Is time universal? NO (and its proof)

[Neddy Bate]

</em>...The laser beams exchanged between the (three) spacecraft in the triangle form a Sagnac interferometer...

I've been thinking a bit on the Sagnac effect. I have noticed that it does not give us any measure of absolute velocity, but rather only a measure of absolute rotation. Otherwise, the lasers exchanged between the three spececraft that you describe (in LISA) would also detect the peculiar motion of the Sun. Remember this post from a different thread?

</em>by Neddy Bate:


"I look forward to finally finding out the "absolute velocity" of the Washington Monument."
================================================================

Why it is 370 km/s of course. It is measured against the CMB, this velocity is the Washington Monument's velocity within the observable universe...

</em>I should add that the figure I posted is what is known as the peculiar velocity...It is based on the speed of our sun within the universe...

I assume that no laser beams in LISA will be arriving 'late' or 'early' due to the 370 km/s peculiar motion of the sun. The delay calculation will probably be based only on the displacement due to the orbital revolution of the satellite system around the sun.

It is tempting to use Sagnac as an argument for anisotropy of light speed, or 'absolute reference frame' hypotheses. I occasionally find myself using it to questioning relativity also. However, the effect seems only capable of measuring absolute rotation (or perhaps absolute acceleration). I am not a physicist, but I think most of them accept Sagnac's experiment as compatible with Lorenz/Einstein relativity theories.

 

[2inquisitive]

One consideration is the statement 'the speed of light is independent of the source of the light'. Remember that the laser beam travels in a straight line from one satellite to the next. A new laser beam is then transmitted to the next satellite in the sequence. The time recorded by first satellite is a combination of three straight 'legs' added together. The difference in time is in the same frame of reference, the difference being that the satellite that emitts the beam is travelling in the same direction as the emitted beam in one case, away from the emitted beam in the other. It's position changes in spacetime while the beams are in flight when the frame is moving relative to this position.

My assertian is the same as it has been for a long time. Clocks change tick rates because of the medium they travel through, whether that medium is called spacetime, an aether, Higgs field, or whatever one wished to name it. I think a better description for 'curved' spacetime is 'compacted' spacetime. It is compacted by gravity, also by an object with mass moving through it, affecting clock rates. Is the triangle 'really' at rest when the times in both directions are equal? Doesn't matter, when satellites are put in motion relative to this spacetime, the increase in motion is detectable, indicating an underlying frame of reference.

One other point, Neddy. The satellite 'system' is orbiting the sun, whether they rotate about an imaginary point along this orbit or not. The difference in clock times comes only when they rotate about this imaginary point. The papers state the time recorded in each direction is identical when no rotation takes place. Each satellite is then moving along the orbital plane at the same speed. It is when a ROTATION in one direction is introduced that the differences ocurr. The rotating frame is along the orbital plane. Did you visit the NASA site and look at the orbital details?

 

[MacM]

You should talk to your NASA friend a bit. He understands this idea well and has attacked relativity correctly, by rejecting one of the postulates. He understands that c must be variant or relativity is correct.-Dale

False statement. The measurement of invariance seems to be correct. However, the interpretation of what that means is incorrect. I do not dispute the postulate that claims light is measured to be invariant.

I simply see a more reasonable explanation for such invariance than relativity.

So you assertion is false.

BTW: My NASA friend seems to think I have an excellent understanding of both the assertions of relativity and correct alternative views in lieu of relativity.

 

[Neddy Bate]

</em>One consideration is the statement 'the speed of light is independent of the source of the light'. Remember that the laser beam travels in a straight line from one satellite to the next. A new laser beam is then transmitted to the next satellite in the sequence. The time recorded by first satellite is a combination of three straight 'legs' added together. The difference in time is in the same frame of reference, the difference being that the satellite that emitts the beam is travelling in the same direction as the emitted beam in one case, away from the emitted beam in the other. It's position changes in spacetime while the beams are in flight when the frame is moving relative to this position.

It sounds like a typical Sagnac arrangement. The same frame of reference that you refer to is basically the one inertial frame in which the sun is at- rest, and the three satellites are revolving around it. The other frame of reference would be a rotating reference frame in which the three satellites are at-rest. However, rotating reference frames are not considered inertial, to my knowledge.

