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  4. Can we measure the one way speed of light?
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Can we measure the one way speed of light?

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guest4091

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Re: Can we measure the one way speed of light?
« Reply #140 on: 25/06/2018 16:31:32 »
David D. #131;
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If we have a turntable rotating and moving along through space, the centre of the turntable is moving along through space at a constant speed while a point on the edge of the turntable is speeding up and slowing down (relative to the space fabric). For every part of the turntable that is slowing down, another part is speeding up, so the energy involved is constant. The speed that a rotating source/detector (on the edge of the turntable) moves at through space changes throughout a revolution, and as it changes, the functionality of that device speeds up and slows down - faster movement through space leads to slower functionality (due to increased cycle distances within the component)
.
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Then you are not in the inertial frame containing the device. The MGP experiment was done in a lab just as the MM experiment. Neither experiment was influenced by the translational motion of the earth in space at 30km/sec. relative to the sun.
The more refined laser ring gyros, developed from the interferometer experiments, are in common use today and work across a wide range of speeds. Reference:
https://en.wikipedia.org/w/index.php?title=Sagnac_effect&oldid=843575092
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Offline Le Repteux

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Re: Can we measure the one way speed of light?
« Reply #141 on: 25/06/2018 16:39:30 »
Quote from: phyti on 25/06/2018 16:18:23
If light propagation is a physical phenomenon, and the rules of physics are the same in all inertial frames, then light speed must be constant in all inertial frames.
Not true! The laws of physics can be the same without the one way light speed being constant, and that's precisely what the MM experiment shows. He took for granted that ether existed, so all his calculations and drawings are based on that principle.

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Neither experiment was influenced by the translational motion of the earth in space at 30km/sec. relative to the sun.
I think it's precisely what David was telling you.
« Last Edit: 25/06/2018 16:50:39 by Le Repteux »
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guest4091

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Re: Can we measure the one way speed of light?
« Reply #142 on: 25/06/2018 16:52:03 »
Quote from: Le Repteux on 25/06/2018 16:39:30
Quote from: phyti on 25/06/2018 16:18:23
If light propagation is a physical phenomenon, and the rules of physics are the same in all inertial frames, then light speed must be constant in all inertial frames.
Not true! The laws of physics can be the same without the one way light speed being constant, and that's precisely what the MM experiment shows. He took for granted that ether existed, so all his calculations and drawings are based on that principle.
If 'he' refers to Einstein, read the 1905 paper again. The 2nd postulate for a constant c is part of the theory. He also stated the ether wasn't needed..
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Offline Le Repteux

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Re: Can we measure the one way speed of light?
« Reply #143 on: 25/06/2018 16:57:41 »
It's Michelson that took for granted that ether existed, not Einstein, and for him, it meant that the speed of light was different going right than going left in the interferometer, which is precisely what his drawings and calculations show.
« Last Edit: 25/06/2018 16:59:48 by Le Repteux »
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #144 on: 25/06/2018 21:27:28 »
Quote from: phyti on 25/06/2018 16:18:23
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Q1: If we have an observer X co-moving with S0 throughout, does he see the pulse of red light pass him more often than the blue light? (The correct answer is yes, and it is also yes for all observers - they see the red light pulse passing him more often than the blue one.)
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the drawings show this

So that's a yes.

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Q2: Does observer X measure the ring as having the same length in both directions from S0 round the ring and back to S0? (The correct answer is yes, and it is also yes for all other observers.)
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A is not moving relative to the ring, and would average the times of returning light.

Did you read the question carefully? It's asking you about a length (or rather two lengths of the same thing which are clearly equal because they are the same length measured in opposite directions). Let's say that A has very long arms and can reach across to any part of the ring with a ruler to measure the length of each sector of the ring - he can do this starting with S0, then S1, then S2, etc, or he can measure it in the opposite direction by starting with S0, then S99, then S98, etc. Do you imagine that he gets a different length measurement of the ring in these two directions? No, he does not. That is how he should measure the distance round the ring from his non-inertial frame of reference.

