Sofia,

why are you making things complex ?

As Information Scientist I like to structure your "complex" relations. Entanglement is effective valid in immediate time. So - as we and I know till now - the state-changes are all made in same moments.Therefor some Physicist think about that speed as highner then that of light. We don't know why!

That's the answer to your model? If you change one of the entangles particles the other will change immediately too. The spatial relations are not important - so that state-change will be done first which is happening first.

The observer is able to see that - if he can observe both particles.

No other possibilities - as I can understand entanglement.

Frantz,

Didn't you learn relativity? What means "immediately"? It's a meaningless word. "Immediately" by WHICH time axis, of WHICH frame of coordinates? Don't you know that the axis of time is different in different frames? Don't you know that what is simultaneous in one frame, is not so in another frame?

What happens with you? It's matter of general knowledge. 

This question is not pulled out of sleeve. What I expect, is a discussion of how, practically, can we do a test according to a moving frame?

Dear Sofia,

im mediate means excatly " at the same time ". If you would make any graphical diagram with one axis for time - then it would be one point on this axis.

Hope that's defined - not all clear facts can be solved by making them complex!

Franz,

What is this answer of yours "immediate means excatly " at the same time " "? Indeed, you don't know relativity?

When dealing with moving frames, "immediate" has no meaning unless you indicate by which time axis, i.e. by which frame you reason.

Also, your remark "Hope that's defined - not all clear facts can be solved by making them complex!", are you joking? What kind of things you say?

You should have told to Einstein: "why invent the theory of relativity? Why make clear facts complex?" The same with quantum theory, "not all clear facts can be solved by making them complex!" Isn't classical mechanics enough clear?

Sofia, I think that after re-editing your questions looks more unclear (at least to me) than before.

I suppose that what you want to ask is:

would an independant observer in a moving (to the laboratory frame) own frame has mismatch in which points (apparatuses) there is a corelation between statistics of the spins against the statistics in laboratory.

If this is your question, I think that the situation is like this (I am not specialist in SR so this is just my view):

After the observer slows down to zero to compare the statistics he can not have different results than laboratory. (otherwise there would be two realities). Also in the process of slowing he can not see a change in the results (jumping of results in other apparatuses). So he will have found correlation in the same apparatuses as the laboratory. He only would have had different distance between the apparatuses and different times of the results. But when he is back in the lab this will be no the case anymore.

Dear Sofia,

I know your verbal style from other dialogs already.

Again a provocative answer to your provcocative ones: These frames can be enumbered by Lorentz Transformation formula. Every property (v, m, l) can be transfered from one frame to the other. But that's realy basic Relativity Theory. Once understood  - than for ever!

For using an observer-frame you can tranfer all properties (including time) into that one - so you can compare them. 

Franz,

I am no prvocative person. Provocative are the people who are unable to explain themselves. There are a couple of people of that type here on RG. Exactly as a baby cries because it cannot make make itself understood, such people resort to insults because of their limitations in self-expressing.

I can explain myself. You used a word that has no meaning in the theory of relativity: "immediately". This word is meaningless. I repeat, two events that according to one frame occur at the same time or at a negligible interval of time from one to the other - i.e. immediately as you said, according to another frame there may be an interval of time between them, even a very big interval of time. That depends on the velocity of the relative movement of the frames with respect to one another. This is why the word "immediately" has no meaning.

When I asked you "what means immediately", it was a rhetoric question. There is no concept of "immediately" in relativity, only within a given frame.

But, Franz, if you say that you learnt relativity, you are supposed to know all these things, they are trivial.

Now, my question IS NOT THIS. It is a TECHNICAL ONE: how can one perform a measurement from a moving frame? Imagine a rocket moving from Alice's lab to Bob's lab. What shall do the observer in the rocket? Shouldn't he land on the two stations and collect the results of the measurements? Is there another possibility?

Dear Ilian,

My question is rather procedural: how can one perform a measurement from a moving frame? Imagine a rocket moving from Alice's lab to Bob's lab. What shall do the observer in the rocket? Shouldn't he land on the two stations and collect the results of the measurements? Is there another possibility?

Best regards

If you have only one observer trying to collect the various data, no issues of locality will arise, since the iformation from Blue and from Red must go to him at mos at light speed. If you have several comoving rockets, then indeed the detection of the Blue event may be, for example, before the detection of the red event, in the rocket frame, whereas in the rest frame, it might be the other way around. That is not a problem though, since in both cases the two events are spatially separated.

While you are of course right to say tha simultaneity has no meaning in SRT, it is nonetheless correct to say that spatial separation is an appropriate substitute.

I am not quite sure whether I am addressing your question, but I hope so.

