How Can Signal Models Resolve the EPR Paradox in Special Relativity?

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The discussion explores how signal models can address the EPR paradox within the framework of Special Relativity. It describes a scenario involving an electron and a positron emitted with specific spin states, emphasizing that changes in one particle's spin can be influenced by signals from the other particle and the measurement device. The model suggests that these signals, whether internal or external, allow for communication between the particles without violating the finite speed of signal transmission. Critics argue that entangled particles do not "change" spins but rather exhibit correlated measurements upon observation, challenging the notion of signals influencing spin states. Ultimately, the conversation highlights the complexities of entanglement and the implications for understanding quantum mechanics and relativity.
  • #61
JesseM said:
I wasn't measuring a single trial result when I gave PA(a.b) = PA(b.c) = -n/[sqrt(2)], I was talking about the expectation value for a sum of results over n trials, for example if I had n=4 trials my expectation value would be -4/[sqrt(2)], while if the actual trials gave results -1, -1, +1, -1 then my sum in this case would be -2.

A "trial" is defined as a single recorded outcome, like a single "click" of the detector. It doesn't matter if at some hidden level unknown to us, the detector is really caused to click by a million brief interactions with a cloud of particles, it's still only a single trial if we only have one outcome.

I have not used the word trial with the meaning of a single recorded outcome. It is simply the impact[or the influence] of the distribution function----and we are considering several such impacts---to get a single recorded outcome.

JesseM said:
That doesn't make much sense. What is a "trial of the distribution function" supposed to mean in physical terms? Physically the distribution function just tells you probability the hidden variables will take various values (each value of lambda represents a complete state of hidden variables), it's true these hidden variables could be rapidly changing during the measurement period, but in his more carefully worded paper La nouvelle cuisine he defined lambda to give the values of the hidden variables in at every point in space time in some complete cross-section of the past light cone of the region of spacetime where the measurement happened, like region "3" in the diagram at the top of this page. So in this case lambda isn't even meant to tell you the value of any hidden variables during the measurement period itself.

What is a "trial of the distribution function" supposed to mean in physical terms?

We are considering the same normalized distribution function to be valid for each instant of time in the measuring interval.One may consider different distribution functions[normalized ones] for different instants. That will not alter the basic nature of my arguments and the conclusions following from them. To get a theoretical estimate of the result of measurement we have to consider the cumulative effect of these functions.I have considered this cumulative effect by using a weight denoted by "n".
 
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  • #62
Anamitra said:
I have not used the word trial with the meaning of a single recorded outcome.
Then you can no longer say that your PA(a.b) is equal to n*PB(b.c), since Bell's PB(b.c) is the result of a single recorded outcome. If you redefine "trial" then you must redefine the meaning of the "expectation value", and there is no reason to expect the same inequality would still apply, since that inequality was derived under the assumption we were talking about a trial as a recorded outcome.
Anamitra said:
It is simply the impact[or the influence] of the distribution function----and we are considering several such impacts---to get a single recorded outcome.
Your language is completely incomprehensible. How can a "distribution function" have multiple "impacts"? Have you ever heard someone say "Ouch! I've just been impacted in the head by a distribution function"? You need to explain your ideas in more physical terms, the distribution function is just mean to give the probability that lambda will take various values, where each value of lambda represents the state of some hidden variables (in Bell's argument it gives the value of these variables in a cross-section of the past light cone of a region of spacetime where a single measurement was performed).
Anamitra said:
What is a "trial of the distribution function" supposed to mean in physical terms?

We are considering the same normalized distribution function to be valid for each instant of time in the measuring interval.One may consider different distribution functions[normalized ones] for different instants.
That doesn't tell me what the distribution function is mean to represent a distribution of, in physical terms! The distribution is assigning probabilities, yes? So what is do you think it is assigning probabilities to, in physical terms?

Again, in Bell's terms the distribution function would give the probabilities that the hidden variables take different possible values in a cross-section of the past light cone of the region of spacetime where the measurement is performed. If you adopt this physical definition of the distribution function, it makes no sense at all to talk about it taking different values at different instants during measurement, because we are talking about the hidden variables in a fixed region of spacetime (region 3 in the diagram, please follow this link to look at the diagram I'm talking about), not the hidden variables from moment to moment during measurement.
 
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  • #63
JesseM said:
Then you can no longer say that your PA(a.b) is equal to n*PB(b.c), since Bell's PB(b.c) is the result of a single recorded outcome. If you redefine "trial" then you must redefine the meaning of the "expectation value", and there is no reason to expect the same inequality would still apply, since that inequality was derived under the assumption we were talking about a trial as a recorded outcome.


The expectation value for each moment/instant may be denoted by P(a,b). This does not correspond to a single click. One may also divide a small click interval interval into even smaller[infinitesimally smaller intervals] and associate the P(a,b) with each such interval.

