Questions on Entanglement and Double-Slit Experiment

[ZapperZ]

Bohr once said that anyone who is not shocked by quantum theory has not understood it.

For example, one point of division between quantum theorists I am familiar with is the single universe/many worlds debate about superposition and quantum indeterminacy.

Granted, these are interpretations. Nevertheless, the responses here indicate that my questions are considered irrational in so far as I am taking such interpretations seriously.

Again, you are seeing the back end of the animal and NOT the whole animal itself. If you wish to tackle such interpretation issues, then shouldn't you at least start by understanding the mathematical formalism that is the SOURCE of such interpretation. NONE of these differing interpretation disagree on the mathematics. Period! All they are trying to do is make sense of what the mathematics is trying to convey in terms of ordinary human language and understanding. You are trying to do this without understanding the source of the whole issues. Do you see how irrational of an approch this is? No? Yes?

At the back of my mind, when I talk about a photon being in a state of superposition I’m aware that there is yet to be a consensus on what this represents. Is it one reality in which a photon has no certain position until measured (Bohr) or two realities in which the photon does have a certain position both before and after measurement (Everett)? The latter seems to rescue Einstein’s view that reality really is out there.

Zapper, you cited examples where twin path superposition of a particle can occur without interaction with anything. I accept that, just as I accept that a single particle cannot be said to be in a state of entanglement. What I was saying – rightly or wrongly – is that in cases where a particle is in a state of superposition and has interacted with other particles – it is those other particles that may be entangled. I based that on a working definition of entanglement, where “the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spatially separated.” To me, this appeared to be the case in the original twin-slit set-up.

Then WRITE DOWN THE ENTANGLED QUANTUM WAVEFUNCTION! I've been asking you to do this since the very beginning, the very first post that I wrote in this thread. The fact that you can't tells me that you are one of those people who Bohr talked about - haven't fully understood QM. This means that your "astonishment" about QM is really based on ignorance and superficial knowledge of QM via 2nd or even 3rd hand information. It is why I find it very hard and frustrating in trying to explain stuff to you, because you understand it differently when what it really means.

Again, tell me in no uncertain terms what are the "interaction" that occurs in the supercurrent for the SQUID experiment that produces the IDENTICAL interference pattern as the double slit.

Zz.

 

[Simon 6]

Zapper, it has to be acknowledged that we're not communicating too well.

It would take weeks, perhaps months, of intensive study for me to master the mathematics of quantum equations. If you do feel that this limitation disqualifies me from testing out a proposition or prevents me from asking the right questions, then so be it.

Recognising what I don't know is something I am prepared to do. The first three words in my initial post on this thread were: "By my understanding" - a phrase that expressed that recognition.

I'm going to give it one more attempt, and then perhaps we'll call it a day. (Others replies are welcome too.)

You have already made the case - very convincingly - that an interference pattern based on particle superposition does not demonstrate entanglement. I accept that. As far as I am aware, the SQUID experiment makes your arguement. It entails no interaction by the particle. If so, there is no question of entanglement, only superposition.

My point is a more basic one: in any scenario where the superposition of a particle is also attended by undetermined interaction with another system (e.g parts of a screen), then does not the superposition also apply to whatever system it may have interacted with?

This question is based on the principle of logical extension. If a given particle's location is undetermined, and there are two possible areas of a screen it could have interacted with, then aren't the two possible conditions of one part of the screen interdependent on the two possible conditions of the other?

I am prepared for a any answer to this. For example, the reply might be: "yes, the screen is in a state of superposition as you describe, but the term entanglement is inapplicable because it must refer to a specific property." If that's the answer, case closed.

Simon

 

[ZapperZ]

My point is a more basic one: in any scenario where the superposition of a particle is also attended by undetermined interaction with another system (e.g parts of a screen), then does not the superposition also apply to whatever system it may have interacted with?

This question is based on the principle of logical extension. If a given particle's location is undetermined, and there are two possible areas of a screen it could have interacted with, then aren't the two possible conditions of one part of the screen interdependent on the two possible conditions of the other?

I am prepared for a any answer to this. For example, the reply might be: "yes, the screen is in a state of superposition as you describe, but the term entanglement is inapplicable because it must refer to a specific property." If that's the answer, case closed.

Simon

OK, so now it is getting confusing. You are now talking about a 'screen' and not the 'slits'? It now the screen that is "interacting". If that is the case, then why would there be only "2" possible location on the screen for the photon to be detected? The interference pattern covers a wide area of the screen.

Again, without the proper mathematical description, what you are describing is extremely vague and hard to understand. You are also doing what I described earlier at trying to focus on a possible "special case" (...in any scenario where the superposition of a particle is also attended by undetermined interaction...) where it isn't necessary at all to explain a whole class of phenomena. Superposition is sufficient to explain your double slit and a whole zoo of others. So think on why your insistance of some form of entanglement is necessary to JUST explain the double slit?

In all of this, I still don't know what property is being "entangled" here, and frankly, I don't think you do either.

Zz.

 

[ttn]

Again, you are seeing the back end of the animal and NOT the whole animal itself. If you wish to tackle such interpretation issues, then shouldn't you at least start by understanding the mathematical formalism that is the SOURCE of such interpretation. NONE of these differing interpretation disagree on the mathematics. Period! All they are trying to do is make sense of what the mathematics is trying to convey in terms of ordinary human language and understanding.

That's not true. Orthodox QM has a Schroedinger type equation (for evolving states when no measurement is happening) and a collapse equation (for evolving states when a measurement is happening). GRW gets rid of the latter but adds a nonlinear stochastic term to the Schroedinger equation. MWI gets rid of the latter and leaves the Schroedinger equation unchanged. Bohm gets rid of the latter and adds a new equation for the dynamics of the particles.