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Q3: Given that the red light returns faster than the blue light each time, should observer X conclude that the red light has passed through the sectors of the ring at a higher average speed relative to them (while it's passing through them) than the blue light? (The correct answer is yes: he should respect mathematics and conclude that R>B.)
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Notice your word association, 'red light' with 'faster'.
In mine, closing speed of (green and A) 1.2, is greater than that for (blue and A) .8.
Light speed is 1.

Where I said "faster", you should interpret that as a time measure rather than speed - to clear up the ambiguity, feel free to replace it with "sooner". As you say, light speed is 1 (as always), while the speed of light relative to the light is 1.2 for the red/green light and 0.8 for the blue (which you call the closing speed). The one-way speed of light is always c relative to the fabric of space, but relative to the material of the ring at any point where the light is adjacent to that material, the one-way speed of the light to the ring is 1.2c on average for the red light and 0.8c on average for the blue.

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Q4: If we have an observer Y next to the rotating ring such that X is with him initially, but then X goes round with the ring next to sector S0 and eventually returns to Y at a moment when the pulses of red and blue light happen to arrive there simultaneously, should observer Y also conclude that the red light has passed through the sectors of the ring at a higher average speed relative to them (while it's passing through them) than the blue light? (The correct answer is yes: he too should respect mathematics and conclude that R>B.)
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U at rest relative to the center of the ring and not rotating, sees green and blue make synchronized revolutions, independently of ring rotation. Light speed is independent of its source. Light speed is 1.

Again (like with Q2) you have not answered the question that was asked. The question is about how fast the light passed the material of the ring while adjacent to it. Observer Y has seen the ring do a complete rotation and has seen the red and blue light go round several times - he knows that the red light passed each sector one extra time compared with the blue light, so he calculates that the red light was moving at a higher speed relative to that material (while adjacent to it) than the blue light was.

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Q5: Do all observers have a perception which should lead them to conclude that R>B? (The correct answer is yes - all possible observers recognise that the red light has travelled through the 100 sectors at a higher speed relative to them on average than the blue light, assuming that they respect mathematics.)
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NO! The MGP experiment is not measuring the 1-way speed of light.
From the Wiki article: https://en.wikipedia.org/w/index.php?title=Michelson–Gale–Pearson_experiment&oldid=736473424

"The aim, as it was first proposed by Albert A. Michelson in 1904 and then executed in 1925, was to find out whether the rotation of the Earth has an effect on the propagation of light in the vicinity of the Earth." (also predicted in 1911 by Max van Laue, using SR).

You're playing a blatant game of avoidance here. All observers conclude that the red light passed the material of the ring at an average speed >c while adjacent to it. This has nothing to do with the aim of the MGP experiment (which I only brought into this to show that when you rotate a ring, the light doesn't take the same length of time to return to observer X in both directions).

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"Thus special relativity is the only theory which explains both experiments (hypothesis of complete aether drag and MGP).

And I pointed out earlier that the text of that Wikipedia page contradicts itself here because it has already admitted that LET also explains both experiments. My thought experiment shows though that SR is failing to account for one thing that LET can account for, and that is the differences in the one-way speed of light relative to objects which manifestly must occur in order to produce the timings that we get from MGP and Sagnac.

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The experiment is consistent with relativity for the same reason as all other Sagnac type experiments. That is, rotation is absolute in special relativity, because there is no inertial frame of reference in which the whole device is at rest during the complete process of rotation, thus the light paths of the two rays are different in all of those frames..."
A related experiment:
The time dilation effects in the H-K experiment resulted from Earth rotation, not variation in light speed.

The light paths can vary wildly for different frames, but in every single frame we have the same light passing the same material with the same average speed difference for the red and blue light as it passes that material.

