[David Cooper]

If Ann is really stationary, her account represents reality while Ben's account is a distorted view of events.

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Red is based on what?

If Ann is really stationary relative to the fabric of space.

In the 'train' example, both observe the extended event 'object falls from passenger hand to floor', but some of the details vary for each. One reality, two descriptions. You aren't allowing for the changing position of the object due to relative motion, which results in different trajectories for the object. The trajectories are images/reality in the mind.

Again there are multiple descriptions (theories) of this, but only one of them can be true - the rest are distorted views of the event.

My experiment, which you are still failing to address, demonstrates that there is a difference in the actual speed of light relative to the material of the ring in opposite directions as it travels through the sectors.

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My answer was:
A, moving with the ring, will meet the cw photon 1st, then the ccw photon 2nd.  A explains the time difference as due to the rotation, not a difference in light speed, i.e. different path lengths. These are shown with the aide of the mirror.
If light clocks were used in the H-K experiment, the same results would occur, due to rotation. Although an absolute frame with acceleration, it can be analyzed with SR.

Why won't you answer the key question? Is R>B? (R is an average speed which you can build up by adding together the speed of the red light through each sector relative to that sector, while B is the equivalent for the blue light.) I've already helped you by telling you that the answer is yes, but I want to hear you answer it yourself. If R=B, observer X (equivalent to your A, but I don't want to use that name as it comes from a different experiment with a mirror in it where the light does something very different) would have both lots of light return to him simultaneously every time it passes him, but we know from the MGP and sagnac experiments that that doesn't happen.

If you insist that R=B, that is incompatible with the results of those experiments. If you accept that R>B though, you are necessarily accepting that the speed of light is higher relative to some of the material of the ring as it passes it in one direction than it is in the opposite direction, and by extension that there is an absolute frame. Where do you put your loyalties: with the universe or with a clergy? Galileo showed the clerics the moons of Jupiter through his telescope and they denied that they were there. Do you want history to look on you as being just like them?

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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You've quoted one of my questions, but it isn't clear that you've answered it. Is your answer "yes"? You might score a point for being the first person other than me to dare to answer any of the questions.

Given a choice, LET or SR, I would choose SR since it doesn't require an ether, and light as particles doesn't require a medium.

Without a medium, there is no travel - you have nothing to support the properties of distance and direction, and nothing to impose a speed limit on light either. Most importantly though for this discussion, SR cannot handle this issue of the one-way speed of light relative to some objects being higher in one direction than the other. We know absolutely from MGP and Sagnac that such objects must exist where the speed of light is definitively not c relative to them in all directions (and indeed where it is >c in some directions), which means that any frame of reference Z that asserts that the speed of light relative to object Z in all directions is c is manifestly not a valid frame in that it cannot be representing reality, but a mere distortion of it. My analysis of the MGP experiment shows that some points with this property (that the speed of light relative to them varies in different directions) must exist and that any frame of reference which portrays them with those objects at rest cannot be a valid frame.

[David Cooper]

Here's another experimental idea. Consider the Doppler shift of received frequency

Δf = 2vf/(c - v)

So you can set up a laser, microwave transmitter, or radionuclide gamma source to provide a one-directional electromagnetic wave, and measure the Doppler shift between a fixed and a moving (e.g.oscillating) receiver. Now rotate the principal axis of the experiment around the receiver station, say from E-W to W-E,  and convince yourself that f and Δf remain the same, so c must be independent of direction.

Note that f varies between up and down - the Pound-Rebka experiment. The explanation depends on the constancy of c!

This sounds like a description of the experiment with a turntable, a detector at the middle and a source at the edge. The detector is tuned to the exact frequency of the source, so it doesn't pick up the signal unless it is exactly that frequency. When the table isn't turning, it detects nothing. When the table's turning round at a particular rate, the movement of the source slows its mechanism down (all moving clocks and mechanisms of any kind run slow) and the detector picks up the signal. If you move the whole turntable along through space, the functionality of the turntable, detector and source all slow down because of their movement though space, but the source is now speeding up and slowing down as it orbits the detector, so its frequency varies. The detector detects the signal from the source the whole time though, not recognising any variation, and this happens because the Doppler effect masks all the variation.

