Emilio Santos joins the dark side

[DrChinese]

Emilio Santos joins the dark side :)

Emilio Santos, one of the most vocal local realists, appears to have finally lined up against EPR and joined the majority view. From his latest paper, posted today:

http://arxiv.org/abs/1203.5688

Santos: "The conclusion seems unavoidable: we cannot assume that physical systems possesses properties independently of measurements. ... We shall assume that the measured properties are contextual, that is they depend not only on the state of the system but on the whole experimental context. This point was correctly emphasized by Bohr..."

I couldn't agree more. But from EPR: "This makes the reality of P and Q depend on the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this."

So my hat is off to Santos for finally throwing in the towel (and throwing EPR under the bus).

------------------

PS: Or maybe not. He goes on to say "Does that assumption prevents[sic] a realistic interpretation of quantum physics?. I think not." I guess he is finding it easier to simply assume what he wishes to prove, since a suitable proof has been elusive to date.

PPS Hoping the readers of this post take it as it is intended, a little bit of humor for your day. Actually my hat is off to Santos for being brave enough to continue his battle in the face of long odds. Probably keeps everyone sharp.

 

[billschnieder]

Emilio Santos, one of the most vocal local realists, appears to have finally lined up against EPR and joined the majority view. From his latest paper, posted today:

http://arxiv.org/abs/1203.5688

Santos: "The conclusion seems unavoidable: we cannot assume that physical systems possesses properties independently of measurements. ... We shall assume that the measured properties are contextual, that is they depend not only on the state of the system but on the whole experimental context. This point was correctly emphasized by Bohr..."

I couldn't agree more. But from EPR: "This makes the reality of P and Q depend on the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this."

So my hat is off to Santos for finally throwing in the towel (and throwing EPR under the bus).

------------------

PS: Or maybe not. He goes on to say "Does that assumption prevents[sic] a realistic interpretation of quantum physics?. I think not." I guess he is finding it easier to simply assume what he wishes to prove, since a suitable proof has been elusive to date.

PPS Hoping the readers of this post take it as it is intended, a little bit of humor for your day. Actually my hat is off to Santos for being brave enough to continue his battle in the face of long odds. Probably keeps everyone sharp.

Hi DrC,
You do remember that contextuality is not contrary to EPR don't you? I remember giving you the following analogy which you appeared to understand at the time:

- Elements of reality = Wide spectrum wavelength photons from the sun
- Observation/Measurement = DrC wears red goggles and looks at the sun
- Observable = Red Sun

- EPR: we can predict the observable with certainty, therefore there is an element of reality corresponding to that observable. We can predict that if DrC wears red goggles and looks at the sun, he will certainly see a red sun. Therefore there exists an element of reality (photons in the red-wavelength region) from the sun.

- DrC: Realism means the "Red Sun" observable exists even if DrC never wears red goggles and never looks at the sun.

- EPR: No. Realism means the "elements of reality" ie, the red-wavelength photons, exist independently of the observation. Just because the "photons from the sun" exist independent of measurement, does not mean all observables like "red-sun" exist simultaneously independent of the actual observation.

... continuing ...
- Emilo Santos: We cannot assume that "Red Sun" observable exists independent of measurements. ... We shall assume that it is contextual, that is, it depends not only on the "photons from the sun" but on the whole experimental context, which includes the "red goggles" worn by DrC.
- DrC: Stop the presses! Emilo Santos has joined the dark-side and thrown EPR under the bus, OR did he?

 

[DrChinese]

This makes the reality of P and Q depend on the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.

I just really don't see how they could be any more clear that a contextual realism is not reasonable.

Further, I don't see how Einstein could be any more clear when he said: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured."

So yes, I would say that contextuality is contrary to both EPR and Einstein. And I would say that Bell shows that an electron cannot have 3 locally & simultaneously determined spin components (x, y and z), which is in direct contradiction to Einstein's statement and the tenor of EPR.

 

[billschnieder]

This makes the reality of P and Q depend on the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.

I just really don't see how they could be any more clear that a contextual realism is not reasonable.

EPR say it is unreasonable to expect the reality of one system to be changed instantaneously by the a measurement performed on a distant system. How does that translate to the claim that the outcome of a measurement must depend only on the pre-existing property of the system being measured without regard for the properties of the measuring instrument. Why even bother to change the angle on the detector if properties of measurement apparatus does not matter.

Further, I don't see how Einstein could be any more clear when he said: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured."

And how does the fact that "the sun produces red wavelength photons independent of any measurements", go contrary to the idea that seeing "Red Sun" is contextual and depends on DrC actually doing the measurement with red goggles?

So yes, I would say that contextuality is contrary to both EPR and Einstein.

Which is blatantly false.