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Light speed is measured relative to a medium (real or imagined), not to an object.
If light propagation is a physical phenomenon, and the rules of physics are the same in all inertial frames, then light speed must be constant in all inertial frames.

Each frame asserts that the speed of light relative to it (the frame) is c in all directions. If an object is at rest in frame A and is moving in frame B, then frame A asserts that the one-way speed of light relative to that object is c in all directions, while frame B asserts that the one-way speed of light relative to that object is >c in some directions and <c in others. It is not possible for both frame A and frame B's accounts to be true - they are both theories as to the speed of light relative to that object and it cannot be the case that the speed of light relative to that object is BOTH c in all directions AND >c in some directions and <c in others. SR makes out though that all frames are equally valid and that there is no absolute frame, but that cannot be so. We have objects which categorically do not have the speed of light relative to them equal to c in all directions, and any frame that makes out that the speed of light relative to them is c in all direction is a fake frame, misrepresenting the speed of light relative to them. Worse, if one frame represents the truth about the speed of light relative to an object in all directions, ALL other frames are misrepresentations of reality. All frames of reference contradict each other fundamentally.
« Last Edit: 25/06/2018 21:31:00 by David Cooper »
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #145 on: 25/06/2018 21:47:15 »
Quote from: phyti on 25/06/2018 16:31:32
David D. #131;
Quote
If we have a turntable rotating and moving along through space, the centre of the turntable is moving along through space at a constant speed while a point on the edge of the turntable is speeding up and slowing down (relative to the space fabric). For every part of the turntable that is slowing down, another part is speeding up, so the energy involved is constant. The speed that a rotating source/detector (on the edge of the turntable) moves at through space changes throughout a revolution, and as it changes, the functionality of that device speeds up and slows down - faster movement through space leads to slower functionality (due to increased cycle distances within the component)
.
----
Then you are not in the inertial frame containing the device.

If I put the turntable in a rocket which is moving at a constant speed in a single direction through space, that system can be analysed using inertial frames. The centre of the turntable does not move relative to the rocket other than rotating. If the speed of the rocket is zero, the speed of any object attached to the edge of the rotating turntable is constant. If the speed of the rocket is >0, the speed through space of the object on the edge of the rotating turntable will vary. Any change in the speed of the object at the edge of the rotating turntable will lead to its functionality speeding up or slowing down, but this change will be masked 100% from a device at the centre of the turntable by the Doppler effect.

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The MGP experiment was done in a lab just as the MM experiment. Neither experiment was influenced by the translational motion of the earth in space at 30km/sec. relative to the sun.
The more refined laser ring gyros, developed from the interferometer experiments, are in common use today and work across a wide range of speeds. Reference:
https://en.wikipedia.org/w/index.php?title=Sagnac_effect&oldid=843575092

Why are you connecting these two things at all? The turntable issue is quite separate from my thought experiment (which has been done as an actual experiment in the form of MGP and Sagnac). The turntable issue is about frequencies generated and perceived as they travel between centre and edge, and it was Alan that brought it up as an experiment that would supposedly show up any change in the one-way speed of light relative to the apparatus. It can't show up any such change though because the changes in speed of the component at the edge of the table has its functionality rate changed by that change in movement speed, precisely masking out the change (when you also factor in the Dopplar shifts, the length contraction of the turntable into an ellipse, and the additional change of speed of the object at the edge of the turntable relative to the centre caused by it moving more slowly forwards than backwards - it takes longer to complete one half of a rotation than the other).
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guest4091

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Re: Can we measure the one way speed of light?
« Reply #146 on: 26/06/2018 20:17:34 »
David C.;
From a distance, A observes B moving at .4c on path x, and a light pulse from A moving at c, on the same path. A calculates A and the pulse, separating at .6c. The pulse reflects from an object on the path, and A calculates A and the pulse, converging at 1.4c.
B calculates the speed of the pulse as c=1, based on round trip transit time.
To calculate the speed of the pulse relative to himself, B would have to know his speed in space. He has no means of detecting this.

