@Csaba Bagyinka

The light velocity is the same in any inertial frame. At least the special relativity was well tested.

"Since Universe is finite one should be able (at least in principle) to measure (or estimate) the momentary speed of all particles in Universe within a limited (local) time frame. (I know that it will be a different local time for every mass, but it does not matter)."

If you speak of the Universe, you don't speak of particles, but of bodies, be they extremely big or extremely small.

"Then it is also possible to calculate (since there is a finite number of measurements) the total momentum or kinetic energy of the Universe."

What is the order of magnitude of this "finite" number of measurements? Does it include the momentum of each particle in the cosmic radiation?

Anyway the total momentum should be null, otherwise the set of all the bodies in the universe has a global movement with respect to the Earth. In the later case, the Earth is at rest in a particular frame, the ABSOLUTE FRAME.

Hello Csaba: You are really asking two diifetent questions, at least.

Q1. Is it possible to define an absolute reference frame? A1. Yes, c=1 for ANY inertial reference frame is absolute, in the sense that c does not change for empty space in the known universe. Other values are also absolute in that sense.

Q2. Since the universe is finite one should be able (at least in principle) to measure (or estimate) the momentary speed of all particles in Universe within a limited (local) time frame. A2. Yes, it has been done. There is an inflationary force that is expanding space in all points, and locally on Earth we have measured it and use it to estimate distances using the red shit of light we see, the redder, the farther; look up Hubble constant. The initial value was 160 km/sec per million-light-years, it is accelerating, i.e., the universe is expanding faster, we think at every point.

Cheers, Ed Gerck

A preferred frame means anisotropy of the 4D space-time. No reason is known for such anisotropy.

Hi Ed,

You are answering the wrong question(s).

A1.

I know that. But it is not one frame, so it is not absolute.

A2.

I knew that too. But that is why I asked: " Why almost all momentums of the (distant and big) masses are (close to) radial? So why the speed distribution is not homogeneous in the Universe? " Your A2 does not answer that.

Sofia,

"A preferred frame means anisotropy of the 4D space-time. No reason is known for such anisotropy."

I just pointed out such an anisotropy asking: " So why the speed distribution is not homogeneous in the Universe? "

No there isn't any absolute reference frame with respect to the "Laws of Physics" Or conversely, we are interested only in those laws which are not specifically valid in a particular reference frame.

Special relativity theory arises when any two inertial frames are equivalent. But still we see that this theory cannot describe gravitational interactions. Going one step further in that direction, if we claim that laws of Physics will also be the same in any two reference frames which are mutually accelerated, then we get the general theory of relativity, which is capable of describing gravity.

Interestingly, now we know that the universe has entered a phase where it is undergoing "accelerated expansion". Consequently galaxies are not moving away from each other with uniform velocity, this motion actually has an acceleration. Einstein would have been very happy to see this, as general theory of relativity is sufficiently equipped to describe accelerated frames and it's relation with gravity.

Biswajoy ,

It is still not answer the question.

In the universe as we see it there is a preferred frame of reference, the CMB (Cosmic Microwave Background) frame. It defines everywhere in the universe an average speed, and this speed is quite close to the speed of the local galaxies.

Globally, this would not define an inertial reference frame in the sense of special relativity, because this is part of general relativity. But it defines a global preferred system of coordinates. In these coordinates, the metric would be \(dt^2 - a^2(t)(dx^2+dy^2+dz^2)\). All galaxies would move approximately, with minor local differences, along lines of constant x,y,z.

Ilja,

So there is a preferred inertial reference frame anyway?

What is the difference between: " this would not define an inertial reference frame " and " But it defines a global preferred system of coordinates "??

It seems to me playing with words.

Csaba, the global preferred system of coordinates defines, in every point, as a local approximation, a local inertial reference frame. But these local inertial reference frames differ from each other - the points at rest in two different far away local inertial systems move away from each other.

Dear Csaba,

your question is very important.

Actually in the observed Universe we have the Global Rest Reference Frame, which is related to the background radiation, more generally all particles with zero rest-masses. E.g. if we relate a reference frame (RF) with the isotropy of Cosmic Microwave Background Radiation, i.e. we see a change of temperature of the CMBR when we are moving in certain direction (now it is usual astrophysical measurements), then we get such reference frame relative to which we can measure all velocities in the Universe. I think that we can call such RF as the Global Rest Reference Frame. In some sense it is the absolute RF, because now we can measure the TRUE velocities (and also accelerations, so a free fall can be distinguished from inertial motion - no equivalence principle ) in the Universe relative to such GRRF. But it is not absolute RF in the sense of special relativity theory.

You also right, that a surprising fact is that the the velocities of galaxies are small in comparison with the velocity of light (our Galaxy has only 600 km/s in the GRRF), so all the matter is almost at rest in the Infinite Universe. This fact should be taken into account in any cosmological model.

It is possible to construct any reference system including absolute, but it will be only game. Absolute reference system used Newton in the flat 3-space. We live in non-homogeneous and non-isotropic space, where exist gravitation, which acts on the course of time. We cannot take into account these changes of temporal temp, which depends on all gravitating bodies including the gravitational field of the Universe. But we can construct partial models of different processes: models of stars of different kinds, models of the Universe. Absolute reference system is our past, we must study many partial tasks that to obtain approximately the structure of the world, which is the Space of the Time. The studies of Time can help us many connections in the Universe. For example: redshift in cosmology is considered as Doppler effect in the Friedman Universe where the time flows uniformly. In frames of the de Sitter model we obtain that redshift is due to non-Newtonian force of repulsion. If astronomers will obtain new results, we must costruct models, which will take into account new dates. And any absolute reference system will be barrier, obstructing further development of science.

Hello Csaba : Your questions are good for someone with a full cup. You seem to have the answers already, just that the qestion and answers you gave, they are a non-sequitur. What you want as absolute must not exist in special relativity, but it exists as an absolute universal rule (c=1). Maybe special relativity is wrong?

Ed,

I was asking:" What is wrong with this argument? ", so I am not fully convinced by myself.

" Maybe special relativity is wrong? " If you cannot argue against my argument then, yes, it might be wrong, because I do can distinguish between two inertial systems.

Larissa,

So you say that we should not care about such questions? It should just be ignored?

Yuriy,

"But it is not absolute RF in the sense of special relativity theory. "

I do not understand this statement. Please tell me what is the difference between a RF in SRT and a RF not in SRT?

Hello Csaba: You wrote, "I do can distinguish between two inertial systems." This is a sure sign of not believing (belief = probability that evidence supports the claim; this is physics) in special relativity. This would deny the universe we know. You could look at a different angle, this dog won't hunt.

Cosmic microwave background is made out of photons only, nothing else. They move with the speed of light, so an (imaginary) observer who is in the rest frame of CMB is moving with a velocity c with respect to rest of us. We (real mortals) can not reach that speed because then we have to have zero mass.

