I QFT made Bohmian mechanics a non-starter: missed opportunities?

[Demystifier]

I've no problem with the field concept but only with the depiction as field lines. For me they are no more than the lines pointing in direction of the field to be depicted. How dense the field lines are depends on my choice of how dense I plot them to get an overview about how the field is directed. It's no clear measure for the field strength so.

I guess you are just not a visual type, for you visualizations of abstract ideas do more harm than good. If I'm right, you probably don't like all these pictures of spacetime in special and general relativity, because they are all misleading if taken too literally.

 

[vanhees71]

Minkowski diagrams and their relatives in GR are indeed more complicated than thought. Already for reading a Minkowski diagram you have to abandon your well-trained thinking in terms of the Euclidean plane and substitute it with the Minkowski pseudo-metric. E.g., you have to construct the right "tic marks" for the axes of inertial frames with hyperbolae. Sometimes such spacetime diagrams may give an intuitive picture about some things like the relativity of simultaneity etc. As you say, one should be very careful in taking them too literally.

 

[martinbn]

I guess you are just not a visual type, for you visualizations of abstract ideas do more harm than good. If I'm right, you probably don't like all these pictures of spacetime in special and general relativity, because they are all misleading if taken too literally.

That is a bad example. The spacetime diagrams are not fantasies or a thinking tool, they are an accurate discription of spacetime.

 

[Demystifier]

That is a bad example. The spacetime diagrams are not fantasies or a thinking tool, they are an accurate discription of spacetime.

I didn't say they are fantasies. I conjectured that @vanhees71 is not a visual type, and proposed a test of my conjecture. If my conjecture is true, he should dislike these diagrams even though they are not fantasies.

 

[martinbn]

I didn't say they are fantasies. I conjectured that @vanhees71 is not a visual type, and proposed a test of my conjecture. If my conjecture is true, he should dislike these diagrams even though they are not fantasies.

And how is this related to the thread?!

 

[Demystifier]

And how is this related to the thread?!

If he is not a visual type, while Bohmian interpretation is intuitive precisely because it's visual, it explains why he doesn't find the Bohmian interpretation intuitive.

 

[martinbn]

If he is not a visual type, while Bohmian interpretation is intuitive precisely because it's visual, it explains why he doesn't find the Bohmian interpretation intuitive.

No, it doesn't, that's why I said it was a bad example. I like space-time diagrams, and I find them intuitive and usefull. But I don't feel the same way about BM.

 

[Demystifier]

No, it doesn't, that's why I said it was a bad example. I like space-time diagrams, and I find them intuitive and usefull. But I don't feel the same way about BM.

I think you dislike BM for different reasons than him. All likers of BM are alike, each disliker of BM dislikes it in his own way.

 

[vanhees71]

Spacetime diagrams, when properly read, provide a picture of observable things ("events"). Bohmian trajectories are illusions. They are not depicting anything observable and may lead to false intuitions.

 

[Demystifier]

Bohmian trajectories ... may lead to false intuitions.

Of course they can. But any intuitive idea may lead to false intuitions, if you don't understand it properly.

 

[martinbn]

I think you dislike BM for different reasons than him. All likers of BM are alike, each disliker of BM dislikes it in his own way.

I agree, there are many reasons why BM is not good.

 

[Demystifier]

I agree, there are many reasons why BM is not good.

What's your most important one?

 

[martinbn]

What's your most important one?

It fails in one of its main claims, to give a better explanation of observed phenemena than QM.

 

[AndreasC]

Spacetime diagrams, when properly read, provide a picture of observable things ("events"). Bohmian trajectories are illusions. They are not depicting anything observable and may lead to false intuitions.

How is your favored interpretation of QM not an "illusion", or depicting "observable" things?

 

[vanhees71]

My favored interpretation is the minimal statistical interpretation, and it describes just the observable things and doesn't invent some unobservable, unnecessary elements just to solve some philosophical pseudo-problems like trajectories in BM.