Neither A nor B observe anything moving at .6c or 1.4c.
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #147 on: 26/06/2018 21:37:38 »
Quote from: phyti on 26/06/2018 20:17:34
David C.;
From a distance, A observes B moving at .4c on path x, and a light pulse from A moving at c, on the same path. A calculates A and the pulse, separating at .6c. The pulse reflects from an object on the path, and A calculates A and the pulse, converging at 1.4c.

That's confusing. Shouldn't it say that A calculates that B and the pulse are separating at .6c and that after the refliction, B and the pulse are converging at 1.4c?

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B calculates the speed of the pulse as c=1, based on round trip transit time.
To calculate the speed of the pulse relative to himself, B would have to know his speed in space. He has no means of detecting this.

Neither A nor B observe anything moving at .6c or 1.4c.

A calculates that the light is moving at those speeds relative to B, and if B reckons itself to be stationary, B will calculate that light is moving at those speeds relative to A.
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #148 on: 26/06/2018 22:13:57 »
I'm now going to set out a similar thought experiment where the ring is eliminated so that practically all the action can take place on a straight line. Imagine a loop of fibre-optic cable (or a flexible tube with silvered interior and a vacuum for the light to travel through). The two ends go round pulleys on the end of a long rod, but most of the cable is spread out in two straight lines close together, the rod between them. The loop of cable is divided into 100 sectors just like the ring, and an observer X will travel round with sector S0. Observer Y stays by one of the pulleys. X starts at that same pulley and then travels round with S0, eventually returning to where Y is. Red light is sent one way through the cable from S0 and blue light is sent the opposite way. By the time X has moved from Y's pulley to the far pulley and back, the light has done several laps of the cable.

The advantage of doing this is that we can make clear statements about the speed of light relative to the material for almost 50% of the material of the course in one go instead of only talking about one point on the ring.

As before, the red light passes X once more than the blue light does by the time X has completed his journey away from Y and back. Again, the red light has passed through the material of the loop that's directly adjacent to it at a higher speed relative to it than the blue light did. We know that we have material here which has light moving relative to it at >c in one direction and <c in the other. If the material in the part of the loop running along over the rod doesn't have this property, then the material in the part of the loop running along under the rod must. Conversely, if the material in the part of the loop running along under the rod doesn't have this property, then the material in the part of the loop running along over the rod must. The third option is that the material in both parts of the loop, both over and under the rod, all has this property. Every frame of reference asserts one of those three possibilities. There is no frame of reference that asserts none of the three options. If the top material has this property, any frame of reference that asserts that it doesn't is automatically a misrepresentation of reality, but if such a frame making that assertion is not a misrepresentation of reality, then the bottom material has that property instead, and any frame asserting that it doesn't is wrong. It is a clear case where it is not possible for both those frames of reference to be correct representations of reality - one of them is necessarily a distortion of the truth.

Let's add two objects W and Z, one co-moving with the lower part of the material of the loop and the other moving with the upper part. We know too that at least one of them must have light moving relative to it at speeds >c in one direction relative to it and <c in the opposite direction, and the thought experiment proves that in any case with W and Z moving relative to each other this will still apply even if we remove the rest of the apparatus. If one frame of reference removes this property from W and another removes it from Z, it is mathematically certain that at least one of those frames is a misrepresentation of reality.