LET predicts the behaviour of all such experiments in full.

[alancalverd]

Wholly different experiment, wholly different result.

In my experiment the source does not move during the measurement.The only moving part is the locally oscillating part of the receiver, and the measurement is of the Doppler shift between the fixed and moving parts of the receiver when the direction of the incoming beam is fixed.

Your "ring experiments" are also irrelevant. c is the speed of light in vacuo, not in a medium. c_m is subject to all sorts of variations.

[Le Repteux]

Hold on cowboy. Don't go putting words into my mouth or motives into my mind. Read what I actually post, not what you think I post

:0)
Sorry sheriff, I was just kidding. Now let's get serious: you said you were going to answer the first message from David, and you didn't. The way your OP was built almost meant that you were turning agnostic, that's exciting. How about being the first scientific forum to promote LET?

[alancalverd]

Here's another example. When an electron and a positron annihilate, they produce two photons, moving in exactly opposite (though unpredictable) directions and each with energy 511 keV. It is no coincidence that m_p c² = m_ec² = 511 keV,and of course the photons can only move at c.

It is "quite" easy (it only took my team 20 man-years) to measure the energy of the photons by several different means, none of which involves any spatial dimension. To nobody's surprise, the energy of the left-right photon is exactly the same as that of the right-left photon and conservation of momentum thus demands that c is independent of direction.

[Le Repteux]

To nobody's surprise, the energy of the left-right photon is exactly the same as that of the right-left photon and conservation of momentum thus demands that c is independent of direction.

The speed of light is also independent of the direction of the source with LET if the source is at rest with regard to the fabric of space, and if the source is moving through space, it is impossible to observe any difference in the speed of its light due to relativity effects, which are the same with SR since they actually are relativity effects.

[Colin2B]

How about being the first scientific forum to promote LET?

How about we don’t, otherwise this discussion might end up in New Theories to make it clear LET is an alternative theory.
As it is, there is interesting and worthwhile discussion here on the technicalities and methods of looking at light speed.

[Le Repteux]

As it is, there is interesting and worthwhile discussion here on the technicalities and methods of looking at light speed.

SR is impossible to simulate on a computer screen, and LET is, so LET is better at summarizing reality even if both theories give out the same numbers.

[alancalverd]

Can anyone enlighten me as to the meaning of LET?

[alancalverd]

the fabric of space

Please set down the physical characteristics of this wondrous fabric. Density? Elastic modulus? Viscosity? ε_FS and μ_FS?

If I can move relative to it, what is it fixed to?

[alancalverd]

Never mind fairy gossamer or whatever you are on about, I have simply given a couple of experimental proofs that c is independent of direction so the one-way speed of light in vacuo is the same as the two-way value.

Some smart-arse will say "but you haven't measured it". To which I reply if two identical cans of beans cost $1, one can costs 50c. Or does fairy gossamer LET give quantity discounts?

[Le Repteux]

the fabric of space

Please set down the physical characteristics of this wondrous fabric. Density? Elastic modulus? Viscosity? ε_FS and μ_FS?

If I can move relative to it, what is it fixed to?

(LET is the acronym for Lorentz Ether Theory.) Space has no other characteristic than to let light and matter travel in it. Matter is considered to be traveling freely through it, though I have a particular viewpoint on that question, an light is considered to propagate through it, so it is not free from it. When we see a diagram of light traveling transversally between the two mirrors of a light clock for instance, we see light traveling through space while the mirrors are moving with regard to it. If it was shown traveling directly between the mirrors, the  diagram would mean that they are at rest with regard to it.

[guest4091]

Bill S.;

I've not been following this thread, so this might well have been seen already.

https://medium.com/the-physics-arxiv-blog/the-one-way-speed-of-light-fcc5f05c5e44

If not, it might be of interest.

The experiment cited is misleading.
Sending light both ways simultaneously is equivalent to the 2-way experiment.
As the drawing shows, the 2nd signal could be sent in the opposite direction, in a duplicate device. As long as the signals return simultaneously, the events c1 and c2 are perceived as simultaneous.
The 2nd postulate, "the speed of light is independent of its source', implies 'its independent of the speed of the source'. Assuming U is the absolute rest frame whose observer Uri made the drawing, Uri concludes, Alice will always measure light speed as c, and perceive herself at rest, regardless of speed.
The 2nd postulate is another equivalence principle.
'An observer moving in uniform motion (free of changes in speed and direction) is equivalent to being at rest'.
If that is true, then the U frame is redundant.

simult axis.gif (4.87 kB . 530x548 - viewed 1526 times)

[Le Repteux]

To which I reply if two identical cans of beans cost $1, one can costs 50c.

