wrt SRT.>>
then it depends: if one shows that clocks in sync in a rocket at distance H head to tail after departure of the rocket reaching speed v, will not desynch at all as vH/c2 which is the prediction of SR, then there will be a serious issue with RoS hence SR.
<<But those experiments are done with measurement definitions that are not recognised in SR.>>
I am sorry but here there is strong disagreement, see the example before
<<SQ: b) the inertial frames as a matter of fact do not exist in nature
PG:How much of one amount of matter is at rest in one single frame is only the question. Inertia with acceleration only needs the size of one proton of to get an SRT result.>>
only in the center of mass frame of the scattering.... the Proton is not be inertial at all.

## Popular replies (1)

29th Mar, 2022
J. David Brown
North Carolina State University
This statement: "It must also be the case that the golf balls in the rows pass each other simultaneously when viewed from frame B." is not correct. The observers riding along with row B are changing their inertial frame while they accelerate. The observers riding along row A stay in the same inertial frame. The observers on row B will see row A golf balls as length contracted; they will not pass B's golf balls "simultaneously".
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## All replies (926)

5th Mar, 2022
Divyansh Baranwal
Indian Institute of Information Technology Guwahati
with respect sir, you have written “simultaneously all golf balls in row B start” in 2nd paragraph 1st line the term simultaneous is frame dependent and if we are to believe in Lorentz transformations then there will be a time dilation factor that will come into play while we switch from frame B to A because of which the phenomea in B is no longer simultaneous wrt A this factor of time dilation will lead in non synchronized distance measurements between A and B which will be the factor of length contraction that is due to the supposed time lag(dilation)
with regards
Divyansh Baranwal
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Divyansh Baranwal I do think that there is a way around the problem of ensuring that all golf balls in row B start simultaneously. We equip all the golf balls in row A with a timer and these timers are all pre synchronised.
At a preset time the golf balls in row A send a signal over the 5cm distance to their corresponding golf ball in row B. The golf balls in row B then set off on their identical paths and so maintain their distance separation of one metre.
Even though there is time dilation in frame B the golf balls of row A and row B will be observed to pass simultaneously whether viewed from frame A or frame B. Therefore distance measurements must be the same in both frames even though objects experience length contraction.
Thank you for the challenge and please let me know if you don’t agree with my answer.
Richard
6th Mar, 2022
Divyansh Baranwal
Indian Institute of Information Technology Guwahati
Richard Lewis sir the crossing of paths of balls in A and B seems to be a frame independent phenomenon so to make things easier I will take some other similar phenomena . I will take a car whose rest length is 5 m and is to be parked inside a garage 4 m long (in rest frame)which is moving with 0.6c . Now the car may get parked inside the garage or it may not and this fact is seemingly frame independent but the thing is it’s not frame independent. in rest frame it’s 5m long and garage gets even smaller and in garage frame car does fit in the garage.Same logic is true with these 2 sets of golf balls.Because distance is not an invariant in space time . So even if we say 2 sets of balls passing is an invariant phenomenon their distances are not invariant
With regards
Divyansh Baranwal
Divyansh Baranwal We have to make the distinction between distances and lengths (see the updated paper March 2022) linked in the original post.
If we had a 4m garage at rest in K0 and a 5m car (measured at this length length in K0) moving at 0.6c then the length contraction is sqrt ( 1 - 9/25) which is 4/5 so the car length is 4m. The car would instantaneously fit in the garage before it crashed into the wall at the end of the garage.
You cannot use the same logic with the golf balls because the distance of separation is not affected by length contraction. If you think through the thought experiment you realise that we are using the fact of translation invariance in frame A.
The golf balls are all lined up in a row and the experiment looks the same if we view it from the next golf ball along in the x direction.
We have already stated that there is a timer in all the golf balls in row A. Let’s put a similar timer in all the golf balls in row B and have them initially synchronised. Of course once the golf balls in row B start to accelerate away the timer for row A T(A) loses synchronisation with the timer for row B T(B). If we imagine being located at one of the golf balls in row A we can read T(A) and T(B) as the next golf ball from row B passes. From translational invariance we know that all the golf balls in row A will be registering the same T(A) and all the golf balls in row B will be registering the same T(B). So we can see that the distance between the golf balls must be the same in frame A and frame B.
Richard
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6th Mar, 2022
Divyansh Baranwal
Indian Institute of Information Technology Guwahati
Richard Lewis sir I know this discussion is kind of long but the confusion still remains because
1) As far as I know length is distance between 2 end points of and object. so making distinctions between them is something that I can’t imagine.
2) you said the 5 m car will become 4m car that is correct in the frame which is moving with 0.6c but the problem is garage is in rest frame so it will measure the length of the car as 5m and its own length as 4m which will cause the crash in the rest frame
3) I get it that you are considering 2 sets of time Ta and Tb for 2 different sets of golf balls and using translation invariance for individual sets of golf balls to make the argument of frame independent distances while they cross each other along x direction and that’s a really good point and if I replace these balls with a meter rod than we can easily take into account the length contraction cause 1 point will replace another in the case of rod(continua of points) but in case of points 1 may argue that length contraction won’t make much sense as it is a discrete point and x axis is an axis and is not frame dependent so I think this may solve the problem.
Thank you for making me think on something I never thought of if there is something I haven’t figured it out please do tell
With regards
Divyansh Baranwal.
Divyansh Baranwal It is difficult to understand the distinction between a distance in space and the length of a physical object.
The key to understanding length contraction lies in understanding the Spacetime Wave theory which we have talked about before.
Electrons, neutrons and protons are looped waves in Spacetime and when a physical object made of these particles moves with velocity v relative to K0 it experiences length contraction. This is why physical objects experience length contraction even though distances are not affected.
To look at another example, we know that muons are created in the upper atmosphere due to cosmic rays. The muons have a very short time before they decay and it is the effect of time dilation which allows these fast moving particles to reach the surface of the Earth.
Looked at from the frame of reference of the muon, the time dilation really does slow down the rate of passage of time for all physical processes including muon decay. However, in the moving frame of reference of the muon, the distance it has to travel to the Earth surface is not subject to length contraction.
Richard
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Hans-Otto Carmesin I have taken a look at the first link in your post and I have started to read what seems to me to be a very well written and argued case. However, I do think you should take a close look at the thought experiment described above.
My conclusion from this thought experiment is that the Lorentz transformations of Special Relativity cannot stand because physical distances are preserved between different inertial frames of reference.
This together with other observational results regarding time dilation and length contraction seem to imply to me that there must be a space rest frame:
This in turn means that we have to give up one of the Einstein equivalence principles that you mention in section 2.2.2: "The outcome of any local non-gravitational experiment is independent of the velocity of the freely falling reference frame in which it is performed."
My contention is that the outcome of any experiment conducted in reference frame Kv is affected by the fact that the rate of passage of time in frame Kv is affected by the time dilation due to the velocity v relative to the space rest frame K0.
The idea of a space rest frame also explains why the speed of light is the same for the binary stars you describe and this is because light travels as a wave disturbance of spacetime in the space rest frame K0. This also explains why the speed of light is independent of the velocity of the source or the observer.
Richard
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Dear friends of cosmology and quantum physics, dear Richard Lewis,
Thank you for your contribution today (20220307) and for your interest in my book (https://www.researchgate.net/publication/358581911_Quantum_Physics_Explained_by_Gravity_and_Relativity).
I have a simple question: How do you measure your relative velocity with respect to the ‘space rest frame’ that you assume.
Kind regards,
Hans-Otto Carmesin
Hans-Otto Carmesin If you take a look at the paper I have given an experimental method of measuring the velocity of the Earth relative to the space rest frame K0.
Richard
RL: Now simultaneously all the golf balls in row B start to accelerate ...
What you are describing is very well known and a useful educational tool for learning SR. It is called "Bell's Spaceship Paradox", you can find a description and analysis here:
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Dear friends of cosmology and quantum physics, dear Richard Lewis,
thank you for your interest in my thought experiment as a basis of special relativity in section 7.8 in the following book:
Thank you also for your paper:
In that paper, you suggest a space rest frame K_0.
I have very simple questions:
What is the time dilation of a frame K_1 moving with v = 0.8c?
What is the time dilation of a frame K_2 moving with v = -0.8c within the system K_1?
Kind regards,
Hans-Otto Carmesin
Hans-Otto Carmesin This is a very good question and thank you. The time dilation always depends on the velocity relative to the rest frame K0. If your frame K1 has velocity v=0.8c and your frame K2 has the same velocity relative to K1 in the opposite direction then frame K2 is identical to K0. This means that the velocity v for frame K2 is zero and there is no time dilation in frame K2.
Richard
Hans-Otto Carmesin I am not sure if I have answered your question correctly. I did see a minus sign in front of the 0.8c for K2 but perhaps you mean that the velocity of K2 relative to K1 is 0.8c in the same direction?
In that case it is a different answer. The answer then is that the frame K2 is impossible because is is not possible to move faster than c relative to K0. If you imagine that you were in frame K1 and you tried to accelerate an object, its mass would increase so that as the velocity relative to K0 approached the speed of light the mass would tend to infinity. So from the frame of reference of K1 it is only possible to accelerate objects by up to 0.2c in the direction of moving frame K1.
Richard
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George Dishman I have looked at the description of the spaceship paradox as linked and I think it differs from the “golf ball” problem that I have described.
in the spaceship paradox as described the distance of separation is maintained in frame S but not in frame S’.
In the golf ball thought experiment distance of separation is the same in frame A and frame B.
Richard
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Dear Richard Lewis,
Thank you for your interest (your contribution from 20220308) in my thought experiment as a basis of special relativity in by book ‘Quantum Physics Explained by Gravity and Relativity’.
The Haefele Keating experiment (1972) showed that atomic clocks exhibit the usual time dilation according to the velocity relative to Earth. In particular, they did not detect a relative velocity relative to the system K_0 that you assume.
Kind regards,
Hans-Otto Carmesin
In your original question, you wrote:
RL: Now simultaneously all the golf balls in row B start to accelerate in the x direction until they reach a steady velocity v at which point the golf balls in row B stop accelerating.
You did not say if the same acceleration was applied to each ball or if they differ. In Bell's paradox, each rocket follows the same predefined flight plan, typically they both apply the same constant acceleration. As measured by observer at rest on the launch pads, the speeds at any instant are the same so the separations remain constant. If you would clarify whether that is the assumption in your question, it would avoid us talking at cross purposes.
The alternative is that the balls in row B are not required to apply the same accelerations but are required to maintain the same spacing as measured from ball to ball as they had at the start. That results in their having different accelerations.
RL: In the golf ball thought experiment distance of separation is the same in frame A and frame B.
That is geometrically impossible in relativity so if you try to impose an impossible condition, you will of course get an outcome that contradicts the theory.
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George Dishman Very good point and I have adjusted the wording to indicate that it is the same acceleration for all the golf balls. I have also added timers to the golf balls in the thought experiment to emphasise the distance invariance between moving frames.
Unless a problem is found with the thought experiment, it must mean that a conclusion is true which is geometrically impossible in relativity.
Here is the revised wording:
Golf ball thought experiment
Imagine a row of golf balls in a straight line with a distance of one metre between each golf ball. This we call row A. Then there is a second row of golf balls (row B) placed right next to the golf balls in row A. We can think of the row A of golf balls as marking of distance measurements within the inertial frame of reference corresponding to row A (frame A). Both rows are lined up in the x direction.
Now simultaneously all the golf balls in row B start to accelerate with the same acceleration in the x direction until they reach a steady velocity v at which point the golf balls in row B stop accelerating. Now we can identify the inertial frame of reference corresponding to row B (frame B). Frame B is now an inertial frame moving in the x direction with velocity v relative to frame A.