 

[Ken G]

I think it should be pointed out that there are (at least) three different arenas in which one can discuss the value, or lack thereof, of interpretations of physical theories. These separate arenas present yet more ways for people discussing interpretations to talk past each other:
1) an interpretation as a guide to correctly applying the theory
2) an interpretation as a means of getting a subjective sense of "what is really happening"
3) an interpretation as a way to see potential incompletenesses that could point to the next theory

For example, if one is looking only at (1), and has no trouble applying the theory with only minimal interpretation, then they see no value in any but a minimal interpretation, obviously. But that does not address (2) or (3). Of course, such a person may have no need for (2), that might not be what proffers the fascination of physics to them. They might also be skeptical of (3), though Einstein himself provided several spectacular examples of making progress in science via this direction (as well as one equally famous failure to do so.) So arena (1) relates to issues like how visual vs. abstract is one's thinking, (2) relates to the subjective and philosophical reasons that various different people do science, and (3) relates to how closely one thinks science needs to be, or at least can be, connected to philosophy. So any discussion about which interpretation is "better" really must start with addressing these much deeper issues, or it will just be people talking past each other.

 

[AndreasC]

My favored interpretation is the minimal statistical interpretation, and it describes just the observable things and doesn't invent some unobservable, unnecessary elements just to solve some philosophical pseudo-problems like trajectories in BM.

Can you give an example where you analyze a phenomenon only in terms of observable things that are not "illusory"?

 

[Demystifier]

It fails in one of its main claims, to give a better explanation of observed phenemena than QM.

"Better" is a subjective notion, and in this case totally vague because you don't present any explanation why do you think so. One could write exactly the same sentence for any other interpretation of QM, and nobody would have any clue why one thinks so. I'm sure you can do better than this.

 

[Demystifier]

philosophical pseudo-problems

Are you using "philosophical" and "pseudo" as synonyms? Or are there philosophical problems (in physics) which are not pseudo-problems?

 

[vanhees71]

Can you give an example where you analyze a phenomenon only in terms of observable things that are not "illusory"?

I don't do this, but my experimental colleagues. They build the LHC and detectors, where they register particles using various types of detectors and store the result to analyze it later on the computer. These are the observations to be described by our theories. On the most fundamental level it's the Standard Model of elementary particles, which is despite being challenged for a long time with all these experiments, still found to be always valid. In my special field, relativistic heavy-ion collisions, the theoretical tools are derived from this fundamental level in various ways: equilibrium and non-equilibrium relativistic many-body theory (Kadanoff-Baym equations), quantum-transport theory and corresponding numerical simulations, relativsitic hydrodynamics derived from it and corresponding numerical simulations, lattice QCD at finite temperature and baryo-chemical potential... All these theoretical tools use the minimal interpretation of Q(F)T. There's no need for extra philosophical quibbles. The purely physical problem is hard enough to tackle without superfluous additions.

 

[Demystifier]

All likers of BM are alike, each disliker of BM dislikes it in his own way.

I agree, there are many reasons why BM is not good.

The correct conclusion should have been that dislikers of BM are unhappy.

Which in fact is not far from truth. At this forum, dislikers of BM seem quite frustrated by the fact that some people feel happy by having BM as their way of thinking.

“If we cannot disprove Bohm, then we must agree to ignore him.”
- Oppenheimer

 

[Demystifier]

I don't do this, but my experimental colleagues. They build the LHC and detectors, where they register particles using various types of detectors and store the result to analyze it later on the computer.

When they analyze it on computer, they use many unobservable ideas. Their analysis contains a lot of theoretical bias.

 

[gentzen]

It fails in one of its main claims, to give a better explanation of observed phenemena than QM.

Better than what?

