[jeffreyH (OP)]

We are not in an inertial frame. As Alan described above. A non inertial frame is actually better for the determination of the one way speed of light. From my perspective this has been put to rest.

[yor_on]

David

" The outcome of the experiment was that the angular velocity of the Earth as measured by astronomy was confirmed to within measuring accuracy. The ring interferometer of the Michelson-Gale experiment was not calibrated by comparison with an outside reference (which was not possible, because the setup was fixed to the Earth). From its design it could be deduced where the central interference fringe ought to be if there would be zero shift. The measured shift was 230 parts in 1000, with an accuracy of 5 parts in 1000. The predicted shift was 237 parts in 1000. According to Michelson/Gale, the experiment is compatible with both the idea of a stationary ether and special relativity.

As it was already pointed out by Michelson in 1904, a positive result in such experiments contradicts the hypothesis of complete aether drag. On the other hand, the stationary ether concept is in agreement with this result, yet it contradicts (with the exception of Lorentz's ether) the Michelson-Morley experiment[citation needed]. Thus special relativity is the only theory which explains both experiments.[6] The experiment is consistent with relativity for the same reason as all other Sagnac type experiments (see Sagnac effect). 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, consequently a positive result must occur. It's also possible to define rotating frames in special relativity (Born coordinates), yet in those frames the speed of light is not constant in extended areas any more, thus also in this view a positive result must occur. Today, Sagnac type effects due to Earth's rotation are routinely incorporated into GPS"

https://en.wikipedia.org/wiki/Michelson%E2%80%93Gale%E2%80%93Pearson_experiment

[yor_on]

Phyti, expand on what you write

[David Cooper]

what you're doing there David is to go out from a 'whole undividable universe'  in where objects must have a defined speed. Relativity does not do that. You can do it as a presumption, but then you also need to refute the experiments relativity use, at least reinterpret them in a way that builds a logic.

What I do is consider all possible speeds of an object from rest to just under c - I don't just make an assumption of a single speed for it because there's no way of knowing its actual speed. To consider all possible cases, it's sufficient to look at a few well spaced examples as you can predict what will happen for any other speeds by looking at the pattern you've built up. That means you try out a number of different frames of reference and generate the numbers for everything involved in a scenario. In one frame, object A might be at rest with light moving at c relative to it while object B is not at rest and has light moving in most directions at speeds other than c relative to it. In another frame, object B may be at rest and A moving. In other frames, neither object is at rest. The experiments all fit with this. What you should not do is change frame in the middle of an analysis and say that light is moving at c relative to both objects A and B in all directions.

What's funny about relativity is that almost everyone I've seen do the same, defending it. And it comes from a presumption, not a fact. What Relativity state is that it's observer dependent, it's not a 'whole undividable universe' in that sense at all

There are two relativity models involved: Lorentz's model and Einstein's (with a number of variants). What relativity universally states is that the analysis from any frame is as useful as any other, producing numbers that are potentially right. I'm not clear as to what your "whole undividable universe" is meant to be, but what MGP shows is that there must be an absolute frame, and our inability to pin that frame down doesn't negate its existence.

[David Cooper]

No. Any terrestrial experiment is conducted with the certain knowledge that we are rotating at about 0.25 degrees per second whilst orbiting the sun at godknowshowmany miles per hour and hurtling away from the center of the galaxy at a significant fraction of c whilst other galaxies are rushing about even faster.

No terrestrial experiment is conducted in the knowledge that we're moving at all at any specific point in time, but over the course of a rotation or orbit, we can be sure that we have been moving most of the time.

Stationary with respect to what?

The fabric of space which limits the speed of light through it to c.

And when we bounce lasers off the moon, or radar waves off Venus, no part of the apparatus is stationary with respect to any other, but the value of c remains remarkably constant.

Of course it does - that's exactly what LET says it is, but c is not the one-way speed of light relative to the apparatus.

Come to think of it, we can measure the doppler shift of a radar or laser reflection from a body moving in a circle if we are standing outside the circle.  Now the reflector has no idea where we are but we know its radius is fixed, and so is the distance from the observer to the center of rotation, so we can calculate its speed relative to the observer in any direction at any time. Lo and behold, the doppler equation applies exactly and everywhere. So c must be constant regardless of direction.

Great: c is a constant, but it is not the one-way speed of light relative to the apparatus.

[David Cooper]

We are not in an inertial frame. As Alan described above. A non inertial frame is actually better for the determination of the one way speed of light. From my perspective this has been put to rest.

Wherever there is a non-inertial frame, there are an infinite number of inertial frames occupying the same location in space, so whatever action you're analysing there must be possible to analyse using any one of those frames and not just your non-inertial frame. If you rule that out, you aren't doing physics any more.

