A corollary to the above question is :

If the top mirror recedes only for a duration (dt,) over which time, the light ray progresses halfway, then does the light ray proceed at first in a bent fashion, and then in a straight fashion, as depicted?

(The ray must, of course, end up at the middle of the receded mirror.)

Justo Pastor Lambare

Dear Professor Lambare,

The original youtube video, can be found here :

https://www.youtube.com/watch?v=Mpw68rvF4pc

This is my commentary on the original video. (Essentially there is no "Relativity of Simultaneity, in the Einstein Light Clock. The rays are coincident-- they arrive at the same time, and not "one after the other" in the stationary and moving frames).

https://www.researchgate.net/post/Does_Einsteins_Light-Clock_discussed_here_by_Professor_Cox_actually_demonstrate_the_reserve_conclusion_to_what_is_propounded

Justo Pastor Lambare

Dear Professor Lambare,

Yes, that's the question I asked. I have altered the usual Einstein Light-Clock experiment, by having the top-mirror receding away uniformly, as shown in the pictures above.

The question is, in that case, will the light have to move-----bend, or go bent then straight,---- as depicted, in the moving frame?

Gary Stephens, I repost as requested "Any thoughts on the above & below?" As usual, flawed starting assumptions confound it. There's no "Light Ray". Emissions expand spherically. Even lasers disperse! Light hitting the original point arrives on a straight vector. Light on the vector you show carries on to hit another part of the mirror. All experimental evidence agrees! as does Feynmans 'sum over paths' analysis.

Peter Jackson

Dear Professor Jackson,

Thank you for your interesting post. You are the first to give a view, on a very baffling question. (I'm baffled myself).

I'm not sure I understand you exactly : ---- are you saying the light ray in the moving frame would proceed in a straight line, but, as the mirror receded, it would "hit another part of the mirror" ? ---- to the right of where it would normally hit without the mirror receding?

Gary Stephens , "I'm not sure I understand you exactly -- are you saying the light ray..." NO. I've said many times; there are NO 19thC "rays" in optical science Only when you drop that concept can reality emerge! If an emitter moves in a medium after an emission it does not DRAG those waves with it! Most emissions are spherical, but yes, if in a more focused 'beam', it'd hit the mirror to the right.

Peter Jackson

Dear Professor Jackson,

Beg Pardon :-----I've clarified the figures --- to be clear, both in the stationary frame, and in the moving frame, the top-mirror is receding uniformly upwards. Confer above.

Peter Jackson

Dear Professor Jackson,

I think the light-ray would have to hit the mirror in the middle, in both the stationary frame (top figure,) and in the moving frame (bottom figure), just as it does in the regular unaltered Einstein Light-Clock (pictured above).

It would be impossible for the light ray to hit the middle of the mirror in the stationary frame (top figure) and then the --same light ray-- hit the mirror at a different place in the moving frame (bottom figure).

This is what makes this example so baffling : since in the moving frame, this vital position is changing, in flight, as the light ray makes its progress up to the middle of the receding mirror.

Gary Stephens , Not baffling if we apply what we know. The TRAIN is an IRF. Only fools OUTSIDE it think that if THEY decide to move they can influence what happens inside it!! The light pulse remains vertical WHATEVER speed & direction the idiots outside are doing! They only see 'apparent' speeds & angles, not reality.

Peter Jackson

Dear Professor Jackson,

Yes agreed.

Imagine a static mirror set at the same height as the end or concluding height of the receding mirror.

We could run these two experiments in parallel.

One with the receding mirror. One with the static mirror.

You will notice that, in the case of the receding mirror, the path must be curved, and it is a longer than the path of the light in the case of the static mirror.

Also you will notice that that light must arrive to the static mirror, and to the receding mirror at the same time, notwithstanding the different paths taken.

In other words, in the receding mirror case, the light must travel further in the same time.

Gary Stephens, You agree! "The light pulse remains vertical WHATEVER speed & direction the idiots outside are doing!" CONGRATULATIONS!! But now you must STOP being one of the 'idiots outside' who write what you did in your latest post!! If the optical length IN the train increases, propagation time is longer. But relative motions of observers do NOT change anything INSIDE the train! I.E. APPLY WHAT YOU'VE ACCEPTED AS OBVIOUS!

Peter Jackson

Dear Professor Jackson,

Yes agreed.

A corollary of this is that the rays must set out from the middle of the bottom-mirror, and arrive at the middle of the top-mirror, in the stationary frame. And this is still the case if the top-mirror is receding away, upwards, in a uniform manner.

(Just to state the obvious).

Gary Stephens, Yes, increasing the optical path length so also time taken.

Gary Stephens Peter Jackson

1) In a vertical light clock at rest and also in motion, the light signal only moves vertically, it does not go in a zig-zag! Please see

Deleted research item The research item mentioned here has been deleted

Jan Slowak , "the light signal only moves vertically", Yes. Gary now finally agrees that, but what observer on OTHER vectors 'see' all differ! because it's apparent 'CO-ORDINATE', not 'PROPER' speed and angle. That's more important to understand that most realise.