Dear François, Franz, Ilian, and other friends,

It seems to me that with the moving frames we have a contradiction about observing spacely separated measurements. Please see:

Assume two stations at equal distance from the Earth, and at rest relatively to the Earth (i.e. moving at such a speed that from the Earth they are seen at rest). In one of the stations works the experimenter Alice, and in the other, the experimenter Bob.

A pair of particles is sent from a lab on the Earth to the two stations, the particle Red to Alice, and the particle Blue to Bob. The particles are tested simultaneosly according to the Earth lab and according to the two stations.

Now, imagine a space-ship travwling in the direction from Bob to Alice. We know that according to the space-ship clock, Alice's experiment is bound to occur before Bob 's experiment. Assume that the space-ship comes from afar and first of all it reaches Bob's station, just in time when Bob does the experiment. Therefore, by the space-ship clock, Alice's experiment was already done and a result was obtained.

Now, for allowing collecting the result of Bob's experiment, the space-ship lands on Bob's station and stops for a while. When the space-ship stops, its clock beats as Bob's clock. So, Alice's experiment wasn't done yet, it is in progress as is Bob's experiment.

Thus, for the physicist on the space-ship, Alice's experiment is done twice.

That seems to me absurd. Does anybody understand what happens here? 

Dear Sofia,

Thanks for your answer and question. What is povocating for you is the word "immediately". This word gets a bigger importance in entanglement of quants - because it's said  till now in a pseudoscientific way that the transmision speed of a change of entangled particles is "immediately". You are right we can't define that attribute exactly but till now we say "immediately = sure quicker then in speed of light".

But in Relativity Theory - as I can understand it till now -  all observed and measured accidents are happening real immediately (= in the same moment of one time of your frame). You can take any time you measure within all your relative moving frames!  By Lorentz-Transformation you can enumber all "immediately times" out of all mesured times in all your frames you observe. They are numerically not of the same value but they are in physical reality "immediately".

So this word is a little bit complex but makes sense. Mathematics and reality is sometimes in interesting relations. 

Dear Franz,

I still have to give you a negative answer - I am sorry. The limited light velocity won't rescue the word "immediate". Let's go to the formulas, it's the simplest thing to do, and you'll see.

Let's label by F0 the frame in which the two particles are tested simultaneously, and by F1 a frame in movement with the velocity V with respect to F0. I'll label the quantities in F0 by an index 0, and the quantities in F1 by an index 1. For shortening formulas I'll use the standard notations  β = V/c,  and  γ = 1/sqrt(1 - β2).

So, according to F1 there is a time-interval between the two measurements

(1) Δt1 = γ(Δt0 - β Δx0/c).

In the frame F0 the measurements are simultaneous s.t.  Δt0 = 0. There remains

(2) Δt1 = -γβ Δx0/c.

This formula tells us that there exists NO "immediately". If V → c, one gets β → 1, therefore γ → ∞. So, Δt1 becomes infinite.

But it intrigues me that it seems that Alice performs her experiment twice. It's even more intriguing than the twins paradox.

Best regards!

Testing is best done in the frame of action, or if not possible, then with results transformed to the frame of action. Otherwise the contradictions occur. The twin paradox is interpreted by the triplet paradox when two siblings travel opposite directions but with identical programs to return them at the same time to the third sibling. Observations made by the travelers of each other are rejected by symmetry. A harder case occurs when the travelers have different programs and return at different times. When the difference is small it should approach the symmetrical case.

Dear Sofia,

I forget you "negative" - that`s not important here - you can make the attribute "I don't agree" - not more.

Please take the kernel ! You loose the kernel of Relativity by too komplex thinking. As Information Scientist I don't need formulas lioke Physicist need. But I need terms and identifiers. The word immedeate is the in relaity a synonyme for "at the same time". Your enumbered time-dieffrerences are valid internal your frames - and they are measured results (by a internal clock). 

But an external observer can have an overview - perhaps in a console related direct to the clocks. And his time is the "immediate time"  = all different time sesults on his console are numerically different but physically "at the same time of him".  And besides all values can be enumbered by Lorentz-Transformation-Formulas you use correctly. What I have as result is that the mathemical numers are different but have "immediately and in one same moment of time (of the observer with the console)" the identical physical validity for the observer!

 I hope I could explain my understanding - that's not new for me - that's basically Relativity Theory! As scientist I  am not God - I know I make errors - but this basics are very old and clear to me!

Dear Franz,

The polemic between the two of us is an excellent illustration of relativity. You think that I make things complex, I think that you make things complex - consoles, directly directed, (please don't take it too seriously, I am joking).

Now, I don't know what an Information Scientist needs, I showed you that the "immediate" of which you talk, may be infinite. No consoles, no other things, would beat the relativity theory. And formulas are important, otherwise, somebody may say that the infinite would come immediately.