</em>My assertian is the same as it has been for a long time. Clocks change tick rates because of the medium they travel through, whether that medium is called spacetime, an aether, Higgs field, or whatever one wished to name it. I think a better description for 'curved' spacetime is 'compacted' spacetime. It is compacted by gravity, also by an object with mass moving through it, affecting clock rates.

If you are localizing all reference frames to the nearest gravity fields, mass, etc., then I think you are onto something bigger than SR, and it is not really fair to criticize Special Relativity for not being as complete as General Relativity. Aside from that, the only part of your statement that I think some people would disagree with is the suggestion that spacetime is just another term for a kind of absolute medium. There are others who can explain spacetime much better than I can, but I do not think there is very much that can be considered 'absolute' about it.

</em> Is the triangle 'really' at rest when the times in both directions are equal? Doesn't matter, when satellites are put in motion relative to this spacetime, the increase in motion is detectable, indicating an underlying frame of reference.

When you say motion in this case, you are really referring to rotation. There is always an underlying frame of reference with respect to all rotation. Unlike the relative motion of inertial frames, the motion of rotating frames is considered absolute.

It appears to me that the LISA (and all other Sagnac devices) cannot detect any absolute or "underlying" frame of reference other than the one in which the arrangement is not rotating. For example, if there were two stars moving apart at a great velocity, and each star was surrounded by its own LISA system, each system would consider itself to be at-rest as long as there was no rotation of the system (in other words, no orbital revolution of the satellites around the star.) Both of the stars cannot be at-rest in the 'absolute' reference frame if they are moving apart at great velocity.

</em>One other point, Neddy. The satellite 'system' is orbiting the sun, whether they rotate about an imaginary point along this orbit or not. The difference in clock times comes only when they rotate about this imaginary point. The papers state the time recorded in each direction is identical when no rotation takes place. Each satellite is then moving along the orbital plane at the same speed. It is when a ROTATION in one direction is introduced that the differences ocurr. The rotating frame is along the orbital plane. Did you visit the NASA site and look at the orbital details?

If the papers state that the time recorded in each direction is identical when no rotation takes place, then this supports my objection to the claim of an absolute reference frame. The system is clearly not able to detect the 'absolute velocity' of the sun (for example, relative to the CMBR).

Perhaps I am missing your point, and you are not arguing in favor of an absolute reference frame -- perhaps just a set of 'preferred' reference frames that can be considered at-rest for most purposes. If that is the case, then I think we probably agree.

I admit that I visited the site only briefly, but I think we are in agreement that this is a Sagnac effect which is measuring rotation.

 

[2inquisitive]

by Neddy Bate:

The other frame of reference would be a rotating reference frame in which the three satellites are at-rest. However, rotating reference frames are not considered inertial, to my knowledge.
==============================================================

In the satellite's frame of reference, are they 'at rest' or or they rotating? When one satellite 'looks' at the next, how does it know of the rotation? Don't mix your frames.
Assume you are in a windowless room in one of the satellites, how do you detect if you are in motion? Sound familiar?

Uhh, I DID NOT claim an absolute reference frame, just the opposite. Even if there were no rotation, the satellites are still orbiting the sun. What do you suppose would be the outcome if there were only two satellites orbiting the sun, one behind the other. Time a laser beam from the rear sat to the front sat projected in the direction of orbit,
then time a laser beam from the front satellite projected to the rear satellite, opposite the direction of motion. I believe the rearward projected beam will arrive in a shorter time. The effect cancels in the non-rotating triangle because one 'leg' will be projected forward and one leg will be projected rearward.

The International Celestial Reference frame, adjusted with regard to the CMB, is a separate reference frame not in use in the above exercise. The ICRF does, however, let one calculate the speed and direction of motion of the sun/satellite system within the visible universe. I am giving you some reference frames not normally seen in undergraduate physics courses. I would think some up-to-date Astronomy and Cosmology courses would at least know of the ICRF.

 

[MacM]

When you say motion in this case, you are really referring to rotation. There is always an underlying frame of reference with respect to all rotation. Unlike the relative motion of inertial frames, the motion of rotating frames is considered absolute.

It is interesting to note that you state absoluteness of rotating frames but that linear relative velocity CANNOT be absolute. NOT that their absolute frames cannot be sensed or measured.

The distinction is important philosophically. It should also be noted that mathematically linear relative velocity is nothing more than a special case of rotation where the radius is infinite.

In other words you should realize that you are saying there IS an absolute referance frame even if it is not measurable.