What the Lorentz relations do is annihilate the "Relativity of Simultaneity". In the regular Einstein Light-Clock case (with a static top-mirror) they ensure the light-rays arrive to the same place (the top mirror and bottom mirror) at the same time, in the moving and stationary frames, as they must.

Actually in the Einstein Light Clock case, the reverse is done. Since there is no "Relativity of Simultaneity" built into the very concept-- ie. the light arrives to the top and bottom mirror, at the same time, in the moving and stationary frames (this is why it is called a "light clock")--- then the Lorentz relations can be obtained directly from this circumstance, via Pythagoras' theorem.

This seems to be the crux of the matter. The "Relativity of Simultaneity" is completely forbidden. ie. there is no new time concept. The alteration is with the light.

When we have a uniformly receding top-mirror, what appears to happen is the light does whatever it must, in order to arrive to the same place at the same time (the middle of the top-mirror).

This appears to include bending "in flight".

So when you both say "the light signal only moves vertically" -- I agree this is one way of looking at it. Viz. looking at it from the perspective of the "stationary frame"-- because this guarantees --- for certain--- there is no "Relativity of Simultaneity".

Indeed to talk of the "Relativity of Simultaneity" in this way of looking at, would be a nonsense. There is only one ray bouncing up and down off of the two mirrors. It can hardly arrive before or after ----itself---.

Apropos Einstein Light-Clock-- modified.

New paradox.

Suppose two light rays are issued simultaneously from the top and bottom of the mirror, in the stationary frame. (Top figure). The top mirror is receding uniformly upward, when these rays are issued.

Suppose these light rays meet in the middle at x, in the stationary frame. (A firecracker could be set to trigger only if both rays hit either side of the firecracker simultaneously-- a delay of either, would cause the firecracker not to fire).

So we can be sure (quite certain)--- the light rays -must- arrive to the x (x marks the spot) in all frames, moving or stationary.

Now suppose, having established the rays -must- both arrive to x, we remove the firecracker.

The lower ray, traveling upward must reach x (x marks the spot) but, later on, it also must reach the middle of the receding mirror.

As you can see, this is impossible, because the light must bend, in flight, from its issue, if it is to reach the middle of the receding mirror.

And the light cannot be in two places at once.

So perhaps this lower ray travels in a straight line, until it reaches x, and then veers off, upon a curved path to end up at the middle of the receding mirror, which is the logical imperitive.

Cf. also

https://www.researchgate.net/post/If_the_top_mirror_recedes_uniformly_in_the_Einstein_Light-Clock_pictured_below_then_does_the_light_ray_have_to_bend_as_shown

Peter Jackson Gary Stephens

2) "the light signal only moves vertically", Yes."

Thank you very much Mr. Peter Jackson.

3) "Gary now finally agrees that "

Where somewhere?

4) "but what observer on OTHER vectors 'see' all differ"

Good... But! Why do you put the word see between apostrophes? It's good that you did that! Because what an observer 'sees' does NOT have to be the way it is in reality. This especially applies to the movement of the light signal. In the first place, an observer can NOT see the changes in the light over a few millimeters or even centimeters. You don't have time!

That what an observer 'sees' differs applies to models that this observer creates. This applies to its SUBJECTIVE model!

But the light does not zigzag between the floor and the ceiling of a vertical light clock! Everyone must take this into account, think about how it works.

5) "because it's apparent 'CO-ORDINATE', not 'PROPER' speed and angle"

I think you shouldn't use the term 'PROPER'! I've analyzed STR and the derivation of LT so many times and I've managed without it. I think you should instead think about the absolute reference system of light. It's everything else that moves relative to this system. Look again at

Light - The Absolute Reference in the Universe.

5) "That's more important to understand that most realize."

Yes. But the most important thing is to understand that there is an absolute reference system against which everything else is referenced!

Gary Stephens

6) "What the Lorentz relations do is annihilate the "Relativity of Simultaneity"

I've been working with STR for years and not once have I had to bring up this concept. It just confuses everyone even more!

7) "In the regular Einstein Light-Clock case (with a static top-mirror) they ensure the light-rays arrive to the same place (the top mirror and bottom mirror) at the same time, in the moving and stationary frames, as they must."

Yes, that's right! They (who advocate STR) distort reality just to get LT!!! In a vertical light clock in motion, the light signal can NOT arrive to the same point as when this device is at rest. See Fig. 4, Fig. 5, Fig. 6 in my article

Deleted research item The research item mentioned here has been deleted

Jan Slowak, "I've analyzed STR and the derivation of LT so many times and I've managed without it." Like most I also did so, for 50+yrs before I found the problem with a single 'absolute' datum. viz; Consider light pulses in two Concordes flying in opposite directions. Each pulse propagates LOCALLY at c within each plane!! So yes, speed c in the plane is the only PROPAGATION speed. All co-moving observers only find various APPARRENT speeds (so 'co-ordinate' speeds). However, there's not only just one case of 'absolute' speed!! It has the speed c for EACH local IRF it propagates in!

