We have a moving platform with midpoint M' passing through the midpoint M of two photon sources A and B just as the sources emit a photon of light directed at M in the stationary frame. The moving platform is moving along the line connecting the photon sources. Later a photon from B is detected on the moving platform at time t1 measured from t = 0, the instant the moving frame midpoint M' was located at the midpoint M, and later a photon from A behind is detected at a position defined by t2, The velocity of the moving platform is known since the point M' passed through M.

SR theory using the postulates of SR that the speed of light is a constant c, as measured in all inertial frames and that the laws of physics are identical in all inertial frames.

The moving and stationary frames described above was that used by Einstein in introducing (see AE book "Relativity") the necessity of discarding concepts such as simultaneity that necessarily are implied by the postulates of SR. The argument goes that as the moving observer sees one light from then the other from A that the moving observer perceives the photons as not having been emitted simultaneously, though the photons were unambiguously measured emitted simultaneously in the stationary frame as well as the moving frames

Suppose our ace SR theorist uses the data at her disposal and determines which light left the source first. Later it is discovered that four clocks were used that clocked the event of the photon emissions. The platform's forward position has a clock, the platforms rearward position has a clock. At the instant the midpoint of the moving platform M' was directly coincidental with M the clocks on the plaform both measured the event of the emitted photons and each had the same number indicating the moving frame time of emission of the photons. Likeiise, on the stationary platform clocks were also located at A and B and also recorded the time the photons were emitted.

We faithfully assume that the moving clocks having been synchronized in the stationary frame much earlier and slowly brought up to the speed at the time of the events here read a "slower" time, say 11:00 A.M. than the stationary clocks, which read 12:00P.M. The observers at A' and B' on the moving platform also observe the stationary observer at A and B also making the recording of the instant the photons were emitted. Each pair of observers swap their recorded time when the photons were emitted. Later, the A' and B' observers compare their data and determined that the moving clocks were perfectly synchronized with respect to the moving platform and that each gave a time reading of 11:00 A.M. Likewise, the stationary times as received by the moving platform of the emission event was 12:00 P.M. The moving time dilation was determined to be consistent with the known velocity of the moving platform.

Without knowedge of the measurements on the moving platform the Chief SR Theorist dutifully determined the photons were emitted at different times in perfect accord with special relativity theory. This determination was checked by an expert panel of SR theorists and found to be perfectly consistent with SR theory which predicted the photon from B was emitted first, followed by the emitted photon from A.

After the calculations were stamped APPROVED the observers who had witnessed the emission of the photons in the moving frame and recorded the times of the emissions showed the data to the Chief SR Theorist and the members of the expert panel.

What affect does the measurement of the simultaneous emission of the photons, as measured on the moving and stationary frames, have on the validity of the calculations, which indicated the photons were not emitted simultaneously?

The platform's forward position has a clock, the platforms rearward position has a clock. At the instant the midpoint of the moving platform M' was directly coincidental with M the clocks on the plaform both measured the event of the emitted photons and each had the same number indicating the moving frame time of emission of the photons.

I don't understand what you mean here.
Firstly, in which reference frame are you working when you refer to the instand of coincidence of M and M'?
Secondly, what do you mean by the clocks measuring the event of the emitted photons? Clocks measure time.

We faithfully assume that the moving clocks having been synchronized in the stationary frame much earlier and slowly brought up to the speed at the time of the events here read a "slower" time, say 11:00 A.M. than the stationary clocks, which read 12:00P.M.
You'll have to spell out your synchornization procedure more clearly. I think you're making assumptions that you might not even realize you're making.

I'd like to post my thoughts on the subject. I participated in a previous thread on
simultaneity, not able to grasp what was happening. In another thread, I thanked
Janus58 for helping me recognize where I was making mistakes in SR. It applies to
simultaniety as well. It IS about frames of reference. I was trying to limit the relativistic frame to the object and its immediate surroundings, not realizing in
effect the whole universe is in this frame with the relativistic object, and (here is
the important part) everything that happened in the rest frame also happens in
the relativistic frame, but you have to use the relativistic frames time and distance
measurements in the moving frame. A midpoint is a midpoint for both frames, but the
timing for each is different. Think of this moving platform in relativistic terms. It is
easy to see that even though the moving platform may receive the photons at the
midpoint, the clock on the moving platform does not correspond to the clock on the
stationary platform. There is a time dilation, they cannot receive the photons at the
same 'instant'. Now, start thinking of the relativistically moving platform at slower and
slower velocities. As the velocities for the moving platform slow in each subsequent
test, the time dilation gets to be less and less, but it is still there. Using a slow-moving
platform as an example, the dilation is so small that it may be impossible to actually
measure it, but it is still there. The two events cannot be simultanious according to
Special Relativity. The theory itself is consistent, but of course, that does not necessarily prove that it actually describes reality accurately. Did I mess up?