JesseM said:
Your language is completely incomprehensible. How can a "distribution function" have multiple "impacts"? Have you ever heard someone say "Ouch! I've just been impacted in the head by a distribution function"? You need to explain your ideas in more physical terms, the distribution function is just mean to give the probability that lambda will take various values, where each value of lambda represents the state of some hidden variables (in Bell's argument it gives the value of these variables in a cross-section of the past light cone of a region of spacetime where a single measurement was performed).

The manner in which the variable lambda influences the expectation value for each moment/instant is governed by the nature of the distribution function.

It is nothing like a force or a ball out of somebody's bat that could hurt a person watching the game.
But this distribution function has a great power from the physical point of view in its capability of determining the component P(a,b) values that add up to produce the final expectation value that gets recorded in a measurement[a click]

You have talked of a region of spacetime where a single measurement is made. Such a region can have millions of time coordinates.At a single spatial point you may consider one million time instants----- corresponding to the interval of measurement.
 
  • #64
Anamitra said:
The expectation value for each moment/instant may be denoted by P(a,b).
Expectation value of what physical quantity, if not an observed "click"?
Anamitra said:
The manner in which the variable lambda
What is the physical meaning of "the variable lambda" in your mind, if it doesn't have the same meaning that Bell assigns to it
Anamitra said:
You have talked of a region of spacetime where a single measurement is made. Such a region can have millions of time coordinates.
Sure, but so what? In Bell's terminology lambda does not represent the value of any hidden variables at a single time coordinate in the measurement region. Rather a single value of lambda tells you the value of all hidden variables at all points in spacetime in another region that's in the past light cone of the measurement, like region 3 in the diagram. Region 3 is not the measurement region, that's region 1 in the diagram. Of course region 3 lasts an extended period of time in Bell's diagram too (though he could have made it just a single instantaneous spacelike cross-section of the past light cone), but that doesn't mean lambda is changing because lambda does not represent the value of the hidden variables at a single instant of time, rather a single value of lambda represents the values of the hidden variables at every point in region 3.

If you have trouble understanding this, suppose we have a hidden variable that at any time can be in two states A or B, and it can only change once every 5 seconds, at T=0, T=5, T=10 etc. Suppose we have a region of spacetime that goes from T=7 to T=13. Then to specify the value of this simple hidden variable in this region, we need to know both its value from T=7 to T=10, and its value from T=10 to T=13. So we could define a new variable lambda that can take 4 values, lambda=1, lambda=2, lambda=3, lambda=4, with the following physical meaning:

lambda=1 means hidden variable in state A from T=7 to T=10, in state A from T=10 to T=13

lambda=2 means hidden variable in state A from T=7 to T=10, in state B from T=10 to T=13

lambda=3 means hidden variable in state B from T=7 to T=10, in state A from T=10 to T=13

lambda=4 means hidden variable in state B from T=7 to T=10, in state B from T=10 to T=13

So if we specify the value of the variable lambda, we have specified the state of that specific hidden variable during both time intervals, we wouldn't say that lambda can "change" at T=10, although the hidden variable itself can. And obviously this could be generalized to a larger region of spacetime where the hidden variable could change multiple times, or to a region of spacetime where there were multiple hidden variables at any given moment in time. In either case, we could define the variable "lambda" in such a way that a single value of lambda tells us the value of arbitrarily many local hidden variables at arbitrarily many different times in whatever region of spacetime we're interested in (like region 3 in Bell's spacetime diagram). This is what Bell's lambda is supposed to represent, it isn't just telling you about a single moment in time. If you want to define lambda differently you need to explain what you mean by it physically, but be warned that any significant change will probably invalidate the derivation of the Bell inequality.
 
  • #65
Bell's treatment/formulation is of a general type, intended to cover all possible situations concerning the hidden variable.

It is quite interesting to observe the valiant attempt of the Scientific Adviser to contradict this basic general nature of the paper.I have reasons to thank him--and he would find it very difficult to understand this.
 
  • #66
Anamitra said:
Bell's treatment/formulation is of a general type, intended to cover all possible situations concerning the hidden variable.

It is quite interesting to observe the valiant attempt of the Scientific Adviser to contradict this basic general nature of the paper.I have reasons to thank him--and he would find it very difficult to understand this.

This is pretty funny. So far, nothing you have said makes any sense that I can see. It is a lot of nice looking formulae that goes nowhere, which is sort of your forte as I read your other posts. JesseM is quite knowledgeable, so I think you are misconstruing the situation greatly.

It would be helpful if you would ask specific questions rather than making general statements which have no specific connection to a technical issue. Nothing you have written remotely supports your brash statements that entanglement can be explained by light speed interactions.
 