Frames of reference flatly contradict each other - they are not a set of equally correct representations of the underlying reality.
« Last Edit: 27/06/2018 20:46:24 by David Cooper »
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guest4091

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Re: Can we measure the one way speed of light?
« Reply #149 on: 28/06/2018 15:27:28 »
Quote from: David Cooper on 26/06/2018 21:37:38
That's confusing. Shouldn't it say that A calculates that B and the pulse are separating at .6c and that after the refliction, B and the pulse are converging at 1.4c?
Yes it should, if I don't make mistakes!
Reciprocity requires that swapping A and B, yields the same results except B is moving in the opposite direction. The fact still remains that neither measure the speed of any object moving at the closing speeds.
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guest4091

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Re: Can we measure the one way speed of light?
« Reply #150 on: 28/06/2018 15:31:40 »
David D. #;

If a rotating device made on Earth is working as designed, and put into a space probe and sent on a mission, the device continues to work as designed, despite moving at high speed relative to Earth. The motion of the device relative to any 'ether' is irrelevant, since measurements by and on the device are done within the device frame of reference. The motion of the Earth, sun, galaxy, etc., did not influence the design and functionality of the device when it was made. That's the claim of postulate 1, physics is the same in any inertial frame. If a manufacturer subcontracts components to another country, as long as they employ the same quality and measurement standards as the manufacturer, they can be confident the parts will fit when assembled.

As for 'false frames' and 'contradictions', the graphic is a slice through the light cone from an event E. It illustrates the statement, 'an event occurs once but can be perceived many times'. Since perception is always historical, or after the fact, the various perceptions occur at different times, none of which are simultaneous with E.
Distant events involve objects, but perception involves images of objects.

A simple example; viewing the details of the moon's surface. You are not 'really' that close, but the telescope modifies the 'image of the moon', AS IF you were closer.
The moon, telescope, viewer, and mental images, are all REAL.

* event-percep.gif (3.55 kB . 672x462 - viewed 1644 times)
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #151 on: 28/06/2018 19:44:54 »
Quote from: phyti on 28/06/2018 15:27:28
Reciprocity requires that swapping A and B, yields the same results except B is moving in the opposite direction. The fact still remains that neither measure the speed of any object moving at the closing speeds.

The fact is that they always measure the speed of light relative to the other object as >c or <c if they consider themselves to be stationary. To measure it as c instead, they have to consider themselves to be moving, at which point the speed of light relative to them is >c and <c (in opposite directions, all the action taking place along a straight line). Your approach is simply to deny those measurements or deny their right to make them, and in doing so you make a mockery of mathematics.
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #152 on: 28/06/2018 20:17:22 »
Quote from: phyti on 28/06/2018 15:31:40
If a rotating device made on Earth is working as designed, and put into a space probe and sent on a mission, the device continues to work as designed, despite moving at high speed relative to Earth. The motion of the device relative to any 'ether' is irrelevant, since measurements by and on the device are done within the device frame of reference.

The movement through the fabric of space is crucial - it's this that slows down the functionality to generate the measurements we get. Without that slowing of functionality, there would be no relativity, but that would also be impossible because it would result in light overtaking light on the same path.

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The motion of the Earth, sun, galaxy, etc., did not influence the design and functionality of the device when it was made. That's the claim of postulate 1, physics is the same in any inertial frame. If a manufacturer subcontracts components to another country, as long as they employ the same quality and measurement standards as the manufacturer, they can be confident the parts will fit when assembled.

Welcome to relativity. No matter how fast you move the apparatus, the movement through space will automatically adjust the speed of functionality and will hide that movement through space.

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As for 'false frames' and 'contradictions',

Which part of mathematics are you rejecting here? We know that at least one of the two objects Z and W has the property (while it maintains its current path and speed) that light passes it relative to it at >c in one direction and <c in the other. If a frame represents W as not having this property, then Z must have it, while if a frame represents Z as not having this property, then W must have it. It is not possible for neither of these objects to have that property, therefore at least one of those frames is misrepresenting reality. There is a clear contradiction in the claims of the two frames and they cannot both be true representations of reality. Mathematics says you are wrong. Do physicists genuinely respect mathematics or do they merely pretend to do so while waving two fingers at it under the desk?

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The moon, telescope, viewer, and mental images, are all REAL.