The golf balls in row B will all pass the individual golf balls of row A at exactly the same instant when viewed from frame A. It must also be the case that the golf balls in row A will all pass the individual golf balls of row B at exactly the same instant when viewed from frame B.
To see that this is the case imagine that each golf ball in row A is equipped with a timer and the timers are all synchronised. A similar timer arrangement is set up in all the golf balls in row B and the timers are also synchronised. During the acceleration of the golf balls in row B the timers remain synchronised with other golf balls in row B because they all have the same trajectory. The timers in row B are not synchronised with the timers on the golf balls in row A due to time dilation effects.
There is an observer at rest in frame A alongside each golf ball in row A and an observer at rest in frame B alongside each golf ball in row B. This arrangement ensures that the observations which are taken are of the timer values of the golf balls in row A and row B as they pass each other. This ensures that any observation is over an arbitrarily small distance and not dependent on light travel time.
The experiment has translational invariance which means that when the experiment is observed from one golf ball, then the symmetry of the experiment must mean that the experiment looks the same from the next golf ball along the row and therefore from all golf balls along the row.
Because of this translational invariance all the observers in row A will report a value of the timer A and a value of the timer B as the golf balls pass each other and this observation will be the same for all observers in row A. Similarly all the observers in row B will report a value of the timer A and the value of the timer B as the golf balls pass each other and this observation will be the same for all observers in row B.
As the golf balls pass each other, we are instantaneously aligning the distance between the golf balls in row A with the distance between the golf balls in row B and this must therefore be the same distance.
So we can see that the distance measurements in the frame of B are the same as the distance measurements in the frame of A. The row of golf balls is in the x direction so this suggests that the coordinate transformation between frame A and frame B should be x - vt.
This contradicts the Lorentz transformation equation for the x direction which implies that the postulates of special relativity have to be changed.
Richard
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Excellent work Richard Lewis, that clears up the ambiguity nicely and allows me to give you a definitive explanation.
RL: Imagine a row of golf balls in a straight line with a distance of one metre between each golf ball. This we call row A. Then there is a second row of golf balls (row B) placed right next to the golf balls in row A. We can think of the row A of golf balls as marking of distance measurements within the inertial frame of reference corresponding to row A (frame A). Both rows are lined up in the x direction.
RL: Now simultaneously all the golf balls in row B start to accelerate with the same acceleration in the x direction until they reach a steady velocity v at which point the golf balls in row B stop accelerating. Now we can identify the inertial frame of reference corresponding to row B (frame B). Frame B is now an inertial frame moving in the x direction with velocity v relative to frame A.
RL: The golf balls in row B will all pass the individual golf balls of row A at exactly the same instant when viewed from frame A.
That is correct.
RL: It must also be the case that the golf balls in row A will all pass the individual golf balls of row B at exactly the same instant when viewed from frame B.
That is incorrect. There are multiple ways to analyse the experiment in SR but all give the same result. For simplicity, I will break it down into well known steps. Only two balls are needed, what I say will apply to every adjacent pair.
As seen from frame A, all the balls start at the same instant and then have the same acceleration so at all times as measured in frame A, they all have the same velocity, and each has then covered the same distance from its launch point.
If the first two balls in row B were held apart by a rod say, we would see "length contraction" in the A frame as their speed increased so their separation in frame A would decrease. That does not happen but the effect is still in force so as measured in the B frame, the distance between the balls must increase.
From the first B ball (the one with the lowest x coordinate as they are accelerating in the x direction), the second ball ahead of it moves ahead so is measured to be exceeding the planned acceleration profile. Conversely, from the second ball, the first appears to be falling behind so accelerating too slowly.
The reason for this is an often missed phenomenon known as the "relativity of simultaneity". If we imagine all the balls accelerate for more than 2 seconds say, just as an example, then when one second has elapsed on the clock carried by ball 1, slightly more time will have elapsed on the clock of ball 2 because they no longer agree which ticks of their clocks happen simultaneously. Someone moving alongside ball 1 will see the clock on ball 2 ticking too fast and would say it is consequently ahead of where it should be. Someone alongside ball 2 would say their clock is fine, it is ball 1's clock is running too slowly.
The consequence in Bell's version is that a string stretched between the spaceships would snap. Those on the ships put this down to the other ship not keeping to the plan, those on the ground say the ships stay the same distance apart but the string gets progressively more length contracted as the speed increases.
To understand it geometrically, draw a spacetime diagram from the point of view of frame A. The balls in row B each have a curved worldline. Then note that their time axis is the tangent to that worldline and construct the normal (remembering it is hyperbolic geometry) to find the surface each ball considers joins simultaneous events.
RL: During the acceleration of the golf balls in row B the timers remain synchronised with other golf balls in row B because they all have the same trajectory.
They remain synchronised as measured in frame A, they move out of sync as measured in any ball B frame (once moving they no longer share single frame).
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George Dishman There is something very puzzling about that explanation. Let’s say that the timers are read by the observers in frame A and they all agree that timer A reads 5 seconds and timer B reads 4 seconds. They might even communicate this observation to the observers in frame B as they flash past.
So we can be sure that the observers in frame B will all agree that timer B reads 4 seconds and timer A reads 5 seconds.
So the balls pass simultaneously when viewed from frame B.
Richard
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Yes, relativity of simultaneity is the one that most people miss. It is also odd because it is first order while the other effects are second order.
When an A observer sees 5 seconds on the A ball and 4 seconds on the B ball, simultaneously in that frame so will all the other A observers.
When one B observer sees 4 seconds on his ball and 5 seconds on the adjacent A ball, simultaneously as far as he is concerned, the balls ahead will have reached 4.1 and 5.1 seconds while the ones following would be roughly 3.9 and 4.9 seconds.
It's late tonight and I'm suffering from Covid (I thought I was nearly over it but apparently not yet) but I'll try to write an animation for this in the morning.
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George Dishman Very sorry to hear that you have Covid so best to rest for a while and take it easy. I hope it is only the mild version.
I have tried to avoid observers looking at the adjacent golf balls as this brings assumptions about the speed of light effect on observations. That is why I try to make all observations at effectively zero or negligible distance and then the observers compare their results after the experiment.
I am planning to put the golf ball thought experiment up on ResearchGate as a preprint paper. It is already up on Academia.com but I want to get the wording right before I put it on ResearchGate because it is difficult to change after publication.
Richard
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11th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<Yes, relativity of simultaneity is the one that most people miss. It is also odd because it is first order while the other effects are second order.>>
and Physics misses it as well, since there is no experimental proof whatsoever of it except some proof on paper. There is no one experiment to show that alleged phenomenon at the first order exists.
Unless you refer to longitudinal doppler at the first order which is experimentally verified. But that does not really need Lorentz transformations, otherwise we could obtain the Doppler in acoustics, exaclty the same as the first order of light, with the Lorentz Transformations.
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11th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
Thanks for the thought Richard, yes it's been very mild for me and my test this morning is considerably faded so I should escape on Monday. It leaves a real fatigue though, I think that'll take longer to go.
RL: I have tried to avoid observers looking at the adjacent golf balls as this brings assumptions about the speed of light effect on observations. That is why I try to make all observations at effectively zero or negligible distance and then the observers compare their results after the experiment.
Yes, you have to deal with that, but as soon as you claim that simultaneity applies to some event for all the B balls, you have that remote determination, you can't avoid it. You said "timer A reads 5 seconds and timer B reads 4 seconds" which would be true locally for every pair but those events are not synchronised in frame B, only in frame A.
RL: I am planning to put the golf ball thought experiment up on ResearchGate as a preprint paper. It is already up on Academia.com but I want to get the wording right before I put it on ResearchGate because it is difficult to change after publication.
In that case I would add another recommendation, be specific about the type of acceleration. If you use the term "proper acceleration", that is a value obtained on board the ball using an accelerometer. You can maintain that value indefinitely. If you use "coordinate acceleration", it is the second derivative of the distance the ball has moved from its starting point as measured in frame A. That can only be maintained up to a maximum of almost the speed of light and requires an ever-increasing proper acceleration.
The other thing I would recommend is that you look at the existing publications on the topic and see if you have something original to contribute. Here are a few, though none use golf balls, but there are many more:
There are a few YouTube videos around too but I haven't examined any, I'll leave that to you.
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George Dishman Here we get to the heart of the thought experiment. If all the observers in frame B see the timer showing 4 seconds as the golf balls pass does that not mean that the passing of golf balls is also simultaneous as seen from frame B?
Richard
RL: If all the observers in frame B see the timer showing 4 seconds as the golf balls pass does that not mean that the passing of golf balls is also simultaneous as seen from frame B?
No, because they see those events happening at different times even though each pair has a 4 and a 5 at that instant.
I've managed to get my simulation running. Click the "play" button next to the t variable to see time progress.
Let me give you a way of looking at this that will get you to the heart of relativity.
An observer, call him Bob, is moving alongside a B ball. He has a clock in his hand and he is taking time measurements which he calls t'. As far as he is concerned, the clock is not moving relative to him. It is always at x'=0 where x' is his measure of distance from him. As far as he is concerned, his clock measurement are separated only by seconds, never metres. If he plots those readings on a time/distance chart, he will place the parallel to his time axis. For him, that is the direction of his time in the 4-dimensional universe we inhabit.
As far as an observer with standing beside an A ball, call her Alice, Bob's time measurements were taken along the curving path shown in the animation, his worldline. As far as Alice is concerned, what Bob calls his "time axis" is actually the tangent to his worldline at the moment of each reading, so it is at an angle to Alice's time axis.
Now the rules of Cartesian coordinates are the the axes must be perpendicular. We are used to that meaning at right angles but technically it means the vector product is zero. Because the geometry of spacetime is hyperbolic, for Bob's spatial axes to be perpendicular to his time axis, it has to rotate in the opposite sense, so you can see Bob's time axis rotates clockwise which means his x axis rotates anticlockwise (y and z are not affected).
Note that it rotates the opposite way but through the same angle, this is why we always work in units where c=1, the maths at work is just an extension of Pythagoras but time enters with the opposite sign to space.
What we mean by "simultaneous events" is those that happen "at the same time but different places", so what Bob considers to be simultaneous is events that lie on a line parallel to his green line.
When you look at it geometrically, all the effects appear quite logical, but you really have to grasp that reality is four-dimensional before it makes sense.
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SQ: and Physics misses it as well, since there is no experimental proof whatsoever of it except some proof on paper. There is no one experiment to show that alleged phenomenon at the first order exists.
When we move in a direction perpendicular to the direction where light comes from, then the light seems to come from a slight angle forward. In a static frame, where we are seen as moving, there the light is observed to have a wavefront perpendicular to the moving direction and thus parallel to our moving direction. In our moving frame the light is observed as coming from slight forward and thus also the wavefront is rotated with that direction.
You can derive that if you imagine a 3D Minkowski diagram with horizontal planes XY and vertical direction time. In the first, rest, frame the light moves perpendicular to our moving direction. So light could come out of the positive x direction and our movement is to the positive y direction. In the Minkowski diagram this means that a single wavefront will trace a slanted surface under 45° that intersects the xy plane in x=0. This is all described in the rest frame. If we now describe it from the moving frame in the moment that the moving observer is at (x,y=0,0), then for the moving observer the light comes from lightly forward, but his moving direction remains the same y direction axis. Thus the wave front should not be seen to be parallel with the y direction axis. If we now take into account the Level Of Simultaneity (LOS) for the moving observer when it is in (x,y=0,0) then towards the positive y direction this LOS is lifted upward above the xy plane and towards the negative y direction this LOS is below the xy plane. It is a plane with an intersection line along the x axis. Now I have described 3 planes, 1) the LOS for the rest frame, the xy plane, 2) the 45° angle wavefront plane, and 3) the LOS of the moving observer. If we now see how the LOS 3) intersects the wavefront plane 2) then we see that the intersection of those two planes gives a line through (x,y=0,0) but in front of the moving observer slanted towards the negative x axis and behind the moving observer slanted towards the positive x direction. So, in the LOS 3) of the moving observer the wavefront is rotated in the same direction as relative direction of the light.