[David Cooper]

According to Michelson/Gale, the experiment is compatible with both the idea of a stationary ether and special relativity.

It is compatible with the predictions of both, but it also disproves SR.

As it was already pointed out by Michelson in 1904, a positive result in such experiments contradicts the hypothesis of complete aether drag. On the other hand, the stationary ether concept is in agreement with this result, yet it contradicts (with the exception of Lorentz's ether) the Michelson-Morley experiment[citation needed]. Thus special relativity is the only theory which explains both experiments.[6]

Did you notice the words in brackets saying "with the exception of Lorentz's ether"? What that tells you is that LET is compatible with both, so when it goes on to say, "Thus special relativity is the only theory which explains both experiments", it's incorrect. It should say, "Thus special relativity and LET are the only theories which explain both experiments". The article needs editing to correct that, but intelligent people should be able to read the truth out of it regardless by noticing the contradiction and making the correction automatically for themselves.

The experiment is consistent with relativity for the same reason as all other Sagnac type experiments (see Sagnac effect). 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, consequently a positive result must occur. It's also possible to define rotating frames in special relativity (Born coordinates), yet in those frames the speed of light is not constant in extended areas any more, thus also in this view a positive result must occur. Today, Sagnac type effects due to Earth's rotation are routinely incorporated into GPS"

And what I've shown is that there is no bar to exploring the whole action from an inertial frame of reference, and that the results of that analysis must not only be valid, but show in every case (using any inertial frame of reference that you choose) that the red light passes through every part of the ring at a higher speed relative to it than the blue light, which means that the one-way speed of light must be different relative to each part when the light is passing through it depending on whether it's red or blue. No amount of applying bogus rules for non-inertial frames can overturn that fact.

[alancalverd]

No terrestrial experiment is conducted in the knowledge that we're moving at all at any specific point in time, but over the course of a rotation or orbit, we can be sure that we have been moving most of the time.

The idea that the earth moves in jerks is beneath contempt.

Stationary with respect to what?

The fabric of space which limits the speed of light through it to c.

So every particle in the universe is dragging the "fabric of space" along with it? So there must be tears in the fabric when two particles move relative to one another. This is beyond bizarre.Whatever happened to Occam?

And when we bounce lasers off the moon, or radar waves off Venus, no part of the apparatus is stationary with respect to any other, but the value of c remains remarkably constant.

Of course it does - that's exactly what LET says it is, but c is not the one-way speed of light relative to the apparatus.

The apparatus is a mirror on the moon, or the atmosphere of Venus. Now these move around in space, so if the speed of light depended on direction, we would get different results for the two-way speed depending on the astronomical coordinates of the target.

Come to think of it, we can measure the doppler shift of a radar or laser reflection from a body moving in a circle if we are standing outside the circle.  Now the reflector has no idea where we are but we know its radius is fixed, and so is the distance from the observer to the center of rotation, so we can calculate its speed relative to the observer in any direction at any time. Lo and behold, the doppler equation applies exactly and everywhere. So c must be constant regardless of direction.

Great: c is a constant, but it is not the one-way speed of light relative to the apparatus.

[/quote] I can't think of any other definition of what we have measured. If c is constant, then the one-way speed must be the same as the two-way speed, or it wouldn't be "constant".

Never mind. Here's how we measure one-way speed directly.

Make two spinning discs A, B with equispaced circumferential holes. Place them as far apart as you like. Spin A at a constant speed. Shine a light through the holes. Spin the disc B, observe A through the holes of B,  and gradually increase the speed of rotation. The light will dim, brighten, and dim again. The difference in rotational speed between maxima depends on the spacing of the holes and the one-way speed of light. I will leave it to you to write down the equation.

[David Cooper]

No terrestrial experiment is conducted in the knowledge that we're moving at all at any specific point in time, but over the course of a rotation or orbit, we can be sure that we have been moving most of the time.

The idea that the earth moves in jerks is beneath contempt.

There are many ideas that you could introduce here and describe as beneath contempt, but it's normal in a discussion to keep it on topic and not drag extraneous garbage into them, and particularly not to do so in any way that implies that the person you're replying to believes in the random idea that you've flung at them as if it's theirs.

Stationary with respect to what?

The fabric of space which limits the speed of light through it to c.

So every particle in the universe is dragging the "fabric of space" along with it? So there must be tears in the fabric when two particles move relative to one another. This is beyond bizarre.Whatever happened to Occam?

Again, you're dragging in random ideas that have nothing to do with the price of fish. Why would the fabric be dragged by anything? LET doesn't have dragging of the space fabric at all. You clearly don't bother to read anything carefully if you don't already believe in it, or you fail to understand what you're reading because you don't bother to switch your brain on if you know that it goes against your existing beliefs, so you're permanently stuck in the same place, arguing against a theory which you evidently don't understand at all.