I agree that one must know the formalism to profitably approach foundational questions. But it's definitely not true that different interpretations are merely different words or feelings about the same exact set of equations. Indeed, more precise language would be to think of the different versions of QM as distinct *theories* which give different accounts of what happens physically, contain different dynamical equations, and (in some cases) make subtly different predictions for what will be observed. Of course, the reason these are still considered viable is that they all make the same predictions for what should be observed in the kinds of cases that have actually been examined experimentally.

 

[ZapperZ]

That's not true. Orthodox QM has a Schroedinger type equation (for evolving states when no measurement is happening) and a collapse equation (for evolving states when a measurement is happening). GRW gets rid of the latter but adds a nonlinear stochastic term to the Schroedinger equation. MWI gets rid of the latter and leaves the Schroedinger equation unchanged. Bohm gets rid of the latter and adds a new equation for the dynamics of the particles.

I agree that one must know the formalism to profitably approach foundational questions. But it's definitely not true that different interpretations are merely different words or feelings about the same exact set of equations. Indeed, more precise language would be to think of the different versions of QM as distinct *theories* which give different accounts of what happens physically, contain different dynamical equations, and (in some cases) make subtly different predictions for what will be observed. Of course, the reason these are still considered viable is that they all make the same predictions for what should be observed in the kinds of cases that have actually been examined experimentally.

I disagree. When I say "classical mechanics", I do not need to specify if I'm talking about Newton's Laws, or Lagrangian/Hamiltonian mechanics. Yet, these two are very different approaches to solving the dynamical system. In the end, they are solving the same thing. So to me, they are "classical mechanics" mathematical formalism.

I use the same thing when talking about "quantum mechanics". I don't have to specify if I'm talking about Schrodinger Equation, matrix mechanics, Feynman path integral, Second Quantization, etc... etc. I'm not doing anything different by solving it using second quantization versus matrix mechanics.

I do not want to go into MWI and Bohm theory AGAIN! It has been talked to death. I will simply point out to you that when we have actual problems to solve beyond JUST basic QM issues, we resort back to STANDARD QM. I'll ask you to point out a single condensed matter, nuclear physics, atomic physics, etc paper that make use of non-standard QM formalism. Till that happens, we ALL know what is meant when I say "standard QM", don't we?

Or do I need to be explictly clear EVERY time we tackle and make use of the name "quantum mechanics"?

Zz.

 

[ttn]

I disagree. When I say "classical mechanics", I do not need to specify if I'm talking about Newton's Laws, or Lagrangian/Hamiltonian mechanics. Yet, these two are very different approaches to solving the dynamical system. In the end, they are solving the same thing. So to me, they are "classical mechanics" mathematical formalism.

I use the same thing when talking about "quantum mechanics". I don't have to specify if I'm talking about Schrodinger Equation, matrix mechanics, Feynman path integral, Second Quantization, etc... etc. I'm not doing anything different by solving it using second quantization versus matrix mechanics.

I do not want to go into MWI and Bohm theory AGAIN! It has been talked to death. I will simply point out to you that when we have actual problems to solve beyond JUST basic QM issues, we resort back to STANDARD QM. I'll ask you to point out a single condensed matter, nuclear physics, atomic physics, etc paper that make use of non-standard QM formalism. Till that happens, we ALL know what is meant when I say "standard QM", don't we?

Or do I need to be explictly clear EVERY time we tackle and make use of the name "quantum mechanics"?

Zz.

I pointed out that the different interpretations don't all share the same formalism. I gather that your first paragraph is meant to express disagreement with that claim. But then I'm at a loss to understand what you think the issue is that you're addressing in the later paragraphs. If, according to you, Copenhagen, MWI, Bohm, GRW, etc., are all just different touchy feely ways of looking at the same exact formalism, there wouldn't even be any *difference* between solving some condensed matter problem using "standard QM" and solving it using Bohm or whatever.

You can't have it both ways. Either you define things in such a way that these are really all just the same theory (in which case it's hardly rational to be so adamantly in favor of one of them and so adamantly against the others), or you define things in such a way that these are really distinct theories (in which case it's hardly rational to support one merely because lots of people use it, in spite of the fact that others make the same predictions and are actually superior qua physics theories).

 

[JesseM]

I agree that one must know the formalism to profitably approach foundational questions. But it's definitely not true that different interpretations are merely different words or feelings about the same exact set of equations. Indeed, more precise language would be to think of the different versions of QM as distinct *theories* which give different accounts of what happens physically, contain different dynamical equations, and (in some cases) make subtly different predictions for what will be observed. Of course, the reason these are still considered viable is that they all make the same predictions for what should be observed in the kinds of cases that have actually been examined experimentally.

In what situations do they "make subtly different predictions for what will be observed"? I thought they all made identical predictions for the results of all possible measurements, which is why they are called "interpretations" and not "theories".

 

[ZapperZ]

I pointed out that the different interpretations don't all share the same formalism. I gather that your first paragraph is meant to express disagreement with that claim. But then I'm at a loss to understand what you think the issue is that you're addressing in the later paragraphs. If, according to you, Copenhagen, MWI, Bohm, GRW, etc., are all just different touchy feely ways of looking at the same exact formalism, there wouldn't even be any *difference* between solving some condensed matter problem using "standard QM" and solving it using Bohm or whatever.

You can't have it both ways. Either you define things in such a way that these are really all just the same theory (in which case it's hardly rational to be so adamantly in favor of one of them and so adamantly against the others), or you define things in such a way that these are really distinct theories (in which case it's hardly rational to support one merely because lots of people use it, in spite of the fact that others make the same predictions and are actually superior qua physics theories).