Einstein also realised this, but after less that 40yrs. That's why it's called 'PROPER' speed (also then giving PROPER time).

Light can only 'propagate' where it IS not where it isn't!!

So a single 'absolute' state ONLY works for EACH light signal. That why I wrote it's 'more important to understand than most realize'!

That realization is why Einstein wrote; “It'd have been more correct if I'd limited myself in my earlier work to emphasizing only the nonexistence of a single ether velocity, instead of arguing the total nonexistence of the ether, for I can see that with the word ether, we say nothing else than that space has to be viewed as a carrier of physical qualities.” (Einstein to H.A. Lorentz, November 15, 1919, in Kostro 1992) And explained it was ether's 'absolute' 'immobility' that had to go. (Leiden 1921).

So 'absolute' can only apply to diffetrent LOCAL cases, so misleads, which is why PROPER is the better word & has the definition it has; PROPAGATION speed.

"the light signal only moves vertically", Yes." ----This is in the case of the Einstein Light Clock. One uses the "stationary" frame to establish what the light actually does.

This is also the case in the AE train-embankment experiment :

We use the "stationary" frame. In the case of the carriage-- the light reaches the middle M' simultaneously if issued from the ends, or the ends simultaneously, if issued from the middle. It has to. The carriage is "stationary".

Similarly, when we deem the embankment to be "stationary" . Ditto the above. -- the light reaches the middle M' simultaneously if issued from the ends, or the ends simultaneously, if issued from the middle.

The reason this is apparently confusing in the case of the AE train-embankment experiment, is because it is supposed that the embankment breadth and the carriage breadth are different breadths. In reality, they are the -same- breadth, view from different perspectives. This follows from the logic of Relative Motion.

So, in all three case, this ensures there is no "Relativity of Simultaneity. This is the right answer to all three (very similar) questions.

This means we have an Absolute character to space and time. (We have no new time concept).

It is impossible to manage without the Lorentz transforms, because they make the following true :

x = ct and x' = ct'

In other words they have the light travel at "c" in the stationary (undashed) frame and light travel at "c" in the moving (dashed) frame.

This is known to be true empirically, and from Maxwell's equations

In reality this is the -same- light ray traveling along the -same breadth-, viewed from different perspective. This follows from the logic of Relative Motion.

The different perspectives produce the "motion" or not, of the breadth.

Peter Jackson

8) "Consider light pulses in two Concordes flying in opposite directions. Each pulse propagates LOCALLY at c within each plane!"

I believe that concepts like 'LOCALLY' and 'PROPER' are unnecessary, they only complicate a model that many already have difficulty grasping.

Pulses of light (I use signals) do NOT move in one or the other. Pulses of light move in a vacuum, in a vacuum frame of reference!

9) "However, there's not only just one case of 'absolute' speed!! It has the speed c for EACH local IRF it propagates in!"

NEVER! Light signals travel at a constant speed c in vacuum (Maxwel: c = 1/(μ0ε0)1/2).

In all other IRF, the relative velocity between the signal wavefront and the respective reference frame is c±v, where v is the absolute velocity of the reference frame in space.

10) "Light can only 'propagate' where it IS not where it isn't!!

This is for you to explain more. But I can say the following: a light signal moves regardless of whether there are any IRF observing this light signal.

11) "That realization is why Einstein wrote; “It'd have ..."

I don't usually interpret phrases or sentences. I prefer to start from a mathematical model, a figure in which the respective phrase or sentence has been implemented. Then we know exactly what we are talking about.

12) "So 'absolute' can only apply to different LOCAL cases, so misleads, which is why PROPER is the better word & has the definition it has; PROPAGATION speed."

The 'Propagation Speed' of light is c (Maxwel: c = 1/(μ0ε0)1/2).

Gary Stephens

13) "This is in the case of the Einstein Light Clock."

Do you mean that light moves one way in the vertical light clock and another way in other contexts?

14) "One uses the "stationary" frame to establish what the light actually does."

In thought experiments (or real experiments) with light signals (here on Earth) there are no 'stationary' reference frames!

15) "We use the "stationary" frame. In the case of the carriage-- the light reaches the middle M' simultaneously if issued from the ends, or the ends simultaneously, if issued from the middle. It has to. The carriage is "stationary".

Similarly, when we deem the embankment to be "stationary" . Ditto the above. -- the light reaches the middle M' simultaneously if issued from the ends, or the ends simultaneously, if issued from the middle."

Consider my answer 14). I would prefer to discuss whether there is a simple figure. I suggest you take a look at my article, if you like.