...And I would say that Bell shows that an electron cannot have 3 locally & simultaneously determined spin components (x, y and z), which is in direct contradiction to Einstein's statement and the tenor of EPR.

What you call "spin components x, y, and z" are not properties of the electron but ways of looking at a property -- spin. You take the spin and you project it along an axis during a measurement. What you observe for "spin components x (or y or z)" is dependent on the measurement setup (ie, the direction of the projection axis) and therefore it is contextual. You could say "spin component x" is a property of the combined electron-instrument system. Once you look at it this way, it becomes obvious why the inability of such a system to have three simultaneous values for"spin components x, y, z, means absolutely nothing about the existence of a pre-existing "spin" property of the electron. If you are naive enough to take such a result and ascribe it to the electron alone without regard for the axis, that is your problem not EPRs.
Just because you can not project the same electron simultaneously along three different axis in any measurement does not mean the electron does not have spin independent of measurement.

Again the EPR claim is that it is unreasonable to expect the reality of a system to be changed instantaneously by a measurement performed on a remote system.

 

[DrChinese]

EPR say it is unreasonable to expect the reality of one system to be changed instantaneously by the a measurement performed on a distant system. How does that translate to the claim that the outcome of a measurement must depend only on the pre-existing property of the system being measured without regard for the properties of the measuring instrument.

I didn't say that. EPR says there is an element of reality *corresponding* to anything which can be predicted in advance. That would be the spin components of a particle. The essential question is whether the corresponding element of reality exists independently of the act of observation. EPR says yes, and they ALL exist simultaneously. Santos states there is no reality outside of a context which includes the measurement device. That is significantly more restrictive as a definition.

 

[billschnieder]

I didn't say that. EPR says there is an element of reality *corresponding* to anything which can be predicted in advance.

So the fact that the "Spin component along x" corresponds to the pre-existing "spin" of the electron together with the pre-existing axis orientation of the measuring instrument is too difficult to imagine?

 

[DrChinese]

So the fact that the "Spin component along x" corresponds to the pre-existing "spin" of the electron together with the pre-existing axis orientation of the measuring instrument is too difficult to imagine?

Quite the opposite, I concur. As a realist, you should be claiming that there exists a pre-existing value for this independent of an actual measurement though. (That's the trouble with realists, you want to have your cake and eat it too! ) Are there or aren't there pre-existing values for x, y and z components INDEPENDENT of an actual measure (i.e. I will pick the component I want to look at sometime later).

If so, what are the values of such components *before* I measure them? And finally, do those values match the predictions of QM?

 

[billschnieder]

Quite the opposite, I concur. As a realist, you should be claiming that there exists a pre-existing value for this independent of an actual measurement though.

You mean as a 'straw man' I should be claiming a position other than the position I am actually claiming?

(That's the trouble with realists, you want to have your cake and eat it too! )

But that is the problem with anti-realists, they want to overturn realism so bad, they define it to be something it is not. Something so absurd, no reasonable human being could ever have claimed in the first place.According to anti-realists, realism means:

"DrC can see a Red Sun even if he is not looking at the sun"

It is convenient but lazy to force the above definition because it is easy to knock down. If you believe this is what realists believe, why do you need Bell's theorem to reject it. It is so absurd and nonsensical it can be rejected immediately without anyone raising an eyebrow.

Are there or aren't there pre-existing values for x, y and z components INDEPENDENT of an actual measure (i.e. I will pick the component I want to look at sometime later).

For the last time:
- "observed spin component along axis x" is the outcome of a measurement. No realist believes that you can observe a spin component along axis x without having performed the measurement. Same for (y, and z).
- You can predict with certainty that given a "pre-existing spin" and a "pre-existing" axis direction, what the "observed spin component along axis x" WILL be. According to EPR, the pre-existing spin, and the pre-existing axis orientation are elements of reality which correspond to the outcome you WILL have IF in fact you do make the measurement.
- Just because you can predict it does not mean it exists. In fact why would you be PREDICTING if it already EXISTS. Obviously, you PREDICT something because it DOES NOT CURRENTLY exist but POSSIBLY WILL in the FUTURE.
- Just because you can predict different things simultaneously does not mean they can all exist simultaneously. Just because you can predict the outcome of measurements along "x, y and z" in advance does not mean "observed spin component along axis x, y and z" all exist simultaneously or can exist simultaneously in the future.
- Just because "observed spin component along axis x" does not exist until an actual measurement is performed, does not mean the particle does not have a pre-existing property called "spin" which exists independent of any measurement.

If so, what are the values of such components *before* I measure them? And finally, do those values match the predictions of QM?