I'd like to post my thoughts on the subject. I participated in a previous thread on
simultaneity, not able to grasp what was happening. In another thread, I thanked
Janus58 for helping me recognize where I was making mistakes in SR. It applies to
simultaniety as well. It IS about frames of reference. I was trying to limit the relativistic frame to the object and its immediate surroundings, not realizing in
effect the whole universe is in this frame with the relativistic object, and (here is
the important part) everything that happened in the rest frame also happens in
the relativistic frame, but you have to use the relativistic frames time and distance
measurements in the moving frame. A midpoint is a midpoint for both frames, but the
timing for each is different. Think of this moving platform in relativistic terms. It is
easy to see that even though the moving platform may receive the photons at the
midpoint, the clock on the moving platform does not correspond to the clock on the
stationary platform. There is a time dilation, they cannot receive the photons at the
same 'instant'. Now, start thinking of the relativistically moving platform at slower and
slower velocities. As the velocities for the moving platform slow in each subsequent
test, the time dilation gets to be less and less, but it is still there. Using a slow-moving
platform as an example, the dilation is so small that it may be impossible to actually
measure it, but it is still there. The two events cannot be simultanious according to
Special Relativity. The theory itself is consistent, but of course, that does not necessarily prove that it actually describes reality accurately. Did I mess up?

You've got it nailed.

There is slight difference of understanding regarding the experimental arrangement. The photons are emitted at A and B as the points M = M'. We added the observational ability to guarantee that A =A', B = B ' and M= M' by anticipating time dilation and shrinking. The photons wereemitted when he noted coordinates wer colocated as shown.

This is the test of simultabneity: were the photons emitted in both frames simultabneouly?

Not What were the calculations. Not what someone perceived later from applied SR theory. What happened physically is the test.

It is a given the photons were emitted in the moving frame simultabeously. This is the end of my argument. SR predicts something else? Later? Then SR sucks.


The photons are emitted from A and B simultaneously in the stationary frame. I designed the moving frame such that with time dilation and shrinking of the platform the photons would be emitted from A and B simultaneouslywhen A =A', B = B' an M = M'. We will agree to all SR restrictions or conditions. The intstant the photons were emitted all clocks are zeroed, or the time is noted. Assume the clocks at A' and B' are perfectly synchronized such that when A' reads 27, so does B'. Similalry for the stationary frame. We care not about timing of the pulses by the moving observer. We assume all along that he will use SR and calculate that the photons were not emitted simultaneously.

However, a big however, the photons were emitted simultaneously in both frames. This is the test of simultaneity. This is the only test of simultaneity.

What were the events of photon emission in the moving frame. Not what is calculated later, but when the photons were emitted. By definition, by experinmental arrangement the photons were emitted simultaneously in both frames.

If theory concludes differently then the observed results directly contradicts the theoretical calculation, right? Let time dilate, and let framjes shrink, as long as for just one small instant, smaller than small instant, the spatial coordinates of the respective frames were, A =A', B=B ' and M = M' when the photons were emitted. This is everything. Calculating later is a waste of time.

One question 2inquisitive: Were the photons emitted in the moving frame simultaneously? Yes, you must say.

One question 2inquisitive: Were the photons emitted simultaneously before any calculations could possibly be made? Yes, you must say.

One question 2inquisitve: SR predicts here a condition unambiguously contradicted by observation. The postulates of SR regarding simultaneity are the invariant physical laws and the constancy of the speed of light in all inertial frames. If SR is contradicted by experimental result then one or both of the SR postulates must be fatally flawed. The constancy of the laws of physics in all inertial frames seems a most unlikely candidate to fail, which points the finger of accustation at the constancy of the speed of light postlate. Who wins the dog fight 2inquisitive?: Theory or experimentally unambiguous observation?

geistkiesel,
Assuming that M is the midpoint of A and B, and that signals are sent from A and B simlutaneously (in the stationary frame) with the coincidence of M and M', then:

If A' is coincident with A when the signal is sent from A, and B' is coincident with B when the signal is sent from B, then M' is not at the midpoint of A' and B'.

Conversely, if M' is the midpoint of A' and B', then it is not possible for both A' and B' to be coincident with their stationary counterparts at the moments that the signals are sent.