Deleted research item The research item mentioned here has been deleted

I should ask both of you. How does the ray behave in the moving frame? both in the usual Einstein Light-Clock (zig zag?), and in the modifed Light-Clock (curve?) with the receding top-mirror.

(I don't think either of you have given an explicit view on this yet).

Gary Stephens

16) "I should ask both of you."

Who?

17) "How does the ray behave in the moving frame? both in the usual Einstein Light-Clock (zig zag?), and in the modifed Light-Clock (curve?) with the receding top-mirror."

I believe we should be satisfied if we can come to a common conclusion regarding the vertical light clock.

Light moves independently of the movements of the observer and the source. We must assume this!

I hope you have had time to look at my article. Look at Fig. 4, Fig. 5, Fig. 6. Thank you.

Dear Slowak,

Yes I think you mentioned this before. Your figures (4,5,6) would mean the Einstein Light-Clock would be impossible. The light ray would simply miss the top mirror, if the apparatus (the two mirrors) were in motion.

Is that what you are saying?

Gary Stephens

18) "Your figures (4,5,6) would mean the Einstein Light-Clock would be impossible. The light ray would simply miss the top mirror, if the apparatus (the two mirrors) were in motion."

It depends on the speed of the device. Have you done any calculations to see when this would happen?

For example: Say the distance between the two mirrors (floor, ceiling) is 10 m (meters). During the time that the light signal travels between these two, the entire device would move 1 mm (millimeter). Here we consider the speed of light to be about 300,000 km/s and the speed of the Earth around the Sun to be about 30 km/s. --> v/c = 30/300000 = 1/10000.

So why should you worry that the light signal would miss the mirror?

Another paradox to do with the Einstein Light-Clock

Lateral de-acceleration of the apparatus:

The odd thing here, is how does the light know to alter its trajectory from straight to bent, -in flight-, so as to hit the middle of the top mirror, -in the future-?

The essential point in all these examples, is that, in order that there is no "Relativity of Simultaneity"-- ie. the light must reach the middle of the top-mirror in the same time, in both stationary and moving frames, then the light does whatever it must, in order the make this happen.

This is also true in the case of the AE train-embankment experiment. Because in the "stationary frame" the light reaches the middle of the breadth (either M or M') simultaneously, then in the moving frame-- light moves however it must, in order to make this happen. In this case we find the light does not move classically (c + v, c - v) in going between frames, in the AE train-embankment experiment.

Jan Slowak, "I believe concepts like 'LOCALLY' & 'PROPER' are unnecessary, they only complicate a model that many already have difficulty grasping." With correct thinking all difficulties are resolved by applying those terms. Your maths only apply to each single case. Other cases move, showing that using maths can mislead us! Gary Stephens That fig is naive and not reality. We can only ever SEE light that interacts with our lenses. Light in a different inertial system isn't visible to us.

Only if the light charges particles in the medium which then emit LATERALLY can we 'track' it's progress. But then it's only a 'co-ordinate' (Pythagorean) speed, so 'apparent' & the limit c is invalid.

Dear Gary Stephens,

18.2) In my answer 18) I have explained my position regarding a vertical light clock. Wouldn't it be more correct on your part to confirm or counter-argue it? You continue by talking about another paradox. That's not right.

19) "Another paradox to do with the Einstein Light-Clock

Quote:

"At the same time, these are the worlds we have the hardest to understand, worlds where illustrative models deceive us and we find paradoxes. But there is only one world and it has no paradoxes. Only our models that hold paradoxes "

[Vid skiljevägen : essäer om människan och hennes framtid; Ulf Sinnerstad; 2006, swedish]

I usually say that if a theory results in a paradox then the theory has inherent flaws, then the theory is nonsense.

20) "Lateral de-acceleration of the apparatus:"

I'm not sure what you mean here. But one thing is for sure: STR does NOT deal with acceleration!

21) "The odd thing here, is how does the light know to alter its trajectory from straight to bent, -in flight-, so as to hit the middle of the top mirror, -in the future-?"

Yes, exactly! "how does the light know to alter its trajectory from straight to bent"? I usually ask: what causes the light in the moving light clock to change its direction from vertical to oblique? That is nonsense and no physicist defending STR can answer it!

22) "The essential point in all these examples, is that, in order that there is no "Relativity of Simultaneity"-- ie. the light must reach the middle of the top-mirror in the same time, in both stationary and moving frames, then the light does whatever it must, in order the make this happen."

a) I have worked with STR for several years and never had to take out "Relativity of Simultaneity". It only complicates an analysis that should be logical and simple.

b) The light MUST NOTHING!

23) "This is also true in the case of the AE train-embankment experiment. Because in the "stationary frame" the light reaches the middle of the breadth (either M or M') simultaneously, then in the moving frame-- light moves however it must, in order to make this happen. In this case we find the light does not move classically (c + v, c - v) in going between frames, in the AE train-embankment experiment."