Misrepresentations are fully real as themselves, but they still misrepresent the reality of the thing they represent. I could draw a politician with a bottom for a face - that would be a misrepresentation of the politician (in most cases), but it would be a real misrepresentation. The point, which you appear to be incapable of grasping is that frames of reference contradict each other fundamentally because they assert different speeds of light relative to the same object - if one frame represents reality correctly, every other frame misrepresents it.
« Last Edit: 29/06/2018 19:18:12 by David Cooper »
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guest4091

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Re: Can we measure the one way speed of light?
« Reply #153 on: 29/06/2018 19:52:22 »
David D. #;

In the graphic, B is moving parallel to A at speed b. B extends a stick forward with a mirror M on the far end. B measures the stick length d, to be 1 unit long.
B sends a signal to reflect from M and return. The graphic is the A description of events.

In the A frame, the round trip time would be 2d/c=2t.
A observes the round trip time for B to be:

Atr = (d/γ)(1/c)[1/(1-b)+1/(1+b)] = 2γd/c = 2γt

Where γ (gamma) is the ratio of a unit of time for a clock at rest to that of a moving clock.   
The term (d/γ) is the contracted length of d resulting from acceleration to its current speed. With adjustment for time dilation (red), Bt = Atr/γ = 2t.
The B-time will be the same as the rest frame A, and independent of speed b.
This is labeled as 'proper' time in the SR community. Since there is no issue of impropriety from the poor choice of words, I favor Einstein's simple and logical term, 'local' time. (it's about location!)

In your scenario, just substitute Y for A and W or Z for B.
Hopefully you noticed the use of (1-b) and (1+b) in the calculations, i.e. closing speeds,  which are definitely used in SR. No one argues that fact. Also notice these are calculations used by a remote observer A. They cannot be used by B, since he and all other inertial frames cannot determine their velocity through space.
If B assumes a pseudo rest frame, he would not expect the times out and back to be different.

* p&r reflection.gif (9.5 kB . 1044x505 - viewed 1593 times)
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guest4091

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Re: Can we measure the one way speed of light?
« Reply #154 on: 29/06/2018 19:55:34 »
David D. #;

In the graphic, B is moving parallel to A at speed b. B extends a stick forward with a mirror M on the far end. B measures the stick length d, to be 1 unit long.
B sends a signal to reflect from M and return. The graphic is the A description of events.

In the A frame, the round trip time would be 2d/c=2t.
A observes the round trip time for B to be:

Atr = (d/γ)(1/c)[1/(1-b)+1/(1+b)] = 2γd/c = 2γt

Where γ (gamma) is the ratio of a unit of time for a clock at rest to that of a moving clock.   
The term (d/γ) is the contracted length of d resulting from acceleration to its current speed. With adjustment for time dilation (red), Bt = Atr/γ = 2t.
The B-time will be the same as the rest frame A, and independent of speed b.
This is labeled as 'proper' time in the SR community. Since there is no issue of impropriety from the poor choice of words, I favor Einstein's simple and logical term, 'local' time. (it's about location!)

In your scenario, just substitute Y for A and W or Z for B.
Hopefully you noticed the use of (1-b) and (1+b) in the calculations, i.e. closing speeds,  which are definitely used in SR. No one argues that fact. Also notice these are calculations used by a remote observer A. They cannot be used by B, since he and all other inertial frames cannot determine their velocity through space.
If B assumes a pseudo rest frame, he would not expect the times out and back to be different.

* reflection measure.gif (6.25 kB . 530x644 - viewed 1628 times)
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Offline yor_on

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Re: Can we measure the one way speed of light?
« Reply #155 on: 29/06/2018 23:25:41 »
Phyti, the way you should use this is to hone your mind. If  you can simplify it, do it. But every question will make you think some more.
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #156 on: 29/06/2018 23:28:54 »
Phyti,

Your previous post doesn't address the issue in question, but simply avoids it. We aren't looking for a round trip time for X, but for the average speeds at which the two light pulses pass through the sectors of the cable relative to the material of those sectors while it's passing through them. You are supposed to be calculating values for these relative speeds (which I call R [for the red light] and B [for the blue]. Let's go through the argument again with the same thought experiment, but with a few added numbers. This may help determine where you part company with mathematics.