 

[Neddy Bate]

The LISA satellites would have to be orbiting the sun, otherwise they would fall into it.* This makes the whole system of satellites 'rotating'. The term I prefer is 'revolving', which is why I refer to "orbital revolution" in my post.

</em>by Neddy Bate:

The other frame of reference would be a rotating reference frame in which the three satellites are at-rest. However, rotating reference frames are not considered inertial, to my knowledge.
==============================================================

In the satellite's frame of reference, are they 'at rest' or or they rotating? When one satellite 'looks' at the next, how does it know of the rotation? Don't mix your frames.

I don't think I mixed the frames. There are two different frames to be considered. An inertial frame in which the satellites are moving, and a non-inertial frame in which they are at rest.

Since you are asking about the satellite's own frame, then the answer is that they are always at rest in their own frame. However, in this case, I do not think the frame can be considered an inertial frame. The whole frame is rotating.

</em>Assume you are in a windowless room in one of the satellites, how do you detect if you are in motion? Sound familiar?

A better question would be, "What experiment can you do to determine if you are in motion?" Therefore, my answer is that I would bring a Sagnac device with me, and it would tell me that I am in a rotating frame.

</em>Uhh, I DID NOT claim an absolute reference frame, just the opposite.

Fair enough. However, getting back to the original topic of this thread, I thought you might have been suggesting that the firecrackers would be sequential in both the train and embankment frames due to a linear Sagnac effect. Perhaps I misunderstood.

</em>Even if there were no rotation, the satellites are still orbiting the sun. What do you suppose would be the outcome if there were only two satellites orbiting the sun, one behind the other. Time a laser beam from the rear sat to the front sat projected in the direction of orbit,
then time a laser beam from the front satellite projected to the rear satellite, opposite the direction of motion. I believe the rearward projected beam will arrive in a shorter time.

I agree. This is the same 'rotation' effect that we have been discussing. However, if this were uniform translational motion of inertial frames, the results might be different.

</em> The effect cancels in the non-rotating triangle because one 'leg' will be projected forward and one leg will be projected rearward.

I agree that in a non-rotating triangle the propagation times would be the same in both 'clockwise' and 'anti-clockwise' directions.*

</em>The International Celestial Reference frame, adjusted with regard to the CMB, is a separate reference frame not in use in the above exercise. The ICRF does, however, let one calculate the speed and direction of motion of the sun/satellite system within the visible universe. I am giving you some reference frames not normally seen in undergraduate physics courses. I would think some up-to-date Astronomy and Cosmology courses would at least know of the ICRF.

I appreciate the information regarding various 'preferred' reference frames which have been defined for their usefulness. Do these frames pertain to the original question of whether simultaneous events in one frame are also simultaneous in other frames?

-----

*I assume that the only reason we speak of the system as "non-rotating" is when we wish to speak of a state in which all of the light signals take the same amount of time to travel 'clockwise' as they do to travel 'anti-clockwise' around the system. This is a hypothetical situation that is only good for an instant before the satellites begin falling into the sun.

 

[DaleSpam]

You should talk to your NASA friend a bit. He understands this idea well and has attacked relativity correctly, by rejecting one of the postulates. He understands that c must be variant or relativity is correct.-Dale

False statement. ... So you assertion is false.

EDIT: After I calmed down a bit I realized that my angry comments were fairly pointless. I re-wrote this post under the assumption that you made an honest mistake instead of deliberately calling me a liar. PS it looks like we are over-posting each other and you are already responding to my upset version. I will give you time to change your tone as well, I hope you take advantage of it. There is no reason to have an uncivil discourse.

I believe that you may have mis-read my statement. Notice that I said your friend's position is that "c must be variant". You may have mis-read and thought I was claiming your friend's position is that "c must be INvariant". Here are some quotes to support my claim that your friend understands the crux of the argument - that relativity is correct unless c is variant:

*********(http://www.extinctionshift.com/details.htm)********
"c' = c ± v"
"c' ≠ c"
"{v = unbounded}"

"All emissions will have the additive velocity c' in all other frames of reference other than that of the primary source. Hence, the additive velocity would be c+v for an approaching primary source, which moves with velocity v relative to that chosen frame of reference. The velocity would be c-v for a receding primary source. The addition of velocities are according to Galilean transformations"

"The waves emitted from an approaching source move undisturbed with velocity c+v in vacuum as illustrated."