The apparatus is a mirror on the moon, or the atmosphere of Venus. Now these move around in space, so if the speed of light depended on direction, we would get different results for the two-way speed depending on the astronomical coordinates of the target.

According to which theory? Not LET. You've still never crunched the numbers by LET's rules to see what happens with these experiments and how they always produce the same results regardless of the difference of the one-way speeds of light relative to the apparatus in different directions.

I can't think of any other definition of what we have measured. If c is constant, then the one-way speed must be the same as the two-way speed, or it wouldn't be "constant".

You are either measuring the 2-way speed of light, or you're measuring the effective 2-way speed due to the synchronisation of your clocks hiding the difference. A basic understanding of LET would be all it takes for you to understand this stuff, but you've never bothered to study it at all.

Never mind. Here's how we measure one-way speed directly.

Make two spinning discs A, B with equispaced circumferential holes. Place them as far apart as you like. Spin A at a constant speed. Shine a light through the holes. Spin the disc B, observe A through the holes of B,  and gradually increase the speed of rotation. The light will dim, brighten, and dim again. The difference in rotational speed between maxima depends on the spacing of the holes and the one-way speed of light. I will leave it to you to write down the equation.

We've covered all of this before - you still don't understand the twist issue as the actual rotation of the leading disc lags behind that of the trailing disc if the apparatus is moving through space - this automatically adjusts the timings to let light pass through the same pair of holes for the same rotation speeds despite the change in the one-way speed of light through the apparatus. But you didn't take that in last time, and there's even less chance of you taking it in now because you're too stuck in your ways; happy to remain ignorant of the facts and just go on repeating bad science. The top experts in SR don't agree with you either, because they understand that LET fits the same facts with all the experiments.

[guest4091]

Here is a simple scenario with the U reference observing Al moving at .5c along +x axis.
On the left, at the origin, Al sends a light pulse at Ut=0, it reflects at Ut=t, and is detected by Al at Ut=t1. Since the A frame experiences td, Al thinks detection occurs at At=2t', event D'.
On the right, he has no means of determining when the reflection event occurs, but relies on the SR simultaneity convention, and assigns R' to half the round trip time.
If light speed relative to Al is used, as described by U, the reflection event occurs at R''.
This example demonstrates that it makes no difference which method is used. The round trip times are equal, the relative light speeds cv can only be known to an external  (relative to A) observer. Al's measurements support his perception of being in a 'rest' frame.
Any argument for absolute or relative speed of light is just fog.
"That light requires the same time to traverse the same path A to M as for the path B to M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which I can make of my own freewill in order to arrive at a definition of simultaneity."
Relativity The Special and the General Theory
Albert Einstein 1961 Crown Publishers Inc. pg 23

p&r reflection.gif (10.89 kB . 1068x531 - viewed 2082 times)

[guest4091]

Phyti, expand on what you write

What do you want clarified?

[yor_on]

I was thinking of this one

" The coordinate transformations reduce to
x’ = γx, and t’ =γt.
Thus speed = distance/time.
If x/t = c, then x’/t’ = x/t = c
The reason, motion alters perception and measurement.
This satisfies the 1st postulate of SR since the expressions using x and t are the same for all inertial frames."

You presume too much from us :)
For example you mentioning the "1st postulate of SR"

[alancalverd]

QuoteNever mind. Here's how we measure one-way speed directly.Make two spinning discs A, B with equispaced circumferential holes. Place them as far apart as you like. Spin A at a constant speed. Shine a light through the holes. Spin the disc B, observe A through the holes of B,  and gradually increase the speed of rotation. The light will dim, brighten, and dim again. The difference in rotational speed between maxima depends on the spacing of the holes and the one-way speed of light. I will leave it to you to write down the equation.We've covered all of this before - you still don't understand the twist issue as the actual rotation of the leading disc lags behind that of the trailing disc if the apparatus is moving through space - this automatically adjusts the timings to let light pass through the same pair of holes for the same rotation speeds despite the change in the one-way speed of light through the apparatus. But you didn't take that in last time, and there's even less chance of you taking it in now because you're too stuck in your ways; happy to remain ignorant of the facts and just go on repeating bad science. The top experts in SR don't agree with you either, because they understand that LET fits the same facts with all the experiments.

How does A know the rotational speed of B? How is the distance AB affected by the rotational speed of B? The experiment does not rely on any prior synchronisation, only that the speed of A and the distance AB remain constant.