It is, however, possible to use the average motion of the galaxy with respect to CMB and construct a frame which is at rest with the galaxy. This frame can be connected with us via a Lorentz transformation, therefore the "laws of Physics" as we know, will be the same in the rest frame of the Galaxy.

Biswajoy,

We do not need to travel with the speed of the light in order to define the "rest frame of CMB". So I do not understand your argument.

I have added a second para in my last answer for clarification.

We use coordinate transformation because it simplifies a problem. But we must ensure that Physical laws remain the same in a new frame, otherwise it will complicate a problem instead of simplifying it. Secondly laws of physics are verified by experiments. So if you write a new law in the rest frame of the photon, you are free to do it. I cannot, however, verify it by doing an experiment.

Ed,

It is not the case of believing or not. Science is not a religion.

When in acient time people thought that the frame connected tothe Earth is an absolute reference frame they were correct because their Universe did not contain anything else just the Earth, Moon, Sun and some planets. They could easily say if someone, somebody moves because there was the Earth and they could compare.

SRT saying that all frames are equivalent, but as I pointed out there is a way to select a special frame, and "anybody" can compare his/her individual frame to it.

The question is that what does it mean? Are we just not observed other Universes running with different speed compare to us, and in a MetaUniverse the speed distribution of the masses is homogeneous, or we have just our Universe to live with and then the principle that all inertial frames are equivalent is simply not true.

That is why I said that I cannot convince myself. I can imagine that we are very similar to an ancient greek, not knowing a lot of things we already do.

Dear Csaba,

You posed rather actual question, which, though the answer is quite evident, till now practically isn’t adopted by the mainstream physics.

The answer is: yes, the Matter’s spacetime is absolute and so there are three “absolute frames” that are at rest relating to concrete Matter’s spacetime dimensions [at rest relating to 3D space, to 1D time and to both], including the usually considered in physics absolute reference frame that is at rest in the 3D space.

This point can be rather evidently proven, because of from the SR postulates that there is no absolute Matter’s spacetime and that so all/every inertial reference frames are completely equivalent any number of evidently meaningless physical and logical consequences directly and unambiguously follow. The most known are the “Dingle problem in the SR” and its version “twin paradox”, “the Bell paradox”, etc. more see, for example https://www.researchgate.net/publication/322798185_The_informational_model_twin_paradox DOI 10.13140/RG.2.2.34064.51201/1 and https://www.researchgate.net/publication/317067896_The_notion_speed_and_the_Lorentz_transformations DOI: 10.13140/RG.2.2.10250.47043

Thus from this fact the incorrectness of the SR postulates and so the SR as a whole directly follows by the proof by contradiction. That’s all. However the true SR/GR believers seems don’t understand this fact on a sub-conscious level and so attempts to explain them this problem rationally as a rule fail.

Including your note that cosmology doesn’t observe cosmic objects that have large “no-radial” speeds and that from this fact follows that seems all macro and giant cosmic objects are practically at rest in the absolute space/[and in corresponding frame] is quite rational, though in the mainstream cosmology this fact practically is adopted – so called “cosmic redshift” is explained in the mainstream not because of that distant galaxies move in the space with speeds even more then the speed of light, but that is the consequence of the “space expansion”.

A version of how such situation could happen, when at first step of Matter’s creation some “ether” of 4D fundamental logical elements (FLEs) was created and further practically uniformly in the ether the material objects [particles, etc] were created [“Big Bang was not in some point but uniformly in whole Matter’s space”]; thus, after composing of “usual” material objects, i.e. atoms, stars, galaxies, etc., they were practically at rest in the space; see

https://www.researchgate.net/publication/260930711_the_Information_as_Absolute , Sec. 6.1.3. “The problem of Beginning and evolution of Universe” and https://www.researchgate.net/publication/273777630_The_Informational_Conception_and_Basic_Physics , at least Sec. 3.3 “Planck mass particles”.

In the reality Matter’s spacetime is the “absolute” [5]4D Euclidian “empty container” [more see the links above], which filled by dense 4D lattice of the 4D FLEs, and disturbances in the ether that are material objects. The ether seems is at the absolute 3D spatial rest.

Since the fact that Matter’s spacetime is absolute is rigorously logically true fact, the problem of observation of the absolute spatial motion and absolute frame is purely technical, and that is possible yet now, see https://www.researchgate.net/publication/259463954_Measurement_of_the_absolute_speed_is_possible DOI 10.5281/zenodo.48709

Cheers

Dear Csaba,

You ask: "But if all reference frames are equal why there are no galaxies travelling with close to the speed of the light from left to right (or opposite)?"

The answer to that lies in the first 50,000 years of the universe. During that time, it was a "radiation dominated" plasma and all particles were ionised so were affected by radiation pressure. Any particle moving at high speed through that environment would see light coming from in front to be blue shifted (by Doppler) and from behind to be red shifted. That means every particle moving at any appreciable speed relative to the local mean (local being of the order of the mean free path length between interactions) would see an anisotropic pressure reaction which would slow it down, essentially a "radiation drag force" or "friction". By the time the photons decoupled to be released as the CMB, the speed of the particles was in thermal equilibrium so there was almost no gross motion relative to the Hubble flow.

None of that has anything to do with an "absolute frame", for that read Newton's definition of "absolute motion" in his Scholium, today we describe his view as "manifold substantivalism" and the generally accepted argument against that idea is called the "Hole Argument" which you can see here:

https://plato.stanford.edu/entries/spacetime-holearg

Let's begin by defining the reference concept in physics. Imagine sitting in a constant-moving train and getting the ball up, because the ball will go up and down with a straight motion but for the outside observer sitting on the pavement, the ball will look like a parabola. The different path of the ball results from the fact that observers in the two different frames as a reference frame are the set of coordinates that can be used to assign all the motion properties (path, speed, acceleration) of an object within that frame.

Dear George,

What you are telling me is that Universe had anisotropy at his 50.000th birthday already. It just strenghtens my argument does it not?

Dear Djaafar,

I understand what you say. I do not understand what it has to do with my questions.

Dear George, in the world of classical GR, the hole argument is fine and makes sense. But there is a quantum variant of the hole argument, see https://arxiv.org/abs/0909.1408v1 It follows that in quantum gravity , at least as long as it is reasonably approximated by semiclassical gravity as well as Newtonian quantum gravity, the background spacetime becomes observable.

Dear Csaba, one can always think that what we see is only a small part of the universe, and other parts will be very different. Then, the preferred frame we see in global universe is nothing but an accidental local velocity. And from a much more global point of view this would be nothing but a local preferred frame of, say, the flow of water around a boat in the ocean, locally preferred but of no fundamental importance.

This is a quite popular philosophy in the physics mainstream today, especially among those who like "multiverse" theories.

Dear Csaba,

Your question is: In searching of an absolute reference frame: is it possible to define one?.

The definition of an absolute reference frame would some fixed reference frame that every observer would agree it is at rest at all times independently of his/her state of motion. Obviously this system of coordinates is not possible in the Special or General Relativity or even in Galilean Relativity where time is an absolute.