Indeed, nobody is God. Maybe you are lucky that you are not a physicist. To be a physicist implies to feel with all the weight, how stupid we are in front of the endless wisdom of the Nature. You know, there are sometimes things WRITTEN in front of our eyes, and we are unable to read them.

With kindest regards!

My very short contribution: the issue of the experimenter in the rocket ``experiencing the same distant experiment twice.'' I am reformulating, but hope to be stating correctly the reason of your puzzlement.

In my opinion, we should not view two spacelike separated events as attributable to *one* observer. We really need two rockets. It can then happen, if both rockets are in motion with respect to the experiment, that one rocket says: the red experiment took place at noon my time, whereas the  other rocket says the Blue experiment  happened at 11.50. But in the rest frame of the experiment, it might be that the red and blue observers agree that red was actually before blue. All of these judgements, however, must all await a time in the future, when the different observers can communicate their time measurements. So all the paradoxes are essentially retrospective, and thus, in my opinion, do not present a serious difficulty.

Best wishes,

Francois

Dear François,

Thank you for trying to answer my question. This question is connected to a difficult problem that I investigate. It is a problem of quantum mechanics, but it is mixed with issues of relativity.

I believe that it's better to separate between the two fields. So, I added a question that contains the purely relativistic part of my problem.

A relativistic puzzle: can somebody solve it?

https://www.researchgate.net/post/A_relativistic_puzzle_can_somebody_solve_it

I am affraid that the problem is more serious than what you explained in your comment. This is why I separated the purely relativistic part, for getting opinions also from people who don't deal with quantum mechanics. Would you want to have a look at the new question?

With thanks in advance!

Dear Sofia,

first of all I see you have changed your question! So we can't find a scientifically satisfying answer. 

I can understand that Information Scientists are in first impression not very interesting for Physicist, but we are usable on higher theoretical levels. Like legace Philosophers - but a little bit more formal or structured! Look at my home http://www.plbg.at - if you like it.

Our original term "immediately" is now expanded by you with a new second one: "infinite". That is quite an greate logically jump!  So "immediately" and "infinite" are in my knowledge not discussable in an easy simple way. That would need a lot of text-lines.....but all the best to you and "read you later"! 

Yes, Franz,

you are right. My question changed, and it's not O.K. from my part.

Please see: I am working on a hard problem of relativistic QM. I formulated this question as simply as possible, but during the time I realized that it may be made clearer from the point of view of what I want in fact to discuss.

You see, the topic on which I work, which is maybe the hardest in QM - the fundaments of the QM - not many people are very competent in it. I have the feeling that the time of the "giants" who were preoccupied by fundamental questions as "what in fact is the wave-function", "how works the collpse", passed away ("adio, bel passato"). The QM physicists deal today with "serious bussiness": quantum computing, and others.

Bottom line, I indeed changed the question to make it accessible to a wider pblic. I appologize a lot.

With kindest regards!

Sofia,

As I understand your question, Alice and Bob are in laboratory frames that are mutually at rest and widely separated spatially but with synchronized clocks. Thus they are in the same inertial rest frame F0 but with a separation, say Alice has x > 0. They each make a measurement at the same clock reading, so in F0 the difference in measurement times is Δt = 0 (since you are including quantum-mechanical effects, neither x nor Δt can be known exactly, nor can the mutual rest of the two instruments be exact, their relative speed v cannot be exactly zero, but that is relevant only for detailed computations of phase and group velocities of the wave packets corresponding to their instruments, so for now we will assume that x > 0, Δt = 0, and v = 0 are known exactly).

Since Alice’s measurement event A and Bob’s measurement event B are separated by a spacelike interval, classically there can be no causal connection between them, but you are clearly interested in EPR effects wherein nonlocal action takes place and seems undeniably causal. In fact, inertial frames with different speeds (as measured in F0) can see A precede B or B precede A in their own moving frames at times measured on their own clocks. This implies a causal anomaly for the EPR nonlocal action.

It has been shown, however (e.g., by Ghirardi, G.C.; Rimini, A.; and Weber, T., “A General argument against Superluminal Transmission through the Quantum Mechanical Measurement Process”, Lettere al Nuovo Cimento Vol 27, N. 10, 1980), that quantum-mechanical randomness not only prevents transmission of encoded information by the nonlocal action, it also removes the distinction between which measurement is the cause and which is the effect. So the cause/effect flipflop has no physical significance.

