Dear Anonumous Coward,
Re: "I'll give you that, I meant to say "inertial rotation". But it's just word play. My point still stands."
You may call it "absolute rotation" or "inertial rotation" — regardless of the arbitrary word of choice, the key point is that the speed of light in a sagnac interferometer is experimentally found to be constant ONLY with respect to "the fixed stars". In other words, a Sagnac interferometer detects rotation not with respect to a lab, not with respect to the Earth, nor to the sun, nor to the galaxy, nor with respect to any arbitrary frame of reference of choice but ONLY with respect to "the fixed stars", an experimentally-found preferred frame of reference that is identical to the one in which the original and not once falsified Theory of Relativity (i.e. The Lorentzian one) is based.
All this is explained in the paper that I pointed out to you, one that you apparently have not studied. Have you ever analyzed how a Sagnac Interferometer actually works? Let me help.
In 1951, P. A. M. Dirac wrote an article in the journal Nature titled "Is There an Aether?" in which he argued that we are “rather forced” to accept its existence. In 1953, Herbert Ives, the inventor of the television system that we all enjoy, explained the significance of the Sagnac Effect as follows:
"Further ground for rejecting the claim that Einstein's "view" renders the ether superfluous is furnished by the consideration that his scheme (even if it were valid) applies only to uniform rectilinear motion; rotational motion is excluded, yet optical signals are transmitted in such systems, and with results which point clearly and unequivocally to their transmission in an independent medium or coordinate system.
If light signals are sent out simultaneously in the "fore" and "aft" directions from a source moving in a circular path, and the two signals are brought back to the source by a series of reflections, they do not arrive simultaneously; the source has moved forward to meet one signal and has moved away from the other. This is the situation in the Michelson-Gale and Sagnac experiments, which yield positive first-order results exactly in conformity with the idea that the light signals travel in a fixed ether. The contractions of length and clock frequencies which account for null effects in uniform motion of translation, being of second order, do not materially alter the rotational effects. The optical phenomena in both uniformly and rotationally moving systems are completely explainable by a fixed ether and the Fitzgerald-Lorentz-Larmor contractions.
This survey of the background of the query "Is there an ether?" shows that the grounds for "abolishing" the ether were mistaken, and consequently Dirac's contribution would more properly have been entitled "Properties of the ether suggested by recent speculations."
Herbert Ives, "Genesis of the Query "Is there an Ether?", 1953.
Re: "You can easily derive it from the equations of SR, as summarized here [mathpages.com]. Also, you stated earlier that Lorenzian Relativity uses the exact same math as SR, so you're contradicting yourself here."
Please, I am not contradicting myself. That paper does not derive the experimentally-validated Sagnac formula using only the two postulates of SR. This shows again that you have not studied Marett's paper.
The original version of Relativity is based on the Lorentzian concepts of absolute time, a variable speed of light and an absolute frame of reference. From such concepts, the equations of Relativity that we continue to use today were derived. Afterwards, Einstein assumed instead his two postulates and derived the exact same equations, using different concepts to derive the exact same equations previously derived by Lorentz, Larmor, Poincaré, et. al.
However, such a mathematical equivalence is ONLY so for rectilinear uniform motion. For rotational motion like the one in the Sagnac Effect, there is a new equation that describes the phenomenon. Such equation is naturally derived from the conceptual framework of Lorentz, but it has never been derived from the conceptual framework of Einstein. To derive the equation, one needs to start from the two Einstein's SRT postulates and arrive to the equation that describes the rotational experiment, never violating the postulates along the derivation.
This derivation has never been done. The link that you have shared is just one of the well-known type of attempts to derive the equation, in which the one who is trying has to invariably use Lorentzian absolutistic concepts instead of Einsteinian relativistic ones to arrive to the experimentally-validated equation. This is thoroughly explained in Marett's paper.
Re: "Irrelevant. It can still be explained with SR."
It is very relevant, in my humble opinion, because wikipedia is very influential and the go-to answer for many people for many things, yet it is misleading the public, teaching them the falsity that there is no controversy about the Sagnac Effect. As mentioned before, the Sagnac effect has never been derived from the two SR postulates without assuming a Lorentzian preferred frame, so, in that important sense, the Sagnac effect cannot be explained from SRT.
Re: "Poor you. These manifolds are the basis for General Relativity. GR perfectly predicts things like the motion and orbital decay of two orbiting neutron stars, or lensing effects due to gravity. All experimental data agree with GR to a very high degree."
You are failing to distinguish the quantitative aspect of physics with its qualitative aspect, an approach that has led us to the long-standing conceptual crisis within physics. The quantitative is constructed from abstract equations, the qualitative is constructed from abstract concepts. Both are maps (or aspects of a map) trying to describe the real territory, i.e. the universe. Numerical predictions are part of the quantitative maps, not the qualitative ones.
If you recall, you said "There is no Aether, unless you update its definition to mean spacetime itself." I commented that spacetime is a "4D Pseudo Riemannian manifold", meaning that it is just a quantitative abstraction that may map or not the material world, just like a purely abstract scalar field may abstractly map or not the real pressure in the material planetary atmosphere (the atmosphere really exists, the scalar field that maps it does not). Now, if you equate aether with spacetime, and then declare aether to be physically real, then you are believing that a "4D Pseudo Riemannian manifold" is physically real. That is an anti-realistic idea, which any realist interested in a coherent and non-contradictory conceptual understanding of the physical world must necessarily reject.