Thus the answer to your question is no in any physical system of coordinates that you can choose: inertial or no inertial, galilean or no galilean.

There is nothing in Special Relativity that "there is no absolute reference frame " although many declarations to this effects are published.

The truth is that Lorentz Transformation alone cannot identify the absolute rest because they are derived from assumptions that every inertial system is at rest. But removing this limitation in thought is possible and it can be proven such unique rest states is definable. I am in a process of publication of my findings which has some non-merit based hiccups but this will be published this way or another in incoming weeks or it will become shareable on one-to one basis.

The key to the identification of the Absolute Rest is defining Absolute Simultaneity which is possible but also pronounced dead by relativity claims without defining what it actually is.

My project will be the place for updates on this matter:

Deleted research item The research item mentioned here has been deleted

https://www.researchgate.net/project/Absolute-Simultaneity-and-Rest-Consistent-with-Special-Relativity

Hello Csaba and all: From other threads, we see what may help here. A divisiveness permeates practically any discussion, at any level, including, especially, cross-disciplines. That does not have to be. The word is belief, and is used as a football.

I suggest that, in sciences, physics and maths, we could understand belief as, no more and no less, than the probability that the evidence supports the claim. For example, when someone says they do not believe in SR, we should know what they mean.

Still, divisiveness can occur, and is good analytically, but no longer about belief itself. It is very old-fashioned, even in religion terms, to assume that we cannot understand what affects us. SR affects us, and the evidence correctly supports the claim. Does it not?

The principle of relativity makes no statement as to how things actually move. Rather, it concerns what you might call ``laws of nature''. In this respect, both Newtonian mechanics and SRT have a principle of relativity.

In both theories, if you have two laboratories A and B, one in uniform rectilinear motion with respect to the other, whatever experimental results are found in laboratory A, stated in terms of its own instruments, will be the same as the results for these same experiments performed in laboratory B and stated in terms of the instruments of laboratory B.

Of course, if laboratory A were close to Earth and laboratory B were to move at a speed close to that of light with respect to A, it would see nearly all galaxies flying in the same direction, opposite to that of its motion with respect to A. That might look strange to the physicists of B, but if they simply decided that galaxies happen to move in this fashion, and if they were to compute the motion of all these galaxies in rapid motion, they would obtain entirely consistent results, at least if they used an appropriate theory of gravity.

A comparison may help: relativity says no velocity is special, but in the immediate world around us, rest with respect to the Solar System is singled out. Similarly, physics says the world is isotropic, no direction is singled out. Yet all planets in the Solar System are very much on the same plane, thereby singling out a direction. It is the same difference between laws and actual configuration of objects.

" whatever experimental results are found in laboratory A, stated in terms of its own instruments, will be the same as the results for these same experiments performed in laboratory B and stated in terms of the instruments of laboratory B. "

Strictly speaking, I would say it is simply not true. Let's say they have to determine the momentum of a third object, of course they would get a different number.

If the question is that both laboratories should determine the momentum of the Universe (and they have all the necessary instruments to do it), the results would also be different.

Since this number has a distribution (it has a minimum) along the different reference frames, it is an anisotropy regarding the whole universe. So the whole Universe is in a special reference frame which should be absolute as regards the Universe.

Dear Daniel,

I would say that you make a slip of speaking. I can agree that SRT says all frames are equivalent.

But I am interested in reality, if we can define an absolute frame and what happens if it contradicts to SRT.

Hello Ed,

In my opinion it is not a good practice to use words with different meaning. I do not want to start a different thread, but I do not agree with your definition: " I suggest that, in sciences, physics and maths, we could understand belief as, no more and no less, than the probability that the evidence supports the claim. "

It is far what I would call belief.

Hello Csaba: You wrote, "It is far what I would call belief". Look for Dampster-Schafer: The Dempster–Shafer (DS) theory is a powerful tool for probabilistic reasoning based on a formal calculus for combining evidence. It is used in physics, and math, as way to make probabilities reflect the intersubjective and subjective. One needs to know better before go talking about it, that's DS.

Csaba Bagyinka

The primitive concept of absolute space and absolute time found in Newtonian mechanics and Galilean relativity is corrected and replaced in special relativity by "infinite number of equivalent reference inertial frames" with the covariance of relativistic physical laws including tensorial or invariant proper time and proper distance, thanks to Albert Einstein.

What you wrote in the introduction of your question that the Universe is finite certainly somehow needs to be corrected. In fact, observations, including the NASA Goddard Space Center Cosmic Background Explorer (COBE), NASA Wilkinson Microwave Anisotropy Probe (WMAP), and Planck maps of the CMB, imply that the expanding Universe is infinite in extent or space with a finite age of the observable universe, as described by the Friedmann–Lemaître–Robertson–Walker (FLRW) models, thanks to Einstein's general relativity , where spacetime is gravitationally quantumly physically curved. As the universe's age increases, the size of the observable universe will continue to expand and vice versa.

The detection of new gravitational waves were consistent with general relativity as explained by Professor Michio Kaku in this very short and CBS News YouTube https://www.youtube.com/watch?v=xb2MD_06ogY&t=59s

Biswajoy Brahmacharin

In one of your comments you wrote ," if you write a new law in the rest frame of the photon, you are free to do it. I cannot, however, verify it by doing an experiment."

A photon has neither a rest frame nor a proper time and as a particle , it is massless.

Hi Ed,

What you mean as belief I would call credit (maybe trust). I am not a native English speaker, so it might be that I do not feel the nuances, but In Hungarian the word belief has a pure (or mainly) religious overtone.

Hi Issam,

I know that there are " "infinite number of equivalent reference inertial frames" with the covariance of relativistic physical laws ", exist, the whole topic is about it. The question is that does this mean that there is no absolute reference frame?

I also know the theories that "universe" and "visible universe" might not be the same. It is, however, not relevant regarding the question I put. Do you think that inhomogeneous distribution of speed of masses in (any future) Universe would change as time going?

Dear Csaba,

I supose that you are conscious that your sentence

But I am interested in reality, if we can define an absolute frame and what happens if it contradicts to SRT.

is pure fiction and which goes against a lot of phenomenogy in Physics. But we could try to enter in this exercice of imagination, if you want:

1. The laws of Electrodynamics would fail and you cannot explain simple things as how one of observer at rest with respect to one electric charge only sees Electric Field, while another moving at a relative velocity v can see Magentic Field too. And what is more important, both have one physical invariant which is the same for every inertial observer respect to them.

2. You could not understand the origin of the spin as a quantum quantity carrying a magnetic moment.

3. You couldn't understand effects as the gravitational waves that were measured quite recently.

And we could add many physical different knowledges that everyday are used by physicists in labs or engineers in practice. Thus this simple contradiction with SRT would be with a disaster of difficult consequences to explain by another form (at least I cannot imagine it).

