Undergrad On the relation between physics and philosophy

[Lord Jestocost]

..... are the weak points of QM.

What are the weak points of QM?

 

[Elias1960]

What are the weak points of QM?

Depends on the interpretation. For most interpretations, the measurement problem. The quite general problem of incompatibility with common sense. For some interpretations, the classical limit is a problem too. For others, Schrödinger's cat is problematic. Then, incompatibility of many things with relativistic principles. Here one can blame relativity instead, but most prefer to blame quantum theory.

 

[Lord Jestocost]

Depends on the interpretation.

Then the "interpretations" have weak points, don't blame QM!

 

[PeterDonis]

If it would need a preferred frame, it would be rejected as Lorentz ether crackpot nonsense.

Go search arxiv.org for papers that use the term "preferred frame". You will find plenty that have been published. "Preferred frame" and "Lorentz ether theory" are not the same thing. The latter is what is off limits for discussion here.

The point is that such a theory can be constructed in a quite simple way.

First, destroy relativistic symmetry. Add some term to the Lagrangian which destroys covariance and prefers some coordinates. Then you already have a GR variant as a field theory on R4\mathbb{R}^4. GR in harmonic gauge would be the most plausible candidate.

Then, use a lattice regularization. With a small enough lattice distance on a big enough cube this will not lead to any problem with GR in our observable universe. Don't care about renormalization, use the lattice regularization as a theory itself. It is a well-defined theory with a finite number of degrees of freedom.

Then use canonical quantization to quantize it. The result is a well-defined theory of quantum gravity compatible with all existing empirical evidence. Which is anathema because it destroys, by construction, relativistic symmetry. No chance to publish it.

Have you tried to publish such a theory? Can you point us to a preprint on arxiv.org of a paper describing such a theory that was submitted for publication and rejected?

Either give us some evidence to back up your claims or stop making them.

 

[Elias1960]

Go search arxiv.org for papers that use the term "preferred frame". You will find plenty that have been published. "Preferred frame" and "Lorentz ether theory" are not the same thing. The latter is what is off limits for discussion here.

Ok, add "and a condensed matter interpretation of the fields":

If it would need a preferred frame and a condensed matter interpretation of the fields, it would be rejected as Lorentz ether crackpot nonsense.

Have you tried to publish such a theory? Can you point us to a preprint on arxiv.org of a paper describing such a theory that was submitted for publication and rejected?
Either give us some evidence to back up your claims or stop making them.

Once you ask for evidence that such a paper would be rejected, here is a reference to a publication of such a thing in a no-name journal. I would guess to discuss the paper itself would be forbidden here, because the journal is dubious, therefore the spoiler and the clarification that this is given only to give evidence for my claim that such a theory would be rejected by established journals.

Spoiler: Link to anathema

http://medcraveonline.com/PAIJ/PAIJ-01-00029.pdf

The author usually publishes his papers on arxiv.org, but this paper is not on arxiv.org. Maybe it was rejected by arxiv.org too?

 

[PeterDonis]

I would guess to discuss the paper itself would be forbidden here

Not because of its general subject matter, but because the views of its author (Ilja Schmelzer) are already well known here and have been discussed ad nauseam, and at this point nobody wants to rehash them again.

Do you have any other examples?

 

[Elias1960]

Not because of its general subject matter, but because the views of its author (Ilja Schmelzer) are already well known here and have been discussed ad nauseam, and at this point nobody wants to rehash them again.

Where?

Do you have any other examples?

Do you think one example is not enough to clarify that this particular type of theory is anathema? Punish one, teach a hundred. Physicists are not stupid, and they know that they have to look for new grants in near future.

 

[PeterDonis]

Where?

Try the forum search feature.

Do you think one example is not enough to clarify that this particular type of theory is anathema?

I have said nothing whatever about one example being enough. I have simply asked you if you have more examples. Are you going to answer a straightforward question, or are you going to continue quibbling and get yourself a warning and a thread ban?