Before you measure any components, all you have is a prediction of what you will get IF you measure them. And yes such a prediction can be very definite but still only be a PREDICTION. The outcome doesn't EXIST until you actually do the measurement!

QM predicts the outcomes of performable experiments on an ensemble of similarly prepared systems. If the predictions are of the same thing, and are both correct, they should match.

For example, they both provide the same prediction to what will be observed in the experiment which involves:

"Simultaneously measuring the spin projection of a series of similarly prepared particles at three different axis orientations x, y, z".

If you think the QM and realist predictions will differ in this case, please explain why.

And Please, I beg you to stop misrepresenting the realist position. This is not the first time I've explained your misconceptions about the realist position to you. What you keep repeating under the guise of the "realist position" is a concept so naive and unreasonable, even in classical physics prior to the 20th century. So I really wonder what the motivation will be for propagating such falsehood.

 

[DrChinese]

Yes, Bill, my perverted definition of realism is that of a naive simpleton:

"I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured."

-A.E."If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity."

-EPROn the other hand, your:


- Just because you can predict different things simultaneously does not mean they can all exist simultaneously. Just because you can predict the outcome of measurements along "x, y and z" in advance does not mean "observed spin component along axis x, y and z" all exist simultaneously or can exist simultaneously in the future.
- Just because "observed spin component along axis x" does not exist until an actual measurement is performed, does not mean the particle does not have a pre-existing property called "spin" which exists independent of any measurement.


Logically translates to:


A particle has spin independent of measurement, but not an x, y or z spin component until measured, even when all can be predicted with certainty.


Also: Your "The outcome doesn't EXIST until you actually do the measurement!" versus above EPR quote which says there exists (an element of) reality in such case.

I would hope the contradictions in these statements are obvious. Or maybe the semantic distinctions are more clear to you than they are to me.

 

[billschnieder]

Yes, Bill, my perverted definition of realism is that of a naive simpleton:

"I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured."

-A.E.

No your perverted translation of the A.E. quote as evidenced by your comments is:

"I think that all measurement outcomes must be a separate reality of particles which exist independent of the measurements"

"If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity."

-EPR

And your perverted translation of the EPR quote is:

"If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then that physical quantity is an element of physical reality."

Either you are unable to see the significant differences in meaning between those, or you do see the difference but would rather misrepresent the two for the purposes of evangelizing for for favorite religion.

 

[DrChinese]

No your perverted translation of the A.E. quote as evidenced by your comments is:...

The reason I keep including the quotes is because the words of Einstein are good enough for me as a definition. I think it is clear from these that Einstein believed a more complete specification of the system is possible than is contemplated by QM. And he believed spin components (and other particle properties) had definite values independent of the act of observation. He certainly didn't picture a reality that was limited to measurement outcomes that had already been performed, as you seem to.

And by that I am specifically referring to ANYTHING that could be classified as an element of reality per EPR. Per EPR, perfect correlations at 19 or 42 or 77 degree polarization imply the reality of those properties. And such reality was not restricted to those outcomes which are actually measured, they apply simultaneously.

So if you don't like what I am saying, please don't say I am perverting the language of EPR. That is what Bell used, it is what I use, and is what is commonly used.

 

[ThomasT]

And he (Einstein) believed spin components (and other particle properties) had definite values independent of the act of observation.

And, the fact of the matter is that wrt individual measurments, Bell showed that this (Einstein's) view is compatible with QM (and subsequently compatible with experimental results).

So, the only problem is with entanglement correlations. Curious, isn't it, that, all of a sudden, wrt entanglement correlations, the assumption of preexisting values becomes irrelevant, or, in the extreme, wrong.

Is it even possible that there's a subtlety here that has been missed? Another rhetorical question. Of course it's possible, and it certainly wouldn't be the first time wrt physical science.

 

[lugita15]

I just really don't see how they could be any more clear that a contextual realism is not reasonable.

So DrChinese, you wouldn't consider Bohmian mechanics a realistic theory? Because it's contextual. Perhaps a better definition of realism is that the particle possesses all attributes, both measured and unmeasured, that potentially could have been measured. In other words, I would consider any theory, contextual or not, that satisfies counterfactual definiteness to be realistic.

 

[Demystifier]

What DrChinese calls "realism" is actually called NAIVE REALISM.
http://en.wikipedia.org/wiki/Naïve_realism

Bohmian mechanics involves realism, but not naive realism.
http://xxx.lanl.gov/abs/quant-ph/9601013

 

[Aidyan]

My anti-realism in Q&A: Once you have studied a map do you know the territory? At best you can say that a street is the element of preexisting reality that corresponds to an observable we call "straight line on a piece of paper". But does this convey any "realistic" representation of the world? Is the 'redness' of the sun an objective property or a subjective qualitative experience? Is a color still there when we don't look at it? And to Einstein's question: "Is the moon still there even if we don't look at it?" My answer is: no, the moon **as we see it** is NOT there even when we look at it. Once we will have grasped this then QM will become a little bit less mysterious.