In these thought experiments, people explain different things in such a way that they fulfill STR's postulates. But it is wrong in many different ways.

a) Light moves in the vacuum reference frame (in vacuum) with its absolute speed c (Maxwel: c = 1/(μ0ε0)1/2)

b) The speed between an IRF and the light signal wavefront is c±v (where v is the IRF absolute velocity in vacuum (and you don't know it)!

c) Therefore, there is NO IRF here on Earth that is at rest.

Peter Jackson

24) "With correct thinking all difficulties are resolved by applying those terms."

With correct thinking, no additional concepts are needed. They only complicate the models.

25) "Your math only apply to each single case."

It would be strange if you could use mathematics in one case but not in another!

26) "Other cases move, showing that using math can mislead us!"

Mathematics is a fantastic tool without which one would NOT be able to do anything today. This tool must be used correctly! Then mathematics will show where one has made mistakes in the mathematical model that is created based on our real physical case.

Jan Slowak, You seem unable of unwilling to think or see outside your small box. As your earlier comments suggested! Are you beyond help? Try this; The word 'absolute' for kinetic states is one 'ultimate' state. So precludes i.e. light speed c on Mars being different to c on Earth even with 50km/sec different speeds! So signals from one to the other must change speed, as NASA telemetry shows! In that case, as AE; ALL PHYSICS IS LOCAL!!. So kinetic systems, with the same maths, are 'hierachical'. See his logic?

Peter Jackson

27) "You seem unable of unwilling to think or see outside your small box."

I could say this about you or about anyone else here at RG. But as you may notice, I am reluctant to talk about the person but about the subject! Can we agree on this? Otherwise our conversation would not be so scientific. Thank you.

28) "As your earlier comments suggested! Are you beyond help? Try this;"

No comment

29) "The word 'absolute' for kinetic states is one 'ultimate' state. So precludes i.e. light speed c on Mars being different to c on Earth even with 50km/sec different speeds!"

It is not impossible that the speed of light on Mars is different from that on Earth, although I don't understand why that would be the case.

But this has NOTHING to do with STR!

In the derivation of LT in various articles/books, the letter c is used for the speed of light. There is NO c1, c2, ... that would denote the speed of light in different environments or different places in the model for each thought experiment.

So for a concrete thought experiment, we consider the absolute speed of light to be c.

30) "So signals from one to the other must change speed, as NASA telemetry shows!"

I am very curious what mathematical model NASA uses when they say they get different values ​​for the speed of light. I really hope they DON'T use LT.

31) "In that case, as AE;"

Do you mean Albert Einstein?

32) "ALL PHYSICS IS LOCAL!!"

What is the opposite of LOCAL? I haven't had to think about this concept until now.

33) "So kinetic systems, with the same maths, are 'hierachical'. See his logic?"

No comment

The picture is misleading, since the motion of Earth is 10 000 times smaller than c.

The assumption of 30 km/s is wrong. Instead we have 0.47 km/s (from rotation).

From _____________ John-Erik

Jan Slowak, "What is the opposite of LOCAL? I haven't had to think about this concept until now." Ahhh! That explains it. The opposite of 'LOCAL' is 'UNIVERSAL' , so a single 'absolute' datum, which fails when dealing with co-moving systems. This IS 'SR', i.e. Einstein's train; Light propagates IN the train at c with respect to the train, an IRF co-moving with respect to man M on the platform. But HE ALSO receives light at LOCAL c, in HIS system. But remember he can't SEE the light propagating in the OTHER (NON-local') system)!!

The issue comes when an emission transits from one system to the i.e. train co-moving one (at v), here it interacts with the glass and changes speed, not just to c/n but c/n in the GLASS rest frame! so an additional change of v (gamma).

This does take careful thought if only used to dealing with one local IRF at a time. Watch this short video carefully a few times as it covers ALL cases.

https://www.youtube.com/watch?v=ZikWs-mBPA0

>

This is all contradicted by x = ct and x' = ct'.

In this case the moving system is the -dashed- system, where the light-ray travel at "c" as shown above. And the OTHER system is the -non dashed- system in which the same light-ray also travels at "c" also shown above.

To get from one system to the other, one must utilise the Lorentz relations. This is what they do-- they are a conduit between the dashed and the non-dashed system.

At a deeper level the Lorentz relations simply ensure there is no "Relativity of Simultaneity".

All this nonsense about the rays being in a carriage and hitting the glass-- is gobbledegook. We can simply have a flat-bed carriage. So both observers can witness the same light ray-- one in the dashed system and one in the non-dashed system, and each would say mine looks like this : x' = ct' or mine looks like this x = ct. ie. Both observers would see the light travel at "c" with respect to their system.

Anyhow, what's interesting about the receding mirror example, above, is that the light-ray has to travel at a greater rate than "c" --- and must have a bent path, as compared to the straight light-ray with the mirror set at that higher elevation.