But you can't have it both ways either.

If you claim that they ARE different, both philosophically AND in their formalism, then the "others" have a major stumbling block in the sense that they are NOT being used at all in high-degree-of-certainty fields such as condensed matter. Point out to me a condensed matter paper that do make use of MWI formalism if you claim it is distinctly different than the standard QM. You'll find NONE.

If you claim that they are the same, then what are we arguing about?

This is going OFF TOPIC. You have had your chance, plenty of it, to do this in other threads. You should not need such flimsy excuse to continue this here.

Zz.

 

[ttn]

But you can't have it both ways either.

If you claim that they ARE different, both philosophically AND in their formalism, then the "others" have a major stumbling block in the sense that they are NOT being used at all in high-degree-of-certainty fields such as condensed matter. Point out to me a condensed matter paper that do make use of MWI formalism if you claim it is distinctly different than the standard QM. You'll find NONE.

If you claim that they are the same, then what are we arguing about?

This is going OFF TOPIC. You have had your chance, plenty of it, to do this in other threads. You should not need such flimsy excuse to continue this here.

Zz.

Fine, I don't want to pursue it either. I just wanted to point out the error in your statement that different versions of QM all share the same formalism. That isn't true, and I'll leave it at that.

 

[ZapperZ]

Fine, I don't want to pursue it either. I just wanted to point out the error in your statement that different versions of QM all share the same formalism. That isn't true, and I'll leave it at that.

Then they are NOT the "QM" that you think I was referring to, because, whoa, they are NOT used in any practical aspect that require them to be CORRECT before they can be used in utmost confidence.[1]

How about them apples?

Zz.

[1] D.F. Styer et al. Am. J. Phys. v.70, 288 (2002).

 

[ttn]

Then they are NOT the "QM" that you think I was referring to, because, whoa, they are NOT used in any practical aspect that require them to be CORRECT before they can be used in utmost confidence.[1]

How about them apples?

Zz.

[1] D.F. Styer et al. Am. J. Phys. v.70, 288 (2002).

So you're saying the different formulations actually make different predictions for what should happen in your precious condensed matter experiment? That, because their formalisms differ from "standard QM", they are not "CORRECT", and that this is why condensed matter physicists don't use them?

If so you're an illiterate idiot. Come down off your high horse and actually learn what you're talking about. You might start by reading from the abstract of the paper you tried to throw in my face:

"The various formulations differ dramatically in mathematical and conceptual overview, yet each one makes identical predictions for all experimental results."

(This, however, is not an endorsement of the papers of Styer et al's foundational papers. Their "common misconceptions" paper is notoriously full of ... misconceptions ... about things like Bell's theorem.)

 

[ZapperZ]

So you're saying the different formulations actually make different predictions for what should happen in your precious condensed matter experiment? That, because their formalisms differ from "standard QM", they are not "CORRECT", and that this is why condensed matter physicists don't use them?

I said NOTHING of that sort. You were the one who claimed that they are different! And who said anything about "condensed matter EXPERIMENT"? You don't think there's any "theoretical" work in condensed matter at all? Try looking at a few papers and point out to me where non-standard QM that isn't part of Styer's paper have ever been used? Why? Because the formulation hasn't been tested to the most rigorous extent as to be USED with utmost confidence. Nowhere in any theoretical description of ANY condensed matter systems are there any usage of non-standard QM. This last part is not an opinion, whether you like it or not.

If so you're an illiterate idiot. Come down off your high horse and actually learn what you're talking about. You might start by reading from the abstract of the paper you tried to throw in my face:

"The various formulations differ dramatically in mathematical and conceptual overview, yet each one makes identical predictions for all experimental results."

But that is what I've been trying to say from the very beginning! It is why I brought up the different approaches in classical mechanics. The different formulations of QM are not "different QM", the same way Newton Laws are not different classical mechanics from Lagrangian/Hamiltonian mechanics! You were the one who indicated that they produce "subtly DIFFERENT predictions"!

(This, however, is not an endorsement of the papers of Styer et al's foundational papers. Their "common misconceptions" paper is notoriously full of ... misconceptions ... about things like Bell's theorem.)

Talk is cheap. I see that you didn't write any rebuttal to that paper that they have published. Why is it that whenever there is a published paper that someone finds something "wrong", the best he/she can do is diss about it on some place like this, rather than staking one's reputation and write a rebuttal?

[I will overlook your personal attack on me this time. However, unless you wish for this thread to go down the gutter, I will onlywarn you just once to cease resorting to such thing.]

Zz.

 

[Careful]

Nowhere in any theoretical description of ANY condensed matter systems are there any usage of non-standard QM. This last part is not an opinion, whether you like it or not.

The reason why, Zapper, is that it would be far too complex to calculate for example the Bohmian trajectories of cooper pairs in a superconductor; if you ever tried to do something far easier than this, then you would figure out that this is a fairly obvious reason.

But that is what I've been trying to say from the very beginning! It is why I brought up the different approaches in classical mechanics. The different formulations of QM are not "different QM", the same way Newton Laws are not different classical mechanics from Lagrangian/Hamiltonian mechanics! You were the one who indicated that they produce "subtly DIFFERENT predictions"!

Newtonian mechanics is not equivalent to the Lagrangian formalism, eg. not every force equation can be written as the Euler Lagrange equation for some Lagrangian.

Talk is cheap. I see that you didn't write any rebuttal to that paper that they have published. Why is it that whenever there is a published paper that someone finds something "wrong", the best he/she can do is diss about it on some place like this, rather than staking one's reputation and write a rebuttal?