Presumably a moving frame F1 that will see A precede B could change its velocity so that now it will see B precede A, then change it back to see A precede B again. But these accelerations demand including General Relativity, wherein the notion of “widely separated but mutually at rest” becomes meaningless (except for certain trivial cases such as static asymptotically flat spacetimes). Also one should distinguish between relationships between frames that can be used to predict what will eventually be observed versus what actually is observed. The former can be changed by changes in motion, but the latter can occur only once per event, namely when the signal from A reaches F1 and when the signal from B reaches F1. In order to see A and B at all, F1 must be separated from them by timelike or null intervals, and the signals from A and B can arrive at F1 only once, but indeed in a chronological order that can be controlled by F1's motion.

In any case, event A has only one set of coordinates (ct,x,y,z), so Alice’s clock has a single unique reading when A occurs, and she can make her measurement only once. I hope these remarks are relevant to your question!

Dear John Wendell Fowler,

You told me a lot of things that are widely known among quantum physicists - this is the situation in a site where participate people from different scientific domains. So, I want to focus on the statement that seems to me central,

==> "Also one should distinguish between relationships between frames that can be used to predict what will eventually be observed versus what actually is observed."

You bring here two issues: 1) QM predicts ONLY what is measured (there is a popular dictum in QM, "non-performed experiments have no results"). 2) non-quantum relativistic mechanics tells us what is the relationship between the space and time coordinates of events, in different frames.

Indeed, my question treats both QM and issues of general relativity. Now, about the issue 1, both measurements are done. About the issue 2, something is obviously wrong. What is wrong?

Please see, in the relativistic QM there are all sort of proofs based on judging according to various moveng frame. The problem I pose is whether mixing different frames - a rest-frame and a moving frame, in one and same rationale, is nonsensical. This is the question.

If you are interested in this issue, maybe you'd want to see a related question of mine that puts the problem purely relativistically, without QM,

https://www.researchgate.net/post/A_relativistic_puzzle_can_somebody_solve_it

Best regards

Dear Sofia,

I looked at the other page with the similar question. It seems that you and K. Kassner are converging on an agreeable interpretation there. K. Kassner is saying basically the same thing as I, namely that the two measurement events are single points in spacetime independently of what frame (inertial or non-inertial) is used to represent them. Since they are separated by a spacelike interval, the fact that simultaneity is not an absolute comes into play.

One can pick a frame, let’s keep it inertial and labeled F1, whose motion results in a “simultaneity plane” that places A before B according to F1's time coordinate. One can pick a different inertial frame F2 whose motion results in a “simultaneity plane” that places B before A according to F2's time coordinate. Neither of these frames can do anything to change the measurement time for A in A’s rest frame F0, and the same for B. The two differently moving frames F1 and F2 simply transform the A and B measurement times differently, and because the A-B separation is spacelike, F1 and F2 need not agree on before/after. These temporal orders exist in F1 and F2, not in F0 where A and B take place in laboratories mutually at rest.

Now one could consider a frame F3 that moves in coincidence with F1 and thus has a simultaneity plane that places A before B; then F3 accelerates to make itself coincident with F2, moving A to a time in F3 that is later than B, thus flipflopping the previous before/after cause/effect relationship within a single frame. Then F3 accelerates again to become coincident with F1 again, restoring the previous order of A and B according to F3's clock. This moving of A and B back and forth across the changing simultaneity plane of F3 does not cause the events A and B to happen more than once in F0 (or in the other frames for that matter); there is only one spacetime event A and one spacetime event B.

One can ask: since the nonlocal EPR action does appear to be causal, doesn’t either F1 or F2 have to be wrong about which was the cause and which was the effect? Your original phrasing made A and B simultaneous in F0; in that case I would say that which was the cause and which was the effect depends on how many angels can dance on the head of a pin. Quantum-mechanical randomness prevents both signaling and assigning cause/effect roles. If the premise were changed, say A came after B in F0, then all the same apparent causal anomalies could still exist in F1 and F2 and F3, but my personal interpretation is that the truth is what you see in the rest frame of the measurements: B caused A. But this can be established only by comparing the two different measurement times. The actual measurement results provide no clue themselves. And like the measurement results, comparing the times requires subluminal communication.

Dear John,

What K. Kassner explained me is a very strong thing. In general he says that it is forbidden, when examining a process, to change the definition of the simutaneity, i.e. which events are simultaneous with which. He says that otherwise one gets paradoxes which don't exist, just, the judgement is wrong.

After such an explanation, I confess that I have to relax a bit, and tomorrow see the consequences. A couple of days ago, i.e. before the talk with K. Kassner, I sent an article to publication. My article criticizes an important proof in which the definition of simultaneity is switched. I have felt, somehow, that switching the simultaneity is questionable, i.e. it is some unpermitted "abracadabra". And now, K. Kassner told me his explanation.

Well, now it's late in my country, let's talk tomorrow.

With best regards!