The reason for this, is so that the light ray hits the same place at the same time (the middle of the top-mirror) in both moving and stationary frames. That is to say, to ensure there is no "Relativity of Simultaneity".

John-Erik Persson

43) "The picture is misleading, since the motion of Earth is 10 000 times smaller than c."

Do you mean the figure that Gary Stephens has attached?

Yes, the speed of light = about 300,000 km/s and the speed of the Earth around the Sun about 30 km/s. Then the proportion becomes 1/10,000.

44)"The assumption of 30 km/s is wrong. Instead we have 0.47 km/s (from rotation)."

I also usually use the Earth's speed around the Sun, about 30 km/s.

Peter Jackson

45) "Ahhh! That explains it. The opposite of 'LOCAL' is 'UNIVERSAL' , so a single 'absolute' datum, which fails when dealing with co-moving systems."

No comment. ???

46) "This IS 'SR', i.e. Einstein's train; Light propagates IN the train at c with respect to the train, an IRF co-moving with respect to man M on the platform."

Light does NOT propagate IN the train, light propagates in a vacuum, in the air in this case. Once again:

a) The speed of light in a vacuum is c (Maxwel: c = 1/(μ0ε0)1/2)

b) The relative speed of light with respect to a reference frame is c±v, where v is the IRF's absolute velocity in vacuum.

Please think about this, once, twice, ...

47) "But HE ALSO receives light at LOCAL c, in HIS system. But remember he can't SEE the light propagating in the OTHER (NON-local') system)!!"

What is this? Who is HE?

48) "The issue comes when an emission transits from one system to the i.e. train co-moving one (at v), here it interacts with the glass and changes speed, not just to c/n but c/n in the GLASS rest frame! so an additional change of v (gamma)."

STR does NOT deal with cases when light passes through different media.

49) "This does take careful thought if only used to dealing with one local IRF at a time. Watch this short video carefully a few times as it covers ALL cases."

In your articles or books, I use figures that are as simple as possible. It's easier to understand.

In your video you use LOCAL c. That can't be right. c is c. c IS NOT LOCAL c. You should use ct, ce.

Check the attached file. My research is explained in detail in the book

Book Light - The Absolute Reference in the Universe

Gary Stephens, So you think you can 'see' a light signal without it reaching your lens!?! Great trick. Look out David Blaine! Or perhaps you weren't thinking clearly. Jan Slowak, "Light does NOT propagate IN the train". Same problem it seems, unless all trains are now 'blacked out'! As I first suspected, you see no way out of that 'box'. Did you really not understand the video?

Jan Slowak

Jan, yes, I mean Gary's figure.

We cannot see 30 km/s, since Earth is in a free fall. We can only see the field generated by Earth, that is 11.2 km/s, vertically and 0.46 km/s due to rotation.

John-Erik

Peter Jackson

50) "Same problem it seems, unless all trains are now 'blacked out'! As I first suspected, you see no way out of that 'box'. Did you really not understand the video?"

You have not understood what I mean. The light moves independently of the beam and the observer (the train). You should also ask yourself whether you yourself are only inside your own box. But let's leave aside this discussion about boxes. It does not fit in science.

I have watched your video. There are tons of such videos explaining STR, time dilation, length contraction. They are all wrong. They all tell the "approved narrative".

I am attaching again the file with my two figures.

Would you please comment on the two figures?

John-Erik Persson

51) "Jan, yes, I mean Gary's figure.

We cannot see 30 km/s, since Earth is in a free fall. We can only see the field generated by Earth, that is 11.2 km/s, vertically and 0.46 km/s due to rotation."

https://en.wikipedia.org/wiki/Earth

Average orbital speed: 29.7827 km/s. I usually round this speed to 30 km/s.

Jan Slowak, I agree doctrinal analyses are wrong, which is why I produced the video. I also DO follow your fig, which uses that doctrinal assumption of an 'IRF' (NOT Einstein's; box in relative motion within a larger box) so also fails his 'logically unavoidable" ('52) test! Indeed the 'IRF' in your 2nd case is NOT 'equivalent' to the 1st, so it fails even SR's postulates. This is where the word 'absolute' misleads. Consider;

Draw another LARGER box around your bottom box and have it moving in whatever direction you wish in relation to the bottom box, which is AT REST. The light propagating in the smaller box arrives at the centre simultaneously. Any signal propagating in the BIGGER (background) IRF/BOX has no validity in the smaller box.

Then the postulates are logically met as his 1952 definition, removing the paradoxes.