"all re-emissions of a photon occur at exactly the velocity c with respect the frame of reference of the photons most primary source only. {Not in all frames of reference.}"

"'If the velocity of light is only a tiny bit dependent on the velocity of the light source, then my whole theory of Relativity and Gravitation is false.' {Quotation of A. Einstein from a letter to Erwin Finley-Freundlich: August 1913}."
**************************************************
etc.

As I said before, your friend understands that c must be variant or relativity is correct. His whole theory, as demonstrated by the above quotes, is about how c is variant therefore relativity is wrong and we should use Galilean transforms instead of Lorentz transforms in calculating frame shifts. He also spends a considerable amount of time (as you would expect) explaining why current measurement techniques consistently get the wrong answer and do not accurately measure the true "undisturbed" c.

The measurement of invariance seems to be correct. However, the interpretation of what that means is incorrect. I do not dispute the postulate that claims light is measured to be invariant.

I simply see a more reasonable explanation for such invariance than relativity.

Again, relativity is not an "explanation for such invariance" at all. The invariance of c is an unproved postulate of relativity, along with no prefered frame. In other words, relativity assumes the invariance of c; everything else is a direct logical consequence of those two assumptions. If c is invariant then time must dilate, etc. Relativity never even attempts to explain the invariance of c, it simply uses it.

It is logically self-consistent to do as your friend does and suggest that the experiments designed to measure c are wrong and they do not actually measure the true "undisturbed" c but rather they consistently measure something else. It is not logically self-consistent to claim that the experiments correctly measure c and that relativity is still wrong. Pick whichever you want to believe. Is c invariant or is relativity wrong? You can't have them both because they are logically incompatible.

-Dale

 

[MacM]

If you ever claim one of my statements is false you better have some actual evidence to back you up.

I do.

I don't know if you are trying to imply that I am a liar, ignorant, or made an honest mistake.

Mistake it is.

In any case, none of the three is correct,

False. You are mistaken.

and it is your own assertion that is false. I do not imply, but state emphatically that your false statement arises from your ignorance.

Don't be so smug. It is you that have made an erroneous assertion.

You don't even understand the main thesis of your friend's theory.

From your friend's own website:

*********(http://www.extinctionshift.com/details.htm)********
"c' = c ± v"
"c' ≠ c"
"{v = unbounded}"

"All emissions will have the additive velocity c' in all other frames of reference other than that of the primary source. Hence, the additive velocity would be c+v for an approaching primary source, which moves with velocity v relative to that chosen frame of reference. The velocity would be c-v for a receding primary source. The addition of velocities are according to Galilean transformations"

"The waves emitted from an approaching source move undisturbed with velocity c+v in vacuum as illustrated."

"all re-emissions of a photon occur at exactly the velocity c with respect the frame of reference of the photons most primary source only. {Not in all frames of reference.}"

"'If the velocity of light is only a tiny bit dependent on the velocity of the light source, then my whole theory of Relativity and Gravitation is false.' {Quotation of A. Einstein from a letter to Erwin Finley-Freundlich: August 1913}."
**************************************************
etc.

As I said before, your friend understands that c must be variant or relativity is correct. His whole theory, as demonstrated by the above quotes, is about how c is variant therefore relativity is wrong and we should use Galilean transforms instead of Lorentz transforms in calculating frame shifts. He also spends a considerable amount of time (as you would expect) explaining why current measurement techniques consistently get the wrong answer and do not accurately measure the true "undisturbed" c.

Correction. It is you that do not understand my position. Dr Dowdye has said I do understand both relativity and the alternative views quite well. I believe that must mean you have some misunderstandings of your own.

******************** Extract *************
Dr Dowdye e-mail comments in RED regarding my statements about my views

See [post=951555]Post[/post]

You have a very good knowledge of this stuff. Just apply the Galilean Transformations. Because the observer on the embankment is not seeing the photons which in the trains frame caused the event. EXACTLY!! The timing of the event would not change but the perception of the cause or sequence of the event might change. EXACTLY, I couldn't have said it better.


REGARDS

EHD

*****************************************************

You should learn the subject material before you make unfounded accusations. Otherwise they only serve to highlight your ignorance and my short temper. Neither of which is worth publishing.

Your temper is not of my concern. Your false assertions regarding my competence in these matters is.

