A case against Relativity

[wisp]

You are an observer fixed in absolute space watching clocks pass between two points, A and B, separated by 1km. The moving clocks are identical in every way, and have observers aboard.

The Sagnac clock observer is traveling at a speed of 1km/s in a circular orbit (radius 1 billion light years), so its path between A and B appears as a straight line. And the Sagnac effect requires that the speed of light must be c+v and c-v respectively (if the Sagnac observer recorded the speed of light as c, then he would not be moving in a circle).

According to Relativity the Inertial clock observer - who is traveling in a straight line at 1km/s - records the speed of light as being c.

You are not told which clock will pass by, but when they pass you cannot distinguish the two apart. And both clocks follow the same straight line, as your measuring device cannot detect any error in their paths.

The case against Relativity is this:
It is an experimentally proven fact that the Sagnac observer measures the speed of light as c+v and c-v. Otherwise the Sagnac effect would not be observed. But according to Relativity, what appears to be an identically moving observer measures the speed of light a c.

Since we cannot distinguish between the moving clock observers in this case, they must both measure the speed of light as being the same. And it is clear that Relativity is at fault and the one-way speed of light is not c, but either c+v or c-v.

[papageno]

The Sagnac observer is not inertial, therefore the 2nd postulate of Special Relativity does not apply.

[Celestial Mechanic]

The Sagnac effect requires that two beams of light travel the complete circuit so that their phases may be compared. Since your circle has radius one billion light-years, that means that at least 6.28 billion years must pass before the "Sagnac observer" can detect anything.

Also, nothing in your gedankenexperiment says anything about light being constrained to travel in a circle. Back to the drawing board!

[Aether]

Special Relativity is just a coordinate system in which the one-way speed of light is defined to be isotropic. This coordinate system (inertial reference system) is convenient in that it can be realized today in any laboratory. An alternate coordinate system in which the one-way speed of light is defined to be anisotropic is just as valid as SR (when both systems are properly specified: see Y.Z. Zhang, Special relativity and its experimental foundations, (1997); http://www.worldscibooks.com/physics/3180.html).

wisp, I think that it is futile to try and make "a case against relativity" per se because relativity is just a coordinate system. Any valid "case" would need to stay focused on the actual experiment(s) needed to realize the alternate coordinate system described above today/tomorrow in any laboratory.

[clj4]

And it is clear that Relativity is at fault and the one-way speed of light is not c, but either c+v or c-v.

This is clearly not the case, this concept (which belongs to Ritz) has been refuted experimentally multiple times in the past 100 years. You have been given ample proof in another thread, you are simply reopening the same discussion

http://www.bautforum.com/showthread.php?t=36020

using an experiment (Sagnac) this time.
Here is one of the many refutations of the 'c+-v'.

http://imaginary_nematode.home.comca...echer_1977.pdf

Here is one of the many correct explanations of the Sagnac experiment:

http://www.mathpages.com/rr/s2-07/2-07.htm

You just opened another identical thread and you got plenty of explanations here:

http://www.physicsforums.com/showthread.php?t=112002

[Aether]

This is clearly not the case, this concept (which belongs to Ritz) has been refuted experimentally multiple times in the past 100 years.

wisp, are you talking about a coordinate system in which the speed of light is defined as an anisotropic function of the observer's velocity with respect to some locally preferred frame or (as clj4 is implying) that the speed of light is a function of the velocity of the source (which it clearly isn't)?

[nutant gene 71]

This is clearly not the case, this concept (which belongs to Ritz) has been refuted experimentally multiple times in the past 100 years. You have been given ample proof in another thread, you are simply reopening the same discussion

http://www.bautforum.com/showthread.php?t=36020

using an experiment (Sagnac) this time.
Here is one of the many refutations of the 'c+-v'.

http://imaginary_nematode.home.comca...echer_1977.pdf

Here is one of the many correct explanations of the Sagnac experiment:

http://www.mathpages.com/rr/s2-07/2-07.htm

You just opened another identical thread and you got plenty of explanations here:

http://www.physicsforums.com/showthread.php?t=112002

(bold mine)