 

[DrChinese]

So DrChinese, you wouldn't consider Bohmian mechanics a realistic theory? Because it's contextual. Perhaps a better definition of realism is that the particle possesses all attributes, both measured and unmeasured, that potentially could have been measured. In other words, I would consider any theory, contextual or not, that satisfies counterfactual definiteness to be realistic.

Sorry, I didn't add the qualifier "local" to this. As Demystifier says, Bohmian theories are (non-local) realistic.

There is some question as to what form of realism is being referred to, whether it might be "naive realism". I personally do not call the EPR definition naive, as this is a generally accepted definition. The issue is not whether an outcome is real, or whether the property being measured is real, the issue is whether there exists an element of reality which corresponds to what is observed. That element could be very complex, such that we are only able to sense a portion of its detail.

To use Bill's example: I am not saying the sun "really" is red every time I look at it with red sunglasses, I am saying there is something "real" which gives rise to that outcome. I make no statement to the effect that the redness itself is real. When I say it is red, I am using a shortcut rather than saying "it has a real set of properties which makes it appear red to me". For it to be real in this sense, it must also be so independent of the act of observation. Further, the likelihood of such outcome is between 0 and 100%.

So again: this is nothing but a standard definition shared by most. I know this because it is the same as used by EPR, Einstein, Bell and those following Bell. I don't think this audience considers their definition of realism to be naive, and I don't label it as such.

 

[DrChinese]

My anti-realism in Q&A: Once you have studied a map do you know the territory? At best you can say that a street is the element of preexisting reality that corresponds to an observable we call "straight line on a piece of paper". But does this convey any "realistic" representation of the world? ...

Look at my tag line. I obviously do not confuse the two. No one is asserting that a spin x component outcome implies that a particle actually has a discrete property called spin x (or y or z). But as EPR says: if we can predict it with certainty, there exists something real which gives rise to the outcome.

But I think you are switching senses of the word "realistic" in your example. Keep in mind that even as I define realism, I am free to reject it based on Bell (assuming I prefer to maintain locality). Don't confuse a suitable definition of realism with the requirement that one must also assert that the world IS realistic. I consider a map a useful representation of it subject.

 

[lugita15]

Sorry, I didn't add the qualifier "local" to this. As Demystifier says, Bohmian theories are (non-local) realistic.

There is some question as to what form of realism is being referred to, whether it might be "naive realism". I personally do not call the EPR definition naive, as this is a generally accepted definition. The issue is not whether an outcome is real, or whether the property being measured is real, the issue is whether there exists an element of reality which corresponds to what is observed. That element could be very complex, such that we are only able to sense a portion of its detail.

To use Bill's example: I am not saying the sun "really" is red every time I look at it with red sunglasses, I am saying there is something "real" which gives rise to that outcome. I make no statement to the effect that the redness itself is real. When I say it is red, I am using a shortcut rather than saying "it has a real set of properties which makes it appear red to me". For it to be real in this sense, it must also be so independent of the act of observation. Further, the likelihood of such outcome is between 0 and 100%.

So again: this is nothing but a standard definition shared by most. I know this because it is the same as used by EPR, Einstein, Bell and those following Bell. I don't think this audience considers their definition of realism to be naive, and I don't label it as such.

So just to make sure we're on the same page, you'd agree with me that a theory that satisfies counterfactual definiteness but is contextual, like Bohmian mechanics, would qualify as realistic, right? So the key property of realism is not that measurement cannot change the properties of a system, rather the key property is that the results of measurements both performed and unperformed are predetermined by the (hidden) attributes of the system, correct? I'm sorry if I'm just quibbling over semantics.

 

[DrChinese]

So just to make sure we're on the same page, you'd agree with me that a theory that satisfies counterfactual definiteness but is contextual, like Bohmian mechanics, would qualify as realistic, right? So the key property of realism is not that measurement cannot change the properties of a system, rather the key property is that the results of measurements both performed and unperformed are predetermined by the (hidden) attributes of the system, correct? I'm sorry if I'm just quibbling over semantics.

Yes, I agree with your description and would label things just the same.

One of the problems is the the words "real/really/reality" and "context/contextual" are also used in sentences frequently *not* referring to the EPR/Bell arguments. Trying to construct a semantically correct sentence that also communicates the relevant idea *clearly* can be difficult.

In many cases, I use "contextual" and "non-realistic" interchangeably. Ditto with "non-contextual" and "realistic", and "realistic" and "hidden variable". But strictly speaking, these are not the same. Most of the time, the differences are not relevant to the conclusion, but I understand that it matters sometimes.