I hope that you can understand the graphical description. Here I have shown that only with the help of the LOS I could get that the relative rotation of the direction of light also includes the rotation of the wavefront. This is the every day practical proof of the existence of the LOS. Without LOS the light would appear to keep its wavefront parallel to the y direction. The fact that light appears to have a waver front perpendicular to the moving direction in every frame is the experimental proof of relativity of simultaneity.
Regards,
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11th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<When we move in a direction perpendicular to the direction where light comes from, then the light seems to come from a slight angle forward. In a static frame, where we are seen as moving, there the light is observed to have a wavefront perpendicular to the moving direction and thus parallel to our moving direction. In our moving frame the light is observed as coming from slight forward and thus also the wavefront is rotated with that direction.>>
ok in general you want to mean also that the light clock works with aberration of light, which is due to pure relative motion.
Unfortunately time dilation is a physical fact experimentally verified and does not depend on pure relative motion. Even with the Lorentz Transformations you do not go anywhere with pure relative motion only.
And again there is no experimental proof whatsoever of the relativity of simultaneity and that is supposed to be one of the main features of SR.
The term vx/c2 which accounts for the ROS in the Lorentz Transformations is just a resych term.
From GPS, we know that the resonant frequency/tick-rate of an atomic clock decreases with its direction-independent speed with respect to the Earth Centered Inertial Reference frame (the ECI) for locations in the vicinity of the Earth. This includes geostationary ground stations which move wrt the ECI due to the Earth's rotation. For interplanetary spacecraft it is their speed wrt the Solar System/Barycenter inertial reference frame.
But this is not time dilation.
According to the Quantum Electromagnetics theory of Prof Ching-Chuan Su, this phenomenon is due to a quantum property of the atoms in the atomic clock. The energy and therefore frequency of the electron transition used to derive the tick-rate is affected by the atoms' interaction with the local-ether. It is akin to how temperature can affect a clock's tick-rate.
A clock's tick-rate is independent of its velocity relative to other clocks. Fewer total ticks are counted by the clock with the higher speed wrt the ECI; it is not symmetrical. This is in contradiction to the predictions of SRT. If SRT was true, the global synchronization of GPS satellites and GPS receivers would be impossible (as many relativists predicted before the first GPS satellites were launched).
James Marsen Hi James. I think we are in some agreement on this. I agree that Special Relativity is not correct. You refer to a local ether I would refer to a universal space rest frame which is the frame of reference in which space (ether) is stationary.
I am interested in your comments about GPS because this is the mechanism that I propose for locating K0 (see paper titled space rest frame)
Richard
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12th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<From GPS, we know that the resonant frequency/tick-rate of an atomic clock decreases with its direction-independent speed with respect to the Earth Centered Inertial Reference frame (the ECI) for locations in the vicinity of the Earth.>>
As a matter of fact clock rates obey strictly to energy conservation laws and it is the only reasonable way to give a Physical understanding to the phenomenon which is not kinematical in nature but dynamical.
a preferred frame is necessary which for the lorentz transformations it is offered by Lorentz Ether Theory. SR is right to the point of the relativitistic energy, it is not when offset of atomic clocks descebd by an artificial resynchronization.
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SQ: ok in general you want to mean also that the light clock works with aberration of light, which is due to pure relative motion.
No. Relative motion gives us the path of the photons. Imagine the observer moving over tracks and the light coming from 90° direction to the tracks. Then the wavefront is parallel to the tracks. If simultaneity would be absolute then the light direction as seen from the moving observer over the track would appear to have aberration, but the wavefront would remain parallel to the tracks. The rotation of the wavefront so that it appears perpendicular to the aberration of the light path is only explained by relativity of simultaneity.
SQ: Unfortunately time dilation is a physical fact experimentally verified and does not depend on pure relative motion. Even with the Lorentz Transformations you do not go anywhere with pure relative motion only.
I don't care in this moment about time dilations. You stated that there is no experimental proof of relativity of simultaneity and I countered with the simple goniometric proof that the rotation of the wavefront follows out of the relativity of simultaneity. Since the rotation is observed we have an experimental proof. That falsifies your statement.
SQ: And again there is no experimental proof whatsoever of the relativity of simultaneity and that is supposed to be one of the main features of SR.
You have not mentioned one word about my goniometric description but diverted to time dilation. You can ignore the experimental proof that light waves are perpendicular to the travel direction, but that means that you ignore the experimental proof. Thus your statement should be if all experimental proofs about relativity of simultaneity that exist are ignored then there are no experimental proofs left.
Regards,
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RL: I am interested in your comments about GPS because this is the mechanism that I propose for locating K0 (see paper titled space rest frame)
There are two aspects to the rate of GPS clocks when observed from the Earth's surface. First, the satellites are moving at orbital speed, that creates a reduction due to the familiar effect of time dilation. If you consider a measurement frame centred on the centre of the Earth but not rotating at all, the ground station is also moving due to the rotation of the Earth but at a much lower speed. The difference in the two time dilation factors is one contributor.
The second factor is called "gravitational time dilation". This says that comparing clocks at different gravitational potentials results in a difference in rates. Note it is related only indirectly to the "force of gravity", the potential difference is the controlling factor.
You may be surprised to find your golf ball experiment can also be used as an analogy for this. There are multiple ways to show it which are equivalent and give an interesting insight into the physics. You have the B set of balls being steadily accelerated by an unspecified mechanism. An accelerometer on each ball would indicate the value of that acceleration.
Now suppose one ball sent a message to the ball following it. As far as the A observers are concerned, both balls are moving at exactly the same speed when the message is transmitted. However, by the time the signal reaches the following B ball, the speed of both will have increased a small amount. The receiving ball therefore sees the signal with a Doppler shift. If the signal carrier is related to the clock rate on the transmitting ball, the receiving ball will measure that and conclude that the clock on the ball ahead is running faster than its own.
As far as the A observers are concerned though, all the B ball clocks are running at the same speed at any given time, although all are slowing due to SR time dilation. He says the apparent higher rate is because the receiver measured the signal against his own clock at a time later than when it was transmitted and since both B ball clocks slowed while the signal was in transit, the signal frequency is unchanged but the receiver's clock is slower when the signal reaches it.
A third explanation goes back to the animation I provided. As the B balls accelerate, the tangent to their worldlines rotates which means their allocation of "simultaneous events" (the green dashed lines) also has to rotate. If you look at where those lines cross the worldline of the B ball next to the right, it progresses upwards faster than the ball, so the receiver is looking at cycles of the signal that were taken from instants farther apart in transmitter times than their own clock measures for receiving times.
That is a more complex way of looking at it but I think emphasises that "simultaneity" is in the eye of the beholder, it is a mathematical designation only hence not physically testable.
Now this all relates back to gravitational time dilation because an observer standing on the Earth holding an accelerometer will see a reading of 1g. If the balls in your experiment had an acceleration of that value, the Doppler shift they would measure would be exactly the same as the gravitational redshift measured by Pound and Rebka over a 22m change of altitude. For the GPS case, it's a little more complex because the gravitation force drops off with height so the potential is -GM/r rather than being linear. The physics is the same but the curve is different. For your B balls, the proper acceleration is the same for all and constant over time.
This equivalence between an accelerated observer and a uniform gravitational field is what Einstein called the "Equivalence Principle" and was key to allowing him to work out his field equations for gravity that we now know as General Relativity.
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George Dishman In the hypothesis of the space rest frame we would like to measure the velocity of the Earth relative to K0.
In the experiment the maximum and minimum values of the time dilation during the orbit are recorded. Then the difference is used in the velocity calculation.
The rationale is that at the maximum time dilation the velocity v of the satellite will be added to the velocity component of the Earth in the orbital plane relative to K0.
At the minimum time dilation the velocity v of the satellite will be subtracted from the velocity component of the Earth in the orbital plane relative to K0.
By calculating the difference between the time dilation values we get a formula 2vV/c^2 which means that we can calculate V.
By repeating the experiment with GPS satellites in 3 orthogonal planes we get a value for the velocity of the Earth relative to K0.
There is an assumption that the gravitational effects of time dilation cancel out in this experiment. We will know when we complete the experiment.
I think it would be a good idea to complete this experiment because it will prove the existence of a space rest frame.
Of course it could also give a null result. For me this experiment has the same importance as the Michelson Morley experiment in relation to the existence of a medium for wave transmission which is stationary.
Richard
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It is well known that both a Lorentz -style aether and SR give the same equations, the Lorentz Transforms, so no experiment can ever decide between them. Any deviation under conditions of negligible gravity would either confirm or falsify both. Since the Lorentz Transforms are part of the Poincaré Group, all calculations if done correctly will always be self-consistent. For that reason it is mathematically impossible to create a real contradiction in any thought experiment. Only real experiments could produce a discrepancy.
RL: For me this experiment has the same importance as the Michelson Morley experiment ...
The GPS satellites orbit at constant altitude so although their clocks would run consistently slow by a fixed amount, in terms of the velocity effects, all you have is a large scale version of the Michelson-Morley experiment. That has been performed many times with increasing resolution and no deviation has ever been found. This is the latest I know of:
Note that it achieves a precision of 10-18 so your proposal would have to be better than that, a really hard task.
The introduction of gravity however changes that picture so your idea was along the right lines. In 1919 Eddington tested General Relativity by observing the deflection of starlight by the Sun during an eclipse. The combination of a Lorentzian aether plus Newtonian gravity would have given a deflection of 0.875 arc seconds, GR predicted exactly twice as much at 1.75 arc seconds. The results confirmed GR and ruled out Newtonian gravity. Now the problem then is that you can take GR, work out the metric in situations where the gravity has a negligible impact and what you get is the geometry of SR. You cannot then add an aether to that picture or it would double the effects like time dilation and length contraction.
What that means is that if you want to introduce an aether (whose rest condition is what would define your preferred frame) then the only way it can be approached is to find an aether-based theory that explains gravity at least as well as GR. Many people have tried that and you'll see summaries of those in many web pages (those based on MOND for example are quite well known) but without a replacement for GR, you cannot get away from SR.
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12th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<You stated that there is no experimental proof of relativity of simultaneity and I countered with the simple goniometric proof that the rotation of the wavefront follows out of the relativity of simultaneity.>>
what kind of goniometic proof based on postulates.
For sure it comes out mathematically. But here we are talking about Physics and the only proof of the constancy of the speed of light is in a platform in a two way.
So there is no experimental proof of the one-way speed of light which is what would be needed to corroborate your HP.
13th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Paul Gradenwitz, thanks for your explanation. As you say, tilted light wave fronts moving in a perpendicaular direction to an observer with velocity v are a clear refutation of relativity of simultaneity. Would you mind adding a reference on this empirical result???
SQ: For sure it comes out mathematically. But here we are talking about Physics and the only proof of the constancy of the speed of light is in a platform in a two way.
You thus want to defend that the wavefront of light stands not perpendicular to the direction of motion of the light?
Regards,
JLJ: Paul Gradenwitz, thanks for your explanation. As you say, tilted light wave fronts moving in a perpendicaular direction to an observer with velocity v are a clear refutation of relativity of simultaneity. Would you mind adding a reference on this empirical result???