The video correctly shows ALL relevant cases, including light crossing the boundary TRANSITION ZONES between the 'boxes'. There's an 'infinite hierarchy' of REAL finite IRF's 'boxes' with states k, k', k", k"' etc etc. Do study it again with that in mind; PROPAGATION in EACH box IRF) obeys, logic, empirical data, the postulates AND his '52 definition of IRF's! Using 'Absolute' returns that to nonsense!!

https://www.youtube.com/watch?v=ZikWs-mBPA0

Peter Jackson

52) "I agree doctrinal analyses are wrong, which is why I produced the video. I also DO follow your fig, which uses that doctrinal assumption of an 'IRF' (NOT Einstein's; box in relative motion within a larger box) so also fails his 'logically unavoidable" ('52) test! "

It's good that you say that some analyses are wrong. But I don't understand what you mean by "doctrinal".

53) "Indeed the 'IRF' in your 2nd case is NOT 'equivalent' to the 1st, so it fails even SR's postulates. This is where the word 'absolute' misleads. Consider;"

*** The principle of relativity – The laws of physics are the same in all inertial frames.***

It is the same as saying that two IRF are equivalent. So my two figures are equivalent!

54) "Draw another LARGER box around your bottom box and have it moving in whatever direction you wish in relation to the bottom box, which is AT REST. The light propagating in the smaller box arrives at the centre simultaneously. Any signal propagating in the BIGGER (background) IRF/BOX has no validity in the smaller box."

I draw my figures according to my logic. If I were to do it according to your logic or Einstein's, I would come to the same conclusion as you.

I draw my figures as simply as possible. If you look at them again and read carefully what is written there, you might come to a different conclusion. Try, objectively!

55) "Then the postulates are logically met as his 1952 definition, removing the paradoxes."

I haven't read about this, do you have a good link?

56) "The video correctly shows ALL relevant cases, including light crossing the boundary TRANSITION ZONES between the 'boxes'."

I remember once getting a request from a magazine or a reviewer that I should remove my boxes from my figures.

57) "There's an 'infinite hierarchy' of REAL finite IRF's 'boxes' with states k, k', k", k"' etc etc. Do study it again with that in mind;"

It doesn't matter how many boxes you draw. The light moves independently of the source/observer's movements.

Book Light - The Absolute Reference in the Universe

Jan Slowak, "I don't understand what you mean by "doctrinal". Just standard teachings. "If I were to (use) your logic or Einstein's, I'd come to the same conclusion as you." Yes. your 'logic' what's at fault, dismissing the doctrinal view of Einstein not his REAL view. I'll simplify it to 2 buses in relative motion; 1) Light propagates at c (c/n) locally in each (so your fig is clearly wrong).

2) The buses have a speed difference v.

3) When a light signal from arrives at the other it's speed is CHANGED on entering the glass; by c/n +v (gamma). So it again propagates at c (c/n).

What you're confusing is the 'co-ordinate' speed of a light pulse in one viewed from OUTSIDE it, so a DIFFERENT inertial system, so c+v is valid.

Peter Jackson

58) "Just standard teachings."

Are standard teachings like the ones you teach? Are there other teachings?

59) "Yes. your 'logic' what's at fault, dismissing the doctrinal view of Einstein not his REAL view."

In my analysis of STR, I have never encountered such a thing as different views on different views! I follow what is written in articles and books/manuals. I follow the theory and NOT the person.

60) "I'll simplify it to 2 buses in relative motion;"

This is your thought experiment. You can write an article and make figures explaining how everything is connected. Then I will analyze your article in great detail.

61) "1) Light propagates at c (c/n) locally in each (so your fig is clearly wrong)"

Try to simplify your thought experiment. There is no point in using c/n, we can agree that everything takes place in a vacuum.

Light does NOT propagate locally or otherwise. Light propagates in a vacuum (in its frame of reference, if we agree that we are doing our experiments in a vacuum).

You use a few sentences and conclude that my figure "is clearly wrong". Can you do that? Is that how a researcher works?

62) "What you're confusing is the 'co-ordinate' speed of a light pulse in one viewed from OUTSIDE it, so a DIFFERENT inertial system, so c+v is valid."

The speed of light is independent of the speed of the source and the observer. If someone says that the speed of light in IRF1 is u1 = c and in IRF2 is u2 = c+v --> u1 = u2 --> c+v = c --> v = 0!

c+v = c --> v = 0!>>

That's right, speeds of (c + v) and (c - v) are a nonsense. Einstein et al use these classical speeds (c + v) (c -v ) to get the "Relativity of Simultaneity". When you stick to the emprical facts, that C = c always, then the Relativity of Simultaneity vanishes, and so does Special and General Relativity. We simply have classical time.

Jan Slowak, "Are standard teachings like the ones you teach? Are there other teachings?" No. And Yes. Einstein removed the paradoxes etc. from those you use ("what is written in (MOST!) articles & books/manuals.") except that in your figs the IRF's aren't equivalent!

"You use a few sentences and conclude that my figure "is clearly wrong". Can you do that? Is that how a researcher works?"

Yes. That why we have brains! Identifying an error of logic can only take one sentence if we apply intellect!