 

[Elias1960]

I have no other example, I thought one is completely sufficient to justify my remarks above, and I will leave this thread. Happy New Year.

 

[PeterDonis]

I thought one is completely sufficient to justify my remarks above

Whether it is sufficient to justify your general claim about certain kinds of research being suppressed is not for me to say; readers can judge for themselves. Though I would note that the one researcher you refer to has had his work published in peer-reviewed journals, as a simple perusal of his web page will show you. Also see further comments below.

However, you also made a claim about discussion of that specific researcher's work being forbidden here. That claim is clearly not justified, as a simple forum search will show you. We have discussed it and reached the point where further discussion is not going to be worthwhile.

Physicists are not stupid, and they know that they have to look for new grants in near future.

The physicist whose paper you linked to describes himself as an "Independent Researcher". So wherever he is getting his support, it does not appear to be from government grants. Yet he is doing research. Other physicists, such as those at the Perimeter Institute, also are doing research independently of government grants.

 

[Julius Ceasar]

It seems that there are two mainstream QMs:

1. The QM working in the practice of the people who need it to understand very practical things, such as semiconductor properties or chemical behavior.

2. The QM as it seen by people driven by some ambition to interpret it better.

Nothing wrong with trying to interpret anything better, You may build a bridge that crosses the knowledge river but there may be a better bridge that someone can build, better may mean stronger, cheaper, simpler, a tunnel under or learn to fly and no bridge at all. The question here is does philosophy play a role crossing this river at all?
I would say it does and if you're only interested in the practical uses that's fine, we'll take it from here.

 

[Elias1960]

Try the forum search feature.

Sorry for disturbing this thread again, but using this search feature I was unable to identify any thread where the theories of Schmelzer have been "discussed ad nauseam".

I have found a lot of posts mentioning Schmelzer without any further discussion

Spoiler: Links to posts mentioning Schmelzer without discussion followed

https://www.physicsforums.com/threads/dbb-and-non-locality.429936/page-7#post-2930098
https://www.physicsforums.com/threa...sics-area-laws-lqg.376399/page-5#post-4438703
https://www.physicsforums.com/threa...-violate-causality.906974/page-2#post-5734150
https://www.physicsforums.com/threads/free-will-in-quantum-theory.979364/post-6253506
https://www.physicsforums.com/threa...-bohmian-mechanics.913098/page-5#post-5774386
https://www.physicsforums.com/threads/wheeler-dewitt-and-timelessness.779866/post-4903417
https://www.physicsforums.com/threa...tion-for-instrumentalists.982171/post-6277926
https://www.physicsforums.com/threads/let-us-assume-feynman-was-wrong.303838/page-3#post-2149545
https://www.physicsforums.com/threads/second-quantization-vs-many-particle-qm.835472/post-5298662
https://www.physicsforums.com/threads/is-string-theory-worthwhile.699898/page-2#post-4437880
https://www.physicsforums.com/threads/free-will-in-quantum-theory.979364/post-6254206
https://www.physicsforums.com/threads/can-grandpa-understand-the-bells-theorem.488690/post-3270918
https://www.physicsforums.com/threa...s-of-brownian-like-motion.563390/post-3690842
https://www.physicsforums.com/threads/einstein-and-the-ether.503290/#post-3336502
https://www.physicsforums.com/threads/the-refutation-of-bohmian-mechanics.490095/page-2#post-3269901
https://www.physicsforums.com/threads/challenge-to-dbb.476982/page-2#post-3177769
https://www.physicsforums.com/threa...terpretation-of-qm.308825/page-2#post-2180927
https://www.physicsforums.com/threads/ohan-prins-of-the-university-of-pretoria.114246/#post-938236
https://www.physicsforums.com/threads/general-lorentzian-relativity.495439/#post-3281040

Then, I have found a welcome thread with 22 entries from 2004
https://www.physicsforums.com/threads/welcome-to-ilja-schmelzer.14258/
and a single thread
https://www.physicsforums.com/threads/generalization-of-lorentz-ether.867072/ with 50 entries from 2016. In this thread I counted 16 post with simple questions and answers about the content of Schmelzer's theories, and the remaining discussion about if it is appropriate to discuss the theory in BTSM or not, to name it ether theory or not, where to publish it, and the history of atomic theory.