I think you misunderstand my description. I explained the process of aberration with a 3D spacetime and not a 4D spacetime. I removed one dimension, Z, from our 3D space. Thus we have stack of equal time planes, levels of simultaneity, that forms this 3D spacetime. I think you have problems to imagine 4D and we have no motion in the z direction. So this reduction allows for you to imagine it. When light moves with its wavefront parallel to the track in the Y direction, then for every next level of time the wavefront has advanced a distance along the x direction. The union of all wavefronts in all levels of time will give you this 45° slanted plane if you have the correct scaling of length and time. So light is not moving as a slanted wavefront. The worldline of the wavefront, the trace it mathematically leaves behind in spacetime, is a 45° plane. In the same way the track leaves a trace behind that is a plane in the (y,t,x=0) place. For the moving observer the levels of simultaneity, the planes that are assumed to be at the same time step, are tilted upwards in front of the moving observer and tilted downward behind the moving observer as seen from the static observer.
I think you will be able to find enough documents teaching SRT that explain this.
Regards,
13th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<You thus want to defend that the wavefront of light stands not perpendicular to the direction of motion of the light?>>
Let's put it this way....
Consider the James Webb telescope now staying exaclty in the Lagrangian 2 (as a matter of fact orbits around it) at 1.5 M Km from Earth.
The straight line which joins the Lagrangian point 2 to the center of Earth represents the shortest path between the two points in Euclidean space.
Since Earth and the satellite move at more than 30 km/s around the Sun, no signal departing from Earth can overlap that straight line, unless having infinite speed (no signal can follow a radius of orbit moving around the Sun).
A light beam departs from Earth normally to the trajectory of Earth and the trajectory of the James Webb. Trivially the light beam will cross the orbit of the satellite behind its actual position.
Trivially again, the relative speed of earth and the satellite, since they belong to the same radius of the orbit around the Sun, is about 1/100 of the speed of Earth around the Sun, or rather .3km/s.
Considering that light takes 5 seconds to cover 1.5M km, there are two options about where the light beam will cross the orbit of the satellite after its actual position
just due to the relative motion of earth and the probe since the beam departed from Earth (should be according to SR)
The light beam, although departing from Earth, moves in the Sun reference frame. The position before departure of the laser beam was 150Km behind the same after 5 seconds, . The light beam will depart perpendicular to earth and will cross normally to the orbit of the probe with NO ROTATION whatsoever of the wave front. (according to the SUN preferred frame).
SQ: The straight line which joins the Lagrangian point 2 to the center of Earth represents the shortest path between the two points in Euclidean space.
That is incorrect, the shortest path as taken by light is the one that has zero proper length. For matter, the inertial path followed is the one that has the greatest proper duration.
I must admit though, I have no idea why anyone thinks aberration is of any relevance to this thread. As written, there are no communications at all, only local measurements as golf balls pass each other, and if we add any signals between balls to establish synchronisation are travelling in exactly the same direction as the balls, purely along the x axis.
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13th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<<SQ: The straight line which joins the Lagrangian point 2 to the center of Earth represents the shortest path between the two points in Euclidean space.
GD: That is incorrect, the shortest path as taken by light is the one that has zero proper length. For matter, the inertial path followed is the one that has the greatest proper duration.>>
I did not say the short path taken by light, simply the shortest path.
It would be the shortest path taken by light if the whole system was in the same inertial frame.
<<I must admit though, I have no idea why anyone thinks aberration is of any relevance to this thread.>>
because Relativity of simultaneity and aberration for SR descend from the same term of the Lorentz transformations.
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13th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Let me ask a question on Richard Lewis paradox. If the balls impact simulteneuosly in the A frame they cannot impact simultaneously in the B frame. If the balls impact simultaneusly in the B frame they cannot impact simultaneusly in the A frame. In which frame do the balls impact simultaneusly????
13th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Yes. The planes of simultaneity are tilted as any Minkowsky diagrama shows, and as a consequence of that, you can easily find that the wavefront of a light plane wave paralel to X,Z must be slanted for any observer moving along X. To be honest, as you said that the wave front is tilted, I thought you were referring to this effect.
So does anybody know how the Deep Space Network actually aims one of its radio antennas to communicate with JWST?
13th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
I might be wrong but I believe that there is no book of physics saying that the relativistic aberration of light is a direct corroboration of ROS. At least in standard books like Rindler, Smith, Resnik, Carrol, Hartle, Shutz, Misner+Th+Wheller, McMahon, ...
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14th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<I believe that there is no book of physics saying that the relativistic aberration of light is a direct corroboration of ROS>>
I agree with you. What you mention is not exaclty the point which is the following:
The invalidation of SR Light Aberration would automatically reject the vx/c2 term which is also the resync term at the base of the offset in ROS.
On the other hand such experiment would corroborate that term which is also at the base of ROS.
For the questions 1 and 2 I go for 1 without checking the exact numbers. 1 is where you only take into account the relative motion of the telescope with the earth.
To take the sun would be an arbitrary number in a list of unknown speeds. We move with a different speed through the galaxy so that then the light would need to end up not behind but also under the telescope. Further the galaxy moves in the local group towards Andromeda and the whole group again to some other direction. All these options could make sense if we would have absolute simultaneity. But since we have relativity of simultaneity the light as it makes sense to us will miss the telescope by some small amount because of the relative rotation.
Regards,
JLJ: I might be wrong but I believe that there is no book of physics saying that the relativistic aberration of light is a direct corroboration of ROS. At least in standard books like Rindler, Smith, Resnik, Carrol, Hartle, Shutz, Misner+Th+Wheller, McMahon, ...
All talk about the Lorenz Transformations. They have have hyperbolic goniometric functions. Those functions are the mathematical description of what I described with the planes.
Regards,
14th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<To take the sun would be an arbitrary number in a list of unknown speeds. We move with a different speed through the galaxy so that then the light would need to end up not behind but also under the telescope.>>
I understand your concern on the degree of arbitrariness.
As you know, you do not notice on earth any effect of the rest of the universe on light (Michaelson-Gale experiment). No influence, of the speed of the earth in the SUN gravitational field, whatsoever was noticed in experiments (they were in the gravitational field of Earth). Since the JWT moves directly in the gravitational field of the Sun (far from Earth), that will be the ecosystem to reference to and that will clarify also on potential effects of gravitational fields in experiments...
<<All these options could make sense if we would have absolute simultaneity. But since we have relativity of simultaneity the light as it makes sense to us will miss the telescope by some small amount because of the relative rotation.>>
right for this reason, experiments are needed in order to determine if these effects exist or not, those would test the Lorentz Invariance to the roots...
So , I guess, your reply about the behavior of the light path in the figure would be 1.5 Km behind.
SQ: I did not say the short path taken by light, simply the shortest path.
Light takes the shortest path, you can't get any shorter than zero.
SQ: The straight line which joins the Lagrangian point 2 to the center of Earth
GD: I must admit though, I have no idea why anyone thinks aberration is of any relevance to this thread.
SQ: because Relativity of simultaneity and aberration for SR descend from the same term of the Lorentz transformations.
The Lagrange points are equilibrium locations in the gravitational field so you cannot use either special relativity or the Lorentz Transforms. Both are valid only in the absence of gravitational effects.
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JLJ: In which frame do the balls impact simultaneusly????
Frame A.
This animation shows how the surfaces of simultaneity rotate for each of the B frames associated with the accelerating balls.
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14th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<Light takes the shortest path, you can't get any shorter than zero.>>
if you prefer the shortest path is relevant to infinite speed , it is simply the radius of the Sun which joins two different orbits (at the same time).
I agree with you, Physically the shortest is the one attained with the highest possible speed, the speed of light (up to the current knowledge).
<<The Lagrange points are equilibrium locations in the gravitational field so you cannot use either special relativity or the Lorentz Transforms. Both are valid only in the absence of gravitational effects>>
There is always a tolerance where these can work since the gravitational field of the Sun is weak at that distance considered so its influence on the aberration (trajectory) of light "as calculated with SR" should be negligible.
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SQ: right for this reason, experiments are needed in order to determine if these effects exist or not, those would test the Lorentz Invariance to the roots...
I just wonder why you still need them. Just consider that all your atoms of your body are held together by EM forces. The other nuclear forces are located within between the protons and neutrons and within them. All these forces communicate with the speed of light. So imagine a 'message', a wave emerging from an electron (yes that is not the best physical description) and going through the atom domain. If you take that domain as a Minkowski space then all the same issues of simultaneity are relevant. For an electron to have a stable orbit around the nucleus its wave function has to fit in the space and come back to it self. Moving around in inertial motion or in accelerated motion will change the configuration of every part of the atoms. So you, as observer will change, when you 'adopt' a different IRF. That made it for me possible to understand why SRT works.
SQ: So , I guess, your reply about the behavior of the light path in the figure would be 1.5 Km behind.
If that would be the calculation out of the closest approximation of a Minkowski space description then Yes. The earth and the telescope rotate with respect to each other once a year. I see the telescope with a backdrop of stars. When I send the light to that backdrop constellation then the telescope has advanced by a distance that seems to be 1.5km by the time the light arrives. When I would aim at the point where I expect the telescope when the light arrives, then it would hit the target correct. An observer far above the ecliptic looking down on the orbiting earth would maybe have the chance to see how a little bit of that light bounces of some dust on the path and then would be able to trace the light as moving in a slanted path forward so that it remains in between the telescope and the earth who both move with 30km/s in the orbit.
Regards,
14th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Dear George Dishman thanks for your information. Your diagram clearly shows that the Bell,s paradox does not exist.
It might be nice to depict the motion of A with respect to frame B as well, to see that the diagrams are the same.
14th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Dear George Dishman, I attach a PDF file (PR-2.pdf) with a very easy problem in case it might be of your interest. Any comment will be wellcome.
SQ: There is always a tolerance where these can work since the gravitational field of the Sun is weak at that distance considered so its influence on the aberration (trajectory) of light "as calculated with SR" should be negligible.
The speed of rotation is once per year so aberration is negligible anyway. The gravitational bending from the Moon is probably a greater angle.
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I don't follow, you say YB-YA=0 fo equation (1) which is just setting up the problem, that's fine. Then you use a Lorentz Transform to apply a boost in the x direction, you say correctly Y=y for A and Y=y for B but that just gives YA=YB=y and therefore YB-YA=0. Where did you get equation (2) from?
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14th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<So imagine a 'message', a wave emerging from an electron (yes that is not the best physical description) and going through the atom domain. If you take that domain as a Minkowski space then all the same issues of simultaneity are relevant.>>
you are considering retardation of signals which is undisputed but has little relevancy on Relativity of simultaneity...
<<Moving around in inertial motion or in accelerated motion will change the configuration of every part of the atoms. So you, as observer will change, when you 'adopt' a different IRF. That made it for me possible to understand why SRT works.>>
not really, since a standard clock is not affected by acceleration, the clock hypotheisis covers that and was demonstrated with experiments. Real atoms eventually are affected to a certain extent but usually in a negligible way.
<<The earth and the telescope rotate with respect to each other once a year.>>
not at all!!!
An observer on Earth will see the telescope always in the same exact position at the same hour of the day.
The JSWT will be seen to occupy the same exact position every 24h, both JSWT and earth belong to the "same rigid system" which move around the SUN.
What happens yearly is just nothing...
<<An observer far above the ecliptic looking down on the orbiting earth would maybe have the chance to see how a little bit of that light bounces of some dust on the path and then would be able to trace the light as moving in a slanted path forward so that it remains in between the telescope and the earth who both move with 30km/s in the orbit.>>
that is a possible way...although a bit unfeasible...
14th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<The speed of rotation is once per year so aberration is negligible anyway. >>
not at all, nothing happens once per year in that configuration which relates a point on earth and L2.
<<The gravitational bending from the Moon is probably a greater angle.>>
I don't see how it can be relevant...