It's commonly flawed assumptions that lead to the errors. You reveal yours in; "The speed of light is independent of the speed of the source and the observer." without giving another datum. 'Speed' is an entirely RELATIVE concept, so must ALWAYS be with respect to (wrt) to 'something'.

What I've shown irrefutably works by passing ALL empirical tests without anomaly is this;

1. In Maxwell's NEAR field regime EM speed c is wrt the emitter (electrons).

2. In the FAR field (past the plasma TZ) c is wrt the last TZ electrons it was re-emitted by. The (helical) fluctuations are then carried in the local medium.

3. In the near field of a moving LENS the surface TZ electrons re-emit at local c in the LENS rest frame.

You'll find NO DATA or LOGIC to challenge that, which resolves ALL confusion, even the old problem of speed of reflections from moving mirrors. Only old 'beliefs' differ. See;

Jackson. P. A., Minkowski. J. S. Resolution of Kantor and Babcock-BergmanEmission Theory Anomalies. Hadronic Journal. Issue No. 5. Vol. 35. October 2012 pp.527-556 http://http://arxiv.org/abs/1307.7163

Peter Jackson

63) "Yes. That why we have brains! Identifying an error of logic can only take one sentence if we apply intellect!"

I like this! Thank you so much! I also use logic, I think.

64) "'Speed' is an entirely RELATIVE concept, so must ALWAYS be with respect to (wrt) to 'something'."

Of course, 'speed' is a concept/quantity that refers to a reference system.

a) Absolute speed of light in vacuum (Maxwel: c = 1/(μ0ε0)1/2). This speed refers to the vacuum reference frame.

b) The relative velocity between the light signal wavefront and an IRF (other than vacuum). This velocity is c±v where v is the absolute velocity of the IRF in vacuum.

65) Your points 1., 2., 3. don't have much to do with STR.

STR:

The special theory of relativity, formulated by Albert Einstein in 1905, describes how time and space are relatively dependent on the motion of the observer. It is based on two main principles:

1. The laws of physics are the same in all inertial frames (where nothing accelerates).

2. The speed of light is constant for all observers, regardless of their motion relative to the light source.

Consequences:

• Time slows down (time dilation) for objects that move quickly.

• Objects become shorter in the direction of motion (length contraction).

• Mass and energy are equivalent, expressed as E=mc2.

>

This is correct. I don't like the phrases "co ordinate speed" or "apparent speed". There is "speed relative to the embankment" or "speed relative to the carriage". That is it.

The paradox is that we have the speed of light "relative to the embankment" coming out as "c" and at the same time the speed of the light "relative to the carriage" coming out as "c".

But this is because the embankment breadth and the carriage breadth are really the same breadth, due to the logic of Relative Motion. This also means the "Relativity of Simultaneity" is ruled out a priori. We have classical time.

Gary Stephens, "I don't like the phrases "co ordinate speed" or "apparent speed". Then you'll find the paradox you identify. They're only removed once you understand the difference between those and PROPER ('propagation') speed. In the train system the TRAIN is the datum for c. Int the track system it's the TRACK. So apparent speeds in the train aren't limited to 'apparent' c. The runner in the train CAN now validly pass you at apparent c+/-v!

The LT only applies to light on entering the train system. Read this carefully; http://www.academia.edu/3715747/The_Optical_Breakdown_Density_Limit_Gamma_giving_the_Lorentz_Transformation_Mechanism

Jan Slowak, You refer to THE "vacuum reference frame" as if there was only 'one'. Einstein's ether is a FLUID medium, as ALL gases, with flows within flows, thus his hierarchical '05 states k, k', k" etc, and '52 "infinitely many spaces in relative motion within spaces". So there's always a LOCAL background rest frame as the datum for PROPER speed. Think about space; that's how it works! (as NASA data & the 2014 Nobel).

If you can't see and rationalise that there can only be 2 reasons; 1) You're very dim and lack common sense, or 2) You've written something different in a paper or book and think you should defend it to the hilt! I suspect it's the latter. And I suggest we should try to FALSIFY our hypotheses, not cling to them come what may!

Gary Stephens

66) "The paradox is that we have the speed of light "relative to the embankment" coming out as "c" and at the same time the speed of the light "relative to the carriage" coming out as "c"."

Of course it is! Although it is not a paradox, it is an error that is introduced and further used in your derivations and calculations.

Peter Jackson

67) "The LT only applies to light on entering the train system."

LT is applied to entire thought experiments: two IRF and the movement of the light signal.

Jan Slowak, (to Gary Stephens) "it is an error that is introduced and further used in your derivations and calculations." There IS a better understanding, where c in ALL IRF's is perfectly logical. EM waves change speed to LOCAL c ON MEETING moving bodies (electrons). Thus the Doppler shifts found. The VLB & NASA data etc. I've posted agree. Too shocking? Think harder!