The course for the light to go round is a loop of flexible cable with an interior space and a mirrored lining which contains the light in that vacuum and ensures that it isn't slowed, though it may be easier just to visualise a loop of normal fibre-optic cable and to imagine that there are no delays caused by any kind of drag. This loop goes round over two pulleys at either end of a very long rod. The loop of cable is marked out into a hundred sectors named from S0 to S99. The pulleys are rotating such that all the material of the cable is moving round this very linear circuit at high speed. Sector S0 moves first to the right at 0.6c from one pulley to the other below the rod, then round the pulley, then it goes back to the left at 0.6c above the rod (if we assume the rod to be stationary). Note that the material of the cable must be length-contracted by this movement to 0.8 of its normal length, so we'd better have a telescopic rod which can contract to 0.8 of its normal length to match (so that we can set up the apparatus and then run it up to speed without the cable being deformed by stress. We also have object Z co-moving with the bottom part of the cable, and object W co-moving with the top part of the cable, so anything that we say about the speed of light relative to the bottom of the cable must also apply to object Z, and anything we say about the speed of light relative to the top of the cable must also apply to object W (and will continue to apply to them even if the rest of the apparatus is removed). Observer Y sits beside the left-hand pulley throughout, while observer X travels round the circuit with sector S0.

X leaves Y at the same time as pulses of light are emitted from S0 in opposite directions, red light going along the top (just over the rod) and blue going along the bottom parts of the cable (just under the rod), this happening once they've got clear of the pulley - initially they're moving upwards and downwards, but they're almost immediately sent round the corner such that both travel to the right. The light pulses eventually reach the far pulley simultaneously and continue their journey round the circuit, returning to the left until they reach Y simultaneously. They then set off to do more laps and repeat the exact same pattern each time.

What does observer X do in comparison to the light pulses? Well, he moves at 0.6c along the bottom of the circuit beside S0 (which he travels with throughout) and encounters a pulse of red light before reaching the right-hand pulley. How many circuits does X have to make before he is next back at Y at the same time as the light pulses return to Y? 5 x 0.6 = 3 (a whole number), so if light goes from one pulley to the other and back five times, X will have made the same trip three times. X has therefore encountered the red light pulse eight times, but has only encountered the blue light pulse twice. This means that the red light has passed through every sector of the loop four times more than the blue light has passed through them.

The speed of the red light relative to the material of the sectors it's passing through (while it's passing through them) can be calculated by measuring the length of the cable and timing how long it took for that light to pass through all the sectors. The length of the cable is either twice the distance between the pulleys, or else it is arguably longer than that because it's been length-contracted - you could allow X to measure it by wandering round the entire length of it and stopping to measure the length of each sector with a co-moving ruler. That longer length certainly doesn't suit you, so you'll want to use the shorter length, but I don't need the longer length either as the real length is the contracted length, and that's more than long enough to illustrate the point. If we call the distance between the pulleys 0.5L, then the length of the cable is L. If the time taken for light to travel from Y back to Y via the far pulley is t, then the speed of travel of the light is unsurprisingly 1/1=1=c. The time taken for X to travel from Y to the far pulley and back to Y is 5t, and during that time the red light has passed through all the sectors of the cable eight times, while the blue light has only passed through the sectors twice. The red light has therefore travelled through 8L of sectors in 5t, which gives us a speed relative to those sectors (while passing through them) of 1.6c, while the blue light has travelled 2L in 5t, which gives us an average relative speed of 0.4c. (What an amazing coincidence: that's the exact same values as we get just by adding or subtracting the speed of light to/from the speed of a moving object!)