14th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Hi, George Dishman . The equations are:
a) YA = 0.5 ET2
b) YB= 0.5 ET2
Lorentz transform for A :
c) Y A = y A
d) T = g (t - vxA/c2)
e) xA = vt
Lorentz transform for B:
f) YB = yB
g) T = g(t - vxB/c2)
h) xB = vt + L/g
Inserting c)d)e) into a) and f)g)h) into b) yields (if I didn’t make any mistake):
2) yB - yA= 0.5 E (L2v2/c4- 2Lv t /c2g)
Then we have:
in S: YB – YA = 0
in s: yB – yA = f(t)
Ah yes, you are accelerating in the y direction but then boosting in the x direction, I missed that.
Yes, you can get a rotation in that case. I haven't checked your maths but this I think relates to the Ehrenfest Paradox which has been extensively studied. There's an animation on Wikipedia which I think is perhaps informative, the rotating wheel also has an acceleration:
I think your line joining the points may be affected in a similar way. You're getting into quite complex effects.
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14th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Yes. There is a rotation associated with the acceleration which is perpendicular to the boost (Wigner - Thomas rotation). The interesting point is that you can get YA = YB = 0 and yA = yB = 0 in both frames by re-synchronizing the clocks of inertial frames. This allows to consider the traslational motion of rigid bodies in SRT.
SQ: you are considering retardation of signals which is undisputed but has little relevancy on Relativity of simultaneity...
you seem to be at the position that you still didn't see how they are intertwined.
SQ: not really, since a standard clock is not affected by acceleration, the clock hypotheisis covers that and was demonstrated with experiments. Real atoms eventually are affected to a certain extent but usually in a negligible way.
A single atom when accelerated needs a force to act on it. The only information the atom has is what happens inside it. Take a pulse from the centre of a proton and let it move out at light speed to the surface of the proton. Then let it bounce and return back to the centre. In inertial motion the pulse will return where it emerged. In accelerated motion the pulse will return offset from where it emerged. That are short distances and even smaller offsets. Yet that is the only information that makes that the proton and with it the atoms resist acceleration. So, before you talk about what is negligible consider that a single proton reacts on the slightest deviation from inertial movement. In the case that there is a gradient in the propagation speed of light, then the gradient over the size of the proton will result in the gravitational reaction we expect from a mass as a proton. That is not negligible.
SQ: not at all!!! An observer on Earth will see the telescope always in the same exact position at the same hour of the day.
And every day they see a different part of the ecliptic as a backdrop.
SQ: The JSWT will be seen to occupy the same exact position every 24h, both JSWT and earth belong to the "same rigid system" which move around the SUN.
What happens yearly is just nothing...
When we stand on the pole then there is no additional speed from the rotation when we stand on the equator then the rotation of the earth adds to the momentary speed. The telescope moves 1% faster in the tangential direction. If both would have the same speed as inertial motion, then light emitted at earth in the exact direction to the telescope would arrive. But since the telescope is on a larger radius orbit around the sun than the earth it has a larger tangential speed. Thus the light will arrive behind the telescope. The earth goes with 30km/s. Thus the telescope goes with 30.3km/s. the distance is 1.5 mio km or 5 seconds light travel. So the telescope has advanced 151.5 km where the earth has advanced 150 km. So only because the earth and the telescope are in orbit and thus because they have different tangential velocity we get the 1.5km. What you discarded as just nothing is the only relevant value that gives the result. I have the impression that you try to convince people by ignoring the items that turn out to be relevant.
SQ: that is a possible way...although a bit unfeasible...
How else could I construct a configuration where there is some acceptable simultaneity between earth and telescope.
Regards,
15th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<SQ: you are considering retardation of signals which is undisputed but has little relevancy on Relativity of simultaneity...
you seem to be at the position that you still didn't see how they are intertwined.>>
for sure with c infinite you do not have RoS, nevertheless that effect goes beyond the retardation due to the SOL although it is also related also to that.
<<A single atom when accelerated needs a force to act on it. The only information the atom has is what happens inside it. Take a pulse from the centre of a proton and let it move out at light speed to the surface of the proton. Then let it bounce and return back to the centre. In inertial motion the pulse will return where it emerged. In accelerated motion the pulse will return offset from where it emerged. >>
this is undisputable, an accelerated atom in principle would suffers such an alteration eventually, but it is not known what is the consequence of it in a quantitative way and it depends on the type of atoms or type of nucleus if I use a nuclear clock for example (MOSSBAUER EFFECT).
But again the clock HP is for standard clocks which in principle do not suffer such alteration, we have to stay in experimental Physics according to which
the MUON RING EXPERIMENT did not find evidences of variations of the muon half lifetime with the radius of the curvature (acceleration) of its trajectory but on its squared speed alone in the lab frame, this is sufficient to wipe away any claim of alteration of the clock rate with acceleration (that would occur with a broken clock).
<<That are short distances and even smaller offsets. Yet that is the only information that makes that the proton and with it the atoms resist acceleration. >>
yes there is an balance between external forces and the internal reaction but again that is not relevant to the actual offset of standard clocks.
<<So, before you talk about what is negligible consider that a single proton reacts on the slightest deviation from inertial movement. In the case that there is a gradient in the propagation speed of light, then the gradient over the size of the proton will result in the gravitational reaction we expect from a mass as a proton. That is not negligible.>>
that is relevant to other matters rather than variation of the frequency of atom oscillators.
<<When we stand on the pole then there is no additional speed from the rotation when we stand on the equator then the rotation of the earth adds to the momentary speed.>>
Yes.
<<If both would have the same speed as inertial motion, then light emitted at earth in the exact direction to the telescope would arrive.>>
if they both were part of the same intertial frame without rotation yes..
<<But since the telescope is on a larger radius orbit around the sun than the earth it has a larger tangential speed. Thus the light will arrive behind the telescope. The earth goes with 30km/s. Thus the telescope goes with 30.3km/s. the distance is 1.5 mio km or 5 seconds light travel. So the telescope has advanced 151.5 km where the earth has advanced 150 km.>>
yes, you are repeating one of the two options I proposed...
<<So only because the earth and the telescope are in orbit and thus because they have different tangential velocity we get the 1.5km. What you discarded as just nothing is the only relevant value that gives the result. I have the impression that you try to convince people by ignoring the items that turn out to be relevant.>>
ok so regardless of the speed of Earth around the Sun (we could take other solar systems), the distance between the JSWT and the point of intersection with its orbit with an incoming beam will always be 1.5km according to your opinion, which is actually what SR would suggest.
So at the end of the day an observer at rest with the SUN, would see a light beam departing from earth and go sideways, to almost reach the JWST, maintaining the lateral kinetics of EARTH at the moment when the radius left earth.....
this quite bizzare behaviour of going SIDEWAYS should be confirmed, don't you think????
Unless you postulate that the trajectory of the beam is already bent according to its relative speed...
Your view is like having in between the emitter and JSWT a medium which more or less spins with the speed of earth around the SUN....and drags the beam with it crossing the orbit of JSWT close to its position.
SQ: But again the clock HP is for standard clocks which in principle do not suffer such alteration, we have to stay in experimental Physics according to which.
A clock is embedded in the volume where a certain propagation speed of light is valid. The rate of the clock is not altered from inertia. F=mxa gives a reaction force on acceleration but no timing change. The Muon experiment should give a difference based on the strength of a gravitational field but not on the radius of a circular orbit. For an orbit only the tangential speed is relevant.
SQ: So at the end of the day an observer at rest with the SUN, would see a light beam departing from earth and go sideways, to almost reach the JWST, maintaining the lateral kinetics of EARTH at the moment when the radius left earth.....
Correct. Only that observer would see the wavefront of that sideways moving light as perpendicular to the sideways movement because his LOS is different.
SQ: this quite bizzare behaviour of going SIDEWAYS should be confirmed, don't you think????
Is confirmed. We move with a speed faster than 30km/sec in a direction different from the ecliptic. (I think Hercules) So we have a significant speed component towards a direction perpendicular to the direction earth JWST. So for an observer at rest with the galaxy the light would move upwards and this deviation here also is never measured. Think of the lasers to the moon.
SQ: Unless you postulate that the trajectory of the beam is already bent according to its relative speed...
I postulate nothing special. Just state that you have no method to get absolute speed out of these experiments. The emitter has a given speed, is at rest in an inertial frame, the light will follow a straight line in that frame according to the direction it is pointed at. This always implies that seen from a different frame the beam will appear to move sideways, but because of ROS the wavefront is seen to be perpendicular to whatever direction the beam seems to move.
Regards,
16th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<The Muon experiment should give a difference based on the strength of a gravitational field but not on the radius of a circular orbit. >>
the muon ring experiment is performed in a circular accelerator. So no gravitational influence is accounted, same gravitational potential.
<<For an orbit only the tangential speed is relevant.>>
It seems you agree that I'm right. Only the tangential (squared) speed in fact is relevant for the time dilation, not the centripetal acceleration, meaning that the force by itself does not affect the decaying rate of the muon.
It is not the gravitational force (hence affected by acceleration which I believed 6 years ago ) which affects clocks but it is the gravitational potential in fact all the experimentally verified formulas relevant to time dilation lead inevitably not to a force but to energy which is the work of a force and the Gpotential is the work per unit mass:
<<SQ: So at the end of the day an observer at rest with the SUN, would see a light beam departing from earth and go sideways, to almost reach the JWST, maintaining the lateral kinetics of EARTH at the moment when the radius left earth.....
Correct. Only that observer would see the wavefront of that sideways moving light as perpendicular to the sideways movement because his LOS is different.>>
at least, even it is not very much, we agree on what is the prediction of SR on this matter....yes that effect is indeed very related to RoS through the LoS.
<<SQ: this quite bizzare behaviour of going SIDEWAYS should be confirmed, don't you think????
Is confirmed. We move with a speed faster than 30km/sec in a direction different from the ecliptic. (I think Hercules) So we have a significant speed component towards a direction perpendicular to the direction earth JWST.>>
the solar system is moving with 400 km/s towards Leo, but such speed is not detectable since we are in the gravitational field of the SUN (only the CMBR can tell us with the longitudinal doppler), same as MM experiment which did not detect anything comparable to 30 m/s since it was in the gravitational field of earth...
<<So for an observer at rest with the galaxy the light would move upwards and this deviation here also is never measured. Think of the lasers to the moon.>>
the LIDAR to the Moon is simply shot and comes back in 2 seconds, what do you want to determine with it?
<<SQ: Unless you postulate that the trajectory of the beam is already bent according to its relative speed...
I postulate nothing special. Just state that you have no method to get absolute speed out of these experiments. >>
never said that, simply a speed relative to where light propagates. Light propagates in the solar system in the gravitational field of SUN since it is affected by it in its direction (bending), don't you think that it has to be also affected in its propagation?
<<The emitter has a given speed, is at rest in an inertial frame, the light will follow a straight line in that frame according to the direction it is pointed at. >>
Which has never been demonstrated but deducted and is really a WIERD Bizzare phenomenon. The same given by a medium in between an emitter and JSWT which more or less spins with the speed of earth around the SUN....and drags the beam with it crossing the orbit of JSWT close to its position.
<<This always implies that seen from a different frame the beam will appear to move sideways, but because of ROS the wavefront is seen to be perpendicular to whatever direction the beam seems to move.>>
from any frame different from the Solar CIF, where in the solar system it propagates, that would just be an optical illusion....it means that you are in the wrong frame... I know that this refutes partially the relative motion and puts back partially a sort of local absolute, but on the other hand there is no proof whatsoever that the things do not behave the way I described!!!!!!!!!!!!!!!!
SQ: at least, even it is not very much, we agree on what is the prediction of SR on this matter....yes that effect is indeed very related to RoS through the LoS.