Maybe I have not found some essential threads? Or maybe some of those threads have been deleted for some inappropriate content? (Schmelzer himself, AFAIU, has been banned, given that user "Ilja" is crossed out.) Or was this IMHO short thread already sufficient for your classification as "discussed ad nauseam, and at this point nobody wants to rehash them again"?

 

[DennisN]

Isn't Rovelli a supporter of shut up and calculate?

I don't know where he stands now, but he was the one who came up with the idea of the Relational quantum mechanics interpretation.

 

[EPR]

Not having a personal philosophy is philosophy.

 

[Julius Ceasar]

Why did the scientist cross the road?
A. To measure the road.
Why did the philosopher cross the road?
A. To find out if there was another side for the scientist to measure.

 

[PeterDonis]

Maybe I have not found some essential threads?

Quite possibly not, since many of them are from many years ago.

In any case, if you absolutely insist on trying to discuss one of his papers again, start a new thread with a specific reference to a specific paper and a specific question arising from it. Then you can run the experiment and see how much discussion you get. Further discussion of his work is off topic for this thread.

 

[vanhees71]

Depends on the interpretation. For most interpretations, the measurement problem. The quite general problem of incompatibility with common sense. For some interpretations, the classical limit is a problem too. For others, Schrödinger's cat is problematic. Then, incompatibility of many things with relativistic principles. Here one can blame relativity instead, but most prefer to blame quantum theory.

"Interpretational problems" are not physical problems. The least what you call "common sense" is relevant for science. The natural sciences deal with objectively observable facts about nature, using quantitative precise measurements to investigate nature and describe it with quantitative mathematical models. Everything else is not within the realm of the natural sciences.

The relativistic spacetime description is among the most successful mathematical models ever. There's nothing to blame about. The most successful single theory in the history of science is the Standard Model of elementary particle physics, which is based on a consistent description of matter using relativistic quantum field theory. What's not yet found is a consistent quantum theoretical description of the gravitational interaction. The problem is that there are no phenomena pointing in the direction of possible solutions of this problem.

Schrödinger's cat is not problematic at all. To the contrary all stringent tests about it (in scientific terms it's about entanglement) have confirmed the predictions of QT to an amazing degree of significance.

 

[A. Neumaier]

The Standard Model of elementary particle physics, which is based on a consistent description of matter using relativistic quantum field theory.

It is not yet known whether the standard model has a mathematically consistent description. This is not even known for QED.

 

[vanhees71]

I talked about the SM as a physical theory, and there it's very successful and also mathematically sound in the sense of renormalized perturbation theory. Maybe the lack of a consistent math for a fully self-consistent interacting QFT is also a hint at how to find a more comprehensive formulation, though all attempts for the last 70 years or so failed so far :-(.

 

[Elias1960]

It is not yet known whether the standard model has a mathematically consistent description. This is not even known for QED.

I disagree. A lattice regularization defines a mathematically consistent description. You may argue that it does not have the symmetries you like, or even that it does not give in the continuous limit the theory one wants, say, because of something like a fermion doubling problem or so. But this does not change the point that lattice theories are, quite general and for quite arbitrary parameters, well-defined, consistent theories.

The field-theoretic limit is, of course, (expected by me to be) ill-defined.

 

[A. Neumaier]

A lattice regularization defines a mathematically consistent description.

... but of an approximation to the standard model only, not to the standard model as defined in the textbooks.

 

[A. Neumaier]

I talked about the SM as a physical theory, and there it's very successful and also mathematically sound in the sense of renormalized perturbation theory. Maybe the lack of a consistent math for a fully self-consistent interacting QFT is also a hint at how to find a more comprehensive formulation, though all attempts for the last 70 years or so failed so far :-(.