Regarding the quantitative predictions that you are mentioning, please note that — as for any prediction in any context, forever — they can be also predicted from different frameworks. If you were tracking closely the "Electricity in space" controversy, you would know that astrophysics is ripe for disruption. As just one example, "lensing" can also be predicted classically. For this topic, I recommend "A Revolution Too Far: The Establishment of General Relativity" by Peter Rowlands (physicist and science historian).
Re: "You probably also don't believe in quantum mechanics then, where all fermions are made up of spinor fields."
For a realist, any real object is made from matter in motion and only from matter in motion. A realist cannot accept a "spinor field" as nothing else than a mathematical abstraction that may be part of quantitative maps that may describe successfully or not physical reality. An anti-realist, however, has no problem with reifications and their related conceptual incomprehension and incoherence.
Of course, the quantitative map of quantum theory is an incredible achievement of mankind. Its numerical usefulness as an abstract recipe that allows you to predict measurements in agreement with experiment is beyond questioning. Regarding its qualitative side, however, quantum theory explains absolutely nothing. What is really physically happening at the atomic scale? Mainstream physics has no answers.
"I think I can safely say that nobody understands quantum mechanics." — Richard Feynman
A realist looks for ways to physically understand the realities abstractly mapped by the empty equations, challenging the usual conceptual absurdities and the assumptions underlying them, without necessarily challenging the accepted equations.
Re: "Yay, another pointless quote/history lesson. Sounds like something Chris Reeve would say. Which one were you again?"
How is it "pointless" to remark that a Nobel Laureate has very recently stated that the materiality of aether (in which Lorenzian Relativity is based) is confirmed everyday by experiment?
Re: "No it isn't. The absolute framework of aether doesn't exist. Science doesn't agree with you."
Well, if you want to remain in denial, I cannot do anything else to convince you otherwise. Whenever you get interested in a more coherent understanding of the physical world, you can study the paper I pasted before, which concludes thus: "the optical evidence to date, as has been shown herein, continues to support the alternative hypothesis that the ether of Lorentz does exist, and this is particularly desirable for those who seek a more rational and consistent description of the physical world."
Re: "So it's basically philosophy, since you just admit it's not measurable."
This is what happens when the natural philosophy aspect of science is removed from the academic curriculum. People just don't realize that they are philosophizing.
ALL physical understanding is rooted in philosophy. Your statement above is a tell that you are an instrumentalist. As Karl Popper — the most celebrated philosopher of science of the 20th century — once explained:
"Modern instrumentalists are, of course, unaware that they are philosophizing. Accordingly, they are unaware of even the possibility that their fashionable philosophy may in fact be uncritical, irrational, and objectionable — as I am convinced it is."
Popper, Karl R., Quantum Theory and the Schism in Physics, Totowa (New Jersey), Rowman and Littlefield, 1982, p. 103.
Equating measurement with physical reality is a philosophy that has lead to the current conceptual crisis within physics.
Re: "Meanwhile all our experiments confirm that the speed of light is constant, and has always been constant since the beginning of time (at least since the earliest light/time we can detect)."
Here you are philosophically assuming a "beginning of time", an idea which was unscientific until the appearance of the catholic priest Georges Lemaître, who first proposed that the creation of the universe ex nihilo should be considered not only a religious belief but also, somehow, a scientific belief.
All the experiments that you are mentioning confirm that the speed of light is variable and time is absolute, exactly as demanded by the original Theory of Relativity, i.e. Lorentz's.
Re: "Obviously the correct interpretation is the one we can measure. That's by definition the "realistic" one."
We can and do measure the same thing under both interpretations, so there is nothing "obvious" if you have nothing but measurements. You need to try to UNDERSTAND what is really, physically happening, and decide wisely.
The Lorenzian interpretation infers that matter is deformed by the physical interaction between a moving body and the all-pervading aether. In other words, the measured effect absolutely happens. You cannot say the same under the Einsteinian interpretation, because "what happens" depends on your choice of frame of reference. One option is more realistic than the other.
Re: "In all real frames of reference we can measure in (which excludes your imaginary ones), the speed of light is constant."
According to original derivation of Relativity, that is because the experimentally demonstrated change in the rate of clocks with velocity and the contraction of matter with velocity.
Re: "History doesn't change the actual laws of nature, so it's irrelevant."
It is EXTRAORDINARILY relevant, because scientists considered the Lorentzian interpretation until Eddington convinced the world otherwise using invalid data.
Re: "You're also ignoring the many, much more accurate experiments that were done in the 100 years that followed and that verified GR with very high precision. Stop living in the past."
I live in the present, one in which there is an exceedingly ENORMOUS amount of conceptual incoherence between physics. What is remarkable is that there is clear historical correlation between the abolishment of aetheric substance and the proliferation of conceptual incoherence within physics.
From the denial of an objective reality existing independently of a given observation to reifications like 0D extensionless particles, 4D warped spacetime and probability clouds; from the wave-particle paradox to random acausality and quantum spookiness; from non-contact actions to matterless motion and actor-less energy; from the paradoxical absolutized relativity of time to the creation of the entire universe out of nothing — the appearance, reproduction and mainstream acceptance of all such a kind of conceptual nonsense happened during a period of time that correlates very strongly with the aetherless period of physics. The abolishment of aether became mainstream and increasing amounts of incoherence became mainstream. The abolishment of aether persists to this day, and the incoherence persists to this day. The aetherless period also coincides with the monument of incomprehension that is the Standard Model of Particle Physics — with its meaningless labels like “charm” and “strangeness” — and with equally anti-realistic concepts like zero-thickness “superstrings” existing in 26 dimensions.
Think carefully and ask yourself: is all this just a spurious correlation?
Have a nice day / evening / night! =)