For me you seem to agree that RoS is demonstrated there. That was what you first declared to be never demonstrated.
SQ: the solar system is moving with 400 km/s towards Leo, but such speed is not detectable since we are in the gravitational field of the SUN (only the CMBR can tell us with the longitudinal doppler), same as MM experiment which did not detect anything comparable to 30 m/s since it was in the gravitational field of earth...
I completely mis the reasoning why the gravitational field can make the MM experiment work and not SR.
SQ: the LIDAR to the Moon is simply shot and comes back in 2 seconds, what do you want to determine with it?
The Lidar uses mirrors with 90° angles so that the light returns with 180° direction. If the movement of the system in a direction perpendicular to the moon orbit plane would be involved like a headwind, then the direction we point at would need to counter that wind. So, with a wind blowing down the plane we need to point upward to counteract the wind. That arrive at the mirror that changes the direction to 180°. So either you interpret that the light in effect arrives in the plane of the moon orbit or it arrives and is still interpreted to point a bit upward. But you never can reason that it arrives at the mirrors pointing downward. Thus the return path at best points horizontal and at worst downward. Thus the light would not return back to the emitter location.
SQ: never said that, simply a speed relative to where light propagates. Light propagates in the solar system in the gravitational field of SUN since it is affected by it in its direction (bending), don't you think that it has to be also affected in its propagation?
Yes the speed of light in the gravitational field of any mass is affected. But so is the observer. The same change in speed of light changes all properties of matter so that with your proper units you still get the same ratio of length and time that we have in "c".
SQ: Which has never been demonstrated but deducted and is really a WIERD Bizzare phenomenon. The same given by a medium in between an emitter and JSWT which more or less spins with the speed of earth around the SUN....and drags the beam with it crossing the orbit of JSWT close to its position.
Then there should be also a strong headwind from the 400km/s. Since that is not there your assumption of the rotation drag is also a problem. The light from earth to JWST lags behind by 1.5km. The light from the JWST to earth arrives in front of the place. The JWST and the earth rotate with one orbit per year. If a medium would be involved then it would keep the beam pointed without deviation.
SQ: from any frame different from the Solar CIF, where in the solar system it propagates, that would just be an optical illusion....it means that you are in the wrong frame... I know that this refutes partially the relative motion and puts back partially a sort of local absolute, but on the other hand there is no proof whatsoever that the things do not behave the way I described!!!!!!!!!!!!!!!!
I don't understand you here. An optical illusion is all we have when we observe how light appears to be for us as observer. The SRT describes how optical things appear to observers in different frames. I have shown you how several assumptions come up different with your description. So, for me you describe things that are observed to perform different.
Regards,
18th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
George Dishman, I think that an easy way to show that the Bell,s paradox does not exist is the following: using hyperbolic motion, the acceletated trajectory X of any ball having constant proper acceleration can be expressed as:
1) E2 = X2 - c2 T2
where E is the horizontal coordinate in the commoving frames of the accelerated ball. As this expression is clearly invariant under Lorentz transformations along the X axis, we get that the horizontal coordinate E is the same in any commoving frame and the distance between two balls will be the same as well.
Nevertheless, an intriguing question arises. Is the horizontal coordinate E constant under a vertical Lorentz transformation along Y ?. Inserting T = g (t-vy/c2) , X =x we get:
2) E2 = x2 - c2 (t- vy/c2)2
which is not invariant (only y2 - c2t2 is invariant). Balls moving with constant proper acceleration along X and constant velocity along Y, woud they have the E coordinate invariant???
A paradox is something that looks like a contradiction but can be resolved when an omission is resolved. What needs to be included here is the effect known as "relativity of simultaneity".
For each rocket in Bell's Paradox, what you say for the distance travelled is true as a function of launch pad time but once they are moving, simultaneity in the rocket frame differs from that in the pad frame so the speeds are not the same in rocket time. You need to calculate the distance between one rocket and the other as measured in the rocket's frame as a function of that rocket's measurement of elapsed time.
2 Recommendations
19th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<SQ: at least, even it is not very much, we agree on what is the prediction of SR on this matter....yes that effect is indeed very related to RoS through the LoS.
PG: For me you seem to agree that RoS is demonstrated there. That was what you first declared to be never demonstrated.>>
RoS is demonstrated no where...there is no experiment in which term vx'/c2 was found.
That term can be the outcome of the following configuration:
a) one absorber at rest A and another one B in motion at speed v.
b) an emitter C is at rest at distance x' from A shoots along the direction of motion towards A and B when the two overlap and get in sync,
c) the time taken by light to reach A is tA=x'/c, the time to reach B is with a good approximation tB=x'/c- x'/c*v/c, hence tA - tB=x'v/c2
That term does not exist if light rays are not communicated and it is just a mere retardation term .
<<SQ: the solar system is moving with 400 km/s towards Leo, but such speed is not detectable since we are in the gravitational field of the SUN (only the CMBR can tell us with the longitudinal doppler), same as MM experiment which did not detect anything comparable to 30 m/s since it was in the gravitational field of earth...
PG. I completely mis the reasoning why the gravitational field can make the MM experiment work and not SR.>>
the gravitational field is an echosystem in which light propagates and is affected We know that from experimentally verified phenomena like gravitaitonal redshift and the Shapiro delay. Gravitation defines a "preferred frame" which does not allow to detect what is outside of it.
<<SQ: the LIDAR to the Moon is simply shot and comes back in 2 seconds, what do you want to determine with it?
The Lidar uses mirrors with 90° angles so that the light returns with 180° direction. >>
ok
<<If the movement of the system in a direction perpendicular to the moon orbit plane would be involved like a headwind, then the direction we point at would need to counter that wind. So, with a wind blowing down the plane we need to point upward to counteract the wind. >>
there is no wind to be detected especially if you are still within earth's gravitational field...
<<SQ: Which has never been demonstrated but deducted and is really a WIERD Bizzare phenomenon. The same given by a medium in between an emitter and JSWT which more or less spins with the speed of earth around the SUN....and drags the beam with it crossing the orbit of JSWT close to its position.
PG: Then there should be also a strong headwind from the 400km/s. Since that is not there your assumption of the rotation drag is also a problem. The light from earth to JWST lags behind by 1.5km. The light from the JWST to earth arrives in front of the place. The JWST and the earth rotate with one orbit per year. If a medium would be involved then it would keep the beam pointed without deviation.>>
everything there is under the influence of the graviational field of the SUN, the light deflection and shapiro delay depend on that, not on the speed of SUN in the galaxy.
<<SQ: from any frame different from the Solar CIF, where in the solar system it propagates, that would just be an optical illusion....it means that you are in the wrong frame... I know that this refutes partially the relative motion and puts back partially a sort of local absolute, but on the other hand there is no proof whatsoever that the things do not behave the way I described!!!!!!!!!!!!!!!!
PG: I don't understand you here. An optical illusion is all we have when we observe how light appears to be for us as observer. The SRT describes how optical things appear to observers in different frames. I have shown you how several assumptions come up different with your description. So, for me you describe things that are observed to perform different.>>
An optical illusion occurs in such case for expample:
two clocks A and B are at rest at a certain distance and in sync, according to a synch procedure which is based on the experimental fact that the speed of light in a two way path is always c in an inertial frame.
if A and B are not seen in sync by a moving observer M...the moving observer M is simply a non suitable point of observation. M has simply an illusion that such clocks are not in sync.
SQ: a) ... b) ... b) ...That term does not exist if light rays are not communicated and it is just a mere retardation term .
When does C shoot? When he observes A and B overlap? That is in the frame of A and C a time t=x'/c later than the overlap happened. That is missing in your calculation.
The RoS is a postulate that allows you to assume that in every IRF the two way speed of light is the same. For that you select from all space-like separated events a set of events as being simultaneous. Those events (points in spacetime) are there. If you define them for you to be in your plane of simultaneity is up to you. All matter seem to react with that, but that does not stop you to do experiments that define other space-like separated event/points to be simultaneous. The GPS system is proof of that. If you interpret the world and you use SRT then you can calculate how under SRT things are timed and located. The fact that light appears to have a perpendicular wavefront to its motion shows that we live in that illusion that is described by SRT.
SQ: the gravitational field is an echosystem in which light propagates and is affected We know that from experimentally verified phenomena like gravitational redshift and the Shapiro delay. Gravitation defines a "preferred frame" which does not allow to detect what is outside of it.
What you state here is a lot of postulates that might need proof. I might go with you that there is something that lets light propagate. That something makes that near mass there is a lower propagation speed. But our path through the galaxy is as well influenced as the minuscule deviations in clusters bending light seen as gravitational lensing and micro lensing. So all mass accumulates its effect and therefore I don't see how the gravitational system of the sun can shield anything outside.
SQ: there is no wind to be detected especially if you are still within earth's gravitational field...
But you used that same 'wind' principle to cary the light off track to the JWST
SQ: everything there is under the influence of the graviational field of the SUN, the light deflection and shapiro delay depend on that, not on the speed of SUN in the galaxy.
But the whole sun path depends on the gravitational field of the galaxy. So how can the total system follow that galaxy path if it is not an integrated part of the local gravitational configuration. Your postulate of an isolated system needs more to get a chance to be credible.
SQ: if A and B are not seen in sync by a moving observer M...the moving observer M is simply a non suitable point of observation. M has simply an illusion that such clocks are not in sync.
That illusion is how you live and look into the world. You see the world move around you and for your observed reality there is a perceived simultaneity. That perceived simultaneity is perceived by every atom in your body. SRT describes nothing more than that. The problem is that you can't get an experiment that proves what should be the universal true rest frame so it could as well be that your clocks A and B are moving and the observer is at rest. Then the clocks were in the illusion that they were synced.
Regards,
19th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<When does C shoot? When he observes A and B overlap? That is in the frame of A and C a time t=x'/c later than the overlap happened. That is missing in your calculation.>>
At the event of overlapping B and A, I explicitly mentioned and the event does not depend on observers. I do not set A and C in sync.
If you prefer out of a continuous shooting from C, one event of shooting will be temporally coincident with the event of A and B overlapping.
<<The RoS is a postulate that allows you to assume that in every IRF the two way speed of light is the same.>>
RoS cannot be a postulate at all, it can only be a consequence of a postulate.
SQ: At the event of overlapping B and A, I explicitly mentioned and the event does not depend on observers. I do not set A and C in sync. If you prefer out of a continuous shooting from C, one event of shooting will be temporally coincident with the event of A and B overlapping.
Are you aware that at the moment that you state that C is at rest with A, and separated from A, that you then define a LOS if you state that something happens at the same time? The two events, shooting and overlapping are space-like separated. The two events have no knowledge, info, until the result of that other event has reached along the lightcone.
SQ: RoS cannot be a postulate at all, it can only be a consequence of a postulate.
Could be a better statement, but that still doesn't invalidate SRT.
Regards,
Paul Gradenwitz Have you studied the original thought experiment involving just row A and row B? Do you agree that this does invalidate SRT?
Richard
19th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<SQ: At the event of overlapping B and A, I explicitly mentioned and the event does not depend on observers. I do not set A and C in sync. If you prefer out of a continuous shooting from C, one event of shooting will be temporally coincident with the event of A and B overlapping.
Are you aware that at the moment that you state that C is at rest with A, and separated from A, that you then define a LOS if you state that something happens at the same time? The two events, shooting and overlapping are space-like separated. The two events have no knowledge, info, until the result of that other event has reached along the lightcone.>>
to be more clear:
• x' is the distance between A and C at rest
• A and C synchronize since at rest with Einstein sync proc
• C is programmed to emit a light beam at tc
• and at tc , in sync with A and overlapped with A, B departs from A at speed v towards C .
