[Hal (OP)]

https://www.researchgate.net/project/Tests-of-the-One-way-Speed-of-Light-Relative-to-a-Moving-Observer

... the speed of light between fixed points on the surface of the Earth is not the same in all directions; light travels faster west than east! GPS engineers try to mask this fact by assuming light speed c and making the so-called "Sagnac Correction".

Has anyone worked with GPS to confirm or refute the claim?

West does not define a unique direction, since west for me is the exact opposite direction as west in Beijing. This is because their 'fixed points' are fixed only in a rotating frame of reference, and yes, in such a frame, light travels faster west than east, exactly as mandated by SR.  SR could be falsified immediately if the Sagnac effect didn't work.  In a light tube going around the Earth, light has less distance to move in the west direction than in the east direction, so of course the westbound light gets to the moving source/detect faster than the eastbound. The Sagnac effect relies on that fact to detect absolute rotation.

 I think I agree that special relativity predicts this difference in propagation time of light in opposite directions between two points of a rotating frame.

But then a self contradiction of special relativity follows.

If I detect difference in propagation times of light in opposite directions between two points in a closed lab on Earth, this is nothing other than detection of absolute motion (remember Galileo’s ship thought experiment).

But you don't.

I think special relativity predicts it.

If special relativity predicts that the time delay of light is different in the two directions in the first experiment, what is the prediction of special relativity ( SRT) in the second experiment?

Special relativity predicts that the time delay of light is the same in the two directions in the first experiment.

That's easy.  Relative to that inertial frame, light takes the same time to go in either direction since the two mailboxes are both stationary. That's one case. There was another one?

I think a better way to put this is af follows:

 Special relativity predicts difference in propagation times of light in opposite directions between two points on a rotating frame, but this leads to a self contradiction of special relativity. I mean, even if this apparent anisotropy of the speed of light is confirmed experimentally, this will only disprove the very principle of relativity - a self contradiction.

[puppypower]

If you know the red shift then you also know how hot it is
You also know how bright it "looks"  and from that you can work  out the relationship between its size and its distance.
Then you can look at spctral braodening and deduce how fast some bits are moving compared to other. That gives information on teh rotation rate.

You can combine that data with the understanding we have of how stars work and get a good idea about the other characteristics- notably size.


But what's interesting is that you didn't realise they could do that, yet you are prepared to make up stuff like this

The solution is we will try to use space and time; photons, to simulate and estimate the mass. This is two variables; 2-D, used to model 3-D. This is nobody's fault, but it is what we have to deal with.

Why not study science?

Have you or anyone gone to any of the distant stars, to double check to see if this these assumptions are correct? Or am I supposed to take your word for it? It is so much easier being a critic.

As an example, before we sent a probe to Mars, there were many bold assumptions, that did not pan out, after early probes, even though Mars has been close and easy to see for centuries. A spatial illusion is not easy to see through without being able to double check yourself with direct observation. It often comes down to the emperors new clothes, and the fear of going against the grain. I have a high tolerance for the crap that will be dished out if you look outside the box and say the emperor is looking to get a full body tan.

I proposed a GR red shift effect, that should stem from the black hole in the center of our galaxy. All points on the perimeter should see a red shift, of some unknown starting wavelength coming from the black hole as space-time expands from the black hole due to GR.

If we assumed only SR, the black hole would appear to be moving away from every reference on the perimeter, simultaneously, while not actually moving. Fortunately, we are close enough to the black hole and perimeter to double check and know this black hole red shift affect much be a GR red shift and not SR red shift. This is good.

Since our universe appears to be expanding, relative to the galaxies, and since many galaxies have black holes in the center, this black hole GR affect, we see from all points on the perimeter of our galaxy, will also appear as a red shift, in all direction going to beyond our galaxy.  If the scientists in a distant galaxy, where black holes are too far to see, attributed this to a SR red shift, the milky way will appear to be moving away, no matter where on that galaxy you stand. If all galaxies give this GR affect this could appear as an expanding universe relative to galaxies.

This is why 2 variable SR can create a spatial illusion. If we were forced to include mass, the GR red shift would have had to be explored, deeper. But if we settle with 2 out of 3, a spatial illusion would become good enough.

Do we see space-time expanding at any point in any lab? Or do we only see this affect if there are galaxies? I do not know all the details of physics, but I am good at conceptual modeling and seeing through spatial illusions. These often are connected to flawed foundation premises. A sag in a house can often be traced to the basement. Not all scientists wish to get dirty to find them. Most want to stay clean in the bright top floors.

[Bored chemist]

am I supposed to take your word for it?

What you are taking "my" word for is the idea that the laws of physics are the same there as here.
If you don't accept that then there is absolutely nothing you can say about anywhere in the universe where someone hasn't physically gone to check.

I proposed a GR red shift effect, that should stem from the black hole in the center of our galaxy.

Have you been to the centre of the galaxy and checked that GR works there/
Are we expected to take your word for it?

Do you see that the criticism you made of my post applies equally to yours?

It is so much easier being a critic.

You just failed at being a critic...
(because your criticism doesn't make sense in the context of your own post.)

Why not study science?

[Bored chemist]

I think special relativity predicts it.

I don't think that matter much.
Because you didn't do the experiment from inside the box.
You relied on things outside the box like GPS and clocks.

You also seem to have assumes that Silverlight and Marinov are correct. that's very much up for debate.

[Hal (OP)]

It only assumes constant speed of light relative to an inertial frame in flat Minkowskian spacetime, and a rotating frame (nor a straight shot between say Earth and Mars, spinning or not) meets this qualification.

Are you saying that the speed of light is constant in a rotating frame, contradicting what you have been saying ? I don't understand what you said about Earth and Mars either.

[Hal (OP)]

But then a self contradiction of special relativity follows.
...
but this leads to a self contradiction of special relativity.

Another repeat. You've not been able to demonstrate this supposed self contradiction mostly due to lack of any precise description of any hypothetical experiment.

Here is the contradiction, which I mentioned already. Imagine an observer and two light sources in a closed lab at the equator. One point is to the East of the observer and the other point is to the West, with the observer at mid point between the two sources.

In the Earth centered rotating frame, the propagation times of light in the two directions (from the two sources) is different, according to special relativity. This is supported by experiments, such as the GPS Sagnac effect.

But this leads to a contradiction. If an observer in a closed room (lab) detects anisotropy of the speed of light, this can only be due to acceleration, or due to absolute motion, ( remember Galileo's ship thought experiment), regardless of reference frames. But the acceleration of the lab due to Earth's rotation is very small. Therefore, special relativity predicts the Sagnac effect in the Earth centered rotating frame but this in turn leads to violation of the principle of relativity.

There is yet another self -contradiction of special relativity. Consider the observer and the light sources again. This time we analyze the problem relative to the lab frame, not relative to Earth centered frames. Consider two reference frames, S and S'. The observer is at the origin of both frames. S is the (almost) inertial lab frame and S' is the rotating lab frame.

We should be able to use our lab frame because it is almost inertial. If you insist that only the ECI frame should be used, this would violate the principle of relativity.

 Rotation of the lab frame (S' )  will not affect the speed of light since we have assumed that the observer is at the origin of the lab frame. My argument is that a rotating  frame will not affect the speed of light between two points if one of the points is at the origin of the rotating frame. For this particular experiment, S' can be considered inertial.Therefore, special relativity predicts that the Sagnac effect cannot exist in this case - a contradiction.

To avoid clock synchronization problems, if any, we can use light interference experiments. But we can also synchronize  clocks from knowledge of our absolute velocity. ( the Silver tooth experiment)

Moreover, we can make S and S' as inertial as possible by assuming enormously increased radius of the Earth, and the angular velocity decreased by the same factor, to keep the tangential velocity the same.



 

[Halc]

Well at least there is a frame reference this time.

Imagine an observer and two light sources in a closed lab at the equator. One point is to the East of the observer and the other point is to the West, with the observer at mid point between the two sources.

In the Earth centered rotating frame, the propagation times of light in the two directions (from the two sources) is different, according to special relativity. This is supported by experiments, such as the GPS Sagnac effect.

But this leads to a contradiction. If an observer in a closed room (lab) detects anisotropy of the speed of light, this can only be due to acceleration, or due to absolute motion

But it is absolute motion. Rotation is absolute, and they're taking their measurements relative to that rotating frame and measuring exactly what the theory predicts, including the fact that light curves instead of taking straight paths. Were they to compute the speed relative to the lab's (momentarily) inertial frame, they'd get identical times in each direction. They'd not even have to measure anything since the speed is isotropic by premise, not by measurement.

You still haven't made any mention of how exactly these guys in the windowless lab have gone about performing their experiment. It's not like a baseball where you can point a radar gun at something to get its speed. I don't think they have GPS satellites in there with them. The only clue you've given is that they're taking their measurements relative to a rotating frame of reference.

Therefore, special relativity predicts the Sagnac effect in the Earth centered rotating frame but this in turn leads to violation of the principle of relativity.

Principle of relativity applies only to inertial frames and their proper equivalents. It's quite trivial to detect that you're not properly inertial via different behavior of objects around you. And no, a rotating frame is not equivalent to an accelerating one. Sagnac effect is due to rotation, and is not observed in an accelerating frame.

There is yet another self -contradiction of special relativity. Consider the observer and the light sources again. This time we analyze the problem relative to the lab frame, not relative to Earth centered frames.

Fine, but you've not indicated how this will change the experiment since you've given no indication as to exactly how any of these speeds are being measured. If you do it relative to the lab frame, the speed will be identical each way by convention, not by measurement. No measurement will contradict that.

Consider two reference frames, S and S'. The observer is at the origin of both frames. S is the (almost) inertial lab frame and S' is the rotating lab frame.

Our observer is at the center of Earth?  If not, he's not at the origin of the ECI frame.

We should be able to use our lab frame because it is almost inertial. If you insist that only the ECI frame should be used, this would violate the principle of relativity.

I insist on nothing. You chose the ECI frame in your post above, and apparently our lab guys are assuming such a frame in some unspecified way.

Rotation of the lab frame (S' )  will not affect the speed of light

Nonsense. Light speed is completely variable relative to a rotating frame. It can even be negative or any arbitrarily high speed.

since we have assumed that the observer is at the origin of the lab frame.

He is not. He's some 6370 km from it.

My argument is that a rotating  frame will not affect the speed of light between two points if one of the points is at the origin of the rotating frame.

Even if the observer is at the origin, this is false. Simple geometry will say otherwise. Not even Newton would agree with your assertion.

To avoid clock synchronization problems, if any, we can use light interference experiments. But we can also synchronize  clocks from knowledge of our absolute velocity. ( the Silver tooth experiment)

If you want to take measurements relative to some random frame which Silvertooth pulls out of its arse (or any random number generator for that matter), then the speed will be locally constant in any direction relative to that frame, and your assertions about west and east light being different fall apart, and SR is still not contradicted.

Moreover, we can make S and S' as inertial as possible by assuming enormously increased radius of the Earth, and the angular velocity decreased by the same factor, to keep the tangential velocity the same.

For what purpose?  The difference in measurements between the two frames will still be the same. You're slowing the spin by X but then increasing the radius by X, which serve to cancel any observed differences.

[Hal (OP)]

Rotation of the lab frame (S' )  will not affect the speed of light

Nonsense. Light speed is completely variable relative to a rotating frame. It can even be negative or any arbitrarily high speed.

My argument is that a rotating  frame will not affect the speed of light between two points if one of the points is at the origin of the rotating frame.

Even if the observer is at the origin, this is false. Simple geometry will say otherwise. Not even Newton would agree with your assertion.

I was actually saying that a rotating frame will not affect the speed propagation time of light between two points if one of the points is at the origin.

I will respond to your other points also.

[Hal (OP)]

You still haven't made any mention of how exactly these guys in the windowless lab have gone about performing their experiment. It's not like a baseball where you can point a radar gun at something to get its speed. I don't think they have GPS satellites in there with them. The only clue you've given is that they're taking their measurements relative to a rotating frame of reference.

They take measurements relative to the rotating lab frame with the observer/detector at the origin. Since the observer is at the origin of the rotating frame, there should be no difference in the time of flight of  the counter-propagating light beams.

The argument is that if there is difference, it is because of absolute motion. Even clock synchronization is not a problem here, because the center of the rotating frame is (almost) inertial.

[Hal (OP)]

But it is absolute motion. Rotation is absolute, and they're taking their measurements relative to that rotating frame and measuring exactly what the theory predicts,

The experiment cannot physically measure / sense rotation (ω), it can only measure ωR which is linear velocity.

Suppose that at first the observer in the closed lab knows that he/she is moving in a circular path around a center, and knows his R and ω. Then the radius of the circle was increased and ω decreased by the same factor, without the observer's knowledge, so that the tangential velocity remains the same. There is no way the observer can tell their new angular velocity by using this experiment. This means that the difference in time of the light beams is because of linear velocity.

If this experiment cannot measure ω,this leads to the conclusion that the observed anisotropy in the speed of light can only be due to linear velocity.

[Halc]

I was actually saying that a rotating frame will not affect the speed propagation time of light between two points if one of the points is at the origin.

I have to disagree.  The time between two events (points in spacetime) is completely frame dependent, and thus the choice of frame, rotating or otherwise affects the propagation time of light between them, by definition.  A frame is an abstract coordinate system, not anything physical. One can assign any coordinates to each event that they like, and that choice of coordinates is what determines the difference in time between events.

You cannot begin to make sense with your posts if you don’t understand the difference between physical things and abstract ones. Coordinate systems and everything defined by them (such as time or distance between physical events) are entirely abstract choices, not something that is real or not.
I know of no coordinate system that maps all events in the universe, so there is no known candidate for a coordinate system that might correspond to a physical arrangement.

They take measurements relative to the rotating lab frame with the observer/detector at the origin.

There is only one observer detector? What’s at the other end of the lab then? Again, we have a lab at the center of the Earth?  The south pole perhaps at least? There’s no sending a signal east or west from there you know. You’re changing the experiment, which is fine since you’ve never really had them actually perform any measurements anyway. All you had them do is assume a rotating coordinate system which can be done without actually being there.

Anyway, you’ve made the mistake again.  This frame you’ve selected defines the time between the events. That time isn’t something measured, it is something assumed by the choice of frame.

Even clock synchronization is not a problem here, because the center of the rotating frame is (almost) inertial.

No it isn’t. The coordinate systems are completely different, and it is these very differences that are driving your argument, so you cannot say that they’re the same just by making the speeds so slow that it takes more digits of precision to express the differences between one abstract choice of coordinates or another.
It takes no fancy experiment with atomic clocks to detect rotation. It can be done with a pair of rocks in a frictionless environment, but my pocket ring interferometer will also suffice.

The experiment cannot physically measure / sense rotation (ω), it can only measure ωR which is linear velocity.

If the observer is held stationary in the rotating frame, it is trivial to physically measure proper rotation (ω) which is absolute. Under special relativity, R can also be measured. It is impossible to measure linear velocity which is entirely abstract coordinate-system dependent and thus only an abstract assumption, not a physical thing that can be measured. ωR can be computed, but it only yields a value relative to the rotating frame, the linear motion of which is completely an abstract assumption.
If your (yet to be described) experiment does not measure it, then they’re not trying to measure their (proper) angular velocity which can be directly measured.

Suppose that at first the observer in the closed lab knows that he/she is moving in a circular path around a center, and knows his R and ω.

One does not need to suppose this. Proper R and ω can be measured, but the velocity of said center cannot be measured, and hence is an arbitrary abstract choice. In all but one of those choices, the path taken by this observer is not a circle but rather a combination of a helix and cycloid.

Then the radius of the circle was increased and ω decreased by the same factor, without the observer's knowledge

They can measure that, so they’d know.

There is no way the observer can tell their new angular velocity by using this experiment.

You haven’t described an experiment. They could tell if they chose to measure their angular velocity and radius.

If this experiment cannot measure ω,

I can run a tape measure over the length of my computer screen here and measure its size. That experiment cannot measure ω. The failure of that experiment to measure ω does not imply that ω cannot be measured.

the observed anisotropy in the speed of light

Any anisotropy assumed is due to the abstract coordinate system chosen. The speed of light in a particular direction is assumed and is not something that can be measured, despite your assertions otherwise.

[Hal (OP)]

I have to disagree.  The time between two events (points in spacetime) is completely frame dependent, and thus the choice of frame, rotating or otherwise affects the propagation time of light between them, by definition. 

They take measurements relative to the rotating lab frame with the observer/detector at the origin.

There is only one observer detector? What’s at the other end of the lab then? Again, we have a lab at the center of the Earth?  The south pole perhaps at least? There’s no sending a signal east or west from there you know.

The experiment cannot physically measure / sense rotation (ω), it can only measure ωR which is linear velocity.

If the observer is held stationary in the rotating frame, it is trivial to physically measure proper rotation (ω) which is absolute.

Then the radius of the circle was increased and ω decreased by the same factor, without the observer's knowledge

They can measure that, so they’d know.

There is no way the observer can tell their new angular velocity by using this experiment.

You haven’t described an experiment. They could tell if they chose to measure their angular velocity and radius.

If this experiment cannot measure ω,

I can run a tape measure over the length of my computer screen here and measure its size. That experiment cannot measure ω. The failure of that experiment to measure ω does not imply that ω cannot be measured.

This time you invoked relativity.

Classically, the time of propagation between two points in a lab on the surface of the Earth is constant independent of lab rotation if one of the points is at the origin of the lab inertial frame.

There is no lab at the center of the Earth. The lab is on the surface of the Earth. We are only analyzing the experiment in the ECI frame and then in the  inertial lab frame.

I was saying that the observer cannot know the ω of his lab by this experiment which only measures the time difference between the light pulses. If rotation was the fundamental cause of the effect observed, the observer would know his ω from this experiment alone.

Trivially, a physicist would not conclude that rotation is the fundamental cause of the effect observed just because he can measure rotation by other means. He may as well hypothesize that temperature is the cause because he can measure the temperature. Ultimately, it is experiments and the scientific method that decide. The physicist, naturally, starts by hypothesizing that rotation is the fundamental caused. But when he did another experiment with a device having larger radius but the same ω, he expected the same time difference but obtained a larger one. After playing with the ω and R variables, he discovered that the fundamental cause is ωR.

[Halc]

Classically, the time of propagation between two points in a lab on the surface of the Earth is constant independent of lab rotation if one of the points is at the origin of the lab inertial frame.

That wasn't even true in 19th century classic physics. Endlessly repeating this statement doesn't make it less wrong.

There is no lab at the center of the Earth. The lab is on the surface of the Earth. We are only analyzing the experiment in the ECI frame and then in the  inertial lab frame.

ECI frame is an inertial frame. ECEF is a rotating frame. The origin of both is the center of Earth since 'EC' stands for 'Earth Centered'.  The origin of a non-Earth centered rotating coordinate system needs to at least be at the axis of rotation, say the south pole, where the direction of 'west' is meaningless.

I was saying that the observer cannot know the ω of his lab by this experiment which only measures the time difference between the light pulses.

Just like I cannot measure the weight of my car with a tape measure. It doesn't imply that the weight (or ω) cannot be measured.
It not possible to measure physical time difference between spatially separated events, especially with an experiment that you refuse to describe. It is only possible to assign a coordinate system that defines that elapsed time, an abstract exercise, not a physical measurement.
To measure the time between spatial locations A to B, you can either assume the one-way speed of light is c and just use a tape measure to see the separation of A and B. The time is then simply distance/c, easy, and no fancy equipment (not even a clock) required.
If you don't assume light speed is c relative to any inertial frame, then you cannot use light to synchronize any theoretical equipment. You need to use other means.

If rotation was the fundamental cause of the effect observed, the observer would know his ω from this experiment alone.

You cannot know anything from an unspecified experiment. You propose to time light between two spatially separated locations in the lab, but have specified no means to actually do that. It cannot be done. People have tried. You can time the round trip if there's a mirror at the far end. That's been done.

Trivially, a physicist would not conclude that rotation is the fundamental cause of the effect observed just because he can measure rotation by other means.

That's right. The fundamental cause is his abstract assignment of the time at the two locations in question, not anything that is observed.

He may as well hypothesize that temperature is the cause because he can measure the temperature.

Funny you bring that up. The Silvertooth experiment was reproduced and found to be an expensive way to measure temperature. The guy didn't put his setup in a temperature controlled lab so the daily variation the thing measured was the temperature swing between night and day.  See the links posted early in this thread.

Fun fact:
In a rotating frame (ECEF for instance), there is an interesting property beyond a certain radius. A light pulse emitted from a sufficient distance (30 AU say) and aimed in the correct direction will take a curved spiral path (Coriolis effect), slowing all the way (centrifugal effect), and finally stopping altogether, only to turn around and return to the emission point along the exact same path in reverse. Seems unintuitive, but there's nothing in physics (not even classical physics) that forbids it.

[Hal (OP)]

Classically, the time of propagation between two points in a lab on the surface of the Earth is constant independent of lab rotation if one of the points is at the origin of the lab inertial frame.

That wasn't even true in 19th century classic physics. Endlessly repeating this statement doesn't make it less wrong.

Correction: I need to qualify what I mean by 'classically'. I was just referring to non-relativistic physics.
So the lab I am referring to is a lab that is at absolute rest (w.r.t translational motion) but rotating. Such a lab is equivalent to an inertial frame in that the speed of light is constant in both, according to the respective theories.                                       If the lab is both in absolute translational motion and rotating, the time taken by light between any two points in the lab cannot be constant.