Even though you did not ask this question to me, I will answer that one. First, if one were to write rebuttals against every rubbish paper that is published on the arxiv, that would be more than a fulltime job. Second, you continue to confuse ``talk'' with argumented opposition, a forum like this seems perfectly suited for the latter.

Careful

 

[ZapperZ]

The reason why, Zapper, is that it would be far too complex to calculate for example the Bohmian trajectories of cooper pairs in a superconductor; if you ever tried to do something far easier than this, then you would figure out that this is a fairly obvious reason.

So forget about "cooper pairs in a semiconductor". Use it to do something a lot simpler, like deriving the Landau Fermi Liquid model!

I'm not arguing if it is easy or not, or possible or not. I'm arguing that in the literature, no where are any of these so-touted formalism are ever used in condensed matter, plasma physics, atomic/molecular physics, etc... etc... i.e. all the subject area in which QM is used as an APPLICATION. This lack of usage seems to be completely ignored in any of the argument touting their strength. It's like a 3000 lb gorrilla that no one seems to talk about. Or maybe it is because one looks down on such "applied fields" that they bare no importance whatsoever in considering the validity of such description? And *I* am the one who is on some "high horse"?

Newtonian mechanics is not equivalent to the Lagrangian formalism, eg. not every force equation can be written as the Euler Lagrange equation for some Lagrangian.

Eh?

In principle, for every equation of motion that one solves with the Newtonian mechanics, one would get the identical equation of motion using Lagrangian/Hamiltonian mechanics. You are welcome to show me an example where it doesn't. There are no "subtle difference" in the outcome of each approach as far as the final result is concerned.

Even though you did not ask this question to me, I will answer that one. First, if one were to write rebuttals against every rubbish paper that is published on the arxiv, that would be more than a fulltime job. Second, you continue to confuse ``talk'' with argumented opposition, a forum like this seems perfectly suited for the latter.

Careful

I never care about rebuttals for anything appearing on ArXiv. That's absured considering that I do not consider such format as a peer-reviewed medium. It is why I gave the complete published citation to Styer's paper. So send a rebuttal to AJP. And no, this forum is NOT suited for such idle comments like that when one cannot make a valid supporting argument. We require that people to base their arguments on valid physics, and that requires supporting documents. Saying Styer's paper is itself full of misconception says NOTHING, because that is a superficial statement with zero explanation and documentation. If one truly has a valid argument, then I'd rather see it being published as a rebuttal, and see how Styer and the rest of the physics community respond to that. That is how physics is done, NOT in open forums such as this, especially when there's a conflict of opinion!

Now I KNOW for certain that someone is going to come up and accuse me of trying to stop all "questioning" of current ideas. I will put it to you that that is not even close to what I'm asking. However, and you know who you are, there are people who are adamant in pushing whatever it is they're pushing that somehow the rest of us who continue to use the standard formalism are ignorant and stupid. To me, it is obvious that these people have already made up their minds and decisions, and thus, know that they are correct. I want them to put their money where their mouths are. Stop dissing this and that, and go put your reputation on the line. For once, do something that counts rather than just wasing your valuble talent on an open forum that will do nothing to enhance your standing as a physicist (or whatever it is that you are choosing to be). There are TONS of published papers that clearly disagree with whatever it is you're pushing. Send rebuttals! Can't do for all of them, try 2, 3, 4... etc. Pick the most important ones, the ones that a lot of people are citing in some prestigious journals. Go burst that big bubble! Go on! I dare you!

Zz.

 

[DrChinese]

First, if one were to write rebuttals against every rubbish paper that is published on the arxiv, that would be more than a fulltime job.

Be fair: ZapperZ's reference was not one from the arxiv.

D.F. Styer et al. Am. J. Phys. v.70, 288 (2002)

At this point, alternative interpretations are NOT making any testable predictions involving their different "formalisms". In fact, it seems to me more the opposite. They lay the groundwork to prove that they do reduce to the QM formalism so they at least get a chance to be taken seriously.

And this makes perfect sense, considering the experimental validation of QM to date.

 

[Careful]

So forget about "cooper pairs in a semiconductor". Use it to do something a lot simpler, like deriving the Landau Fermi Liquid model!

I'm not arguing if it is easy or not, or possible or not. I'm arguing that in the literature, no where are any of these so-touted formalism are ever used in condensed matter, plasma physics, atomic/molecular physics, etc... etc... i.e. all the subject area in which QM is used as an APPLICATION.

Right, and the reason is that this would be way too difficult : I recall you the recent paper I referred you to about atomic transitions of electrons in BM for the H atom.

Eh?

In principle, for every equation of motion that one solves with the Newtonian mechanics, one would get the identical equation of motion using Lagrangian/Hamiltonian mechanics. You are welcome to show me an example where it doesn't. There are no "subtle difference" in the outcome of each approach as far as the final result is concerned.

Look again at the conditions on the force function in d'Alembert's derivation of the Euler Lagrange equation from Newton's second law. For suitable force functions (eg. conservative force fields), both appraoches agree of course ... (the restriction obviously is that you cannot play the trick of increasing the number of dynamical variables, or add Lagrange multipliers or so... ).

Saying Styer's paper is itself full of misconception says NOTHING, because that is a superficial statement with zero explanation and documentation. If one truly has a valid argument, then I'd rather see it being published as a rebuttal, and see how Styer and the rest of the physics community respond to that. That is how physics is done, NOT in open forums such as this, especially when there's a conflict of opinion!

I did not read this paper, neither did I read the comments offered by ttn; it was just a general remark based upon the assumption that ttn had done his homework.