The 'refutation' of Sagnac experiment may be spurious, in that it involves 'renormalizing' relativistic proper Time, where the difference in 'travel time' is adjusted. In effect, we have time factor=(1-v^2/c^2)^1/2 in one direction, while we have time factor=(1+v^2/c^2)^1/2 in the counter direction. If you make 'proper Time' variable, you get around the fact that it will take less time in one direction and more time in the counterdirection. Or, as the paper referenced says:

Of course, the result represents the time difference with respect to the axis-centered inertial frame. A clock attached to the perimeter of the ring would, according to special relativity, record a lesser time, by the factor y = (1-(v/c)2)1/2, so the Sagnac delay with respect to such a clock would be [4Aw/c2]/(1-(v/c)2)1/2. However, the characteristic frequency of a given light source co-moving with this clock would be greater, compared to its reduced value in terms of the axis-centered frame, by precisely the same factor, so the actual phase difference of the beams arriving at the receiver is invariant. (It's also worth noting that there is no Doppler shift involved in a Sagnac device, because each successive wave crest in a given direction travels the same distance from transmitter to receiver, and clocks at those points show the same lapse of proper time, both classically and in the context of special relativity.)

Once you adjust Time, you get the relativistic effect desired. How can it be claimed to falsify the experiment, if the experiment is designed, using relativity, to achieve invariant results? The only clue you get something is variant (in Sagnac experiment) is in the Doppler lightshift.

That said, I stand to be corrected if I got it wrong.

[wisp]

The Sagnac observer is not inertial, therefore the 2nd postulate of Special Relativity does not apply.

We could make the radius bigger than 1 billion light years, which in turn would make it impossible for you to detect the curvature of the moving sagnac observer within the 1km window. In this limiting case there is very little difference between the inertial and sagnac observers. Why should one measure light’s speed as c, and the other as c+v or c-v?

Just saying “therefore the 2nd postulate doesn’t apply” is an excuse for letting relativity of the hook. Is relativity immune from a limiting case?

[wisp]

The Sagnac effect requires that two beams of light travel the complete circuit so that their phases may be compared. Since your circle has radius one billion light-years, that means that at least 6.28 billion years must pass before the "Sagnac observer" can detect anything.

Also, nothing in your gedankenexperiment says anything about light being constrained to travel in a circle. Back to the drawing board!

Time is not important here, if it takes 6.28 billion years, so be it. Also light doesn’t have to travel in a circle, it can be reflected of 4 mirrors - forming a square pattern. And the sagnac observer’s circle touches it tangentially at four points.

[wisp]

This is clearly not the case, this concept (which belongs to Ritz) has been refuted experimentally multiple times in the past 100 years. You have been given ample proof in another thread, you are simply reopening the same discussion

http://www.bautforum.com/showthread.php?t=36020

using an experiment (Sagnac) this time.
Here is one of the many refutations of the 'c+-v'.

http://imaginary_nematode.home.comca...echer_1977.pdf

Here is one of the many correct explanations of the Sagnac experiment:

http://www.mathpages.com/rr/s2-07/2-07.htm

You just opened another identical thread and you got plenty of explanations here:

http://www.physicsforums.com/showthread.php?t=112002

Thanks for all the links clj4. But this case against relativity is as simple as it needs to be. My question of why in this limiting case, do the observers measure the speed of light as being different.
A simple explanation has not been given, because relativity fails at in this case.

[wisp]

wisp, are you talking about a coordinate system in which the speed of light is defined as an anisotropic function of the observer's velocity with respect to some locally preferred frame or (as clj4 is implying) that the speed of light is a function of the velocity of the source (which it clearly isn't)?

I'm referring to the coordinate system in which the speed of light is defined as an anisotropic function of the observer's velocity with respect to some locally preferred frame.

[Jim]

You are an observer fixed in absolute space...

"Absolute space" is in violation of the conditions of relativity, where - by definition - everything is relative and nothing is absolute.

We could make the radius bigger than 1 billion light years, which in turn would make it impossible for you to detect the curvature of the moving sagnac observer within the 1km window. ...

But, no matter how much you flatten the circle and no matter how difficult it is to detect that circle over a finite distance, it is still a circle and requires acceleration. The circle traveller cannot be in an inertial frame.

[clj4]

Thanks for all the links clj4. But this case against relativity is as simple as it needs to be. My question of why in this limiting case, do the observers measure the speed of light as being different.
A simple explanation has not been given, because relativity fails at in this case.