Dear Leyvraz,

I don't doubt that you know SRT, but you have written very "undefined" sentences in your post that need to be clarified for the rest of the readers. When you write (let me concentrate only in this one):

A comparison may help: relativity says no velocity is special, but in the immediate world around us, rest with respect to the Solar System is singled out

Obviously the SRT has a very special velocity, i.e. the velocity of the light c. This velocity is a limit of the reacheable velocities for every observer and what is more important it is always with the same value independently of the state of motion of any observer or emitter.

Perhaps you were not speaking in general and just mentioning an hypothetic constant velocity at rest with the Solar System. That is non sense for me without explaining what is the velocity of the Solar System. Assume that you have a center of mass where you can concentrate all the mass of this systema in a point, are you telling us that this point must be at rest with respect to any observer? Or do you prefer the take the Sun as reference? Is this also at rest? I supose you know that the Sun follows the overall rotation of the Milky Way, except for roughly 20 km/s in the direction with respect ot the overall rotation; this direction is known as the Solar apex and so on.

Dear Biswajoy Brahmachari,

agreed

sorry but here I see a big mistake!!! The CMB is a "stationary gas of photons" same as it occurs in a black body chamber. It is in average stationary which means that the net flux across any volume of space is 0. It does not have a priviledged direction and can be used as Yurij Baryshev just said as a rest frame.

So what you say that an observer stationary with it has to go at the speed of light is quite wrong. The CMBR makes the universe a "big black body chamber" and thanks to it we can refer the motion of bodies to this "chamber" by measuring doppler shifts.

Dear Csaba,

correct, this basically what SR says.

I would add that the speed of light is postulated as c in every IRF.

>

I have the same feeling but this is not what really counts. What counts is experimental verification.

So far what is the closest to an Absolute rest frame is the CMBR discovered in 1964 by chance although somehow previously predicted.

What is worth investigating is the contradictions we can find within SR which on one side do not allow for any priviledged/preferred frame, on the other side has to allow asymmetries:

a) the relativity of simultaneity descends from the LT and the constancy of the speed of light in every reference frame and is a predictionof SR. According to SR two moving frames should see eachother in delay (neither so far received an experimental verification).

which is clashes with:

b) It is not only derived mathematically (by Leonard Shiff 1960) in a very simple and elegant way but also experimentally verified (Ives, Kunding et al) , that thanks to the transverse Doppler shift, one is able to detect which frame accelerated in regards to the other, or better which is the frame travelling faster. One is able, by reading the shifts (redshift or blueshift), to identify an asymmetry in the motion, in line with the asymmetry found in the twin effect as an accumulation of delay per unit time of one clock in regards to the other.

What Schiff derived is quite well mathematically and physically sound, he applied twice the LT, and correctly for bodies going at constant speed hence IRFs.

Dear Daniel,

"is pure fiction "

I do not think it is pure fiction since I just have definied an absolut frame (at least I think so). You can say that this definition is not good because...., or say that it does not contradict to SRT, because...., but you cannot say it is a fiction.

I have to admit that although I am a physicist, I am working on a completely different field. Therefore I am not a specialist of SRT. But

Your #1.

I do not understand what you state. You do not need special relativity in order to explain all these things. Maxwell laws are enough (as far as I remember). c as upper limit does not come from electrodynamics.

#2. You cannot explain the existence of the spin from SRT (as far as I know).

#3. As far as I know gravitational waves are not the consequence of the SRT.

Dear Stefano,

I think that when SRT says that the physical laws are really independent on the reference frame it does not mean that there is no absolute frame. Physical law is the same as a result of an experiment.

I can agree that if someone is checking the conservation of energy, the conservation of momentum, three laws of thermodynamics, etc the result would show that all these principles are valid and they are the same in any inertial reference frame.

But if you are looking for an individual experimental number or phenomenon (let say total momentum of the Universe, or how much the background radiation is anisotropic), the result of these concrete experiments are - of course - different and they can serve as a method to define an absolute reference frame, which is also an inertial reference frame but somehow - depending on the experiments - it is dedicated.

It is still a question if these different experiments result in different or the same reference frame.

My guess is that they are the same .

Dear Andrew,

" There is nothing in Special Relativity that "there is no absolute reference frame " although many declarations to this effects are published. "

I tend to agree with you. Physical laws might be the same in any reference frame but the results of concrete experiments might not. And this is obvious.

Using the results of such experiments one can define an absolute reference frame.

Dear Csaba,

I think you may have misread my response. I was answering your specific question because I think you said that other people had given good responses but had not answered what you asked.

You asked: "if all reference frames are equal why there are no galaxies travelling with close to the speed of the light from left to right (or opposite)?". The answer is that radiation pressure acts like friction so that all matter was effectively brought close to rest in terms of bulk flow, that is why there are no high speed galaxies. Speeds within clusters are of the order of 1% of the speed of light and such high speeds have arisen more recently from gravitational interactions between galaxies.

Dear George,

That was part of my question. And not the main part.

And I asked a further question interpreting your answer.

What did I misred?

Csaba Bagyinka

"Equivalent inertial frames" , in Einstein's special relativity,means there isn't any absolutely privileged or preferred frames in such a way that all physics laws take the same form; thus, as a consequence, there isn't any Newtonian absolute reference frame since it is already an absolutely privileged frame.

If you insist on using an absolutely privileged reference frame, you may possibly shift ,to a certain extent, to another kind of relativity, such as Newtonian-Galilean relativity , Selleri 's relativity, or Tangherlini's relativity.But, generally,in that case, speed of light will not be anymore a physical law and will not be of the same value in all inertial frames.

For almost decades, satellite communications, GPS and GLONASS satellite positioning navigation systems, and NASA spacecrafts, all count on both special and general relativity to work properly, and it will remain so in the future. Even US cruise missiles use GPS signals to accomplish their missions provided that locational coordinates of targets are known in advance.

If the concept of absolute reference frame were useful, it would be used by NASA scientists and engineers.

Please enjoy watching the attached, very short, and amusing YouTube video, which was shot in Hungary, where Einstein gives an excuse for being late in the presence of his friend Max Planck and speaks about the relativistic mass, time delay, and the failure of Newton's gravity. https://www.youtube.com/watch?v=n2ZWOYv_0Mk

Dear Issam,

" "Equivalent inertial frames" , in Einstein's special relativity,means there isn't any privileged or preferred frames and all physics laws take the same form; thus, as a consequence, there isn't any absolute reference frame since it is already a privileged frame. "

(Just in brackets: I do not want to question any well done physical experiment. I accept that many experiments are based on SRT and they gave correct results so far. I am not stupid (at least I think so :-) ) so I would not state completely stupid things (again, at least I hope so). My problem is about the interpretation of the experiments and SRT).

The question is, if your statement above is true or not. I mean the "as a consequence" part of your statement. I agree that all the physical laws take the same form in any reference frame. I agree that SRT states that, and it is proven by several experiments.