I want them to put their money where their mouths are. Stop dissing this and that, and go put your reputation on the line. For once, do something that counts rather than just wasing your valuble talent on an open forum that will do nothing to enhance your standing as a physicist (or whatever it is that you are choosing to be). .

The reason for me to be on this forum from time to time is my own business. And yes, I am still working on QM and making some progress recently ; only I do know very well how hard it is to do something truly original and *useful* on such a longstanding problem. As I once said, it is not difficult at all to think of local realist scenario's behind entanglement (holography, extra dimensions and so on), but it is damn difficult to find a plausible one !

Cheers,

Careful

 

[ZapperZ]

Right, and the reason is that this would be way too difficult : I recall you the recent paper I referred you to about atomic transitions of electrons in BM for the H atom.

Is it really?

If you look at the stuff listed in Styer's papers, at some stage, some area of physics makes use of a particular formalism. I have seen the standard "Schrodinger" method, the Heisenberg matrix method, density matrix, path integral, variational method, second quantization, etc... etc. In other words, at some point, one of these approaches were used in condensed matter, atomic/molecular physics, nuclear physics, particle physics, etc... I would think it would raise a lot of eyebrows if a particular technique is (i) "too hard" and (ii) isn't missed at all such that it isn't used in the applied field. I mean, with such variety of applications and usage, there's not even ONE single area in which such formalism would be the least bit useful to be used? What one has "invented" then is something that is utterly useless other than to make someone's philosophical view of the world better. It sounds like something that would qualify for an Ig Nobel.

Zz.

 

[Careful]

Is it really?

If you look at the stuff listed in Styer's papers, at some stage, some area of physics makes use of a particular formalism. I have seen the standard "Schrodinger" method, the Heisenberg matrix method, density matrix, path integral, variational method, second quantization, etc... etc. In other words, at some point, one of these approaches were used in condensed matter, atomic/molecular physics, nuclear physics, particle physics, etc... I would think it would raise a lot of eyebrows if a particular technique is (i) "too hard" and (ii) isn't missed at all such that it isn't used in the applied field. I mean, with such variety of applications and usage, there's not even ONE single area in which such formalism would be the least bit useful to be used? What one has "invented" then is something that is utterly useless other than to make someone's philosophical view of the world better. It sounds like something that would qualify for an Ig Nobel.
Zz.

First, you know very well that in order to compute the trajectories, one would first need to solve the full dynamical problem (since as far as I remember these trajectories show chaotic behavior), which is very hard to do even just for a system of radiating electrons. Second, I have always agreed with the statement that as far as I am concerned all popular existing alternatives to standard QM such as MWI, BM are window dressing as they stand now, so yes I can also imagine from that point of view why people did not care so much. There are exceptions such as the work of Adler and GRW, but these are all explicitely nonlocal, Barut self field is for now the only local exception, but it isn't QFT. However, a good local realist theory behind QM would for sure be useful for quantum gravity and for the sake of understanding physics. However, I doubt it would be useful for computations in condensed matter physics; likewise we do not use deterministic microphysics when dealing with macroscopic systems, we have thermodynamics for that.

Careful

 

[ttn]

What one has "invented" then is something that is utterly useless other than to make someone's philosophical view of the world better. It sounds like something that would qualify for an Ig Nobel.

Zz.

You're talking about Bohmian Mechanics here, right? You truly don't get it. Bohmian Mechanics and orthodox QM make identical predictions (at least in cases where the predictions of the latter are unambiguous). So it begs the question to just dismiss Bohm's theory as you do here. One could equally well dismiss orthodox QM (i.e., all the idiotic philosophical ramblings of Bohr) on the same basis -- namely, that what Copenhagen adds to the rigorous formulation of the pilot wave approach is just a bunch of used-to-be-trendy positivist, anti-realist, existentialist-motivated philosophical mumbo jumbo whose only function is to make some moron feel better about their anti-scientific philosophical view of the world. If you actually have any serious interest in this issue, you might start by reading Jim Cushing's book "Quantum Mechanics: Historical Contingency and the Copenhagen Hegemony". Or if you don't have any serious interest, maybe you shouldn't discuss them in public.

As to your big challenge that I should publish a rebuttal to Styer's "misconceptions" paper, see section IV of

http://puhep1.princeton.edu/~mcdonald/examples/QM/norsen_ajp_73_164_05.pdf

This is all particularly ironic given the following:

http://tech.groups.yahoo.com/group/undernetphysics/message/857

 

[JesseM]

You're talking about Bohmian Mechanics here, right? You truly don't get it. Bohmian Mechanics and orthodox QM make identical predictions (at least in cases where the predictions of the latter are unambiguous). So it begs the question to just dismiss Bohm's theory as you do here. One could equally well dismiss orthodox QM (i.e., all the idiotic philosophical ramblings of Bohr) on the same basis

They aren't really comparable, at least not if "orthodox QM" is taken to mean the ordinary shut-up-and-calculate version (which is basically what the purely positivist version of the Copehagen interpretation is, although some people use 'Copehagen interpretation' to mean the view that the collapse of the wavefunction is a real physical event), which is just a recipe for making predictions about probabilities without any assumptions (one way or another) about hidden variables, other worlds, or any other aspect of reality that can't be tested directly. Of course, you could also use the formalism of Bohmian mechanics as a recipe for making predictions, without any assumptions about the "reality" of hidden variables or the pilot wave, but this isn't what people usually mean by Bohmian mechanics.