Well, consistency means logically consistency, and this includes mathematical consistency.

At present, the standard model is not a fully consistent scheme but a large collection of very successful theroretical and computational recipes related to ill-defined foundations by means of ill-defined approximations.

I believe that the mathematical obstacles that so far prevented finding a consistent formulation of QED are also the obstacles that prevent finding the correct unification with gravity.

 

[Demystifier]

Then the "interpretations" have weak points, don't blame QM!

The weak point of QM is that it does not contain its own interpretation.

 

[vanhees71]

Which physical theory contains its own interpretation? It's not clear to me, what you mean by this.

 

[Elias1960]

... but of an approximation to the standard model only, not to the standard model as defined in the textbooks.

If on follows Wilson, so what? Field theories are large distance approximations of unknown low distance theories, and using a lattice theory as a straightforward example for such a low distance theory is not worse than presenting nothing at all for the limit of very small distances.

If we look for logical consistency of QFT as an effective field theory, one toy construction of a more fundamental theory so that both can be evaluated for consistency (the lattice theory as a theory itself, the field theory as its consistent large distance approximation) is sufficient.

For the textbooks, it would be also much better to teach, first, a model known to be consistent and easy to understand - as a field theory which approximates a lattice theory, similar to condensed matter theory approximating atomic theory would be, and together with a quite universal way to compute something - and then, if necessary or useful, to criticize for whatever reasons this approach and to argue why one wants more, namely a field theory working for all distances or so, or some numerically better even if conceptually dubious approximation schemes like dimensional regularization.

 

[Elias1960]

The weak point of QM is that it does not contain its own interpretation.

I would reformulate it in the following way: There is no straightforward interpretation of QT where it is a fundamental theory of everything.

The Copenhagen interpretation is quite natural - a statistical scheme of predicting things in a domain where we simply cannot see what really happens. One has to get rid of its fundamentalist claims, namely that it is complete, in the sense that there is no more fundamental theory which describes more. (Maybe one has really misinterpreted Bohr, and he has in fact meant with "completeness" something weaker, namely internal consistency.) In this case, Copenhagen becomes simply an interpretation where we have restricted abilities to prepare states and therefore can prepare only states where we can make only statistical predictions.

And there is the "classical part" where we can access information which quantum theory does not give (like if Schrödinger's cat is dead or alive). So, this interpretation contains parts which show that QM is not complete, thus, cannot be the fundamental theory.

 

[atyy]

Ok, add "and a condensed matter interpretation of the fields":

But some attempts are published in rather mainstream fora.
https://arxiv.org/abs/cond-mat/0407140
https://arxiv.org/abs/1106.4501 (see section 9 for speculation on how some parts of string theory could come out of "emergent relativity")

Of course there are some attempts that are not yet published in any peer-reviewed place: https://arxiv.org/abs/1809.11171

But overall one can't say that this is a forbidden line of work, when it is quite mainstream.

 

[Demystifier]

Which physical theory contains its own interpretation? It's not clear to me, what you mean by this.

By interpretation, I mean claims on ontology (or on the lack thereof). Classical mechanics, for instance, has a clear ontology in the sense that particles have positions at any time, irrespective of their measurement. Relativity theory (in the Minkowski formulation) has an explicit claim on the lack of ontology, in the sense that space and time do not exist separately unless they are measured.

 

[vanhees71]

The natural sciences don't give any ontology at all. They aim at a most accurate description of the observable objective facts about nature. No more no less. I don't see, why the mathematical abstract concepts of Newtonian mechanics should provide "more ontology" than that used in relativistic physics or even quantum theory. Math has been found to be the (so far only) adequate description of what's objectively observable in nature, no more no less!

 

[Lord Jestocost]

And there is the "classical part" where we can access information which quantum theory does not give...

What the heck are now "classical parts"?
All informations which are relevant for your subjective experience are given by quantum theory! Knowledge you might lack it is simply not there to be known.