The question is, if there is no way to distinguish between different reference frames simply checking the validity of the physical laws (so within the SRT) does this mean "there isn't any absolute reference frame", because SRT does not point to a single one?

My answer would be that this is not a contradiction. SRT does not mark any reference frame but there are other ways to mark it. And of course the physics will remain the same in any inertial reference frames (why would it be different??) and physics would not collapse.

A next time here: the answer on the thread’s question is evident:

Because of that from the main SR postulates that all/every inertial reference frames are completely equivalent and completely legitimate directly and unambiguously any number of evidently meaningless consequences follow. An utmost known example: the Dingle problem in the SR, when in both of two relatively moving frames every observer [i.e. simultaneously both of them], if he is a true SR believer, must think that in his vis-à-vis’s frame “the time is dilated” and “the space is contracted”.

That is evidently logically false assertion, if to adopt that Matter’s spacetime is unique. There can be “A>B and BA and AB and B>A”, what the postulate about the equivalence establishes. On the other hand it becomes be logically true only if to adopt that in this case there are two Matter’s spacetimes that are peculiar for every frame; and so how many frames exist, so many spacetimes exist; what is evident physically meaningless assertion.

From what [and not only] by the proof by contradiction rigorously follows that there are preferred inertial reference frames that are at 3D spatial rest in Matter’s absolute spacetime. That’s all.

As to when and why the SR postulates above don’t interfere to obtain, nonetheless, adequate to the objective reality results at application of the SR in concrete physical tasks, see https://www.researchgate.net/publication/317620440_About_some_conventions_in_mechanics DOI 10.5281/zenodo.1142628; and SS post above and the papers linked in the post as well would be useful.

Cheers

Dear Csaba,

since SR is based on the constancy of the speed of light in every IRF ; the universal value c implies the CONSTANCY and ISOTROPY, although the constancy has been verified experimentally only in the averaged two way speed of signals in vacuo.

As Issam is correctly reporting, only assuming that the speed of light is not constant in every IRF or changing the LT, it is possible to conceive a different picture with a preferred frame of reference.

Tangherlini transformations, which are considered valid as well in accelerators, presume the existance of a preferred frame of reference, making the simultanieity absolute with the non-invariance of the speed of light.

The big difference between TT and LT is in the syncs method adopted for the TT:

a) infinite speed of the signals (not Einsteinian) initial version of the transformations

or

b) External sync procedure (EST) referred to the Einstein sync proc.

the Einstein Sync procedure is instead internal in LT.

The time transform of the TT is simply

t'=t*gamma-1

instead of

t'=gamma(t-vx/c2 )

so basically there is no space-time in the TT.

in addition they do not define a Group of transformations since the inverse does not have the same form as the direct, as requested by the definition of Group. It is a pseudogroup.

TT decribe straighforwardly the Twin-effect and are much more intuitive for certain aspects.

The Selleri transformations (ST) instead use the same sync method, internal Einstein sync proc. but assume a variation of the speed of light such that the simultaneity of the phenomena are kept invariant (not relative as LT).

The time dilation in the Selleri Transformations, is governed by a mechanism, where in SR there is not, since it descends directly from the structure of the space-time.

What are the implication of a preferred frame of reference?

The photons would travel in such frame independently on the direction and the speed of the system which shot them.

a) The one way speed would be c only in their reference frame.

b) They would not take the "side speed" from the platform where they departed from, but will proceed in exactly in the direction they were shot as if they are "guided" by the preferred frame of reference.

I like much better a) and b) than the actual description of SR with the artifact of the space-time...

Dear Stefano,

I am not an expert on these transformations, moreover I did not even know about ST and TT. So I cannot comment your answer. What I think is, that the conclusion of "there is no absolute (or resting, or preferred) reference frame" should not be valid, since nature is giving us such reference frames (maybe not even with only one definition).

I do not know exactly what are the consequences of the existence of such a frame regarding SRT. I can imagine (I do not know) that there are no serious consequences, but you say different. It is not my field.

Anyway the speed of the light is constant per definitionem, so it is not possible to repeat the MM experiment. Once I red a paper (I cannot recall where) comparing the results of the measurements on the light speed (before fixing) and the results had a tendency.

"Anyway the speed of the light is constant per definitionem, so it is not possible to repeat the MM experiment. "

I dont' agree.. there are at least two experiment which should be done in order to clarify about the actual prediction of Phsical phenomena:

a) the constancy of the speed of light can be tested by the following experiment by testing the prediction of accelerated clocks

Working Paper THE TIME OF THE EINSTEIN'S TRAIN, a test of the relativity o...

b) the independence of the light rays can be tested on a very wide inertial platform far from gravitational fields. The "drift" of the EM waves with the plaform can then be detected (or not).

Any other then the Lorentz ones transformations don’t form corresponding group and so, for example, give the velocities addition results, which have no relation to the objective reality and thus are practically non-applicable at considering dynamics of bodies.

More see SS posts above and papers that are linked in the posts.

Cheers

Dear Csaba,

me and Stefano already explained that in the real Universe there is the Global Rest Reference Frame which is confirmed experimentally - it the reference frame based on measurements of isotropy of the teperature of the Cosmic Microwave Background Radiation. It is established by real experiments and can be used by any observers, and it is a matter of time (developing of suitable technikal devices) to use it in all applications.

Relative to this GRRF we can measure the true values of all observed velocities and accelerations. So for your question

"In search of an absolute reference frame: is it possible to define one?"

positive answer already exists, but if under the "absolute RF" we shall mean the global rest frame relative to the background photon gas.

The question does the existence of global rest frame contradicts SRT or not is the separate subject for discussions. Important thing is that such unique RF exists according to real physical experiment.

Yuriy,

Yes, I concluded to this view as well. But, as you see it is not obvious to anybody.

Moreover I think it is not in contradiction with SRT, since it does not say anything about absolute reference frame. It simply cannot distinguish between them.

Hello Yurij and all: Any reference frame based on measurements of isotropy of the temperature of the Cosmic Microwave Background Radiation, depends on the slice of spacetime used, just like simultaneity -- space and time are interchangeable according to special relativity. In other words, space and time are not absolute, one can transform into the other.

It is against experiments to think that one place in the known universe is unique, permanently, forever, and all the way 13.772 bilions years back to the Big-Bang, which is what is beind said, repeatedly, by some in this question.

There is, however, no absolute place, and different observers will see different measurements of isotropy of the temperature of the Cosmic Microwave Background Radiation, as it should be clear by following the equations.

And, btw, anyone can discover that theirs or anyone else's pointer finger is the center of the Solar system, call it a preferred absolute frame, and all equations can be correctly written for it. That does not mean that current physics should change, it rather affirms it.

Dear Csaba,

Let me to answer you just taking your comments to some applications that I have found enough clear for explaining you what would be changed in Physics if you had one absolute reference frame as you ask in your question:

1. Electrodynamics it is only covariant under Lorentz transformations and they don't allow to have a fixed reference frame that every observer would agree it is at rest at all times independently of his/her state of motion.