You could assert that the length of the cable is four times shorter if you go round it anticlockwise than if you go clockwise, but there is nothing in SR that allows you to do so. It's really much better just to accept the measurements and stop trying to prop up a theory which conflicts with the facts.

Once we have established that the speed of light relative to some sectors is at least 1.6c , we know that either object W or object Z has the property that light passes it in one direction at a minimum speed of 1.6c relative to it. If a frame represents W as not having this property, then Z must have it, while if a frame represents Z as not having this property, then W must have it, so at least one of those two frames is a misrepresentation of reality because it asserts a falsehood about the speed of light relative to W or Z. When you extend this principle, it becomes clear that it's only possible for one frame be a true representation of reality, while all other frames misrepresent it, and that means we have an absolute frame.

What we see from SR adherents is a denial of the validity of all relative speeds other than c whenever light is one of the two things being compared. Z and W are moving relative to each other at 0.6c, but you are required by an authority to assert that light is moving relative to both of them at c in all directions, and in doing so, you necessarily generate the conclusion that Z and W must be co-moving, at which point you have to sweep that conclusion under the carpet and hope no one noticed. To tolerate these contradictions is a rejection of mathematics and I don't understand why anyone wants to defend a theory which generates such contradictions (particularly when there's another theory in existence which has been recognised as accounting for all the same experiments as SR and GR without generating any contradictions).

[When you press the top experts though, they attempt to escape into Minkowski Spacetime, at which point the speed of light becomes either zero or is infinite, depending on how you want to think about it - all the paths it follows are reduced to zero length. This leads to other fatal problems though, which we can explore later if anyone wants to take things in that direction - that's where the event-meshing failures come into play if you don't have a block universe, and it becomes impossible to generate a block universe under the rules of SR.]
« Last Edit: 29/06/2018 23:37:55 by David Cooper »
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Offline David Cooper

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Re: Can we measure the one way speed of light?
« Reply #157 on: 29/06/2018 23:39:34 »
Quote from: yor_on on 29/06/2018 23:25:41
Phyti, the way you should use this is to hone your mind. If  you can simplify it, do it. But every question will make you think some more.

There's a more important purpose than that, and that is to address the issue. He (and anyone else who holds the same position) should provide his own values for R and B and explain how he imagines they can be equal (or else admit that they are not equal). It shouldn't take pages of avoidance bloat to get round to that - it should have come in his next reply after I set out the original version of the experiment on page 2 in reply #77.
« Last Edit: 29/06/2018 23:48:45 by David Cooper »
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Re: Can we measure the one way speed of light?
« Reply #158 on: 30/06/2018 16:04:14 »
Quote from: David Cooper on 29/06/2018 23:39:34
Quote from: yor_on on 29/06/2018 23:25:41
Phyti, the way you should use this is to hone your mind. If  you can simplify it, do it. But every question will make you think some more.

There's a more important purpose than that, and that is to address the issue. He (and anyone else who holds the same position) should provide his own values for R and B and explain how he imagines they can be equal (or else admit that they are not equal). It shouldn't take pages of avoidance bloat to get round to that - it should have come in his next reply after I set out the original version of the experiment on page 2 in reply #77.
There seems to be a history of David Cooper trying to discredit Relativity here.
No amount of evidence will convince you, you don't understand SR. The imagined 'problems' made me wonder, why your site is named 'magic school'.
This is tiresome and boring, so I have projects to work on, which are more constructive.
 
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Offline Le Repteux

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Re: Can we measure the one way speed of light?
« Reply #159 on: 30/06/2018 16:43:34 »
Why the term discredit? Do you consider relativity to be so perfect that it can never be improved? It's not how science is expected to work. History of science shows that, like any other theory, relativity should one day become obsolete and be replaced by a more accurate idea. It is thus not relativity that is discredited here, but those who defend their belief with unfunded accusations instead of using logical ideas.
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