I think you are begging the question - you appear to be assuming that simultaneity is not violated in order to prove it.

geistkiesel,
Assuming that M is the midpoint of A and B, and that signals are sent from A and B simlutaneously (in the stationary frame) with the coincidence of M and M', then:

If A' is coincident with A when the signal is sent from A, and B' is coincident with B when the signal is sent from B, then M' is not at the midpoint of A' and B'.

Conversely, if M' is the midpoint of A' and B', then it is not possible for both A' and B' to be coincident with their stationary counterparts at the moments that the signals are sent.


I think you are begging the question - you appear to be assuming that simultaneity is not violated in order to prove it.

Not quite. I merely use the same experiment as AE. with the added measuring devices described below. I do rig the game, but fairly as I do not interruopt any SR theory or fromalism whatever in the determinatuion using SR theory that the photons are not emitted simultaneously. I will concede this

Experiemntal results vs. theory.
Take you pick Pete


The problem is defined that when M' is at M the photons are emitted from A and B and M is the midpoint of A and B. You are right I want to rig the gme in my favor. So I want to provide a measuring device that wil be guarntreed to be colocated at A and B when the photons are emitted. from A and B. Let us use a series of state of the art light sensitive diodes with the smallest physical resolution avaliabble in smeicinductor devices now on he market. We carefull place the devices such that wh ,ay dtermine which device was colocated with A and B when the photons were emitted. This is the only purpose.

You must grant me that if A and B can be located equidistant from A and B using the laws if physics in the stationary ftrame then so can the measurement that measures the distance between the excited devices, say at B' and A' as newly defined here, using the same laws of physics that were used in measuring the midpoint distance M in the stationary frame. OK?


The located devices shall not be identified for one week after all calulations were made regarding the simultaneous emission of the photons or not in the moving frame, which is stipulated. The sole purpose of the reading the device location is to insure that the location of the triggered devices were equidistant from the midpoint M'. If the distances between the devices and M' are equal then the photons were emitted simultaneously in both frames. period. This is the defnition of simultaneioty.

Can you think of any physical reason why the diodes that were triggered on by the emitted photons in the moving frame should not be equidistant to M'?

The frame is made of the same material throughtout, the laws of physics are invariant throughout and there is no rational reason to think time dilations are different in both ends of the moving frame even though we never use this fact. Neither do we use the fact of shrinking of the moving frame. The observer O' at M' measures the time the photons arived at M' from B and the time of arrival of the photon from A. SR theory says O' will calculate that the photons were emitted at different times, hence, says SR theory, unconmtested by myself, the photons were not emitted simultaneously in the moving frame as predicited by the theory only. This is my stipulation theory oredicts nionsimultabeity...

The chioice is:
Experimental results using unambiguous data taken at the instant the photons were emitted at A and B unambiguously located the positon of the photons in the moving frame within a billion-bilionth of a second simultaneously with the emission of the photons in the stationary frame. located at A' and B'.

contrasted to:The SR calculations using the postulates fo SR theory that 1. the laws of physics and 2) the measured speed of light in inertial frames is invariant.

I say the invariance of the laws of physics remain steadfastly unaffected, ergo we axe the 2nd postulate.

I don't understand what you mean here.
Firstly, in which reference frame are you working when you refer to the instand of coincidence of M and M'?
Secondly, what do you mean by the clocks measuring the event of the emitted photons? Clocks measure time.


You'll have to spell out your synchornization procedure more clearly. I think you're making assumptions that you might not even realize you're making.

Clocks also can be used to measure an instant of time, but see an earkier post in reply to your post I have omitted all clocks, synchronization and calibration (which is the word I should have been using). If the photons can be made to make an indelible mark when omitted, on the moving paltform
even if to make only a mere expsoure of a photosensitive piece of paper, this location can be measured for distance from M' with the same laws of physics and accuracy that located M in the stationary platform. You can have shrinkage , time dilation all you want. When the papers are exposed at both ends of the moving platform as M = M ' A and B emit photons detected "perfectly" by the photosensitve paper segemnts placed along the moving frame guaranteeing an overlap of A anb B locations. OK? .

Do you see any way that we cannot assure ourselves that the exposed piece os paper say a hundreth of micron in width is colocated with A and B in the statioanry frame when the paper ws exposed?

Nicely stated question. Instructive also. Thank you.

Can you think of any physical reason why the diodes that were triggered on by the emitted photons in the moving frame should not be equidistant to M'?

Special Relativity says that they will not.

This is a valid experiment to test Special Relativity.
If the diodes at A' and B' are found to be equidistant from M' on the moving frame, then Special Relativity fails.

The chioice is:
Experimental results using ...
The problem is that you don't have any results, do you? You are predicting the results based on your own theory.