 

[ZapperZ]

You're talking about Bohmian Mechanics here, right? You truly don't get it. Bohmian Mechanics and orthodox QM make identical predictions (at least in cases where the predictions of the latter are unambiguous). So it begs the question to just dismiss Bohm's theory as you do here. One could equally well dismiss orthodox QM (i.e., all the idiotic philosophical ramblings of Bohr) on the same basis -- namely, that what Copenhagen adds to the rigorous formulation of the pilot wave approach is just a bunch of used-to-be-trendy positivist, anti-realist, existentialist-motivated philosophical mumbo jumbo whose only function is to make some moron feel better about their anti-scientific philosophical view of the world. If you actually have any serious interest in this issue, you might start by reading Jim Cushing's book "Quantum Mechanics: Historical Contingency and the Copenhagen Hegemony". Or if you don't have any serious interest, maybe you shouldn't discuss them in public.

As to your big challenge that I should publish a rebuttal to Styer's "misconceptions" paper, see section IV of

http://puhep1.princeton.edu/~mcdonald/examples/QM/norsen_ajp_73_164_05.pdf

This is all particularly ironic given the following:

http://tech.groups.yahoo.com/group/undernetphysics/message/857

Who said anything about Bohmian Mechanics in particular? In fact, this IS included in Styer's text.

Again, it is YOU who said that there ARE formulations that make subtle difference in predictions. Bohmian mechanics does this? Yes? No? If it makes "identical predictions", then why are you up in arms here with this one? It is obviously not what YOU included in your original claim. Yet, you're picking it as an example. So you're right, I DON'T get it.

And thank you for your reference. Unfortunately, your paper has more of a problem with Bell's theorem in general rather than Styer's paper itself! You are claiming that Styer didn't have the "misconception", but rather the whole of quantum mechanics community is the one that did. And yes, I thought it was a good paper because it does present a "historical account" of a thought experiment that has been overlooked. That was it, which was essentially what I said when I pointed it out, no?

[BTW, this also falsifies the often-made claim that I only advertize papers that do not challenge the conventional ideas, even when *I* myself don't think is convincing]

Zz.

 

[ttn]

Who said anything about Bohmian Mechanics in particular? In fact, this IS included in Styer's text.

Funny, since he claims in his earlier paper that Bell's Theorem proves it can't exist.

Again, it is YOU who said that there ARE formulations that make subtle difference in predictions.

There are. GRW for example.

Bohmian mechanics does this? Yes? No?

No, as I said in the previous post, Bohm's theory makes the same predictions as orthodox QM wherever the latter is unambiguous.

If it makes "identical predictions", then why are you up in arms here with this one? It is obviously not what YOU included in your original claim. Yet, you're picking it as an example. So you're right, I DON'T get it.

My original claim was that the different versions of QM don't share the same formalism. You keep trying to twist things around and change the subject in order to win this argument. I frankly don't care about who wins; I just wanted to convey to all the reasonable people who read this that they needn't be bullied by your arrogant dismissiveness about foundational questions. I think I've achieved that, and there's no point continuing to argue about whether my "original claim" was true, so the last word is yours.

And thank you for your reference. Unfortunately, your paper has more of a problem with Bell's theorem in general rather than Styer's paper itself! You are claiming that Styer didn't have the "misconception", but rather the whole of quantum mechanics community is the one that did.

Those aren't exactly mutually exclusive. Styer was simply repeating, without real understanding, a misconception that is widely held in the physics community. Does it somehow invalidate my claim because it is targeted more widely than Styer's paper in particular? That makes no sense -- unless your goal is to follow any path, no matter how ridiculous, in order to try to win an argument.

 

[ZapperZ]

Funny, since he claims in his earlier paper that Bell's Theorem proves it can't exist.

There are. GRW for example.
No, as I said in the previous post, Bohm's theory makes the same predictions as orthodox QM wherever the latter is unambiguous.

My original claim was that the different versions of QM don't share the same formalism. You keep trying to twist things around and change the subject in order to win this argument. I frankly don't care about who wins; I just wanted to convey to all the reasonable people who read this that they needn't be bullied by your arrogant dismissiveness about foundational questions. I think I've achieved that, and there's no point continuing to argue about whether my "original claim" was true, so the last word is yours.

Those aren't exactly mutually exclusive. Styer was simply repeating, without real understanding, a misconception that is widely held in the physics community. Does it somehow invalidate my claim because it is targeted more widely than Styer's paper in particular? That makes no sense -- unless your goal is to follow any path, no matter how ridiculous, in order to try to win an argument.

No I'm not, because this thing has become so convoluted, I doubt if anyone else reading this even CARE who said what when.

My original point was, in case you forgot, that the different formulations of QM are simply variations to the SAME set of principles in the SAME way that Newtonian and Lagrangian/Hamiltonian mechanics are in classical mechanics. They may have different approaches and different "philosophical" views, but no one would call them as different classical mechanics. The list provide by Styer is a clear example where different formalism of QM essentially ARE what we ALL call "quantum mechanics" in the standard sense. My evidence? Other than Bohmian mechanics (which is nothing more than QM with an "action"), all those formulations one encounters either in textbooks, or used in various "applications". None of them produce any results that contradict each other. I don't know why this is such a sticky point!

Now you, however, decided to include what I would call non-standard QM and not only that, claim that one can also arrive and a different result using these. So by bastardizing and redefining what I said, you claim that I made a mistake in judgement. I really don't care if you have an affinity to one thing versus the other, but even YOU can see the absurdity if I have to defend something that I never claim. I never brought up bohmian mechanics till you somehow interpreted my claim as referring to it. I never make any claim about non-standard QM until you decided to claim that I did. The FACT that I repeatedly refer to what is being used in the application of QM as a measuring stick of a very mature formalism of QM somehow, according to you, is my "high horse" position. What ELSE is there, as an evidence, for something to be so well-known and well-accepted other than being used for applications?! For some odd reason, you took offense at this!