For example, it doesn't matter to me if Bohmian Mechanics is non-local realistic or non-local contextual. Because either way it follows Bell, which is the relevant point for me. MWI often claims to be local realistic, but obviously cannot be realistic in the sense of Bell. Relational Block World is local, but being explicitly contextual, cannot be Bell realistic either.

 

[ThomasT]

I'm sorry if I'm just quibbling over semantics.

No need to apologize, imo. The quibbling isn't just quibbling. Clarifications by you, DrC, et al. are helping me to better understand the language surrounding Bell issues.

 

[billschnieder]

There is some question as to what form of realism is being referred to, whether it might be "naive realism". I personally do not call the EPR definition naive, as this is a generally accepted definition.
The issue is not whether an outcome is real, or whether the property being measured is real, the issue is whether there exists an element of reality which corresponds to what is observed. That element could be very complex, such that we are only able to sense a portion of its detail.

My problem with your statements which you still do not appear to have understood is that you keep implying that it is the experimental "OUTCOME" that must pre-exist the experiment according to EPR. This is false.

For example you say:

So yes, I would say that contextuality is contrary to both EPR and Einstein.

Realism is the idea that particles have well defined properties at all times whether or not those properties are measurable or not. Realism does not mean outcomes of experiments must EXIST simultaneously independently of the measurement as you seem to imply often with your "DrC challenge".

So again: this is nothing but a standard definition shared by most. I know this because it is the same as used by EPR, Einstein, Bell and those following Bell. I don't think this audience considers their definition of realism to be naive, and I don't label it as such.

No, we do not consider EPR's definition of realism to be naive. But despite your denials, you do in fact imply that their definition is the naive one.

Almost a year ago I provided this analogy to illustrate the difference:

The fact that every observable corresponds to an element of reality and all elements of reality are simultaneously well defined does not mean all observables are simultaneously measurable. Consider the following analogy:

We have a tablet with two well defined chemicals X and Y (aka elements of reality). In addition we have two glasses of different liquids A and B. In addition we have a theory which predicts with certainty the following *observables*:

a) if you place the tablet into liquid A, and drink it, it will taste sweet (X interacts with A to produce the sweetness).
b) if you place the tablet into liquid B, and drink it, it will taste bitter (Y interacts with B to produce the bitterness).

It is obvious that each observable (a) or (b) above *corresponds* to an element of reality. The two elements of reality (X,Y) in the particle are simultaneously well defined even before any experiment is performed. The prediction of the *observables* are certain and are made prior to experiment. This is exactly what EPR were talking about.

Until the measurement is actually performed, the elements of reality (X,Y) exist. But the outcomes of the measurements do not exist yet and can not exist yet. The outcome of the measurements are contextual because they depend on the context of the measurement (ie, the type of liquid used). There is nothing in EPR which is against this situation which is obviously classical.

YET! And please pay particular attention here: The *observables* (a) and (b) can NEVER be simultaneously real, simply because you can only place your tablet into one of the two liquids. Once you place your tablet, you destroy the tablet. Nothing here goes against EPR or realism. Therefore, the fact that a realist says elements of reality are well defined even when experiments are not performed, does not mean the results of all possible *observables* which can correspond to those elements are also simultaneously real and pre-exist the measurements. This is the part that you either do not understand, or do understand yet refuse to acknowledge.

This is not simply a matter of semantics, as it is immensly important when you start comparing real outcomes from already performed experiments with inequalities derived using mutually exclusive possibilities/predictions.

 

[DrChinese]

The fact that every observable corresponds to an element of reality and all elements of reality are simultaneously well defined does not mean all observables are simultaneously measurable. Consider the following analogy:

We have a tablet with two well defined chemicals X and Y (aka elements of reality). In addition we have two glasses of different liquids A and B. In addition we have a theory which predicts with certainty the following *observables*:

a) if you place the tablet into liquid A, and drink it, it will taste sweet (X interacts with A to produce the sweetness).
b) if you place the tablet into liquid B, and drink it, it will taste bitter (Y interacts with B to produce the bitterness).

It is obvious that each observable (a) or (b) above *corresponds* to an element of reality. The two elements of reality (X,Y) in the particle are simultaneously well defined even before any experiment is performed. The prediction of the *observables* are certain and are made prior to experiment. This is exactly what EPR were talking about.

Until the measurement is actually performed, the elements of reality (X,Y) exist. But the outcomes of the measurements do not exist yet and can not exist yet. The outcome of the measurements are contextual because they depend on the context of the measurement (ie, the type of liquid used). There is nothing in EPR which is against this situation which is obviously classical.