Again, relativity is not an "explanation for such invariance" at all. The invariance of c is an unproved postulate of relativity, along with no prefered frame. In other words, relativity assumes the invariance of c; everything else is a direct logical consequence of those two assumptions. If c is invariant then time must dilate, etc. Relativity never even attempts to explain the invariance of c, it simply uses it.

False again. Relativity is NOT the exclusive solution to the measured invariant speed of light. Also the assumption of an invariant measurement of v = c does not imply relativity is required.

It is one thing to do as your friend does and suggest that the experiments designed to measure c are wrong and they do not actually measure the true "undisturbed" c but rather they consistently measure something else. It is quite another thing to claim that the experiments correctly measure c and that relativity is still wrong. Pick whichever you want. Is c invariant or is relativity wrong? You can't have them both because they are logically incompatible.

-Dale

False still.

Even Dr Dowdye does not say the measurement is false. He says (as I have said) that the interpretation of that measurement is incorrect. Dr Dowdye does not say light measurement is not invariant. He says that invariant measurement merely means you have not measured an undisturbed primary photon. You are measuring a secondary photon.

It seems you are the one that does not understand. My view infact is very simular to Dr Dowdye.

What I am saying is photons are frame dependant and when you switch frames you are not observering (or measuring) the same photons. That is why simultaneity is not linked directly to relative velocity.

Dr Dowdye says you are measuring secondary emissions (not the same photon) which has had its frequency shifted and its velocity reset to v = c when measured.

 

[DaleSpam]

MacM, Please look at my edits.

-Dale

 

[2inquisitive]

Dr. Dowdye's theory is wrong. One reason lies specifically with the Sagnac effect. He asserts that the reason the light signals are of different time measurements is because the photons are emitted, absorbed, then re-emitted over and over again in their travels throught the atmosphere. An atmosphere is not necessary for the Sagnac effect to arise. It also happens in the vacuum of space where no absorption/re-emission is happening. In GPS, the effect is calculated correctly from the satellites orbital position in mid-high orbit to the distance corresponding to the surface of the Earth. Most of the signals travel is through the vacuum, the atmosphere only a part of the distance. The Sagnac effect has been demonstrated in other in-space interferometer experiments, leading to the inclusion of the effect in the LISA mission I outlined above. Sorry, Dr. Dowdye.

 

[Zephyr]

I don't get it. Is MacM trying to disprove a theory on theoretical grounds? That's a bit backwards. This endless rehashing of a gedanken experiment isn't going to lead to any fixed conclusion when MacM working from completely different assumptions...

 

[quadraphonics]

In the satellite's frame of reference, are they 'at rest' or or they rotating? When one satellite 'looks' at the next, how does it know of the rotation? Don't mix your frames.
Assume you are in a windowless room in one of the satellites, how do you detect if you are in motion? Sound familiar?

You definitely CAN detect rotation, as you will feel a force accelerating you. There's no way that you can be rotating without a force acting on you, which you can easily measure.

See here:

http://id.mind.net/~zona/mstm/physics/mechanics/framesOfReference/nonInertialFrame.html

and specifically here:

http://id.mind.net/~zona/mstm/physics/mechanics/framesOfReference/nonInertialFrame2.html

 

[2inquisitive]

You definitely CAN detect rotation, as you will feel a force accelerating you. There's no way that you can be rotating without a force acting on you, which you can easily measure.

See here:

http://id.mind.net/~zona/mstm/physics/mechanics/framesOfReference/nonInertialFrame.html

and specifically here:

http://id.mind.net/~zona/mstm/physics/mechanics/framesOfReference/nonInertialFrame2.html

I see you did not read the link to NASA that I provided. There is no acceleration felt within any of the satellites. Don't you wonder what would keep them in triangular formation if there was? The satellites are 5 million km apart and no 'string' connects them to offset the supposed acceleration. A cut and paste from NASA and a link:

"In their orbits, the three spacecraft will form an equilateral triangle with a distance of five million kilometers (about three million miles) between any two spacecraft. Each spacecraft orbit, slightly elliptical and slightly tilted with respect to the other individual orbits and to the plane of the Earth's orbit, will maintain the triangle formation of LISA. The selected orbits will minimize the changes in the distances between spacecraft. This is important because laser interferometry measurements are more difficult to make if the distances between pairs of spacecraft are not nearly equal. Additionally, the distance between spacecraft was carefully chosen to allow LISA to observe in the frequency band of the most interesting sources. The center of LISA's triangle will follow Earth's orbit around the Sun, trailing 20 degrees behind, maintaining——like the Earth——an average distance of 1 AU from the Sun. An AU (one astronomical unit) is the average distance between the Earth and the Sun."
http://lisa.jpl.nasa.gov/STRATEGY/getThere.html

 

[quadraphonics]

Right, all of the satellites are *in orbit* and so feel a force (gravity from the sun and earth) acting on them. Thus their rest frame is not inertial. The fixed relative positions of the satellites in their rest frame is because all of them are subject to the *same* gravitational forces.