We ALL know the formalisms being used often and repeatedly in solving problems in physics beyond JUST the field of foundational QM. I cited the FACT that NO papers, theoretical or experimental, that use the non-standard formalism for problem solving/application as evidence that such formalism is still not fully matured nor accepted YET. This ISN'T a criticism of the formalism! As someone who cares more about how to get to the final result, I cannot trust something new and untested to solve my problem when it isn't part of what I care about. Why is this causing you such a problem?

BTW, are you preparing the possible rebuttal to Marcella's preprint?
http://arxiv.org/abs/quant-ph/0606141

.. and I must have missed your response to Shimony's counter argument against' your paper.
A. Shimony AJP 73, 177 (2005).

Zz.

 

[ttn]

No I'm not, because this thing has become so convoluted, I doubt if anyone else reading this even CARE who said what when.

My original point was, in case you forgot, that the different formulations of QM are simply variations to the SAME set of principles in the SAME way that Newtonian and Lagrangian/Hamiltonian mechanics are in classical mechanics. They may have different approaches and different "philosophical" views, but no one would call them as different classical mechanics. The list provide by Styer is a clear example where different formalism of QM essentially ARE what we ALL call "quantum mechanics" in the standard sense. My evidence? Other than Bohmian mechanics (which is nothing more than QM with an "action"), all those formulations one encounters either in textbooks, or used in various "applications". None of them produce any results that contradict each other. I don't know why this is such a sticky point!

Now you, however, decided to include what I would call non-standard QM and not only that, claim that one can also arrive and a different result using these. So by bastardizing and redefining what I said, you claim that I made a mistake in judgement. I really don't care if you have an affinity to one thing versus the other, but even YOU can see the absurdity if I have to defend something that I never claim. I never brought up bohmian mechanics till you somehow interpreted my claim as referring to it. I never make any claim about non-standard QM until you decided to claim that I did. The FACT that I repeatedly refer to what is being used in the application of QM as a measuring stick of a very mature formalism of QM somehow, according to you, is my "high horse" position. What ELSE is there, as an evidence, for something to be so well-known and well-accepted other than being used for applications?! For some odd reason, you took offense at this!

We ALL know the formalisms being used often and repeatedly in solving problems in physics beyond JUST the field of foundational QM. I cited the FACT that NO papers, theoretical or experimental, that use the non-standard formalism for problem solving/application as evidence that such formalism is still not fully matured nor accepted YET. This ISN'T a criticism of the formalism! As someone who cares more about how to get to the final result, I cannot trust something new and untested to solve my problem when it isn't part of what I care about. Why is this causing you such a problem?

Since I promised to give you the last word, I won't respond to this part.

But I will answer the questions you posed:

BTW, are you preparing the possible rebuttal to Marcella's preprint?
http://arxiv.org/abs/quant-ph/0606141

.. and I must have missed your response to Shimony's counter argument against' your paper.
A. Shimony AJP 73, 177 (2005).

If you really want to discuss this topic -- i.e., the validity of the Einstein's Boxes argument for the incompleteness/nonlocality dilemma faced by orthodox QM -- I would be happy to oblige. Why don't you start a new thread and we'll just wipe the slate clean and focus on this topic?

But to answer the specific questions: no, I am not preparing a rebuttal to that paper of Marcella, since it is very poorly done. (He doesn't even understand what the argument is he thinks he's rebutting.) And, for what it's worth, the same is true of Shimony's piece. I would be happy to elaborate further in the other thread if you're interested in discussing it. Maybe you could get the discussion going by briefly summarizing your own objections to the arguments I made in the paper (you suggested before that you didn't find it convincing) and then summarize the alleged rebuttals of Shimony and Marcella and explain why you agree with those (if you do).

 

[ZapperZ]

But to answer the specific questions: no, I am not preparing a rebuttal to that paper of Marcella, since it is very poorly done. (He doesn't even understand what the argument is he thinks he's rebutting.) And, for what it's worth, the same is true of Shimony's piece. I would be happy to elaborate further in the other thread if you're interested in discussing it. Maybe you could get the discussion going by briefly summarizing your own objections to the arguments I made in the paper (you suggested before that you didn't find it convincing) and then summarize the alleged rebuttals of Shimony and Marcella and explain why you agree with those (if you do).

No, I'm not trying to get in the "last word" here, but I want to make an important clarification.

No where in here did I objected to your arguments. Remember what brought this about. You accused Styer's paper as being full of misconception. That was what I questioned. You tried to support my question by producing your paper. I brought up others that also questioned yours.

What was my point in doing this? It is to show you that what you believe to be a "misconception", others find that YOUR work to also be that, a misconception. At some point, till this is worked out, it becomes as matter of opinion.

This is also EXACTLY my point in why we (as in those of us who have to QM to solve things, and NOT just study the "fundamental" aspect of it) will stick to the standard QM, because we know that works! I know you probably put very little importance to such a concept, but the reality is, if people's lives depend on us getting it right, we have to stick to what we know works. I find no higher degree of validity than that. I use that as a test of ANY theories out there.

Zz.

 

[DrChinese]

You're talking about Bohmian Mechanics here, right? ...One could equally well dismiss orthodox QM (i.e., all the idiotic philosophical ramblings of Bohr) on the same basis...

While you are busy trying to diss QM with an ad hominem attack on Bohr, you might consider balancing the equation with some of Bohm's equivalent jewels. "Wholeness and the Implicate Order", perhaps?

Just a minor comment: your genuinely thought provoking ideas are much more cleanly presented when you skip the gratuitous insults.