RESULT
• a) the light time to A is measure by A as tA= x'/c,
• b) the light time to B moving is (at least as a first approx) tB= x'/c- x'/c*v/c, hence tA - tB=x'v/c2
that is just the difference of light-time between a stationary target and a relative moving target. That is how that term makes sense and can be found. It is an offset due to the retardation of light.
<<SQ: RoS cannot be a postulate at all, it can only be a consequence of a postulate. Could be a better statement, but that still doesn't invalidate SRT.>>
if an experiment is made eventually that does not find any RoS, then SR can be certainly partially invalidated, the Lorentz Invariance would be at stake.
1 Recommendation
20th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Yes, you have to consider relativity of simultaneity on applying the Lorentz transformation. But I´m not clear if you don´t agree that the balls follow hyperbolic motion (constant proper acceleration). I might be wrong but it seems to me that considering it, the solution to the Bell´s paradox becomes pretty straightforward without the need of doing quite any calculation.
José Luis Junquera HI Jose. Can you explain to me your concept of hyperbolic motion (constant proper acceleration). My understanding would be that regardless of the nature of the acceleration, the velocity of all the golf balls in row B would be the same. How the golf balls in row B reach the state in which they stop accelerating and become a representation of the inertial frame B seems to be not relevant to the thought experiment as the observations only start when we have two inertial frames A and B.
Richard
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20th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Richard Lewis , I was referring to the Bell´s paradox.
Regarding to your paradox, I think that the question that is dificult to answer is: in wich inertial frame A or B does the length contraction (and the ROS) appear?? It seems to me that there is no answer to this question.
On the other hand, length contraction must be considered if you agree with the aberration of light.
20th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Stefano Quattrini , can we consider the Sagnac effect to be a ROS experiment??
JLJ: Yes, you have to consider relativity of simultaneity on applying the Lorentz transformation. But I´m not clear if you don´t agree that the balls follow hyperbolic motion (constant proper acceleration).
They do as measured in the launch pad frame. In the frame of one accelerated ball, the motion of the others becomes more complex. It introduces the idea of Rindler Coordinates.
JLJ: I might be wrong but it seems to me that considering it, the solution to the Bell´s paradox becomes pretty straightforward without the need of doing quite any calculation.
The solution is simple but not obvious if you don't know about relativity of s=simultaneity. From the launch pad frame, a string tied between adjacent rockets breaks because its length reduces as the speed increases while the rockets stay a fixed distance apart, both following hyperbolic motion.
From the frame of any one rocket, the strings break because the other rockets seem to depart from the flight plan because simultaneity rotates.
JLJ: can we consider the Sagnac effect to be a ROS experiment.
Yes, and in fact there is a practical example where that occurs. Communication satellites orbit the Earth and we can consider each to be synchronised to a common ground clock. In practice it is international atomic time, but for a thought experiment you can imagine a ring of them orbiting round the equator and linked to a single clock at the north pole. All the satellite clocks have an offset in their rate to match the ground rate so we can ignore gravitational time dilation and just think about synchronisation.
Each satellite has a helical worldline around that of the centre of the Earth. The orthogonal to that is also a very shallow helix which cuts the worldline of the satellite to the east a little ahead so that satellite seems to be running at the same rate but set a bit behind. Similarly the one to the west seems to be a bit ahead. That is true all the way round the ring, so after a complete loop, each satellite seems to be out of sync even with itself!
This is not just a thought experiment, it is observed in the real world.
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RL: Can you explain to me your concept of hyperbolic motion (constant proper acceleration).
That applies while all the balls in set B are accelerating. For high school physics we learn that constant acceleration adds a constant amount to the speed per units time. It's a good approximation normally but when dealing with speeds that are a significant fraction of the speed of light, the simple addition needs to change to this formula:
That gives a hyperbolic speed instead of a linear increase.
RL: My understanding would be that regardless of the nature of the acceleration, the velocity of all the golf balls in row B would be the same.
That would be true after they stop accelerating. Because of the effect known as "relativity of simultaneity", all the balls in set B start accelerating at the same time but relative to any one ball, those behind it seem to start with the same acceleration but then gradually reduce it. That means they have to keep accelerating longer to reach the common final speed.
RL: Do you agree that this does invalidate SRT?
No, it only indicates that you haven't yet learned the impact of "relativity of simultaneity". That is probably the hardest part for students of the theory to grasp.
20th Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
As George Dishman says, hyperbolic motion appears when particles move with constant proper acceleration with respect to an inertial frame. In newtonian physics the corresponding equation of motion is x = 0,5 at2 and in SRT the equation of motion is x2 = c2t2 - constant. The first expression is parabolic and the second hyperbolic. It can be shown that for v<<c, both expressions coincide.
1 Recommendation
20th Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<Stefano Quattrini , can we consider the Sagnac effect to be a ROS experiment??>>
it does not have anything to do with RoS whose existance has still to be demostrated...
it is just the interference between two simultaneously emitted light beams in opposite directions traveling in a close loop. They do not arrive simultaneously at the emitter due to the longer path that one has to cross due to the circular motion in the same direction of the beam.
It can be modeled as two combinations of Zeno's effect...
RL: Paul Gradenwitz Have you studied the original thought experiment involving just row A and row B? Do you agree that this does invalidate SRT?
Two questions here. First: yes studied it. Second: I disagree. The thought experiment shows that there is some lack of understanding of SRT. That doesn't invalidate SRT it invalidate the statement:
<<It must also be the case that the golf balls in the rows pass each other simultaneously when viewed from frame B.>>
It should state: under the definition of what is called simultaneous in SRT the balls will not pass simultaneously when viewed in frame B. Every ball of row B has its own world-line. The world-line is the sequence of events that describe the history for each ball.
What happens simultaneous is beyond our direct observation. We know only after a message has traveled with the speed of light from a simultaneous event to the observer that the event happened (is part of the world-line of a ball). Then, under SRT definition that light travels with c in every frame, we select that message of an event from the world-line that matches the definition of SRT to be the message that comes from the the simultaneous event.
If you define some other sets of events to be simultaneous, then the only conclusion can be that that level of simultaneity disagrees with the definition of SRT. It can't invalidate SRT. The set of points with equal distance to a point in 3D is called a sphere. When you find a method to get a different set of points then you also don't argue that thus the definition of a ball is wrong. You just conclude that your set of points doesn't mach the definition of a ball.
Regards,
SQ:
• a) the light time to A is measure by A as tA= x'/c,
• b) the light time to B moving is (at least as a first approx) tB= x'/c- x'/c*v/c, hence tA - tB=x'v/c2
that is just the difference of light-time between a stationary target and a relative moving target. That is how that term makes sense and can be found. It is an offset due to the retardation of light.
I think you studied SRT already quite some time. The emission of the light happened simultaneous for A and not simultaneous for B under the definition what is called simultaneous in SRT. You can jump up and down, but when you come up with a setting and a definition what should be simultaneous for you, and then your definition of simultaneity turns out to disagree with SRT then the only conclusion will be that you have a setup that disagrees with SRT. It never invalidates SRT.
SQ: if an experiment is made eventually that does not find any RoS, then SR can be certainly partially invalidated, the Lorentz Invariance would be at stake.
No, if an experiment finds no RoS, then that experiment is not in agreement with SRT. If an experiment finds sets of mass points that are arranged as cubes, then that doesn't invalidate the shape of balls. The only conclusion then is those sets found are not balls. Those experiments that are consistent with each other within SRT are valid in SRT other experiments that are inconsistent are not valid inside SRT. Those experiments that are executed in lab A are done in lab A, an experiment done in lab B can not invalidate the existence of lab A. It might be annoying for you, but SRT is in it self consistent.
Regards,
José Luis Junquera Referring to your comment:
"Regarding to your paradox, I think that the question that is difficult to answer is: in which inertial frame A or B does the length contraction (and the ROS) appear?? It seems to me that there is no answer to this question.
On the other hand, length contraction must be considered if you agree with the aberration of light."
You are correct in your comment. However, it is a follow on question after accepting the conclusions of the thought experiment. The answer must be that there is a distinction between distances and the length of objects.
In my paper on the space rest frame I replaced the SR postulates with:
1. There is a unique space rest frame K0 in the universe. When a source emits light it travels at speed c in the frame K0.
2. Objects travelling with velocity v relative to K0 experience length contraction and time dilation by the factor √( 1 - v2 / c2).
I think this is a necessary follow on conclusion from the result of the thought experiment and so the answer to your question is that length contraction occurs in both frame A and frame B depending on the velocity of those frames relative to K0. However, this length contraction applies to moving objects not to distances between objects.
Richard
George Dishman In talking about the relativity of simultaneity you are using a concept of special relativity which the thought experiment seeks to disprove. I think if you go back to the thought experiment itself and consider it logically without any preconceived ideas from SR you will agree that distances must be preserved between frame A and frame B.
Richard
Paul Gradenwitz Referring to your comment: "It should state: under the definition of what is called simultaneous in SRT the balls will not pass simultaneously when viewed in frame B. Every ball of row B has its own world-line. The world-line is the sequence of events that describe the history for each ball."
The reason why I included timers in the moving golf balls was to provide a means of making observations at an arbitrarily short distance to avoid any effects due to the speed of light. Also the observers in row A are adjacent to the golf balls in row A and the observers in row B are adjacent to the golf balls in row B and moving with the golf balls in row B so all observations are being made at an arbitrarily short distance.
An observer in row A makes an observation of both timers as the golf balls cross and the passing observer in row B makes the same observation with the same timer readings. The experiment is the same when viewed from the next golf ball along in either frame. So after the experiment is complete, all the observers in row B get together and compare notes and find that they all have the same timer values recorded for row B and they all have the same timer values recorded for row A even though the values differ between row A and row B.
From the timer readings being the same they conclude that all the golf balls passed simultaneously.
Richard
1 Recommendation
21st Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<You can jump up and down, but when you come up with a setting and a definition what should be simultaneous for you, and then your definition of simultaneity turns out to disagree with SRT then the only conclusion will be that you have a setup that disagrees with SRT. It never invalidates SRT.>>
I did not provide definitions of simultaneity, I simply found a way to calculate, out of a simple configuration the term which in LT is responsible for RoS.
I did not say that it invalidates SRT , I simply say that such term for real may appear only if one exchange EM waves in a certain way. Hence it is quite unlikely that it does occur in practice without EM waves.
<<No, if an experiment finds no RoS, then that experiment is not in agreement with SRT. If an experiment finds sets of mass points that are arranged as cubes, then that doesn't invalidate the shape of balls. The only conclusion then is those sets found are not balls.>>
if an experiment in which a certaionl value of RoS is predicted by SR and should be measured, but the measurement is 0, then SR is invalidated...sorry for having expressed in a way to induce to misunderstanding.
Ok, you have added clocks to the balls and observers next to them. The observers and the clocks will adapt their internal biological and physical timing so that it matches the IRF where they arrive. That is the meaning of proper time. The meeting of one ball B with the next ball A is synchronous in IRF A. But since IRF B and all the balls there are moving it is not simultaneous for B. That means when all observers in slow transport come together, then they come together according to the level of simultaneity of B. That means the moment when the meeting of balls happened is registered on each clock. Then the reading on each clock is the same, but those at the front have to wait a bit longer till they are in the same simultaneous moment as those in the back. So, we can compare the clock reading but then also need to compare the clocks. Those in the front have progressed further, they are older, than those in the back.
RL: So after the experiment is complete, all the observers in row B get together and compare notes and find that they all have the same timer values recorded for row B and they all have the same timer values recorded for row A even though the values differ between row A and row B.
Not only the notes count. Also the comparison that all clocks still run synchronous needs to be taken into account. It in not on the notes where you will find a difference. It is on the clocks where you will find how they are shifted in time.