2. You could have Dirac fermions in such a fixed reference but never Weyl ones, even you cannot define a spin properly. These are quantum field (QED) magnitudes clearly dependent of the Lorentz group transformations.

3. I was speaking on the possibility of an absolute reference frame as your questions said and no of SRT. Gravitational waves are consequence of the Lorentz transformations for non inertial observers. I tried to give you also one example for non inertial observers.

In summary, as you have asked for the consequences of your "fictitious" assumption that a fixed system could be found in classical, quantum and non inertial systems. In all of them this would lead to a non physical result.

Dear Ed,

the traveling time of photons change nothing for the global rest frame, which is defined relative to photon's gas.

For the global rest frame it is important that the photon which have the universal limiting velocity, actually has changing frequency which can be used for determination of the rest frame.

As for Big Bang and expanding space, I hope you aware about deep paradoxes of this cosmological model, which cannot be accepted as a standard physical theory (see review: arXiv: 1501.01919).

Dear Daniel,

You are stepping back. Lorentz transformation is not exactly the same as SRT. Especially in electrodynamics. It can live without SRT and will live fine.

An absolute reference frame does not mean that Lorentz transformation becomes invalid or false. Lorentz transformation is not incompatible with an absolute reference frame in electrodynamics. It just will not distinguish between them. So physics will not collide.

I do not accept your examples. They are not valid.

AND, you did not falsify my example.

Dear Ed,

I agree with Yurij. You did not give any estimated result what happens with the Cosmic Microwave Background Radiation if you are running with 0.9C towards the Andromedes? Will it be isotropic? Will it not?

What you are repeating is well known as a usual example of SRT. What is needed from you is a prognosis, what will you observe?

Then you can continue explaining why the speed distribution in entire Universe is anisotropic?

Waiting.

Dear Csaba,

Obviously you don't need to accept my examples at all, even if they are right and you don't remember that Einstein published "on the electrodynamics of moving bodies" instead of SRT. I doubt that you are understanding what I tried to explain you, because your question is based in a wrong concept in Physics. My advice is that you try to understand the different answers and see what is the relation with your question.

I remind you (what you have already cited) that Einstein was speaking about "on the electrodynamics of moving bodies" . In electrodynamics (Maxwell equations) there is no mass just charge (and fields). There you need Lorentz transformation to find the covariant transformation. But there is no word about the absolute reference frame, neither about the limit speed (I also remind you that MM experiment was for measuring the speed of light in different directions). Since you do not have masses there is no singularity.

Einstein extended it to objects with masses (bodies). There you have singularity and you need a limit speed.

But there is still no word about the absolute reference frame.

Lorentz transformation just simply cannot distinguish between different reference frames. That's all. It does not mean that other physical experiment cannot either.

Dear Ed,

in the FLRW coordinates, all places are equal, and in all points they define locally the CMBR frame. We are in GR here, not in SR, so that the CMBR frame is not a global inertial frame as known from GR, but only a local approximation.

Note also that in our universe (with the spatial curvature parameter zero) the FLRW ansatz gives simply \(dt^2 - a^2(t)(dx^2+dy^2+dz^2)\) so that the spatial coordinates x,y,z are also harmonic, and one can easily make time harmonic too. Harmonic coordinates are the essentially only plausible candidate for preferred coordinates, even if in GR ideology they are not accepted as preferred.

Note also that there is nothing anisotropic if one interprets, following the Lorentz ether interpretation, the preferred coordinates as defining a global true background and the distance and time measurements as distorted by the ether. In this interpretation, the a(t) defines the distortion, everything in in rest, and what is interpreted as expansion now is simply the process of shrinking of the rulers - they shrink everywhere in the same way, but everything remains in rest (modulo local velocities).

Dear Csaba,

Let me to remember that light is nothing but one electromagnetic field which follows the laws of electrodynamics, as the one that its velocity only depends of electromagnetic parameters as permittivity and permeability. On the other hand if this velocity were with a limit you would have Galilean transformations instead of the Lorentz's ones.

The main problem which has made difficult to progress the real laws of transformation, mainly in Optics, was the assumption of an absolute system of coordinates associated to one physical body as the Ether. And Einstein was enough clever to avoid to repeat so mistake just saying that it was not necessary. If it is not necessary it means, given that this is just a tool in the transformation laws, that it doesn't exist. Thus your question:

In search of an absolute reference frame: is it possible to define one?

is coming back in the history of Physics for trying to find something useless and without a physical object whose behaviur needs it.

Dear Csada,

Although your sentence is not directly related with our discussion

In electrodynamics (Maxwell equations) there is no mass just charge (and fields)

First, the charges always have mass and second, the electromagnetic fields always have also linear momentum and therefore an equivalent mass.

Please, don't confuss the study of the fields associated with the mass (gravitation) with the mass itself.

Dea Daniel,

I know that it is a long time debate. I just wanted to point out, that electrodynamics can live without SRT because there are no masses in electrodynamics.

The problem arises when masses are coming into picture. There you need a limit speed. And I agree that " Einstein was enough clever to avoid to repeat so mistake just saying that it was not necessary ". It is not necessary but anyway it might exist. It is not excluded!

And we see in the Universe that there is an anisotropy which marks the absolute system.

Do you see the anisotropy?

Dear Csaba,

You are absolutely wrong when you say:

"I just wanted to point out, that electrodynamics can live without SRT because there are no masses in electrodynamics".

https://global.oup.com/academic/product/geometry-of-electromagnetic-systems-9780198591870?cc=es&lang=en&

Once again, one thing is to gravitation as a field associated to the mass and the mass itself which works with electrodynamic, weak and strong interactions (and in our everyday life).

What kind of anistropy are you speaking about? There are infinite things which are not excluded of the reality but which they don't exist, the literature is full of them or the philosophy, but science tried to avoid them: the simplest explanation always is the best.

Dear Csaba,

You asked: "if all reference frames are equal why there are no galaxies travelling with close to the speed of the light from left to right (or opposite)?" which I answered previously. You then state: "Since Universe is finite" but that may not be the case. We don't know if it is finite or infinite, but since we can only observe a small region due to the finite speed of light, that probably doesn't matter.

CB: "one should be able (at least in principle) to measure (or estimate) the momentary speed of all particles in Universe within a limited (local) time frame."

We could do that or, more easily, any astronomer anywhere in the universe could find his local frame in which there is no dipole in the CMB due to the Doppler effect. The Solar System for example is moving at 368km/s relative to the CMB.

CB: I think this series of numbers have a finite limes which gives you the absolute reference frame for our Universe. What is wrong with this argument?

The error in the argument is that it doesn't give a unique frame because two observers, both of whom see their local matter at having no mean momentum, will still be moving apart due to expansion. Two such observers 1 Mpc apart would be moving apart at around 70km/s, the Hubble constant. In special relativity, if two objects are both at rest in one frame, the distance between them should be constant, for cosmology, you need to use general relativity.