  • #67
Anamitra said:
Bell's treatment/formulation is of a general type, intended to cover all possible situations concerning the hidden variable.
Not true, if you define lambda in arbitrary ways then you may not have a basis for claiming that the result A at one detector can be deduced in a deterministic way from only the detector setting a and lambda, in other words you may need to use a probabilistic function P(A|a,lambda) rather than a deterministic function A(a,lambda), and in fact Bell does use a probabilistic function in most of his later papers. But even if you use a probabilistic function, to derive a Bell inequality you still need a step like the on on p. 15 of this paper where you say P(A,B|a,b,lambda)=P(A|a,lambda)*P(B|b,lambda) which depends on the assumption that lambda "screens off" any statistical correlation between the result/setting A/a and the result/setting B/b due to influences from the region where the past light cones of both measurements overlap (because of the possibility of such influences, you could not say that that P(A,B|a,b)=P(A|a)*P(B|b), for example). If you don't make some assumption like treating lambda as telling you all hidden variables in a cross-section of the past light cone of the measurements this step may not be justifiable. And of course here we are defining "A" and "B" as the observable measurement outcomes, whereas you seem to be defining them differently yet you refuse to actually explain what physical quantity you are calculating an "expectation value" for if not the observable measurement outcome. In this case there is obviously no justification for either the claim that this "expectation value" is equal to an integral involving deterministic functions (A|a,lambda) and (B|b,lambda), or the probabilistic claim that P(A,B|a,b,lambda)=P(A|a,lambda)*P(B|b,lambda). Neither of these steps is justified on the basis of pure probability theory, they both depend on physical assumptions about the physical meaning of expectation values P, so if you change the meaning you can't justify these steps unless you provide a clear definition of what physical quantity you are computing an expectation value for.
Anamitra said:
It is quite interesting to observe the valiant attempt of the Scientific Adviser to contradict this basic general nature of the paper.
Certainly the paper is fairly general, but you only show your lack of comprehension if you think it's so general that you don't have to worry at all about the physical meaning of various terms like lambda and the expectation values P(a,b) etc. The paper involves multiple steps that can't be justified on the basis of abstract mathematics alone, you can't arbitrarily change the physical meaning of the symbols and expect it to still work.
 
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  • #68
We can consider three points G1,G2 and X at the time of measurement. G1 and G2 correspond to the gadget locations while X is a point inside the closed system where the particles are present. The intersection of the past light cones of (G1 , X) and (G2,X) with the exclusion of (G1,G2 )is considered at the time of measurement. The influence of the hidden variable can be explained by influences/signals from such regions.

We may always have formulations of the type:
{E}_{h}{(}{a}{,}{b}{)}{=}{\int}{n}{\rho}{(}{\lambda}{)}{P}{(}{A},{B}{\mid}{a}{,}{b}{,}{\lambda}{)}{A}{(}{a}{,}{\lambda}{)}{B}{(}{b}{,}{\lambda}{)}{d}{\lambda}
"n" takes care of the short time of measurement. {E}_{h} on Lhs: Expectation
Where,
{\int}{n}{\rho}{(}{\lambda}{)}{P}{(}{A},{B}{\mid}{a}{,}{b}{,}{\lambda}{)}{d}{\lambda}{=}{m}
[m is larger than or equal to two: one can make this quantity flexible following this condition]
But I would like to stress an important point here. If the separating particles are to influence each other by signals right from the time of their creation, we have to consider the past light cones of these particles[their intersection].
At the time of measurement we have to consider the intersection of the past light cones of these particles[Considering the time of their creation we have to consider truncated light cones[past] for interaction between the particles]. This will coincide with[precisely, be a subset of] the intersection of past light cones of the gadgets at the time of measurement. It is not necessary to exclude such a region[though it is conventionally excluded. In fact I have followed this exclusion in the initial part of this posting].
 
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  • #69
JesseM said:
Not true, if you define lambda in arbitrary ways then you may not have a basis for claiming that the result A at one detector can be deduced in a deterministic way from only the detector setting a and lambda, in other words you may need to use a probabilistic function P(A|a,lambda) rather than a deterministic function A(a,lambda), and in fact Bell does use a probabilistic function in most of his later papers.

In the relation:

{P}_{h}{=}{\int}{n}{\rho}{(}{\lambda}{)}{A}{(}{a}{,}{\lambda}{)}{B}{(}{b}{,}{\lambda}{)}{d}{\lambda}

the functions A and B are not as deterministic as one might be tempted to think of. There is a lambda controlling these functions and this lambda in turn is being governed by the probability distribution function rho(lambda).

One may use other controlling functions like P(A,B/ a,b,lambda).This function establishes the association between the measurements A and B through the influence of lambda.In the other formula lambda works out this association by its presence in A and B. But the basic conclusion does not change----we can always evolve forms of Bell's Inequalities consistent with QM results/predictions
 
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