Regards,
SQ I did not say that it invalidates SRT , I simply say that such term for real may appear only if one exchange EM waves in a certain way. Hence it is quite unlikely that it does occur in practice without EM waves.
How do you want to have any relation without EM waves? Your atoms in the molecules of your body hold together with them. The acoustic sound comes from air that has pressure because of EM interaction of gas molecules. So I don't see an application without EM waves.
SQ: if an experiment in which a certain value of RoS is predicted by SR and should be measured, but the measurement is 0, then SR is invalidated...sorry for having expressed in a way to induce to misunderstanding.
Then the measurement is wrong. SRT is a mathematical set of rules. Your dream seems to be that there might be an experiment that shows that we can have a perfect sphere of finite size with a flat are on its surface. If you find a crystal ball where on one place there is a flat surface so that you can place it on your desk without it rolling away, then you will agree that that ball is not perfect but has a domain where the surface deviates from the perfect sphere. That will not invalidate the principle of a bal. In the same way, if you measure something as simultaneous that is predicted not to be simultaneous in SRT, then your measurement setup violates SRT. SRT describes how a set of events, points in 4D spacetime, relates with each other under certain conditions. That is a bit more complex but at the same level as the description what set of 3D points relates to each other as a ball. You can't invalidate that. Even if we could learn to travel in time and become our own father, then simultaneity and order of events gets scrambled. Yet then that doesn't invalidate SRT. It only gives a method of measuring events that is invalid in SRT.
Regards,
21st Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<How do you want to have any relation without EM waves? Your atoms in the molecules of your body hold together with them. The acoustic sound comes from air that has pressure because of EM interaction of gas molecules. So I don't see an application without EM waves.>>
two clocks which do not exchange em waves are linked by Lorentz Transformations as well according to SR, this I know quite well... in principle only with RDE you need radiation...
<<SQ: if an experiment in which a certain value of RoS is predicted by SR and should be measured, but the measurement is 0, then SR is invalidated...sorry for having expressed in a way to induce to misunderstanding.
Then the measurement is wrong. SRT is a mathematical set of rules>>
It is a math set of rules exactly....with some postulates:
a) equivalence of inertial frames
b) global constancy of the speed of light
although mathematically indisputabile, the postulates are not necessarily Physically verified, because
a) the speed of light is verified in a 2way experiment only
b) the inertial frames as a matter of fact do not exist in nature
you can make the hp to be sufficiently close to the condition of inertiality but this has serious limitations depending on the configuration of the problem.
This just to illustrate quickly that what you are talking about is not Physics.
Physics is an experimental science first, then such experiments are driven by models produced through the language of math, that's all.
To say that a measurement has to be wrong because it does not comply with SR in a effect which has never been experimentally verified is uust an ARISTOTELIAN ipse dixit, abandoned 400 years ago with Galielei...
For sure before claiming that one measurement is right in falsifying a consolidated theory, one has to be very very sure and experiments repeated several times.
SR is not a faith...
<<SRT describes how a set of events, points in 4D spacetime, relates with each other under certain conditions. That is a bit more complex but at the same level as the description what set of 3D points relates to each other as a ball. You can't invalidate that.>>
you cannot invalidate that mathematically according to the postulate that you have set, for sure...
but again postulates are restriction provided by human mind to try to understand something in a certain way, most of the time in a simplistic way...
Physics is the study of nature with observation and experiments, math just help human beings with its very powerful synthesis and prediction power....
RL: In talking about the relativity of simultaneity you are using a concept of special relativity which the thought experiment seeks to disprove.
The equations of SR are part of the Poincaré Group which is inevitably self-consistent. That means that in any thought experiment, it is mathematically impossible for there to be an inconsistency in the results. The three phenomenological effects commonly known as length contraction and time dilation are all derived from the same pair of Lorentz Transform equations, so if you have any one, you must also have the other two, that is inevitable again purely out of the maths. The alternative is that you have Galilean Invariance and none of these effects exist.
RL: I think if you go back to the thought experiment itself and consider it logically without any preconceived ideas from SR you will agree that distances must be preserved between frame A and frame B.
No, distances would only be preserved if you make the assumption that simultaneity is preserved, but then clocks must have ticks that progress uniformly for all observers and then travelling the length of a rod must take the same duration for all observers and that means neither time dilation or length contraction would exist either.
The bottom line is that thought experiments are good for learning SR but pointless if you want to test it. Only real experiments have the possibility of finding any discrepancy.
I'll say it again in the hope that it avoid you wasting time on a lost cause, finding any inconsistency in a thought experiment on SR is mathematically impossible.
2 Recommendations
21st Mar, 2022
José Luis Junquera
Universitat Politècnica de Catalunya
Applying Relativity of Simultaneity we get the following: if the balls impact simultaneously in frame A they cannot impact simultaneusly in frame B. If they impact simultaneusly in frame B they cannot impact simultaneusly in frame A. There is no way to know which is the real situación. On the other hand, if you consider length contracción you must also consider Relativity of Simultaneity.
2 Recommendations
SQ: [SR] is a math set of rules exactly....with some postulates:
SQ: a) equivalence of inertial frames
SQ: b) global constancy of the speed of light
Those are not the postulates. What they actually say is:
• The laws of physics take the same form in any inertial frame and
• The speed of light is isotropic at any point
The first is basically the definition of what constitutes a physical law.
The second derives from Maxwell's Equations where the speed is given by:
c = 1/√(ε₀ μ₀)
Since ε₀ and μ₀ are both scalars, the speed cannot depend on the direction. Einstein derived SR from those.
SQ: a) the speed of light is verified in a 2way experiment only
SR does not involve the actual speed, only the postulate that it is isotropic at any given point in space.
SQ: b) the inertial frames as a matter of fact do not exist in nature
They do, any free-falling frame is inertial locally.
2 Recommendations
SQ: two clocks which do not exchange em waves are linked by Lorentz Transformations as well according to SR, this I know quite well... in principle only with RDE you need radiation...
The time it takes for an electron to buzz around a carbon atom in your body reacts on the same way as any clock. We need radiation of EM waves to keep our body together and our nerves communicating.
SQ: To say that a measurement has to be wrong because it does not comply with SR in a effect which has never been experimentally verified is just an ARISTOTELIAN ipse dixit, abandoned 400 years ago with Galielei...
The measurement can be perfect, accurate, but according to rules that disagree with SRT. Then they are invalid wrt SRT.
SQ: For sure before claiming that one measurement is right in falsifying a consolidated theory, one has to be very very sure and experiments repeated several times.
You don't get it. I am not talking about measurement errors. Any sloppy measurement would disqualify immediately. I talk about high quality 5 sigma or better experiments. But those experiments are done with measurement definitions that are not recognised in SR. A clock synchronisation from one central earth clock at a pole is theoretically possible In GPS we have a similar synchronisation. But what is called synchronous there, with accuracy that allows us to position us with inches of error, is not called synchronous in SRT. So results from there don't invalidate SRT.
SQ: a) the speed of light is verified in a 2way experiment only
To measure a one way speed you need two points that are synchronised. So, based on what you select as synchronisation you can get any one way speed of light. That is like a single equation with two unknown variables. You can only come with a relation between the two variables. That relation states that with the right choice of simultaneity then the speed of light appears the same in both directions. You are fighting that.
SQ: b) the inertial frames as a matter of fact do not exist in nature
How much of one amount of matter is at rest in one single frame is only the question. Inertia with acceleration only needs the size of one proton of to get an SRT result.
Regards,
22nd Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<SQ: [SR] is a math set of rules exactly....with some postulates:
SQ: a) equivalence of inertial frames
SQ: b) global constancy of the speed of light
GD: Those are not the postulates. >>
what are they if not assumptions...inertial frames are abstract entities, comfortable tools for a reductionist approach.
<<What they actually say is:
The laws of physics take the same form in any inertial frame and The speed of light is isotropic at any point>>
yes in a 4D space-time which is a mathematical abstraction a comfortable tool preform calculations especially good in accelerators.
<<The first is basically the definition of what constitutes a physical law.>>
mathematical relations, models which hold to a certain degree of accuracy.
<<The second derives from Maxwell's Equations where the speed is given by:
c = 1/√(ε₀ μ₀)>>
that is what you determine locally with local measurements... not globally, the measurement devices change accordingly, so you will never notice changes locally...
<<SQ: a) the speed of light is verified in a 2way experiment only
GD: SR does not involve the actual speed, only the postulate that it is isotropic at any given point in space.>>
and constant because what is written is c, it is the Lorentz Invariance.
<<SQ: b) the inertial frames as a matter of fact do not exist in nature
GD: They do, any free-falling frame is inertial locally.>>
yes only locally, Local lorentz invariance....in suitable restricted regions:
if mismatch-->restrict the region,
22nd Mar, 2022
Stefano Quattrini
Ordine degli ingegneri della provincia di Ancona
<<SQ: two clocks which do not exchange em waves are linked by Lorentz Transformations as well according to SR, this I know quite well... in principle only with RDE you need radiation...
PG: The time it takes for an electron to buzz around a carbon atom in your body reacts on the same way as any clock. We need radiation of EM waves to keep our body together and our nerves communicating.>>
I'm talking about two atomic clocks with digital gauges, they do not exchange anything at all between eachother as the muon which is in motion, whose half lifetime is measured, with a clock at rest which just measure such time.
<<SQ: To say that a measurement has to be wrong because it does not comply with SR in a effect which has never been experimentally verified is just an ARISTOTELIAN ipse dixit, abandoned 400 years ago with Galielei...
PG:The measurement can be perfect, accurate, but according to rules that disagree with SRT. Then they are invalid wrt SRT.>>
then it depends: if one shows that clocks in sync in a rocket at distance H head to tail after departure of the rocket reaching speed v, will not desynch at all as vH/c2 which is the prediction of SR, then there will be a serious issue with RoS hence SR.
<<But those experiments are done with measurement definitions that are not recognised in SR.>>
I am sorry but here there is strong disagreement, see the example before
<<SQ: b) the inertial frames as a matter of fact do not exist in nature
PG:How much of one amount of matter is at rest in one single frame is only the question. Inertia with acceleration only needs the size of one proton of to get an SRT result.>>
only in the center of mass frame of the scattering.... the Proton is not be inertial at all.

## Similar questions and discussions

Discussing the consequences of the existence of a rest frame in the universe
Discussion
473 replies
• Sydney Ernest Grimm
The detection of the existence of the Cosmic Microwave Background Radiation (CMBR) from everywhere around in the universe has puzzled theorists. Not least because of the discovery of a Doppler effect in the data that can only be interpreted as direct related to the velocity and the direction of the motion of the solar system. But if it is correct we have to accept that there exist a rest frame in the universe. Actually we can determine the existence of absolute space and that is not in line with the “belief” of most of the theorists.
There is another method to verify the results: counting the numbers and measuring the brightness of galaxies from everywhere around. The first results – using visible light – were not convincing. But a couple of days ago The Astrophysical Journal Letters published a paper from Jeremy Darling with results that were obtained with the help of radio waves: “The Universe is Brighter in the Direction of Our Motion: Galaxy Counts and Fluxes are Consistent with the CMB Dipole” (https://iopscience.iop.org/article/10.3847/2041-8213/ac6f08).
In other words, it is real. We can determine the existence of "absolute space". Moreover, we know from set theory (mathematics) that absolute space and phenomenological reality must share the same underlying properties otherwise we cannot detect the existence of absolute space. The consequence is that absolute space has a structure too, because phenomenological reality shows structure.
None of the grand theories in physics is founded on the structure of absolute space. Therefore we are facing a serious problem in respect to the foundations of theoretical physics (the conceptual framework of physics).