You have received several explanations in this thread. Since you advanced the idea that "relativity fails (in this case)" and since everyone else refuted your statement, could you, according to the rules of this forum:

1. explain your position mathematically (with formulas, not with words)
2. defend the ballistic theory that you keep advancing?
3. explain why the ballistic theory that has been proven wrong by so many experiments (see the many links and the other thread you have opened under "Have we been conned by Einstein") proves correct in the case of the Sagnac experiment?

[clj4]

You are an observer fixed in absolute space ....

Such a thing does not exist. The rest of the post is invalidated by the premise.

[Aether]

I'm referring to the coordinate system in which the speed of light is defined as an anisotropic function of the observer's velocity with respect to some locally preferred frame.

That's what I thought.

[swansont]

Thanks for all the links clj4. But this case against relativity is as simple as it needs to be. My question of why in this limiting case, do the observers measure the speed of light as being different.
A simple explanation has not been given, because relativity fails at in this case.

You haven't presented a limiting case. CM's note about the length of time it takes to traverse the apparatus was relevant not because of the waiting around to get the answer, but to the actual effect: even at low speed, you will get a large amount of movement in that time, and thus a large number of fringes if you are looking at interference. Looking at the linear speed on the circumference is the wrong metric; if you want to make a Sagnac interferometer more sensitive, you make the enclosed area larger.

A limiting case is where the enclosed area approaches zero as well as the rotation speed.

edit: fix typo

[Aether]

You are an observer fixed in absolute space...

Such a thing does not exist. The rest of the post is invalidated by the premise.

You are both half right. wisp is entitled to define an observer as being "fixed in absolute space" within the coordinate system that he intends to be using, but he does need to define this coordinate system more clearly and to stop confusing it with relativity.

wisp, once you define the speed of light to be an anisotropic function, then you're outside of relativity because relativity defines the speed of light to be isotropic.

[Celestial Mechanic]

Time is not important here, if it takes 6.28 billion years, so be it. Also light doesn’t have to travel in a circle, it can be reflected of 4 mirrors - forming a square pattern. And the sagnac observer’s circle touches it tangentially at four points.

You miss the point. There is nothing to measure until the circuit has been completed. It doesn't matter what the shape of the circuit is. If you've got 6 billion years to wait, more power to you.

You have not presented a valid argument. Case dismissed with prejudice.

[wisp]

You have received several explanations in this thread. Since you advanced the idea that "relativity fails (in this case)" and since everyone else refuted your statement, could you, according to the rules of this forum:

1. explain your position mathematically (with formulas, not with words)
2. defend the ballistic theory that you keep advancing?
3. explain why the ballistic theory that has been proven wrong by so many experiments (see the many links and the other thread you have opened under "Have we been conned by Einstein") proves correct in the case of the Sagnace experiment?

1. Why complicate a simple case with maths. Two almost identically moving observers (inertial and sagnac) travelling between two points A and B measure the speed of light as being different. Why?

I doubt either observer will know which is inertial and which is sagnac. But if they carry out a test to measure the speed of light, they will only get one answer, c+v or c-v.

2 & 3. I've never supported the ballistic theory. It's basic knowledge that the speed of light is independent of the motion of the source that emits the light - this is supported by the ether medium and SR. But if the source moves towards or away from the light, the source observer measures light's speed as c-v and c+v, respectively.

[Aether]

1. Why complicate a simple case with maths. Two almost identically moving observers (inertial and sagnac) travelling between two points A and B measure the speed of light as being different. Why?

I doubt either observer will know which is inertial and which is sagnac. But if they carry out a test to measure the speed of light, they will only get one answer, c+v or c-v.

The speed of light isn't a measurable quantity within an inertial reference system, it is defined as a constant c.

[wisp]

You miss the point. There is nothing to measure until the circuit has been completed. It doesn't matter what the shape of the circuit is. If you've got 6 billion years to wait, more power to you.

You have not presented a valid argument. Case dismissed with prejudice.

It's the principle that's important, not how quick you get the result.

If both observers carried out a one-way speed of light measurement between points A and B, what would the speed of light be?

If the answer in this small interval "limit case" is c, then it must be c for other intervals. So how can the sagnac effect be possible. But if the answer is c+v or c-v, then the sagnec effect is possible? But the inertial observer must therefore measure the one-way speed of light as c+v or c-v, which puts a case against relativity.

And whilst they travel between points A and B, would you be able to tell the observers apart?

[clj4]

1. Why complicate a simple case with maths. Two almost identically moving observers (inertial and sagnac) travelling between two points A and B measure the speed of light as being different. Why?

Because it will prove either that:

a. You can't really calculate things correctly
b. You can calculate correctly and you will get the correct result which is that A and B see the SAME speed of light. And this is the universally known (i.e. by everyone else) result of the Sagnac experiment.

Either a or b will make you go away.

I doubt either observer will know which is inertial and which is sagnac. But if they carry out a test to measure the speed of light, they will only get one answer, c+v or c-v.

Wrong. Go to point 1 and prove it with calculations, not with statements.

2 & 3. I've never supported the ballistic theory. It's basic knowledge that the speed of light is independent of the motion of the source that emits the light - this is supported by the ether medium and SR. But if the source moves towards or away from the light, the source observer measures light's speed as c-v and c+v, respectively.

You are contradicting yourself in the same phrase. To avoid all this confusion caused by all your contradictory statements please answer with a set of calculations. It is not very difficult, you have received several links that in about 3 lines of calculations show you what happens inside the Sagnac experiment, I am asking you to write down your 3-4 lines of equations that support your point. I think that everyone on this thread would want to have a look at them.

[clj4]

Before you get started please re-read the following from:

http://www.mathpages.com/rr/s2-07/2-07.htm

"Nevertheless, it remains a seminal tenet of anti-relativityism (for lack of a better term) that the trivial Sagnac effect somehow "disproves relativity". Those who espouse this view sometimes claim that the expressions "c+v" and "c-v" appearing in the derivation of the phase shift are prima facie proof that the speed of light is not c with respect to some inertial coordinate system. When it is pointed out that those quantities do not refer to the speed of light, but rather to the sum and difference of the speed of light and the speed of some other object, both with respect to a single inertial coordinate system, which can be as great as 2c according to special relativity, the anti-relativityists are undaunted, and merely proceed to construct progressively more convoluted and specious "objections". For example, they sometimes argue that each point on the perimeter of a rotating circular Sagnac device is always instantaneously at rest in some inertial coordinate system, and according to special relativity the speed of light is precisely c in all directions with respect to any inertial system of coordinates, so (they argue) the speed of light must be isotropic at every point around the entire circumference of the loop, and hence the light pulses must take an equal amount of time to traverse the loop in either direction. Needless to say, this "reasoning" is invalid, because the pulses of light are never (let alone always) at the same point in the loop at the same time during their respective trips around the loop in opposite directions. At any given instant the point of the loop where one pulse is located is necessarily accelerating with respect to the instantaneous inertial rest frame of the point on the loop where the other pulse is located (and vice versa). As noted above, it’s self-evident that since the speed of light is isotropic with respect to at least one particular frame of reference, and since every other frame is related to that frame by a transformation that explicitly preserves light speed, no inconsistency with the invariance of the speed of light can arise.



Having accepted that the observable effects predicted by special relativity for a Sagnac device are correct and entail no logical inconsistency, the dedicated opponents of special relativity sometimes resort to claims that there is nevertheless an inconsistency in the relativistic interpretation of what's really happening locally around the device in certain extreme circumstances. The fundamental fallacy underlying such claims is the idea that the beams of light are traveling the same, or at least congruent, inertial paths through space and time as they proceed from the source to the detector. If this were true, their inertial speeds would indeed need to differ in order for their arrival times at the detector to differ. However, the two pulses do not traverse congruent paths from emission to detector (assuming the device is absolutely rotating). The co-rotating beam is traveling slightly farther than the counter-rotating beam in the inertial sense, because the detector is moving away from the former and toward the latter while they are in transit. Naturally the ratio of optical path lengths is the same with respect to any fixed system of inertial coordinates."

[Kesh]

1. Why complicate a simple case with maths.

That's like saying, "why complicate measuring a triangle with maths." If you actually want to know the results, you have to do the math.

A bridge doesn't get built without math. Try telling an engineer you have this great idea for a bridge, but he doesn't need to do the math.

Your technique is the same here. You can't refute relativity with a wag of the finger and misunderstanding of the math involved.

[Ken G]

Before you get started please re-read the following from:

http://www.mathpages.com/rr/s2-07/2-07.htm

This is a wonderfully lucid article, thanks clj4. I actually think it is less clear in how it describes the situation in the rotating frame, but it makes a very clear argument in the inertial frame. In the rotating frame, it says that it is OK for light to have different speeds, but this can be misleading. Another way to think about what happens is a process called frame dragging, whereby in the corotating frame where everything looks stationary, the light going in the two opposite directions actually does travel different distances, in contrast to our intuition. In this view, the noninertial rotation alters the space coordinate in a nonisotropic way, so light is still behaving isotropically. At least, those are the analog of SR-type coordinates-- note you can choose other coordinates in which the speed of light does appear to be c+v and c-v. The bottom line: you can get the speed of light to be anything you like by taking some choice of coordinate system. The statements of special relativity apply only to a particular class of coordinates, the inertial coordinates, and the beauty of SR is any law (like the isotropy of c) that holds in one such coordinate system holds over the entire class. In my limited understanding, differential geometry tells you how to map the SR laws into general constraints in any coordinate system of your choosing, and GR tells you how to include gravity.

[clj4]

This is a wonderfully lucid article, thanks clj4. I actually think it is less clear in how it describes the situation in the rotating frame, but it makes a very clear argument in the inertial frame. In the rotating frame, it says that it is OK for light to have different speeds, but this can be misleading. Another way to think about what happens is a process called frame dragging, whereby in the corotating frame where everything looks stationary, the light going in the two opposite directions actually does travel different distances, in contrast to our intuition. In this view, the noninertial rotation alters the space coordinate in a nonisotropic way, so light is still behaving isotropically. At least, those are the analog of SR-type coordinates-- note you can choose other coordinates in which the speed of light does appear to be c+v and c-v. The bottom line: you can get the speed of light to be anything you like by taking some choice of coordinate system. The statements of special relativity apply only to a particular class of coordinates, the inertial coordinates, and the beauty of SR is any law (like the isotropy of c) that holds in one such coordinate system holds over the entire class. In my limited understanding, differential geometry tells you how to map the SR laws into general constraints in any coordinate system of your choosing, and GR tells you how to include gravity.

Yes, the rotating frame is non-inertial , so the calculation is a little trickier .
In the inertial frame, the situation is much clearer. There is no ambiguity of any sort.
An even better solution can be found in Stedman, here (see 1.2):

http://www.physics.berkeley.edu/rese...Review1997.pdf

Stedman shows how the "c+-v" comes to be.
I am quite sure that everyone on this thread got this....

Some very good description can be found here:

http://en.wikipedia.org/wiki/Sagnac_experiment

While the paragraph on "Relativistic interpretation" can stand some improvement (especially the nonsense about H.Ives who was a brilliant experimentalist who never understood relativity), the references are excellent. All of them put away any antirelativistic "explanations" of the Sagnac effect.

[swansont]

The speed of light isn't a measurable quantity within an inertial reference system, it is defined as a constant c.

I'm not sure what you mean by this. Of course it is a measurable quantity. We choose to define it, but it would still be a constant if we chose to define the length of the meter instead, as we used to do.

[swansont]

It's the principle that's important, not how quick you get the result.

It's not a matter of an inconvenience of waiting. You physically will not get an answer until the light completes the travel. There will be no signal to measure.

[Aether]

I'm not sure what you mean by this. Of course it is a measurable quantity. We choose to define it, but it would still be a constant if we chose to define the length of the meter instead, as we used to do.

The one-way "speed of light" isn't measurable in any coordinate-independent way whatsoever. There is no experimental basis at all for supposing that the speed of light is a constant; such a statement is coordinate-system dependent.

[clj4]

The one-way "speed of light" isn't measurable in any coordinate-independent way whatsoever. There is no experimental basis at all for supposing that the speed of light is a constant; such a statement is coordinate-system dependent.

This is definitely incorrect, there are multiple experiments that disprove your above statement.

http://imaginary_nematode.home.comcast.net/

And there are many more such experiments that refute your statement.

Either way, your posts have done nothing but to confuse the points even further.