YET! And please pay particular attention here: The *observables* (a) and (b) can NEVER be simultaneously real, simply because you can only place your tablet into one of the two liquids. Once you place your tablet, you destroy the tablet. Nothing here goes against EPR or realism. Therefore, the fact that a realist says elements of reality are well defined even when experiments are not performed, does not mean the results of all possible *observables* which can correspond to those elements are also simultaneously real and pre-exist the measurements. This is the part that you either do not understand, or do understand yet refuse to acknowledge.

This is not simply a matter of semantics...

Sorry, it IS completely semantics.

I perfectly agree with your first statement, all potential observables are not necessarily measurable. Past that, the issue is that MOST folks believe that there are 2 simultaneous elements of reality in your analogy: 1) With A, you get sweet; with B, you get bitter. I don't say the element of reality IS the certain outcomes, but it corresponds with those. How you choose to make the association is not really important. What is real is the certain result regardless of the performance of the experiment. And with Bell, we have a situation where we see that there are severe limits on the number of simultaneous elements of reality that can apply to any particle. And it turns out that it precisely matches the predictions of the Heisenberg Uncertainty Principle. A classical object has no such inherent limit.

So NO, you can shape the words as you like, but Einstein would NEVER have made an argument like yours. He thought that spin - and spin projections - had values at all times. I am not misrepresenting realism; how could I, Bill? ... I follow the mainstream! You simply have a different definition than most, and by failing to adopt the standard definition, find yourself on a small island in the Pacific (hey, that isn't such a bad thing if it is the right island).

 

[Gordon Watson]

Sorry, I didn't add the qualifier "local" to this. As Demystifier says, Bohmian theories are (non-local) realistic.

There is some question as to what form of realism is being referred to, whether it might be "naive realism". I personally do not call the EPR definition naive, as this is a generally accepted definition. The issue is not whether an outcome is real, or whether the property being measured is real, the issue is whether there exists an element of reality which corresponds to what is observed. That element could be very complex, such that we are only able to sense a portion of its detail.

To use Bill's example: I am not saying the sun "really" is red every time I look at it with red sunglasses, I am saying there is something "real" which gives rise to that outcome. I make no statement to the effect that the redness itself is real. When I say it is red, I am using a shortcut rather than saying "it has a real set of properties which makes it appear red to me". For it to be real in this sense, it must also be so independent of the act of observation. Further, the likelihood of such outcome is between 0 and 100%.

So again: this is nothing but a standard definition shared by most. I know this because it is the same as used by EPR, Einstein, Bell and those following Bell. I don't think this audience considers their definition of realism to be naive, and I don't label it as such.

1. It is most certainly NAIVE REALISM for me.

2. If I could be sure that it was being diligently and consistently used as you say (Quote: "I know this because it is the same as used by EPR, Einstein, Bell and those following Bell.") then I could rest my case (and apologise no more) for being a local realist!

 

[billschnieder]

I perfectly agree with your first statement, all potential observables are not necessarily measurable. Past that, the issue is that MOST folks believe that there are 2 simultaneous elements of reality in your analogy: 1) With A, you get sweet; with B, you get bitter.

Most folks are naive. What has that got to do with EPR.

I don't say the element of reality IS the certain outcomes, but it corresponds with those. How you choose to make the association is not really important. What is real is the certain result regardless of the performance of the experiment.

But your misunderstanding is based on this misconception that "realism means the predicted result is already real even though the experiment has not been performed" and I'm pointing out to you that this is NOT the meaning of realism.

And with Bell, we have a situation where we see that there are severe limits on the number of simultaneous elements of reality that can apply to any particle.

False. There is nothing new with Bell's inequality. It is exactly the same inequality which Boole discovered a hundred years before Bell which he called "Conditions of possible experience", interesting name isn't it. And his conclusion was that any three variables that EXISTED simultaneously or could be simultaneously experienced MUST obey those inequalities, and violation implies the three variables can not be experienced simultaneously. Now we have Bell and his proponents on the basis of that claiming that particles can not have simultaneous elements of reality, based on the misunderstanding that predictions of experimental outcomes are themselves elements of reality contrary to EPR.

So NO, you can shape the words as you like, but Einstein would NEVER have made an argument like yours. He thought that spin - and spin projections - had values at all times. I am not misrepresenting realism; how could I, Bill? ... I follow the mainstream!

Einsten certainly believed particles had pre-existing elements of reality such as spin, position, etc. However, Einstein certainly did not believe "spin projections" along arbitrary axis EXISTED SIMULTANEOUSLY before any measurements were made. Einstein certainly would not have believed the tablets possessed simultaneously pre-existing BITTER TASTE and SWEET TASTE property independent of a measurement. This is the mainstream view. Anything else is just a "straw-man".