[David Cooper]

Never mind. Here's how we measure one-way speed directly.Make two spinning discs A, B with equispaced circumferential holes. Place them as far apart as you like. Spin A at a constant speed. Shine a light through the holes. Spin the disc B, observe A through the holes of B,  and gradually increase the speed of rotation. The light will dim, brighten, and dim again. The difference in rotational speed between maxima depends on the spacing of the holes and the one-way speed of light. I will leave it to you to write down the equation.

We've covered all of this before - you still don't understand the twist issue as the actual rotation of the leading disc lags behind that of the trailing disc if the apparatus is moving through space - this automatically adjusts the timings to let light pass through the same pair of holes for the same rotation speeds despite the change in the one-way speed of light through the apparatus. But you didn't take that in last time, and there's even less chance of you taking it in now because you're too stuck in your ways; happy to remain ignorant of the facts and just go on repeating bad science. The top experts in SR don't agree with you either, because they understand that LET fits the same facts with all the experiments.

How does A know the rotational speed of B? How is the distance AB affected by the rotational speed of B? The experiment does not rely on any prior synchronisation, only that the speed of A and the distance AB remain constant.

The way you've described the experiment is deficient, so I don't know how you envisage the one-way speed of light having any relevance to it - you can increase the distance between A and B without noticing the behaviour changing unless you're also making precise timings and introducing them into it in some way that you haven't specified. For my previous reply, I assumed additional requirements of the experiment which you hadn't provided, and twist (synchronisation issues) will always hide the one-way speed of light from you. Without a better description of your experiment though, and if I'm to take it exactly as you've set it out, the distance AB can be set to any length you like without it changing the result of the experiment.

[David Cooper]

Here is a simple scenario with the U reference observing Al moving at .5c along +x axis.

It may be simple, but I can't map the description to the diagram. It would be a lot easier to follow these things if you'd describe the scenario in ordinary words and if the things in the description also exist in the diagram.

Any argument for absolute or relative speed of light is just fog.

On the contrary, looking at the actual reality with the speed of light varying relative to the experiment is where you clear the fog and look at what might actually be going on instead of fooling yourself into thinking every experiment you do is at rest.

[alancalverd]

David: you are right. My experiment is wrong.

Not that it matters,since c = 1/√ε₀μ₀ so it is independent of direction anyway, as ε and μ are scalar quantities.

[yor_on]

Alan, you can't use rotating discs for it

[guest4091]

I was thinking of this one

" The coordinate transformations reduce to
x’ = γx, and t’ =γt.
Thus speed = distance/time.
If x/t = c, then x’/t’ = x/t = c
The reason, motion alters perception and measurement.
This satisfies the 1st postulate of SR since the expressions using x and t are the same for all inertial frames."

You presume too much from us
For example you mentioning the "1st postulate of SR"

I thought everyone participating in these 'relativity' subjects was familiar with the 1st and 2nd postulates of SR.
The 1st: the description/equations of physics is the same in any inertial frame.
Example:
The expression x=vt should work in any frame.
With light speed =1, on Earth, Al calculates the distance of object D as x=vt/2=1*8/2 =4 lyr. ( He needs a return signal)
In a spacecraft moving at .5, past Earth, toward D, he calculates x=.5*7=3.5 yrs.
As an anaut in a pseudo rest frame, he has to allow for length contraction of the universe as it moves past him at .5 in the opposite direction.
Does the moving anaut cause the universe to contract by moving extremely fast? No.
Do the particles in an accelerator cause the universe to contract by moving at near light speed? No.
This is actually his perception or interpretation of events, to reconcile the effects of time dilation.
On Earth D was 4 ly distant. Now, in his craft, it's arrived early, according to his clock (biological and mechanical). He can't deny his time nor his speed, so the only thing left is distance. If he sent a signal to D as he passed Earth, his conclusion would be the same, lc, i.e. verified by measurement.
The formula does not require any modifications.
In a world of absolute motions, you would have to know the location of the center of mass or absolute reference frame,) which is impossible in a dynamic universe. That's the beauty and utility of Relativity.
Imagine if you could have a conversation with someone, anywhere on Earth without requiring a translation.

[guest4091]

David Cooper#53;

Never mind. Here's how we measure one-way speed directly.Make two spinning discs A, B with equispaced circumferential holes. Place them as far apart as you like. Spin A at a constant speed. Shine a light through the holes. Spin the disc B, observe A through the holes of B,  and gradually increase the speed of rotation. The light will dim, brighten, and dim again. The difference in rotational speed between maxima depends on the spacing of the holes and the one-way speed of light. I will leave it to you to write down the equation.

Who is measuring the light transit time?

[jeffreyH (OP)]

@phyti You could actually come down off your high horse and help others.
https://en.m.wikipedia.org/wiki/Postulates_of_special_relativity