I agree, there are many reasons why BM is not good.Demystifier said: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.
What's your most important one?martinbn said:
It fails in one of its main claims, to give a better explanation of observed phenemena than QM.Demystifier said:
How is your favored interpretation of QM not an "illusion", or depicting "observable" things?vanhees71 said:
Can you give an example where you analyze a phenomenon only in terms of observable things that are not "illusory"?vanhees71 said:
"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.martinbn said:
Are you using "philosophical" and "pseudo" as synonyms? Or are there philosophical problems (in physics) which are not pseudo-problems?vanhees71 said:
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.AndreasC said:
Demystifier said:All likers of BM are alike, each disliker of BM dislikes it in his own way.
The correct conclusion should have been that dislikers of BM are unhappy.martinbn said:
When they analyze it on computer, they use many unobservable ideas. Their analysis contains a lot of theoretical bias.vanhees71 said:
Better than what?martinbn said:
vanhees71 said:
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.weirdoguy said:
I think he meant better than shut up and calculate.gentzen said:
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 said:
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.gentzen said:
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.vanhees71 said:
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.Demystifier said:
Well, a big part of my choice of the minimal statistical interpretation, which is very similar to a flavor of Copenhagen, which neither assumes a collapse (which cannot occur for causality reasons and it's not needed at all to use the quantum formalism to compare what's predicted concerning physical observables and what's found when measured) nor a quantum-classical cut (for which there is not the slightest evidence; rather the classical behavior of macroscopic objects is well-understood as an effective description of coarse-grained macroscopically relevant observables), is Occam's razor.AndreasC said:
Hmm, I kind of object to that, because I don't think Occam's razor makes any kind of rigorous sense almost every time it is applied, and even when it does, there is no guarantee it's not misleading.vanhees71 said:
Ok but where's the problem? Don't calculate them if you don't want!vanhees71 said:
Right, that is a completely different and more valid argument, although @Demystifier disagrees that it matters. Maybe they are right, I don't know, haven't read the papers.vanhees71 said:
The issue I have with that is that I don't see how you can coherently partake in some kind of "fiction designation" and "fiction counting" in these theories. Also it's kind of weird because while arguing in favor of a specific interpretation, it feels like you are arguing against the very concept of the argument. I mean, if all that matters is the calculations you make, how can you possibly argue in favor of one or the other interpretation? You can make the same calculations with any of them.vanhees71 said:
He is a polite guy, this is why he doesn't directly tell anybody to shut up. But it seems to me that this is what he means.gentzen said:
The https://arxiv.org/abs/2205.05986 is really a light read, from a technical point of view. Just saying.AndreasC said:
This by itself is not really an objection however, because there are lots of other examples in physics where we calculate things that we don't need to calculate because we don't measure them. A classic example is the "force of gravity", taught to essentially every single physics major in the world. Not only don't we measure that, our best theory of gravity says it is actually impossible to measure it, but this does not prevent every first year physics course from going on about it! The reason is clear, it is regarded as a nice fiction, which means the term "fiction" cannot be categorically perjorative. The true skeptic regards all of physics as similarly a "nice fiction," and expects every single current physics law to be regarded as incorrect at some point in the future.vanhees71 said:
I would agree that we don't want our interpretations of some theory to impose limitations the theory itself does not impose. Still, even if it is true that BM cannot be made to interpret relativistic QM (a point that I believe @Demystifier has provided counterargument to, ironically in the spirit of saying that BM might not be able to match the "fictions" of relativity, like Poincare invariance, but can be made to match the observables), one could still correctly say that BM interprets nonrelativistic QM. It is perfectly all right to have an interpretation of a theory that has a domain of application, we do it all the time (e.g., the "force of gravity" again). The overarching point is, we should not take any of our theories so seriously that we think the "best" version is "the truth" that we are trying to interpret. (Again, the true skeptic sees the flaw in that thinking.)vanhees71 said:
But again, I would bring up "the force of gravity." Your statement here condemns the use of that notion categorically! I think it is perfectly fine to explain your own philosophical preferences, which is essentially what you are doing, and to recognize that those preferences have a context that is pragmatic for your purposes, but it is difficult to apply them as objective principles over all of science. How would you respond to the characterization of Poincare covariance, and Occam's Razor itself, as exactly the kind of "fiction" about which you object? You hold that a minimal interpretation is absent of any "religion," but is it not already a kind of religion of its own?vanhees71 said:
Of course, we need the "force of gravity" (in Newtonian mechanics) to calculate the motions of planets, stars, moons etc. E.g., you can derive Kepler's Laws from it. That's well observed (indeed Kepler figured them out by analyzing observations).Ken G said:
I don't know, how you come to this conclusion about gravitation or Poincare covariance. The letter is key to our most fundamental understanding of physics and thus for sure no superfluous metaphysical addition to our fundamental theories but to the contrary a key element of it. It's, of course, also based on precise observations of Nature.Ken G said:
We don't need it. We have other ways that never refer to it at all, even within Newtonian mechanics (like Hamiltonian or Lagrangian approaches). That's what I mean, the force of gravity is an unobservable fiction that doesn't exist in a minimalist interpretation of Newtonian mechanics, and never needs to be calculated, so why would you?vanhees71 said:
Poincare covariance is a property of the equations, nothing that can be observed. If @Demystifier is correct in his claim that the observations of relativistic quantum mechanics can be correctly predicted using forms of BM that do not obey Poincare covariance, then that is the extent to which your aversion to including elements in a theory that cannot be observed applies to Poincare covariance as well. You put it like, " as a natural scientist one should look at what's observed/observable." So this raises the questions, how does one observe Poincare covariance? How does one observe the force of gravity? If you are actually saying one does not have to observe something, but it is convenient to invoke it when one makes predictions that can be observed, then you are in the subjective realm of "what is convenient" and not in the objective realm of "what can be observed."vanhees71 said:
I added the edit (sorry I tend to do that, in hopes the answer isn't read immediately!) that I am talking about Hamiltonian or Lagrangian approaches. What I mean is, let's say Hamilton came along 100 years before Newton, and demonstrated his approach to calculating the motions of planets. Huge success, all of physics seems to now be deterministically accessible. Then Newton comes along and says, "hey you can understand all this if you invoke the existence of forces, including the force of gravity." Hamilton's followers accuse him of inventing philosophical fictions that can't be observed!vanhees71 said:
Well here my position is contingent on @Demystifier's claim that the observations of relativistic quantum mechanics can also be predicted correctly with a form of BM that is not Poincare covariant. I don't know if that is actually true or not, so my logic is if it is true, then BM must be regarded as a successful interpretation of relativistic quantum mechanics by your own reasoning, and if it is not true, then we must fall back to the position that BM is a successful interpretation of nonrelativistic quantum mechanics, like you are arguing that the force of gravity is a successful interpretation of Newtonian mechanics. At issue is, if interpretation X successfully interprets theory Y, and if theory Y passes all the same observational tests as theory Y', then interpretation X also successfully interprets theory Y'. If one adds the further requirement that interpretation X is not successful unless it is minimal, then the Newtonian force of gravity is not a successful interpretation of Newtonian mechanics because the Hamiltonian, or Lagrangian, or Einsteinian with untested c parameter, or Huygensian with untested h parameter, approaches have no such object in them as anything but an unnecessary add on, like Bohmian trajectories.vanhees71 said:
I would like to note that the so called "minimal" interpretation is not minimal at all:Ken G said:
It doesn't see like that to me.Demystifier said:
gentzen said:
So with respect to BM, the relevant question for me seems to be whether you or other Bohmians could have benefitted from his input. (I will try to "invent" such a possible scenario below, just for fun.)gentzen said:
My impression is that neither Ballentine nor Einstein would agree that the minimal statistical interpretation is a flavor of Copenhagen.vanhees71 said:
My impression is that you don't understand Bohr's position at all, and "accidentally" side with Heisenberg's position with respect to the cut. But from the perspective of the minimal statistical interpretation, only Bohr's position seems to be valid.vanhees71 said:
Maybe the situation is rather the opposite, and BM could actually benefit from input of skeptics like you. If you compute the complete evolution of the whole wavefunction anyway, then the trajectories of BM cannot really give you additional experimentally relevant information. But maybe there is another way to look at BM, where the trajectories are really helpful? What if you compute more than a single trajectory, and really sample from the ensemble of trajectories? The trajectories now tell you which part of the wavefunction you have to compute, and which parts you can ignore. Because now your predictions are really based on the trajectories alone, and no longer on a MWI-like wavefunction.vanhees71 said:
May be. I thought the key issue with the Copenhagen flavors is just to take the probabilistic meaning of the quantum state in addition to the other postulates, and that's common to all Copenhagen flavors. Then there are as many Copenhagen interpretations as there are early quantum physicists under sufficient influence of Bohr and Heisenberg...gentzen said:
What precisely IS Bohr's position? All I read by him is just some philosophical gibberish. There's no concrete math, and without this you can't clarify the meaning of the words. Where does he think this quantum-classical cut should be? How is this consolidated by experiment?gentzen said:
Bohr's position is that you have to describe your experiment before you can apply QM, and you have to describe your experiment (i.e. what you actually do in your laboratory) in terms of classical physics (edit: or rather classical concepts), because that is the description that can be communicated.vanhees71 said:
The following could perhaps clarify few things. N.P. Landsman in “Between classical and quantum”, chapter 3.2 “Object and apparatus: the Heisenberg cut” (https://arxiv.org/abs/quant-ph/0506082):vanhees71 said: