Age of Universe relative to what?

[my_wan]

I want to respond to this again, and add two more objections:

Your method implicitly assumes Einstein synchronization, i.e. that the one-way speed of light equals the two-way speed, so it is actually measuring the two-way speed.

1) The usual reason given for the difficulty in measuring the one way light speed is the need for synchronizing a pair of clocks. So where is the implicit second clock in this setup? In fact the second clock is not a clock but a distance, and it is this relationship between clocks and distance that is in question. Hence to say the distance is an implicit clock requires assuming that a distance really is a valid clock, as per relativity, in order to claim a second clock. Yet if a distance does not covary with clocks as relativity dictates then this test will show it in the curve ratios. Hence I have not assumed Einstein synchronization.

2) Mathematically I am only assuming Newtonian synchronization and an infinite speed of light. Relativity alone doesn't require me to assume any more than this. Therefore, the assumption of Einstein synchronization is neither contained in the geometry or mathematics, nor is t=0 predefined for any pair of clocks.

 

[Q-reeus]

Quite some time back I dabbled with the idea of detecting a one-way c variation based on differential phase-shift in adjacent optical fibers (no clocks). Never pursued it though once the realization came what detecting an actual one-way c anisotropy, by any arrangement, implies: https://www.physicsforums.com/showpost.php?p=3080684&postcount=64 - see last paragraph. Physics would be (inertial) frame dependent - period. I hesitate to rule that out absolutely, but it does tend to make one think rather more carefully.

 

[ghwellsjr]

Well now Q-reeus let the cat out of the bag. I was going to try to understand your setup, my_wan, but it really doesn't matter. Let's stipulate that your apparatus will work as you believe it will. Now the question is: will your apparatus ever be able to measure a one-way speed of light that differs from c?

For example, let's say that you use it to measure the light from the two stars in a binary star arrangement where one of them is known to be traveling toward you and the other one is traveling away from you. Don't you agree that any apparatus will measure an equal speed for both light beams, correct? And your apparatus will measure that speed to be c, correct? Now let's say that you are able to send one copy of your apparatus at a high speed toward the binary star and a second one at a high speed in the opposite direction away from the binary star. Don't you agree that both of these will also measure c as the speed of the light coming to them from the pair of distant stars in the binary star system?

 

[my_wan]

Quite some time back I dabbled with the idea of detecting a one-way c variation based on differential phase-shift in adjacent optical fibers (no clocks). Never pursued it though once the realization came what detecting an actual one-way c anisotropy, by any arrangement, implies: https://www.physicsforums.com/showpost.php?p=3080684&postcount=64 - see last paragraph. Physics would be (inertial) frame dependent - period. I hesitate to rule that out absolutely, but it does tend to make one think rather more carefully.

I'm quiet aware of the consequences, which is why I expressed a lack of interest before defending the workability of the method. This is also behind my objection of calling an empirically equivalent model somehow physically distinguishable, of which LET is an example but other anisotropic models can also have similar physically moot content. Also why I said the only people it would have any bearing on is the Einstein is wrong crowd.

The notion that it would actually measure anything unexpected is far fetched to say the least. On the other hand theories like LET are no strictly invalidated. Just made moot by the lack of any empirical point or expanded domain of applicability. That could at least in principle change though.

Well now Q-reeus let the cat out of the bag. I was going to try to understand your setup, my_wan, but it really doesn't matter. Let's stipulate that your apparatus will work as you believe it will. Now the question is: will your apparatus ever be able to measure a one-way speed of light that differs from c?

Q-reeus didn't say anything I didn't already explain in this thread, after expressing a general lack of interest in actually seeing this experiment performed for that very reason. When you ask: "will your apparatus ever be able to measure a one-way speed of light that differs from c?" That depends on what you mean by differ. If you mean differ by establishing an "absolute" speed C, then no, as I already explained about relational variables. If measure a differing relation value C different than what we assume it to be, then yes if and only if it does differ relationally. And yes if space and time covary differently from what Relativity predicts. I can't even measure my nose without a relational value to measure it against with or without relativity theory, so that's nothing new.

By the way, we already know that in some sense GR predicts that the speed C cannot be an absolute constant. Einstein spent a significant amount of time in one of his books on GR making this point clear. So theories in which the speed of light is not constant in relation to some choice of metric internal to the model does nothing out of the ordinary to what is contained in GR. The only problem is that people keep mixing coordinate choices in as if it has absolute physical meaning.

 

[ghwellsjr]

It was in the link that Q-reeus provided that I meant he let the cat out of the bag.

I have no idea what you are trying to say. I ask a simple question: will your apparatus ever measure a value other than c and you say it depends on what I mean by differ. The value of c is 299,792,458 meters per second. Will your apparatus ever measure a value other than 299,792,458 meters per second? I'm assuming that you can build an apparatus that has a digital readout on it that can display the measured value. I should stipulate that we are talking about an inertial measurement in vacuum--I should hope that goes without saying.

So now that you know what I mean by differ, will your apparatus ever measure a value for the one-way speed of light that differs from c?

 

[my_wan]

It was in the link that Q-reeus provided that I meant he let the cat out of the bag.

I have no idea what you are trying to say. I ask a simple question: will your apparatus ever measure a value other than c and you say it depends on what I mean by differ. The value of c is 299,792,458 meters per second. Will your apparatus ever measure a value other than 299,792,458 meters per second? I'm assuming that you can build an apparatus that has a digital readout on it that can display the measured value. I should stipulate that we are talking about an inertial measurement in vacuum--I should hope that goes without saying.

So now that you know what I mean by differ, will your apparatus ever measure a value for the one-way speed of light that differs from c?

To say that the "value of c is 299,792,458 meters per second" is awfully simplistic when many models have differing definition of both what constitutes a "meter" and what constitutes a "second". However, measuring the one way speed of light in a Newtonian sense it does. How you want to interpret that in the context of some model is not my problem.

The red letters: where you say digital readout. Apparently I failed to get even the basics of the measurement across. To perform this measurement requires at least dozens of measurements if not hundreds. A different measurement for every point plotted on a curve. To get a single measurement for a digital readout not only requires extreme accuracy with a highly accurate known light source intensity, but also requires making all the assumptions I was falsely accused of making. If I'm allowed to make all those assumptions that SR is in fact empirically valid in this respect then it might at least in principle be possible to read it on a digital readout, with enough accuracy and a predefined reference light source. Probably not technically feasible though.

 

[Dale]

Basically Born rigidity as he was the first to introduce the notion.

OK, I am certainly aware of Born rigidity. I have no issues with you specifying Born-rigid rotation as long as the angular velocity is fixed at one specific RPM.

However, Born-rigid motion does not in any way negate length contraction. The issue is not rigidity, it is the anisotropy of length contraction. If the one-way speed of light is anisotropic then length contraction is also anisotropic. This causes geometrical distortions even in a Born-rigid device such that the predicted experimental result is the same as for standard Einstein synchronization. You cannot measure anything other than what you assume.

I did not assume Einstein synchronization was uniquely valid. I do not assume that relativity claims that Einstein synchronization is uniquely valid. I only assume it is one of an unknown number of equally valid solutions.

OK, then by this do I correctly understand that you now agree that it is impossible to measure the one-way velocity of c without assuming it via your synchronization convention?

 

[Q-reeus]

Having now gone over my wan's proposal in #61 and later expounded, I see no basic objection to a one-way differential detection per se. Do one run as described, then rotate the apparatus 180 degrees about an axis normal to the pipe rotation axis, and in principle you can detect a difference in c in two opposite directions. Problem is more refined versions have attempted essentially that with nothing positive yet to show: e.g http://arxiv.org/abs/1103.6086 - which seems basically similar in principle to my wan's. One team claiming positive results uses a quite different technique: http://arxiv.org/abs/astro-ph/0604145v1 - but note nothing more has been heard from them for several years now! A fairly up to date list of many different one-way (and two-way) tests is at http://arxiv.org/abs/1011.1318 Another not so up to date list is at http://www.phys.ncku.edu.tw/mirrors/physicsfaq/Relativity/SR/experiments.html

 

[ghwellsjr]

Having now gone over my wan's proposal in #61 and later expounded, I see no basic objection to a one-way differential detection per se. Do one run as described, then rotate the apparatus 180 degrees about an axis normal to the pipe rotation axis, and in principle you can detect a difference in c in two opposite directions.

According to what principle? It certainly is not in accord with the principle of relativity.

 

[my_wan]

According to what principle? It certainly is not in accord with the principle of relativity.

Which principle of relativity would that be? The test itself is expected to be null, or more specifically returning a constant value of C regardless of alignment in space. Hence a null result would mean it is precisely in accord with the principle of relativity. Only if you presume the one way speed of light really is different can you suppose anything is not in accord with the principle of relativity. But that would be a consequence of the result, not the test.

 

[my_wan]

Having now gone over my wan's proposal in #61 and later expounded, I see no basic objection to a one-way differential detection per se. Do one run as described, then rotate the apparatus 180 degrees about an axis normal to the pipe rotation axis, and in principle you can detect a difference in c in two opposite directions. Problem is more refined versions have attempted essentially that with nothing positive yet to show: e.g http://arxiv.org/abs/1103.6086 - which seems basically similar in principle to my wan's. One team claiming positive results uses a quite different technique: http://arxiv.org/abs/astro-ph/0604145v1 - but note nothing more has been heard from them for several years now! A fairly up to date list of many different one-way (and two-way) tests is at http://arxiv.org/abs/1011.1318 Another not so up to date list is at http://www.phys.ncku.edu.tw/mirrors/physicsfaq/Relativity/SR/experiments.html

The setup in http://arxiv.org/abs/1103.6086 is sufficiently close to what I proposed to qualify the general idea, and expressed in reference [7] (Phys. Rev. D 45, 403–411 (1992)) therein. It summed up the point quiet well with:

Will[/PLAIN] [7] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities.”

I was worried that introducing a second leg, via beam splitters as done in http://arxiv.org/abs/1011.1318 would reintroduce the synchronization problem wrt the pair of detectors. So I was curve fitting lots of measurements to fit the speed c as some factor of diameter. However, after skimming through the paper I see that concern was unwarranted.

http://arxiv.org/abs/astro-ph/0604145 is very interesting for reason unrelated to an anisotropic speed c. It was after all a Doppler shift, not a speed of c carrying the Doppler information. To call it a measure of an anisotropic speed c is tantamount to claiming the Doppler shift measured by police radar is a measure a light speed anisotropy induced by the speeders car.

 

[my_wan]

OK, I am certainly aware of Born rigidity. I have no issues with you specifying Born-rigid rotation as long as the angular velocity is fixed at one specific RPM.

However, Born-rigid motion does not in any way negate length contraction. The issue is not rigidity, it is the anisotropy of length contraction. If the one-way speed of light is anisotropic then length contraction is also anisotropic. This causes geometrical distortions even in a Born-rigid device such that the predicted experimental result is the same as for standard Einstein synchronization. You cannot measure anything other than what you assume.

Born rigidity is not what negates the length contraction, it is merely a practical prerequisite for quantitatively defining length contraction in a given circumstance. Herglotz-Noether theorem is what negates the need for quantitative concerns about the effects of length contraction when defining raw uninterpreted measurement relations, i.e., raw uninterpreted experimental results.

It seems that you have come to the same conclusion by way of geometrical distortions that undo the very measurement being attempted. That is in fact the whole point of the Herglotz-Noether theorem here, and is not limited to just Einstein synchronization but also applies to Galilean synchronization in this particular context. That's what makes LET physically defensible.

The problem, as I have already stated, is that by claiming these types of distortions reintroduce absolute speed variances implies that coordinate choices have absolute meaning. I have no doubt that LET is physically valid, and even less doubt that SR is physically valid. Any attempt to try to prove otherwise is tantamount to trying to test the physical difference between this and that coordinate choice. The problem when models are created that different in these types of coordinate transforms is that people then often think this coordinate choice has some kind of uniquely valid reality.

OK, then by this do I correctly understand that you now agree that it is impossible to measure the one-way velocity of c without assuming it via your synchronization convention?

By that if you mean do I expect a null result given the experiment I proposed, absolutely! Neither would such a null result invalidate LET, nor SR. The only thing worth bothering with even trying to detect is physically differing theories, not theories that merely operate differently solely on the basis of a differing coordinate choice. LET is SR as defined by the perspective of a particular choice of a Galilean frame. SR makes no claims to the contrary.

 

[ghwellsjr]

According to what principle? It certainly is not in accord with the principle of relativity.

Which principle of relativity would that be?

That would be Einstein's first postulate:

the unsuccessful attempts to discover any motion of the Earth relatively to the “light medium,” suggest that the phenomena of electrodynamics as well as of mechanics possesses no properties corresponding to the idea of absolute rest. They suggest rather that, as has already been shown to the first order of small quantities, the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good.1 We will raise this conjecture (the purport of which will hereafter be called the “Principle of Relativity”) to the status of a postulate

--from the second paragraph of Einstein's 1905 paper introducing Special Relativity. See also the beginning of section 2.

The test itself is expected to be null, or more specifically returning a constant value of C regardless of alignment in space. Hence a null result would mean it is precisely in accord with the principle of relativity. Only if you presume the one way speed of light really is different can you suppose anything is not in accord with the principle of relativity. But that would be a consequence of the result, not the test.

The principle of relativity guarantees not that the test is null or the result is null but that there cannot be a test. It is not possible to measure the one-way speed of light, meaning that we cannot determine how long it takes for light to propagate between two points.

Consider this: in any inertial Frame of Reference, the one-way speed of light is defined to be c. That means that for an observer at rest in that frame, the one-way speed of light is c and because of this, the stationary coordinate clocks remote to that observer can be synchronized. But for an observer moving in that frame, the one-way speed of light, that is, the propagation time for light is not the same in different directions, which is why we have the relativity of simultaneity, which is why we cannot, even in principle, measure the one-way speed of light. The information we need to make the measurement simply is not available to us. The principle of relativity guarantees that.

 

[my_wan]

We seem to be circling around semantics mostly, but there is a fundamental point here that the principle of relativity is a product of coordinate independence.

The principle of relativity guarantees not that the test is null or the result is null but that there cannot be a test. It is not possible to measure the one-way speed of light, meaning that we cannot determine how long it takes for light to propagate between two points.

There is a test here. The test ask if the principle of relativity is a strictly valid postulate. Thus when you say the principle of relativity "guarantees", well then do the test and see if the "guarantee" holds. Yet somehow I was the one accused of presupposing the validity of SR in order to get the results?

Why might this be interesting to anybody (not me)? Because it has been said that measuring a one way speed of light was impossible as a result of the need to synchronize a pair of clocks. This is wrong, and I've learned that others have already demonstrated that here. Yet SR, as expected, remains valid as does LET.

The thing is that if you accept that a coordinate choice is not in itself a physical choice (coordinate independence) then you get the same effect without resorting to any dependence on the principle of relativity.

Consider this: in any inertial Frame of Reference, the one-way speed of light is defined to be c. That means that for an observer at rest in that frame, the one-way speed of light is c and because of this, the stationary coordinate clocks remote to that observer can be synchronized. But for an observer moving in that frame, the one-way speed of light, that is, the propagation time for light is not the same in different directions, which is why we have the relativity of simultaneity, which is why we cannot, even in principle, measure the one-way speed of light. The information we need to make the measurement simply is not available to us. The principle of relativity guarantees that.

So here you have used the Galilean coordinates of one frame o to say that the Galilean coordinates of another frame o' does not match, $o \neq o'$. Yet LET speaks in terms of the coordinate choice in which it is defined. In terms of coordinate independent this is tantamount to saying I have a theory that says 1 inch is 2.54 cm, such that $1 \neq 1'$. Then arguing over whether we can measure the difference between 1 inch and 2.54 cm.

Einstein also brought up mechanics in the very 1905 quote you provided, where it said:

[...]suggest that the phenomena of electrodynamics as well as of mechanics possesses no properties corresponding to the idea of absolute rest.

In fact it was very well understood, apparently more so than today, prior to Einstein that mechanical variables did not have absolute values, meaning, or locations, only relational ones. Thus that simple statement is a claim that electrodynamics is a mechanical property.

This is trivially demonstrated by asking which of two meteors with a relational kinetic energy between them is the kinetic energy actually located at? Depends on which coordinate choice you use, but a coordinate choice is not in itself a physical thing. Hence that very quote validates the consistency of LET before ever even being published. Hence the notion that LET makes claims not already contained in SR is just plain wrong. Yet people still keep piling on $o \neq o'$as if it means that 1 inch can't mean 2.54 cm. Mechanistically, and independent of the principle of relativity, the location of kinetic energy is a function of the non-physical coordinate choice, just as the notion of a location itself, and distance derived thereof, is in SR. What the principle of relativity provided was an operational definition of coordinate independence under which laws could be given a coordinate independent form. It does not invalidate or quantitatively disagree with the coordinate dependent form of the same laws.

Hence the Einstein is wrong, and LET must be right, crowd is defining a false dichotomy. SR MUST be valid in order for LET to be valid in order for Einstein's claim that electrodynamics is mechanics to be valid. The only reason I bothered posting the one way speed c post was because it has been falsely said that the reason it couldn't be measured was due to the need to synchronicity two clocks. If you thought I was trying to make a experimental distinction between LET and SR I refuted that way back. Yet any model that does covary space and time differently from SR is detectable in principle.

 

[my_wan]

I should stipulate that we are talking about an inertial measurement in vacuum--I should hope that goes without saying.

I want to come back to this because we tend to assume it a priori, since it makes things easier to conceptualize, even though GR doesn't allow this simplification. A couple of quotes to avoid my own explanation:

The[/PLAIN] speed of light is constant only in the absolute space-time frame, which is also called the Newtonian rest frame.

So,[/PLAIN] it is absolutely true that the speed of light is _not_ constant in a gravitational field [which, by the equivalence principle, applies as well to accelerating (non-inertial) frames of reference].

Here I want to describe a situation where restrictions to local inertial measurements do not allow us to escape this simplification. This results from the fact that in GR time dilation is the result of depth of field, rather than gravitational acceleration alone.

If you have a massive hollow sphere then inside this sphere time dilation, relative to a far removed observer, will remain slowed to that on the surface. Yet, for an observer in this sphere, there no gravitational acceleration anywhere within the sphere. The spacetime inside is effectively flat and inertial.

Here's the problem. We know that $c = \Delta x/\Delta t$ such that the spacetime interval $\Delta s^2 \equiv -\Delta t^2+\Delta x^2$ is the actual constant. Now in this effectively flat region of inertial space we know that $t \neq t'$ relative to another far removed comoving flat inertial space such that the velocity $c \neq c'$. This in spite of both spaces being both effectively flat and inertial, and two comoving observers in these respective regions can share a constant relative distance, yet still we have, as in GR, $c \neq c'$.

Can we presume that the Universe as a whole has a constant gravitational depth? Possibly in principle, but extremely doubtful observationally or even a priori. Could the relativity of simultaneity then produce observational effects not otherwise locally observable?

 

[ghwellsjr]

We know that $c = \Delta x/\Delta t$ such that the spacetime interval $\Delta s^2 \equiv -\Delta t^2+\Delta x^2$ is the actual constant.

Actually the spacetime interval is $\Delta s^2 \equiv -c^2\Delta t^2+\Delta x^2$.

 

[ghwellsjr]

We seem to be circling around semantics mostly, but there is a fundamental point here that the principle of relativity is a product of coordinate independence.

The principle of relativity is not Einstein's Theory of Special Relativity. It's just his first postulate. The principle of relativity is also the first (assumed) postulate of LET. What distinguishes LET and SR is their respective second postulates. LET assumes (which is the same as postulates) that the propagation of light is c only in one inertial state of motion, the rest state of the ether. SR postulates that light propagates at c in any inertial state of motion. There can be no test or measurement to choose between the validity of these two postulates. Any test that would claim to indicate that light propagates at c in all directions and in all states of inertial motion will have a built-in assumption that presumes SR's second postulate. Any test that would claim to indicate that light propagates at different speeds in different directions and/or in different states of inertial motion will have a built-in assumption that presumes LET's second postulate. Any claim that there can be such a test is a claim that denies the validity of the first postulate and would also deny the validity of both SR and LET because both share the same first postulate.

 

[my_wan]

Thanks for the correction.

The principle of relativity is not Einstein's Theory of Special Relativity. It's just his first postulate.

I wouldn't necessarily boost an assumption to a postulate. I can assume the kinetic energy of two meteors on a collision course is contained in the meteor that is approaching the meteor I am standing on. That is neither a postulate nor gets me in any mathematical trouble with quantifying what's about to happen. In fact the fundamental mistake here is to assume that just because my equation presumptively associated the this energy with one of the two meteors entails a postulate is the problem with the whole Einstein is wrong line. Einstein did not associate velocity-vectors with points in a vacuum. LET attempted a perfectly reasonable extension which did. It is not the model LET attempted that is a problem. It is this boost in a LET coordinate choice to the status of a postulate which destroys validity. The validity of this "postulate" is destroyed by the same issue involved with trying to experimentally determine which meteor "really" contains the kinetic energy. Drop this "postulate" to a mere coordinate choice, as demanded by the simplistic mechanics of a pair of rocks, and the validity issues of LET goes away, and instead merely justifies SR. Once you accept that the differing speed c, as defined by LET, is the product of a coordinate choice rather than a relational physical state then LET also demands that the speed of light is constant wrt any given Galilean frame, in the same way SR claims it to be. This is evidenced by the fact that it provides no observable distinctions.

The principle of relativity is also the first (assumed) postulate of LET. What distinguishes LET and SR is their respective second postulates. LET assumes (which is the same as postulates) that the propagation of light is c only in one inertial state of motion, the rest state of the ether. SR postulates that light propagates at c in any inertial state of motion. There can be no test or measurement to choose between the validity of these two postulates. Any test that would claim to indicate that light propagates at c in all directions and in all states of inertial motion will have a built-in assumption that presumes SR's second postulate. Any test that would claim to indicate that light propagates at different speeds in different directions and/or in different states of inertial motion will have a built-in assumption that presumes LET's second postulate. Any claim that there can be such a test is a claim that denies the validity of the first postulate and would also deny the validity of both SR and LET because both share the same first postulate.

Promoting a coordinate choice to the status of a postulate obviously demands a varying speed of light. Much like I showed how relativity provides a method of defining $c \neq c'$. It also demands that you explain which meteor the kinetic energy is really contained in. It's simply absurd to hold a coordinate choice up to the status of a postulate, and LET works better without it than with it. Even today classical thermodynamics is rife with so called extensive properties (state variables) in which the mean field limits which define them are inextricably dependent on a 'proper' Galilean frame choice. This coordinate choice promoted to "postulate" creates an insidious false dichotomy that goes well beyond SR and LET.

 

[ghwellsjr]

I take it you don't agree with Einstein's position in his 1905 paper introducing SR?

 

[my_wan]

I was trying to work around a latex issue a few post back that apparently is only a problem with chrome. Figures showing up in strange places.

 

[my_wan]

I take it you don't agree with Einstein's position in his 1905 paper introducing SR?

WOW! After all that explaining why the SR version is superior!

 

[ghwellsjr]

I take it you don't agree with Einstein's position in his 1905 paper introducing SR?

WOW! After all that explaining why the SR version is superior!

Do you agree with this statement:

If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions of the hands which are simultaneous with these events. If there is at the point B of space another clock in all respects resembling the one at A, it is possible for an observer at B to determine the time values of events in the immediate neighbourhood of B. But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an “A time” and a “B time.” We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.

 

[my_wan]

Do you agree with this statement:

If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions of the hands which are simultaneous with these events. If there is at the point B of space another clock in all respects resembling the one at A, it is possible for an observer at B to determine the time values of events in the immediate neighbourhood of B. But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an “A time” and a “B time.” We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.

Of course I agree. Also note what I marked in red. This indicates that we are of course naturally talking about a definition, not a uniquely valid definition but simply a valid definition. Just like coordinate choices are non-unique but valid definition of metrics, as is which meteor the kinetic energy is located at.

 

[ghwellsjr]

Well, then, I'm wondering why you made this statement:

It is also possible to measure the one way speed of light...

 

[Dale]

That's what makes LET physically defensible.

I don't think that LET is on-topic for this thread. However, I am in agreement with the remainder of your response.

 

[Dale]

Because it has been said that measuring a one way speed of light was impossible as a result of the need to synchronize a pair of clocks. This is wrong, and I've learned that others have already demonstrated that here.

Here is where you and I disagree. The definition of the synchronization convention and the definition of the one-way speed of light are the same thing.

Suppose you have a flash bulb and a ring of detectors at some fixed distance d away from them. The flash bulb goes off at t=0 and the detectors each detect a flash. When does each detector detect the flash? If they all detect them at the same time, t=d/c, then the one way speed of light is c and they detect them simultaneously. If they detect at different times, then they are not simultaneous and the speed of light is not c for each path. The one way speed of light any your synchronization process are the same thing.

Your claims to the contrary are incorrect.

 

[my_wan]

However,[/PLAIN] Will [7] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities.” Hence the synchronization is irrelevant for our one-way speed of light test since we express our results in terms of physically measurable quantities.

That's why I said it. Already said that to.

 

[my_wan]

Here is where you and I disagree. The definition of the synchronization convention and the definition of the one-way speed of light are the same thing.

Suppose you have a flash bulb and a ring of detectors at some fixed distance d away from them. The flash bulb goes off at t=0 and the detectors each detect a flash. When does each detector detect the flash? If they all detect them at the same time, t=d/c, then the one way speed of light is c and they detect them simultaneously. If they detect at different times, then they are not simultaneous and the speed of light is not c for each path. The one way speed of light any your synchronization process are the same thing.

Your claims to the contrary are incorrect.

I don't have a flash period, I have a light on 100% of the time. Neither do I have a t=0 anywhere period, or t= anything. Nor is there any pair of events that I measure for comparison. The pure geometry does all that for me, and if you want to make a case about it then respond to what I already responded to. Instead of this t= strawman when clearly i do not label t= to say what RPM something is rotating. I don't care when its rotating nor when the light was on.

 

[ghwellsjr]

Originally Posted by http://arxiv.org/abs/1103.6086
However, Will [7] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities.” Hence the synchronization is irrelevant for our one-way speed of light test since we express our results in terms of physically measurable quantities..

That's why I said it. Already said that to.

OK, now I understand what's going on. That paper, which you said, "is sufficiently close to what I proposed to qualify the general idea" is not talking about measuring the value of the one-way speed of light or measuring the propagation time of the light traveling in one direction. Rather it is measuring the constancy of the speed of light which does not require synchronized clocks.

The wikipedia article on "The one-way speed of light" that I encouraged you to read back in post #60 makes this clear. If you look at the section entitled "Experiments that can be done on the one-way speed of light" you will see that "it is possible to carry out experiments that measure a change in the one-way speed of light". As the article points out, "In such experiments the clocks may be synchronized in any convenient way, since it is only a change of speed that is being measured." In other words, it doesn't matter if the clocks are synchronized at all or even if actual clocks are used which is the case in the paper and in your proposed experiment.

But these experiments cannot and do not claim to measure the value of the speed of light which is what we mean by the statement that the one-way speed of light cannot be measured.

The experiment in the paper (and I presume your proposed experiment) is measuring how the speed of light changes during a period of 24 hours as the Earth points the apparatus in different directions and they did measure a sinusoidal pattern. They pointed their apparatus along a North-South direction to minimize the difference. If they were to repeat their experiment on the equator instead of at Toronto, this sinusoidal pattern may be eliminated and if they were to point their apparatus along an East-West direction, they would maximize the amplitude of the sinusoidal pattern, I believe.

Have you thought about why there should be a sinusoidal pattern with a period of approximately 24 hours? Are they measuring an actual change in the one-way speed of light as the apparatus is pointed in different directions? Are they now finally measuring an ether wind?

 

[my_wan]

The wikipedia article on "The one-way speed of light" that I encouraged you to read back in post #60 makes this clear.

The[/PLAIN] "one-way" speed of light from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector.

and:

Although[/PLAIN] experiments cannot be done in which the one-way speed of light is measured independently of any clock synchronization scheme,[...]

And I'm telling that is wrong, as the sources I quoted and will quote again states, again repeating myself over and over on this point only to be ignored and told I said something else. Yet here you are pretending I must not have even read it! Was it me not reading when I bent over backwards explaining the superiority of SR and have you response say I must not agree with SR?

Get this straight:
1) The ONLY timing device is the RPM of the pipe, period.
2) The ONLY variable this relates to is a distance, not time.
(Hence when wiki says "synchronize clocks" it is dead wrong.)
3) The ONLY assumptions being made is Newtonian, in spite of knowing that is going to be wrong.
Only by insisting that my tape measure is a clock can you claim I am synchronizing a pair of clocks. Hence this is a one way speed measurement in precisely the same way Michelson Morley was a two way speed test.

Note the red letters:

Will[/PLAIN] [7] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities.” Hence the synchronization is irrelevant for our one-way speed of light test since we express our results in terms of physically measurable quantities

Also in the other paper:

However,[/PLAIN] Will [49] showed that experiments which test the isotropy in one-way or two-way (round-trip) experiments have observables that depend on test functions $a(v^2)$, $b(v^2)$, and $d(v^2)$ but not on the synchronization procedure. He noted that “the synchronization of clocks played no role in the interpretation of experiments provided that one is careful to express the results in terms of physically measurable quantities”. Hence the synchronization is largely irrelevant.

The experiment in the paper (and I presume your proposed experiment) is measuring how the speed of light changes during a period of 24 hours as the Earth points the apparatus in different directions and they did measure a sinusoidal pattern.

The only reason for comparing changes over such periods of time not to measure "a" one way speed of light, but to search for differing one way speeds. Hence in my setup, instead of dual directional beams at different times, I use differing RPMs to establish a numerical value of c as defined by one, and only one clock, and one and only one tape measure. Hence my approach was to measure "a" one way speed where synchronization is irrelevant.

Even if you suppose my method is invalid you still have to invalidate E Riis et al, Phys. Rev. Lett, 60(2) (1988), and C. M. Will, Phys. Rev. D 45(2), 403-411 (1992), to justify the false claims on wiki.

 

[Dale]

I don't have a flash period, I have a light on 100% of the time. Neither do I have a t=0 anywhere period, or t= anything. Nor is there any pair of events that I measure for comparison.

I know. That is not the point.

The pure geometry does all that for me

The point is that the "pure geometry" depends on the synchronization convention. I.e. if the tube is straight under one synchronization convention then it is curved under another convention, and both predict the same experimental results.

Instead of this t= strawman when clearly i do not label t= to say what RPM something is rotating. I don't care when its rotating nor when the light was on.

Just because you don't label anything t doesn't imply that time is unimportant.

 

[ghwellsjr]

Yet here you are pretending I must not have even read it!
...
Even if you suppose my method is invalid you still have to invalidate E Riis et al, Phys. Rev. Lett, 60(2) (1988), and C. M. Will, Phys. Rev. D 45(2), 403-411 (1992), to justify the false claims on wiki.

Since you read the wikipedia article on "The one-way speed of light", why do say that I have to invalidate C. M. Will's paper when the article pointed out that:

In 1997 the experiment was re-analysed by Zhang who showed that, in fact, only the two-way speed had been measured. Will later confirmed that this conclusion was indeed correct.

And the paper by Riis was not claiming to measure the value of the one-way speed of light, it was similar to the previous experiment we discussed.

But you are claiming to be able to measure the one-way speed of light with your apparatus but I'm confused by this:

Hence my approach was to measure "a" one way speed where synchronization is irrelevant.

Are you saying that your approach would measure a speed that is different from 299,792,458 m/s?

 

[my_wan]

Since you read the wikipedia article on "The one-way speed of light", why do say that I have to invalidate C. M. Will's paper when the article pointed out that:

And the paper by Riis was not claiming to measure the value of the one-way speed of light, it was similar to the previous experiment we discussed.

But you are claiming to be able to measure the one-way speed of light with your apparatus but I'm confused by this:

These approaches were designed not to measure the speed of light in either direction, but rather to measure an anisopy in two directions of light. Yet you are confused by my my attempt at correcting this. So first let's look at the criticisms of these designs. Here is the abstract by Israel Pérez, which Zhang referenced:

In[/PLAIN] this contribution the question of the isotropy of the one-way speed of light from an experimental perspective is addressed. In particular, we analyze two experimental methods commonly used in its determination. The analysis is aimed at clarifying the view that the one-way speed of light cannot be determined by techniques in which physical entities close paths. The procedure employed here will provide epistemological tools such that physicists understand that a direct measurement of the speed not only of light but of any physical entity is by no means trivial. Our results shed light on the physics behind the experiments which may be of interest for both physicists with an elemental knowledge in special relativity and philosophers of science.

So why is my not closing paths in the setup I outlined so confusing?

Are you saying that your approach would measure a speed that is different from 299,792,458 m/s?

It bothers that that you would use the word "would" in red, simply on the grounds that it implies I am making a claim that the two-way light speed differs from the one way speed. Even in the context of GR, where GR doesn't hold light speed at an absolute constant, the speed is the same in both closed directions from anyone frame. GR has effectively the same contraction factor LET style transforms posit. The difference being that these transforms LET style theories invoke correspond to gravitational distortions in GR.

So before answering your question, to preempt a strawman as seems warranted, let's look at speed and distance variances that can be measured. If we are talking about a length contraction of some factor which exactly corresponds to an inverse time dilation factor $\Delta L \equiv 1/\Delta t$, then (unless you want to invoke coordinate dependence) the notion that you are even talking about a different distance in any local frame is moot. Measurability will strictly be dependent on a local interval in which the measurement is performed that differs from the intervals of the local space being measured. Not possible in a local measurement. Under GR these transforms are allowed, even required for gravitational effects. Thus in GR you have have a depth of field over a given distance with varying relational lengths. Yet comparing lengths in both directions will still be the same even if the speed of light is not.

So for GR type distance variations, which can't be measured via speed comparisons with closed paths, yes it will measure a differing speed of light. For interval type measurements, where distance is strictly defined by a choice of units under which $\Delta L \equiv 1/\Delta t$ is constant, no such measurement is possible. This later case is exactly the specified by SR with our inertial assumptions. Hence I do not expect the experiment to measure squat, as the "would" in your question implies. However, it does measure the one way light speed. There are two ways to get a speed c measure that differs from c, the first being fairly absurd but technically valid. (1) If an only if $\Delta L$ and $1/\Delta t$ was not separably constant in the manner specified by SR in a contiguous inertial space. (2) In situations, such as defined by GR, where $\Delta L$ and $1/\Delta t$ covaries over the space of $L$.

Given the above qualifications of what constitutes a measurement of speed c, yes, in situations where $\Delta L$ locally varies over $L$ or locally $\Delta L \neq 1/\Delta t$ in violation of SR, the measurement I describe will measure c different from 299,792,458 m/s. The later case is fairly absurd, though postulated by some. The former case is a standard part of GR, in which much of the spacelike interval $\Delta L$, on which the measurement depends, is not local to the frame in which the measurement is performed. Relativity then predicts that there must then exist a varying gravitational potential somewhere across $\Delta L$ even if the endpoints are effectively in flat spacetime.

The setup I defined is in fact a one-way measure light speed, not simply a comparison of speeds from both directions as in the referenced experiments.

 

[my_wan]

One other remark I have about Israel Perez's paper in the European Journal of Physics:
http://arxiv.org/abs/1102.4837

From[/PLAIN] this analysis representative expressions of the problem will be derived for the one-way and two-way speed of any physical entity (PE).

Although not explicitly stated here, the notion of labeling speed as a physical entity (PE) is implied. It cannot even mechanistically be labeled a physical variable in any strict sense even with purely Galilean transforms. I often use the kinetic energy of a pair of meteors to illustrate this, but this obviously also applies to speed. Like asking which if either meteor has a speed of 0. Speed is not a PE, it is the product of a coordinate choice. It seems to me that often what is being chased with one-way light speed arguments is a speed which is supposed by definition to constitute a PE. Though the Galilean linearity of simultaneity makes ignoring the facts trivial, speed labeled as a PE is not even entirely defensible under Galilean relativity. It's a coordinate choice, not a PE.

 

[Dale]

Speed is not a PE, it is the product of a coordinate choice.

Then how do you think that your device can measure it independently of the simultaneity convention which is part of your coordinate choice? You seem to be arguing against the key point you are making.

Suppose we have a theory where the one-way speed of light in the +x direction is infinite and the one way speed of light in the -x direction is .5 c and the speed of light is c in the y and z directions and distances are unchanged wrt standard SR. If we have a standard coordinate system T,X,Y,Z in units where c=1 then our non-standard system is:
$t=T-X$
$x=X$
$y=Y$
$z=Z$

Do you see how this is nothing more than a change in simultaneity and how your device cannot distinguish between these two simultaneity conventions?