:0)
Two identical particles also carry the same energy, but if we observe their light while one is moving with regard to us and the other not, we don't get the same energy. In other words, we can't get rid of a relativity problem with classical physics.

[guest4091]

David C;
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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Wanted to make a simple drawing, since they show multiple relations easier than a page of text.
The drawing shows the ccw photon needing more time than the cw photon to complete 1 revolution relative to A. This is still a case of closing speed, since A is moving at .2 and the photon is moving at 1.0 in space. The average light speed would still be 1.0
If confused, imagine the flat surface wrapped around a tube with the 2 A-lines joined with the times aligned..
If m(1-v) = n(1+v), then v = (m-n)/(m+n). In this case v=1/5 = .2. The pattern repeats after 3 short and 2 long cycles.

light ring c.gif (5.85 kB . 416x612 - viewed 1529 times)

[David Cooper]

Wholly different experiment, wholly different result.

In my experiment the source does not move during the measurement.The only moving part is the locally oscillating part of the receiver, and the measurement is of the Doppler shift between the fixed and moving parts of the receiver when the direction of the incoming beam is fixed.

If you move the receiver instead of the source, you speed up or slow down the functionality of the receiver in such a way as to maintain the perceived frequency again - this change in the speed of functionality and the Doppler effect always cancel out the differences that you imagine the experiment will detect if you don't bother to do the maths correctly to see that no effect should be detectable.

Your "ring experiments" are also irrelevant. c is the speed of light in vacuo, not in a medium. c_m is subject to all sorts of variations.

If you read my experiment description carefully, it's a vacuum in a mirror-lined tube, although it works fine in a fibre-optic cable too because the delays from the medium are tiny.

[David Cooper]

Hold on cowboy. Don't go putting words into my mouth or motives into my mind. Read what I actually post, not what you think I post

:0)
Sorry sheriff, I was just kidding. Now let's get serious: you said you were going to answer the first message from David, and you didn't. The way your OP was built almost meant that you were turning agnostic, that's exciting. How about being the first scientific forum to promote LET?

That's asking a lot. This thread isn't about promoting LET either, but about discussing the evidence and looking at the point where SR fails to account for the facts.

[David Cooper]

Here's another example. When an electron and a positron annihilate, they produce two photons, moving in exactly opposite (though unpredictable) directions and each with energy 511 keV. It is no coincidence that m_p c² = m_ec² = 511 keV,and of course the photons can only move at c.

How do you detect the energy of a photon? if your detector is moving away from the light, it records a lesser energy for it, so you're actually biasing your experiment by putting your detector at rest in a frame of reference in which your electron and positron system is also at rest.

Every time, your experiments contain a hidden bias that you've failed to recognise.

[David Cooper]

SR is impossible to simulate on a computer screen, and LET is, so LET is better at summarizing reality even if both theories give out the same numbers.

It's more complicated than that, but this thread is not here to promote LET. I only mention LET in it to show that a theory with variable speed of light relative to objects predicts the same results of experiments as SR - whenever someone claims that a difference in the one-way speed of light relative to an object would be detectable by an named experiment, I have to respond to that to explain why the experiment would not be capable of detecting any such thing - the person proposing it always has a naive understanding of what the experiment can do.

[David Cooper]

Never mind fairy gossamer or whatever you are on about, I have simply given a couple of experimental proofs that c is independent of direction so the one-way speed of light in vacuo is the same as the two-way value.

Some smart-arse will say "but you haven't measured it". To which I reply if two identical cans of beans cost $1, one can costs 50c. Or does fairy gossamer LET give quantity discounts?

You haven't produced any experimental proofs that the one-way speed of light in vacuo is the same as the two-way value. All you have done is present experiments which are incapable of determining anything relevant to that at all. In every single case, you build an assumption into it and then read that assumption back out at the end.