If we sit on opposite ends of a merry-go-round, we'll remain stationary relative to one another no matter how fast it spins. But we'll sure as shit be able to tell whether the thing is spinning or not, even with our eyes closed.

 

[Billy T]

....
1 - Are the explosions simultaneous in the train frame?

2 - Are the explosions simultaneous in the embankment frame?

Simple questions. Give us an answer.

Sorry if already answered (In two days absence, I am 5 pages behind, but want to answer.)
(1)Yes, unqualified.
(2)No, qualified as below:

The ground observers (especially if they accept SRT) can compute that the explosions were simultaneous in the train frame, but by their own clocks, which is what they judge simultaneity by, the rear explosion precedes the front one.

Do you not use the clocks of your own frame to judge simultaneity?

Recall that there is some frame in which my birth is simultaneous with that of Christ. (I think Christ's birth proceded mine by about 2000 years - but I stupidly compare simultaneity using only my clocks, without computation for all other frames.)

Thus, to consider other frames when judging if two events are simultaneous (for you) or not is ridicules.
I designed this scenario to avoid using any theory.* Only use your mind and fact speed of light is independent of direction of travel. (I do not even require that it is the same in all frames!) It could be 3x10^8 on train and 2x10^8 on the ground and my thought experiment still shows:

Events Simultaneous in one frame are NOT Simultaneous in any other.

I assumed only that MacM has a mind, not SRT, not constant speed c for all frames, nothing else! I did this to try to limit the number of “duck” and “weaves” available to him. His ability to produced 14 irrelevant duck and weaves, confirms he has a mind, but unfortunate it is so closed, he will not discuss the real issue.
______________________________________________
*In another post MacM ignores this and claims that SRT is not proven so his theory is just as good. (Of course SRT is not proven - only confirmed in every test - and there have been zillions if one only considers muons reaching the surface of the Earth and zillions more with accelerated particles. - but I agree that is not proof.)

SRT has been confirmed by man’s observations, at least a million times more that the theory that the sun will rise tomorrow!

 

[Billy T]

...You need to justify your assertions that the explosions are simultaneous in one frame but not simultaeneous in the other. It is really that simple.

Yes, and that is shown by the thought experiment of this thread.

 

[Billy T]

...Then this argument isn't about the laws of the universe, but more about the laws of perception isn't it? Should it really be in Physics and Math ???

No - The clocks are adjacent to explosions and record the time of the explosions. Humans only look at them weeks later - perception has nothing to do with this thought experiment.

 

[Billy T]

...
Acording to special relativity, the explosions in the scenario the original post are simultaneous in the train frame.
Acording to special relativity, the explosions in the scenario the original post are not simultaneous in the embankment frame. ...

What you say is true, but I like my answer (first of my few below) much better as I do not assume special relativity. (Not a good idea to prove things to MacM as he rejects SRT.)

 

[Billy T]

...The emission of the photons from the flash propagate at the speed of light from the event. This event does not move in spacetime. If there is no relative velocity between the event and the bombs at the ends of the train, they will explode simultaneously. Notice I said the 'event', not the device that emitts the photons. Now let the bombs be moving while the 'event' takes place. The event does not move in spacetime, but the bombs do in this case. The rear bomb is approaching the event while the photons propagate, reducing the flight time needed for the photons to reach the bomb. The forward bomb is retreating from the event while the photons are propagating, increasing the flight time of the photons. ...
So if the bombs are stationary (train frame), they explode simultaneously.
If the bombs are moving (embankment frame), they do not.

Nicely stated. You make a good point that the flash is an "event" fixed in space time. I hope this helps some that are troubled by fact the expended flash bulb is traveling with the train.

However, I do not understand your point about the three laser in orbit of 1AU in equalateral triangle geometry. I can detect rotation, with a bucket of water a lot less expensively. Please tell my more clearly your point.