Besides, if Bohmian Mechanics had come first and paved the way, then PERHAPS the conversation would be reversed. No one gets much credit for being the second to discover something. At this point, it has been about 50 years and we still have nothing novel from this interpretation (BM that is) that I am aware of. But you never know, perhaps the big validation is right around the corner.

 

[ttn]

What was my point in doing this? It is to show you that what you believe to be a "misconception", others find that YOUR work to also be that, a misconception. At some point, till this is worked out, it becomes as matter of opinion.

Well, like I said, I would be delighted to actually work it out in discussion with you. If you're interested, start a thread (so we don't hijack this one any more than we already have).

This is also EXACTLY my point in why we (as in those of us who have to QM to solve things, and NOT just study the "fundamental" aspect of it) will stick to the standard QM, because we know that works! I know you probably put very little importance to such a concept, but the reality is, if people's lives depend on us getting it right, we have to stick to what we know works. I find no higher degree of validity than that. I use that as a test of ANY theories out there.

I don't disagree with any of that. But if you think we can be sure that Copenhagen QM "works", but we aren't or can't presently be sure whether Bohmian Mechanics "works", you still haven't understood what is at issue here. Perhaps that point will come out into the light if we take this up in another thread.

 

[ttn]

While you are busy trying to diss QM with an ad hominem attack on Bohr, you might consider balancing the equation with some of Bohm's equivalent jewels. "Wholeness and the Implicate Order", perhaps?

Yup, Bohm was a loony in his later years. But, like you, I don't think this is relevant. My point wasn't to argue for Bohm by dissing Bohr with some kind of ad hominem. My point was just that any argument of the form "Copenhagen is great because it works, while Bohm just muddies and encumbers things with his pet philosophical bias" is invalid -- because it can trivially be turned around. What actually matters is, as ZZ has said, whether or not a theory "works" -- i.e., whether it makes the right predictions and satisfies time-tested standards for what constitutes a good scientific theory (e.g., that its formulation be clear and precise and its predictions unambiguous).

Besides, if Bohmian Mechanics had come first and paved the way, then PERHAPS the conversation would be reversed. No one gets much credit for being the second to discover something. At this point, it has been about 50 years and we still have nothing novel from this interpretation (BM that is) that I am aware of. But you never know, perhaps the big validation is right around the corner.

Several points here. First, in a very real sense, Bohmian Mechanics *did* come first. De Broglie discovered it before the full orthodox Copenhagen theory was worked out, but (unfortunately) abandoned the ideas in the face of tremendous negative peer pressure from the Copenhagen crowd. See

http://www.arxiv.org/abs/quant-ph/0609184

for an extremely eye-opening, book-length treatment. And by the way, this is quite important because it establishes rather clearly that it *was* philosophical bias which made the community reject the deterministic pilot-wave theory in favor of what emerged as orthodox QM. Which shows the preposterousness of the kind of argument I mentioned above (that one should just accept Copenhagen as a good scientific theory purely on the grounds that it "got its foot in the door", and then reject any alternatives on principle as just "mumbo jumbo motivated by philosophical bias" or whatever).

Second, it's not clear what you mean by "the big validation". Do you mean some experimental result which shows Bohm's theory to be true and Copenhagen to be false? That's not likely since they basically make the same predictions. Of course, you'll want to respond: aha, that just shows that Bohm's theory doesn't add anything new, and so shouldn't be considered. But you see, that's based on the unjustified taking of Copenhagen as somehow better merely because of the foot-in-the-door point. To whatever extent it's really true that Bohm and Copenhagen make identical predictions, there can be no valid argument that some experiment (or lack thereof) is a special problem for one of the theories and/or a reason for support of the other.

Third, you suggest that nothing useful or important has ever come of Bohm's version of quantum theory. But that's definitely wrong. "The most profound discovery of science" (Stapp's description of Bell's Theorem) was directly motivated by Bell's discovery (more than a decade after Bohm published his theory in 1952, and hence several decades after de Broglie had originally advocated the theory) that Bohm had "done the impossible" -- i.e., provided a direct explicit counterexample to von Neumann's so-called "proof" that one couldn't understand the quantum predictions as arising from a normal, causal, underlying physical process. You should actually read what Bell says and does, instead of accepting as gospel the misconceptions of people like Styer (who, remember, claimed that Bell's theorem actually *refutes* the possibility of a theory like Bohm's... quite a miconception since in fact it was Bell's stumbling onto the really-existing Bohm theory that led him to the famous theorem).

 

[JesseM]

Yup, Bohm was a loony in his later years. But, like you, I don't think this is relevant. My point wasn't to argue for Bohm by dissing Bohr with some kind of ad hominem. My point was just that any argument of the form "Copenhagen is great because it works, while Bohm just muddies and encumbers things with his pet philosophical bias" is invalid -- because it can trivially be turned around.

Do you have a response to my counterargument above, then? Again, "Copenhagen" in the logical-positivist sense and not the "wavefunction collapse is real" sense is basically just the shut-up-and-calculate interpretation, and as such you can't turn it around, because this "interpretation" makes no assumptions one way or another about the existence of any physical realities which can't be measured directly, while Bohm's interpretation does.

 

[Careful]

Several points here. First, in a very real sense, Bohmian Mechanics *did* come first. De Broglie discovered it before the full orthodox Copenhagen theory was worked out, but (unfortunately) abandoned the ideas in the face of tremendous negative peer pressure from the Copenhagen crowd.

True, de Broglies theory was even more complicated than Bohm's (actually you could say that Bohm did not do his homework of crosschecking the literature properly). But de Broglie remained in favor of locality for his entire life and would never have agreed with Bohm's opinions about nonlocality. In that context he remarked that accepting Bell's theorem as an absolute truth testified of a lack of imagination - something I deeply agree with.