Have you done this experiment? Has anyone done this experiment?

I suspect that if the experiment is actually performed, it will be found that A' and B' are not equidistant from M'.

I don't understand what you mean here.
Firstly, in which reference frame are you working when you refer to the instand of coincidence of M and M'?
Secondly, what do you mean by the clocks measuring the event of the emitted photons? Clocks measure time.


You'll have to spell out your synchornization procedure more clearly. I think you're making assumptions that you might not even realize you're making.

Pete this is the simplified version of the same experiment. Clocks and shrinking have been removed as parameters needing scrutiny, at least I trust you will agree.
.
The physics of the original problem I posed is modified her, simplified actually.

Photons are emitted from A and B in a stationary frame, just as a moving observer M' arrives at M, the midpoint of A and B. M' is heading toward B, away from A. Later a photon from B is detected at M', then a photon from A is detected at M', in the moving frame. SR theory, as I understand, concludes that the photons emitted simultaneously from A and B in the stationaary frame are not emitted simultaneously in the moving frame. I accept that SR pedicts this.

Suppose we included on the moving frame an extension rod stretching a distance A'B' > AB (to account for any shrinking in the moving frame). At each end of the rod is a section of photo-sensitive strips each numbered such that the number 1 strip at one end is equidistant fom M' as is the number 1 strip at the other end of the rod and so on for a few thousand strips in each section. The strip widths are fractions of a micron. The ||||are the photo-sensitve strips in long enoughsecions to account for any relativity shrinking.

--|||----------------M'------------------|||--> motion
--A---------------M-------------------B--- stationary

These are the relative positions of the moving and stationary frame at the instant the photons were emitted from the stationaary frame at A and B.

The common midpoint M' for the numbered strips was determined by the same laws of physics that determined the midpoint M of A and B in the stationary frame.

Just as the photons are emitted simultaneously in the stationary frame photons expose a few photo-sensitive strips in each section, at equal distances from M' in the moving frame.

What affect does considering the simultaneous exposure of the photo-sensitve strips in the moving frame have on the logic and physics of applying special relativity postulates that determined the photons were not emitted simultaneously in the moving frame?

I would really appreciate a focus on the specifics of the question as I stipulate the results of applying SR to the problem. SR pedicts as I have stated.

What I said earlier was incorrect. I am sorry.

geistkiesel, I am not sure how you are drawing your conclusion.
You have shown that M' is at the midpoint of the photon emissions.
You have shown that the emission events are simultaneous in the stationary frame.

How do you conclude that the emission events are simultaneous in the moving frame?

If each photo-sensitive strip has a clock attached (all clocks duly synchronized in the moving frame) which records the time of exposure, can you demonstrate that the recorded times will be the same?

I suggest that if the experiment were performed appropriately that the recorded times would be different.

Can you show otherwise?

What I said earlier was incorrect. I am sorry.

geistkiesel, I am not sure how you are drawing your conclusion.
You have shown that M' is at the midpoint of the photon emissions.
You have shown that the emission events are simultaneous in the stationary frame.

How do you conclude that the emission events are simultaneous in the moving frame?

If each photo-sensitive strip has a clock attached (all clocks duly synchronized in the moving frame) which records the time of exposure, can you demonstrate that the recorded times will be the same?

I suggest that if the experiment were performed appropriately that the recorded times would be different.

Can you show otherwise?

I don't show. It is basic Special relativity theory. Remove the clocks. Just a have h ephoto dsensitve strips located where the photons are emitted at A and B, within say one wav klength of light. Whant eh photonsare emitted they will expose he light sensitive strips in both moving and stationsry frames, where evr the moving frame and stationary frame =s meet at A and B. The midppoint of the moving frame will be the BM' = BM and A M' =AM whoel moving. Of course spatial dilation will ruin the spatial colocations, but we calculated the shrinking such sthawe get bM' = BM. As long as the expsoed strips are located equally from the midpoint of gthe moving frame the exposed strips at A and B P'prove' the re is no physical event occuring at the emission site. How could there be?

If the photons are emitted 100 light years in the past and today a moving frame detects the emitted photons (emitted simultaneously in the stationary frame) like our hypothetical, that event 100 years in the past, cannot be affected by a measurement today. This is all I am saying, nothjing more. So the moving frames perceives something different, what is the big deal? The conditions of what is being measured are grossly different . One expects diffeences, nothing else.

So, you are simply asserting that because the emissions are simultaneous in the stationary frame, they must also be simultaneous in the moving frame.

Thank you for your assertion, I'll take it on board.