I have already shown you in this thread: https://www.physicsforums.com/showthread.php?t=499002&page=5 how such a simple classical case like tablets and solutions can lead to Bell inequality violation due to simple misconceptions like the one you exhibit.

You simply have a different definition than most, and by failing to adopt the standard definition, find yourself on a small island in the Pacific (hey, that isn't such a bad thing if it is the right island).

At the very least, this is an admission that I am right and violation of Bell's inequality does not mean realism as defined by me ("particles have well defined properties at all times whether those properties are measurable or not") is false.

 

[DrChinese]

At the very least, this is an admission that I am right and violation of Bell's inequality does not mean realism as defined by me ("particles have well defined properties at all times whether those properties are measurable or not") is false.

Your position "particles have well defined properties at all times whether those properties are measurable or not" is a meaningless definition. It is essentially circular/untestable, which is in essence the core of your anti-Bell views. Despite my requests, you won't tell me what the value of those properties are, were they to be revealed upon measurement. They exist without distinction, I guess. But are real. OK, it's your definition, you are entitled.

And it is quite unlike the EPR definition, which is more like: "properties that can be predicted with certainty imply particles possesses well defined properties independent of the act of observation."

------------------

I think we have *once again* reached the point where we both see our own position favorably and the other's, not so much. Further discussion seems pointless.

 

[Gordon Watson]

And it is quite unlike the EPR definition, which is more like: "properties that can be predicted with certainty imply particles possesses well defined properties independent of the act of observation."

DrC, Do you imply: "properties that can be predicted with certainty imply particles possesses [STRIKE]well defined[/STRIKE] those properties independent of the act of observation." ??

 

[DrChinese]

DrC, Do you imply: "properties that can be predicted with certainty imply particles possesses [STRIKE]well defined[/STRIKE] those properties independent of the act of observation." ??

Yes, for all intents and purposes that IS the EPR definition of elements of reality. If I look for red and am certain I will see red, it is red. Now, the semantic point is whether the property of redness is a real property, or if it is something that is associated with ("corresponds to") some other set of one or more real properties. That I don't know, and honestly, I fail to see what the issue is. EPR was quite careful to avoid that, I presume because they knew few scientists would quibble over the point. (In the 75 years since, the only questions I have seen on that point are on this board; Bell never mentioned any qualms about "what" is real.) Their exact words:

"...there exists an element of physical reality corresponding to this physical quantity."

So the physical quantity in this case is the observation of redness, and that corresponds to an element of physical reality. For ease, I say it has the red property but what is meant is per the prior sentence. It I looked for yellow and saw it too, then it is both red and yellow.

So to be clear: By normal definition (i.e. generally accepted within the physics community), realism is the idea that there is a set of "elements of reality" a la EPR which exists simultaneously and independently of the act of observation. It matters not to this definition how many can be measured at the same time (nor under what constraints), as long as each individually can be predicted with certainty without otherwise disturbing the particle under study. That is about as clear and concise as I can make it.

 

[billschnieder]

Your position "particles have well defined properties at all times whether those properties are measurable or not" is a meaningless definition.

It is not meaningless it IS the meaning of realism. I will end this discussion with a couple of quotes from Norsen's article "Against Realism" http://arxiv.org/abs/quant-ph/0607057

We have surveyed four different ‘realism’ concepts. Each has some relation to Bell’s
Theorem and related issues. Yet none of them has provided a promising candidate
for what users of the phrase ‘local realism’ mean by ‘realism’ – which leads me to
speculate that the users of that phrase don’t, themselves, know what they mean, and
that the phrase has, in fact, become widespread through sheer, unthinking inertia.
At very least, I hope the present analysis will put users of this dubious phrase
on the defensive: anyone who claims that Bell’s Theorem is a theorem about ‘local
realist’ theories (and/or who claims that the associated experiments have empirically
refuted ‘local realism’ and thus leave us with a choice between rejecting Locality and
rejecting Realism) needs to explain clearly what they mean by ‘realism’ and show
precisely where such ‘realism’ is assumed in the derivation of Bell’s inequalities.

Wolfgang Pauli, in a 1954 letter to Max Born...

“Einstein gave me your manuscript to read; he was not at all annoyed
with you, but only said that you were a person who will not listen.
This agrees with the impression I have formed myself insofar as I was
unable to recognise Einstein whenever you talked about him in either
your letter or your manuscript. It seemed to me as if you had erected
some dummy Einstein for yourself, which you then knocked down with
great pomp.​

Or, as Einstein himself elaborated ...