• Better than Ballentine's statistical interpretation, which is also the interpretation favored by vanhees71? (The one which is most easily applied to repeatable experiments, but which can cause disagreement when it comes to applying it to non-repeatable scenarios, like to actual measurements of sufficiently complex samples, and especially to cosmology and the universe as a whole.)
• Better than the "literal" variant of Copenhagen presented in some of Mermin's papers? (Papers like In praise of measurement (2006) or Copenhagen Computation: How I Learned to Stop Worrying and Love Bohr (2003) that advocate that a literal "discontinuous collapse" interpretation of measurement works perfectly fine in quantum computer science.)
• Better than the "moderately" epistemic variant of Copenhagen that Rudolph Peierls explained in his 1991 paper In defense of "measurement"? Or better than the "radically" epistemic QBism?
• Better than [... please insert some no-nonsense interpretation that you actually have in mind here...]?

 

[weirdoguy]

My favored interpretation is the minimal statistical interpretation, and it describes just the observable things and doesn't invent some unobservable, unnecessary elements just to solve some philosophical pseudo-problems like trajectories in BM.

The thing I don't understand is why are you wasting so much time actively participating in lengthy discussions about philosophical pseudo-problems. I would assume that you at least does not consider them as philosophical pseudo-problems.

 

[Demystifier]

The thing I don't understand is why are you wasting so much time actively participating in lengthy discussions about philosophical pseudo-problems.

He would like to stop it, but he can't, it's stronger than his rational will, because he's a philosopher in his heart.

 

[Demystifier]

Better than what?

I think he meant better than shut up and calculate.

 

[gentzen]

I think he meant better than shut up and calculate.

Oh, good point, I didn't expect this. I guess I could even agree to the "calculate" part. I don't like the "shut up" part, but vanhees71 doesn't subscribe to that part anyway. Let him calculate and explain the interesting part of the physics, i.e. the non-pseudo stuff. As for martinbn, well, he can speak for himself.

 

[Demystifier]

I don't like the "shut up" part, but vanhees71 doesn't subscribe to that part anyway.

There are two kinds of shut up and calculate guys. Those who shut up and calculate, and those who tell others to shut up and calculate.

 

[AndreasC]

I don't do this, but my experimental colleagues. They build the LHC and detectors, where they register particles using various types of detectors and store the result to analyze it later on the computer. These are the observations to be described by our theories. On the most fundamental level it's the Standard Model of elementary particles, which is despite being challenged for a long time with all these experiments, still found to be always valid. In my special field, relativistic heavy-ion collisions, the theoretical tools are derived from this fundamental level in various ways: equilibrium and non-equilibrium relativistic many-body theory (Kadanoff-Baym equations), quantum-transport theory and corresponding numerical simulations, relativsitic hydrodynamics derived from it and corresponding numerical simulations, lattice QCD at finite temperature and baryo-chemical potential... All these theoretical tools use the minimal interpretation of Q(F)T. There's no need for extra philosophical quibbles. The purely physical problem is hard enough to tackle without superfluous additions.

But I don't really see how any of that speaks to the power of one interpretation or the other. I don't really see what you mean by saying that these theoretical tools "use" one interpretation or the other. Supposing the interpretations are all observationally equivalent, then at that level you would be working with the same equations. Theoretically, you could have started from the Bohmian picture or whatever other interpretation you may think of, derived the same things, and then claim you don't need to tackle with the superfluous quibbles of the MS interpretation. At the end of the day, as you said, at the LHC they receive data that they analyze with computers. At that level, all of the entities in any interpretation, including your preferred one, are intermediate "fictions" to explain the results. They don't somehow make direct observations of particles etc, there is a huge theoretical structure at play to even produce these "observations", and that includes a ton of what you call "fictions". So I don't think saying a theory has an "unobservable" element is a strong enough argument on its own.

In general I think it's usually a little bit suspect when some idea is called "minimal", or "simplest possible" and thus supposedly better. It reminds me of how dubiously Occam's razor is always invoked.

 

[gentzen]

There are two kinds of shut up and calculate guys. Those who shut up and calculate, and those who tell others to shut up and calculate.

But vanhees71 is neither of those "shut up" guys. Neither does he shut up himself, nor does he tell you or me to shut up. He openly admits that he doesn't like BM, but that is different from telling somebody to shut up.