The other error is that you are only trying to define the frame of the mean momentum of the matter in the universe, not the absolute frame. It might be that the whole of the universe had non-zero motion in the absolute frame.

Dear George,

GD. "You asked: "if all reference frames are equal why there are no galaxies travelling with close to the speed of the light from left to right (or opposite)?" which I answered previously. You then state: "Since Universe is finite" but that may not be the case. We don't know if it is finite or infinite, but since we can only observe a small region due to the finite speed of light, that probably doesn't matter".

I don't understand what is the role that the finiteness of the Universe plays with respect to the velocity of the Galaxies. What is relevant is the relation of their velocities with their inner energy and with the limits of relativity.

DB: I don't understand what is the role that the finiteness of the Universe plays with respect to the velocity of the Galaxies ..

Neither do I Daniel, I was quoting Csaba. I think he just meant that the sum could be calculated without worrying about infinities.

Dear George,

Your argument is wrong (or maybe I do not understand it).

" both of whom see their local matter at having no mean momentum "

I was not speaking about local matter. I was speaking the whole Universe (finite or infinite). So it depicts a different story, not mine.

" Two such observers 1 Mpc apart would be moving apart at around 70km/s, the Hubble constant. "

Then none of them would measure zero momentum.

I do not understand what you are trying to explain.

Dear George,

" You asked: "if all reference frames are equal why there are no galaxies travelling with close to the speed of the light from left to right (or opposite)?" which I answered previously. "

What you did was, that you have shown, that this anisotropy is built in the theory of Big bang and the Universe's expansion (if we accept your explanation). But it is there.

Dear George and Daniel,

" Neither do I Daniel, I was quoting Csaba. I think he just meant that the sum could be calculated without worrying about infinities. "

Yes, that was the point.

Dear George,

" The other error is that you are only trying to define the frame of the mean momentum of the matter in the universe, not the absolute frame. It might be that the whole of the universe had non-zero motion in the absolute frame. "

Why it is a problem? I said there is a minimum, I did not say it should be zero.

Dear Csaba,

CB: Your argument is wrong (or maybe I do not understand it).

The latter.

GD: " both of whom see their local matter at having no mean momentum "

CB: I was not speaking about local matter. I was speaking the whole Universe (finite or infinite). So it depicts a different story, not mine.

Each observer sees matter around him moving radially outward from him. It is moving at some speed which depends only on the distance from him (after averaging out "peculiar velocities") in accordance with Hubble's Law. That means that each observer sees the momentum of the universe as zero provided he isn't moving quickly through it. An observer who sees exactly zero momentum for the whole observable universe is called "co-moving".

GD: "Two such observers 1 Mpc apart would be moving apart at around 70km/s, the Hubble constant."

CB: Then none of them would measure zero momentum.

Yes, each would see exactly zero because all the matter is moving away from them (including the other observer) with a speed that depends only on radial distance, there is no anisotropy.

CB: I do not understand what you are trying to explain.

I hope it is clearer this time. It is simply the effect of Hubble's Law.

CB: What you did was, that you have shown, that this anisotropy is built in the theory of Big bang and the Universe's expansion (if we accept your explanation). But it is there.

No, what I explained was that all local speeds are reduced to nearly zero by the drag caused by radiation pressure, all that is left is the expansion described by Hubble Law which is isotropic, there is no anisotropy.

CB: Why it is a problem? I said there is a minimum, I did not say it should be zero.

The minimum is zero for each observer because momentum is a vector, but that still doesn't identify any absolute frame or even prove that one exists, it only characterises the motion of matter. The real problem is that the minimum (zero) momentum for different observers identifies differnt frames due to the Hubble Law.

Dear George,

First, I am aware of Hubble law. And I know that momentum is a vector.

Second, I have the feeling that you are explaining me my own statement. So you also think that there is a reference frame in which Universe has no (or has a minimum) momentum? That was my original statement (question).

Then what we are arguing about?

Dear Csaba,

CB: First, I am aware of Hubble law.

That should make the conversation easier.

CB: Second, I have the feeling that you are explaining me my own statement. So you also think that there is a reference frame in which Universe has no (or has a minimum) momentum?

No, I am pointing out that there cannot be such a frame if the Hubble Law is true.

Dear George,

Ok, I understand your point. But you are speaking about "observers" connected to a mass, or sitting around a mass with no relative motion.

I was speaking about an observer, who is - let say - running with 0.9 c from a distant galaxy to another distant galaxy. SRT says that this observer is equivalent with the observer - let's say on the Earth.

What I say the momentum of the Universe for this observer would be different as compare to the observer on the Earth.

I have to admit now - you convinced me - that there are groups of reference frames regarding the total momentum of the Universe, and there is not just one. What if we change to kinetic energy?

CB: I was speaking about an observer, who is - let say - running with 0.9 c from a distant galaxy to another distant galaxy. SRT says that this observer is equivalent with the observer - let's say on the Earth.

Ah, OK, I see why there was confusion. Such a fast moving observer would obtain all the usual laws of physics if he ran experiments in a closed lab, which is why he would be equivalent to on on Earth, but he would see a blue shift of the CMB from ahead and an extreme redshift from behind. I always assume we are talking of "comoving observers" who see the same temperature of the CMB in all directions.

CB: I have to admit now - you convinced me - that there are groups of reference frames regarding the total momentum of the Universe, and there is not just one.

That is exactly the problem. Any other measure would produce the same result, it follows from the Hubble Law.

Dear Daniel,

Sorry answering so late, but I overlooked your answer.

"First, the charges always have mass and second, the electromagnetic fields always have also linear momentum and therefore an equivalent mass."

In the Maxwell equations there are no charges, (sorry I have to correct I ment NO MASSES) that is what I pointed to. Of course charge is always associated to a mass but Maxwell equations do not care about it. The equation which is connected somehow to the masses (not directly) is the Lorentz force, this force will affect masses.

I know that photon has a linear momentum and consequently it has mass. I ment resting mass of course. The relativistic mass is already the consequence of relativity theory but not the electrodynamics itself.

Please, don't confuss the study of the fields associated with the mass (gravitation) with the mass itself.

Sorry I do not understand this sentence. I think I did not confuse.

You are absolutely wrong when you say:

"I just wanted to point out, that electrodynamics can live without SRT because there are no masses in electrodynamics".

https://global.oup.com/academic/product/geometry-of-electromagnetic-systems-9780198591870?cc=es&lang=en&

I followed the link but there was a commercial about your book, encouraging me to buy the book. I do not know what you are pointing to.

Once again, one thing is to gravitation as a field associated to the mass and the mass itself which works with electrodynamic, weak and strong interactions (and in our everyday life).

I do not think that I have confused all these things. Where did you observe confusion? In SRT there is no gravitation field but there are masses. It is a confusion? I do not understand your statement.

