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.

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

__________________
papageno


"Why waste time learning, when ignorance is instantaneous?" - Hobbes (Calvin and Hobbes)

"It's all about context!" - Vince Noir (The Mighty Boosh)

"I've never heard of such a brutal and shocking injustice that I cared so little about!" - Zapp Brannigan (Futurama)

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!

__________________
Microsoft is over if you want it.

The bar has been lowered for the promotion of ATM ideas; the bar for the acceptance of ATM ideas must remain high.

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.

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

Have we been conned by Einstein?

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

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)?

(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: 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.

__________________
Credibility is simply incredible... sometimes even to me.
disclaimer

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?

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.

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.

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.

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

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.

__________________
Never attribute to malice what can be adequately explained by ignorance or stupidity.
Isaac Asimov

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?

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

That's what I thought.

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

__________________
"I have a cunning plan that cannot fail."
S. Baldrick

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.

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.

__________________
Microsoft is over if you want it.

The bar has been lowered for the promotion of ATM ideas; the bar for the acceptance of ATM ideas must remain high.

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.

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