If one asks what ... is characteristic of the world of ideas of physics, one
is first of all struck by the following: the concepts of physics relate to a
real outside world, that is, ideas are established relating to things such
as bodies, fields, etc., which claim a ‘real existence’ that is independent
of the perceiving subject...”​

 

[DrChinese]

It is not meaningless it IS the meaning of realism. I will end this discussion with a couple of quotes from Norsen's article "Against Realism"...

And Norsen knows how I feel about his viewpoint on realism. Of course, he instead follows Bell via the non-locality exit, and I think he makes some strong points. His basic position is that Bell tests absolutely demonstrate non-locality.

 

[lugita15]

It is not meaningless it IS the meaning of realism. I will end this discussion with a couple of quotes from Norsen's article "Against Realism" http://arxiv.org/abs/quant-ph/0607057

billschnieder, let me ask you a simple question: do you or do you not believe that realism, as you define it, requires counterfactual definiteness?

 

[billschnieder]

billschnieder, let me ask you a simple question: do you or do you not believe that realism, as you define it, requires counterfactual definiteness?

I have answered that question very clearly previously here: https://www.physicsforums.com/showpost.php?p=3298338&postcount=106. and https://www.physicsforums.com/showpost.php?p=3302241&postcount=126 I will rather not repeat that discussion again.

 

[lugita15]

I have answered that question very clearly previously here: https://www.physicsforums.com/showpost.php?p=3298338&postcount=106. and https://www.physicsforums.com/showpost.php?p=3302241&postcount=126 I will rather not repeat that discussion again.

OK, so if I understand your first link correctly, you DO believe in counterfactual definiteness, in the sense that there is always a definite answer to the question "what would happen if you had measured this", but you don't believe that the RESULTS of unperformed measurements exist. Is that correct? So if you measure the polarization of one photon at -30 degrees and the polarization of the other photon at 30 degrees, then you don't think it makes sense to talk about the 0 degree polarization, but it does make sense to talk about what WOULD have happened if you had INSTEAD made a 0 degree polarization of one of the photons, right?

 

[billschnieder]

OK, so if I understand your first link correctly, you DO believe in counterfactual definiteness, in the sense that there is always a definite answer to the question "what would happen if you had measured this", but you don't believe that the RESULTS of unperformed measurements exist. Is that correct?

Correct!

So if you measure the polarization of one photon at -30 degrees and the polarization of the other photon at 30 degrees, then you don't think it makes sense to talk about the 0 degree polarization, but it does make sense to talk about what WOULD have happened if you had INSTEAD made a 0 degree polarization of one of the photons, right?

Correct! Sometimes we can be loose with language and talk about "0 degree polarization" when actually what we mean is "what we would observe if we measure at 0 degree" so long as we don't extrapolate our linguistic lazyness and make unwaranted conclusions from that.

That is why I argue that in Bell's inequality |P(a,b) - P(a,c)| <= P(b,c) + 1, the terms P(a,b), P(a,c), P(b,c) can not all be measured simultaneously, therefore a genuine experimental test of Bell's inequality is impossible.

In words:

P(a,b) = What they would have obtained had they measured along a and b
P(b,c) = What they would have obtained had they measured along b and c instead
P(a,c) = What they would have obtained had they measured along a and c instead

Now you combine those and obtain an inequality -- good. Unfortunately it is impossible to test this experimentally because in any experiment that is doable, measuring anyone of them makes the others impossible to measure. So the experimentalists perform three different things on three different ensembles and fool themselves into thinking they are measuring the terms in Bell's inequallity.

 

[DrChinese]

...but you don't believe that the RESULTS of unperformed measurements exist. Is that correct? So if you measure the polarization of one photon at -30 degrees and the polarization of the other photon at 30 degrees, then you don't think it makes sense to talk about the 0 degree polarization, but it does make sense to talk about what WOULD have happened if you had INSTEAD made a 0 degree polarization of one of the photons, right?

Hope this makes more sense to you than it does to me. Good luck!

 

[nonequilibrium]

The reason I keep including the quotes is because the words of Einstein are good enough for me as a definition. I think it is clear from these that Einstein believed a more complete specification of the system is possible than is contemplated by QM. And he believed spin components (and other particle properties) had definite values independent of the act of observation. He certainly didn't picture a reality that was limited to measurement outcomes that had already been performed, as you seem to.

Okay I didn't read through the whole thread, so I might be coming into flog a dead horse here, but I think you are slightly misinterpreting Einstein: he merely states that he believes that the values have a reality independent of measurement, but you seem to be saying that they're values are a part of reality prior to a measurement (as Einstein says) and that those values are the ones that your measuring apparatus eventually displays. The latter doesn't necessarily follow from the former: indeed, the measuring apparatus non-trivially alters the values of the system under inspection.

Forgive me if I'm perhaps missing the point, but I thought it might be helpful. Let me know if you think I erred myself.