Dear George,

" That is exactly the problem. Any other measure would produce the same result, it follows from the Hubble Law. "

Nevertheless we can say, that

1./ There are infinite number of inertial reference frames (IRF, Lorentz transformation connects them)

2./ There are inertial reference frames where Universe seems to be only radially expanding (I will call them as Closer to Absolute reference frames CTARF). Also infinite number of them.

3./ We can say that CTARF

Csaba,

>

it does not have a rest mass once it is emitted, the mass is only what gets transformed in pure energy at the emission or retransformed in mass at the absorption process which is pure Quantum Physical.

photons do not have relativistic mass either. They go natively at the speed of light. The relativistic mass is a property of all particles (fermions for example) with a non zero rest mass.

Dear Stefano,

You misunderstood me (or maybe I expressed myself wrongly). I agree with you. "I ment rest mass" belonged to the previous conversation not to the photon.

Dear Csaba,

I don't understand how you use the electrodynamics when it is obvious that you haven't too much expertise on it and you know that you have one specialist discussing with you. Let me try to answer you som basic concepts:

1.When you say

In the Maxwell equations there are no charges,

Obviously you are wrong, the charges, currents or different densities of them are fundamental for producing fields. What, perhaps, are you confusing is with electrons, protons...that we nowadays know that they are the real sources of charge.

2. What you follow speaking about the mass in Maxwell electrodynamics is partially true, but curiously you introduce the photon when it is out completely of this Electrodynamics. The mass of Classical Electrodynamics is associated to its energy-momentum tensor or if you want in a pure classical point of view in the Poynting vector.

3. If you were into the book or to other book of Electrodynamics, one thing that would find is that it doesn't follow the Galileo's group but the one of Lorentz's. In my book there are two chapters devoted to show it and the rest of the book only use the relativistic formalism for solving practical problems. The curious is that since Maxwell till Einstein they were using SRT without knowing it, but in fact using it and SRT has not changed this field of knowledge practically in nothing relevant.

I hope that you can see some of the things that you confuss.

Dear Csaba,

the second order Doppler effect gives you a sort of hierarchy of frames in the sense of motion.

I explain you why:

consider an absorber and an emitter endowed with same atoms.

An absorber in circular motion sees the radiation coming from the center of rotation blueshifted, viceversa redshifted if the emitter is on the disk and the absorber in the center. The shift depends on the squared speed referred to the center of the disk, the tangential speed and the effect can be described as tangential Doppler effect. it is clear that the center is still and the rest of the disk is in motion. It has been detected in several experiments.

If the emitter departs from a very massive platform, reaching a speed v, the emission will be seen redshifted from the platform. In this case it is evident also that the platform did not alter its "status" while the emitter gained speed (got accelerated) to a certain v2 .

this is basically the famous experiment of IVES and Stillwell, the first to measure the transversal Doppler. Unlike the opposite interpretation of SR, they were sure that it was the phenomenology of a preferrred frame (they were supported of the Langevin-Lorentz-Larmor ether)

This tells us that there is a method, by using photons, to understand by means of the transversal frequency shift, what is the object emitter or absorber more in motion than the other.

Basically I could build a sequence of these platforms starting one from the other at speed v, each of which will see a transversal redshift of a certain amount.

If the transverse is made between the fist platform and the last one directly, the wider redshift of the incoming radiation from the last platform will show its actual squared speed in regards to the first.

Dear Daniel,

#1. You are right "charges" are wrong, it was a typo from me. But in all previous notes I wrote MASSES, so I might expect that you recognise the typo. I do not confuse, I have just mistyped.

#2 ok, using the name of photon was incorrect.

#3 I said the same in my previous notes.

Speaking about typos: " The mass of Classical Electrodynamics " Classical Electrodynamics has no mass since it is a theory. You see, I can be picky as well.

I always try to understand what others try to say and not trying to find errors even if they do not mean wrongly.

Hello Csaba and all: This discussion, whatever you may think, should be above board. Calling extensive sections of dis-contributions as "typos" is not, they should be called errors. There is no " rest mass" either, and more errors.

And the author is expected to edit or delete both types, the error and calling them "typos" , there are tools for this, it is in the platform. And we all expect the author to be grateful, or at least say nothing, to anyone who uses their time in these exchanges. They are helping you, it is not an ad hominem attack. So, please use RG as expected.

Dear Ed,

" Calling extensive sections of dis-contributions as "typo" is not, and the author is expected to edit or delete them, there are tools for this, it is in the platform. "

The author (I) was not aware about the typo. After Daniel's answer I did corrected it, with a note that it is a correction. It is there and anybody can see it taking the effort.

Dear Ed,

" it is time and space to move on. "

You are not tied down. You can do whatever you want.

Dear Stefano,

" the second order Doppler effect gives you a sort of hierarchy of frames in the sense of motion. "

I need some time to understand your experiment.

Dear Csaba,

Let me try to be positive with your question. Although George was trying to explain in detail (and quite well) how there are not comoving observers allowing a fixed system, I think that the impossibility to associate an absolute system of coordinates to the cosmic microwave background radiation (CMB) is really very easy to understand. While the expansion and the CMB are phenomena that look simpler in the comoving coordinates, the laws that govern the expansion and the CMB, when expressed in Lorentz tensor form,we have the same form in any coordinates and there are nothing which can make this physically distinguishable. This is in absolute coherence to employ the background of Einstein's Relativity which assumes the equivalence of all the inertial observers and follows the general reasoning that I have tried to show you.

Dear Daniel,

Now I am really confused. You say:

" Although George was trying to explain in detail (and quite well) how there are not comoving observers allowing a fixed system, I think that the impossibility to associate an absolute system of coordinates to the cosmic microwave background radiation (CMB) is really very easy to understand. "

It implies tha you and George are in agreement.

George said (and I agree with him):

" Such a fast moving observer would obtain all the usual laws of physics if he ran experiments in a closed lab, which is why he would be equivalent to on on Earth, but he would see a blue shift of the CMB from ahead and an extreme redshift from behind. "

and you say:

" and there are nothing which can make this physically distinguishable"

I have accepted that isotropy of CMB selects a group of reference frames not just one (George convinced me). For me you and George seem to be in a contradiction. Why do you think that observing anisotropy in CMB in some RFs but not in others does not select a subgroup of inertial reference frames? What is wrong with my statement:

"Nevertheless we can say, that

1./ There are infinite number of inertial reference frames (IRF, Lorentz transformation connects them)

2./ There are inertial reference frames where Universe seems to be only radially expanding (I will call them as Closer to Absolute reference frames CTARF). Also infinite number of them.

3./ We can say that CTARF

Dear Csaba,

I think that I was in agreement with George from the principle. The arguments are not the same because I was using a very general abstract one, instead of entering in details of the Big Bang model of the Universe or so on. For instance, George needs to use the Hubble law which for me is not at all necessary because the reason of not having an absolute frame of reference is just relativistic property and not due to accept an special solution of Einstein's gravitational equations. How have you thought that I was not in agreement with George? In one of his post he also agreed with me too.