I What is the current perspective on quantum interpretation?

[Zaitsev Maxim]

But even if even without registering it it still changes for some reason, then it's still not the end. Before you say, that it's Only looking that's affecting your results, you should be sure it's not measurement in itself in any form. You've made it so that it doesn't influence it in any form, but maybe you've just forgot to exclude inquiring information in itself as a possibility.
It may change depending on what type and how much of information you ask from it, so that if you ask one information, it loses another. (Or if it has one property, it loses another.) If you try to make very imprecise tool, which can ask its position in such a way that in the process of inquiring this position this thing Never needs to have position with more than some precision (the larger the better), then it may not lose this another property fully. (Again) So far (I think) you've just asked it very very precisely, so it should have it very very precisely, but if you ask it imprecisely, then it may change something. The less information you ask the better, because anyway you will see the end result.

 

[Zaitsev Maxim]

A little more (not very useful, if you understood already). Again from Beyond Weird book.

At the end of the book is written, that we should say:
" Not
‘here it is a particle, there it is a wave’
but
‘if we measure things like this, the quantum object behaves in a manner we associate with particles; but if we measure it like that, it behaves as if it’s a wave’
Not
‘the particle is in two states at once’
but
‘if we measure it, we will detect this state with probability X, and that state with probability Y’ "
That's right thing to say.

And also written:
"knowledge we possesses affects what is knowable"
That's baseless.
If you claim it only depending on one example, "looking at position", then it's really baseless. And you can never truly claim that something other that quantum object may behave like this - you can only create theory without proof and think "It Might be so", until you have another examples or something better.

 

[vanhees71]

I'd not say ‘if we measure things like this, the quantum object behaves in a manner we associate with particles; but if we measure it like that, it behaves as if it’s a wave’. I'd rather say with "new quantum theory" (discovered by Born, Jordan, Heisenberg; Schrödinger; Dirac in 1925/26), overcomes the intrinsically contradictory idea of "wave-particle dualism". There is no such thing. All there is are probabilities for the outcome of measurements given the state of the system.

That's indeed what the book seems to say too:
‘if we measure it, we will detect this state with probability X, and that state with probability Y’
That's right thing to say.

It's indeed nonsense to say that if a system is in the superposition of two (or more) states (correct is that it is in a pure state $|\psi \rangle \langle \psi|$ where $|\psi \rangle=\sum_n \psi_n |u_n \rangle$ with $|u_n \rangle$ a complete orthonormal set), it is in all these states at once. Each ket defines simply a possible pure state of the system, namely $|\psi \rangle \langle \psi|$.

I don't understand what "knowledge we possesses affects what is knowable". What does this refer to?

 

[romsofia]

I like any model that invokes some gravitational interaction i.e GRW, or Penrose's interpretation. It's actually where I got my icon from, a paper of his called "Gravity and state vector reduction" (By Roger Penrose) where Bohr, Wigner, Everett, and Von Neumann are all trying to hold $\psi$ from collapsing.

I also like the idea from "Continuous state reduction" put forth by Tony Sudbery, but I haven't really kept up with the emerging ideologies that have been put forth (outside of Bryce DeWitt's work where he LOVES to sprinkle in his admiration for MWI haha)

 

[Sunil]

All this was possible, because Bell had the ingenious insight how to make the philosophical vagueness of EPR, Bohr, et al a clear scientific question addressable by experiment.

And all this was possible only because EPR, Bohr etc. have tried to interpret quantum theory in a way you reject as "philosophical vagueness" and Bohm has developed some interpretation which is, AFAIU your position, not useful at all because it makes no different predictions.

 

[vanhees71]

That's the point. Bohm brought the philosophical vagueness of this paper to a scientific level, i.e., made it testable by measurement. The result is that Nature rather behaves as predicted by quantum theory (with an amazing significance and accuracy) and not like what some philosophically inspired physicists thought it should behave. Case closed. We can move on after 85 years now!

 

[Demystifier]

Bohm brought the philosophical vagueness of this paper to a scientific level, i.e., made it testable by measurement.

You meant Bell. But the point is, if there were no philosophers results before Bell, there would be no Bell's results. So philosophers results are useful for science.

Philosophy is one of inspirations for science. Many of the deepest results in science would probably never happen if there was no philosophical inspiration.

Saying that science does not need philosophy is like saying that future scientists do not need child play or SF literature.

 

[vanhees71]

Of course Bell... I think indeed child play, literature (including but not only SF) is indeed much more impotant as inspiration than philosophy, which rather leads to confusion of the mind ;-)).

 

[Sunil]

Of course Bell... I think indeed child play, literature (including but not only SF) is indeed much more impotant as inspiration than philosophy, which rather leads to confusion of the mind ;-)).

Is this a comment about string theory?

 

[Demystifier]

Of course Bell... I think indeed child play, literature (including but not only SF) is indeed much more impotant as inspiration than philosophy, which rather leads to confusion of the mind ;-)).

Philosophy can indeed be confusing, but so can science. And that's not necessarily bad, confusion can produce inspiration. Anyway, if philosophy confuses you, then why do you spend so much time on this subforum on doing philosophy?

 

[Fra]

Philosophy is one of inspirations for science. Many of the deepest results in science would probably never happen if there was no philosophical inspiration.

I think it also helps to distinguish between formal philosophy in some general sense (which usually does not interest me at least) and the philosophy of science, knowledge and nature. If one claims that is irrelevant to science itself, that must be one of the most mysterious forms of denial.

The historial roots of philosophy and science are the same, some roots of philosophy of knowledge are also common to sine foundations of mathematics such as probability theory, resulting from the philosophical insight that one needs a quantiative measure of degree of belief. So even mathematics and logic rests on philosophical foundations.

/Fredrik

 

[physicsworks]

I also don't think that "my interpretation" of QT is much different from Ballentine's.

I also don't like to say, "quantum theory is nonlocal", because it can be misleading.

I completely agree. An amusing fact about Ballentine's book (at least the lastest edition and printing that I have) is that in its Index the item "Nonlocality" is listed as:

Nonlocality (see Locality)

 

[bhobba]

I completely agree. An amusing fact about Ballentine's book (at least the lastest edition and printing that I have) is that in its Index the item "Nonlocality" is listed as:

An interesting thing about Ballentine is he thinks decoherence has nothing to do with QM interpretation:
https://core.ac.uk/download/pdf/81824935.pdf.

Formally I hold to the ensemble interpretation but include decoherence. I think these days, many do not believe (but not all) decoherence solves the measurement problem except in the sense of FAPP (For All Practical Purposes).

Thanks
Bill

 

[physicsworks]

An interesting thing about Ballentine is he thinks decoherence has nothing to do with QM interpretation:
https://core.ac.uk/download/pdf/81824935.pdf.

Thanks, that's interesting, I haven't read this one yet.

Formally I hold to the ensemble interpretation but include decoherence.

Yes, but also Tom Banks's arguments on locality and the classical limit of QM are very important and are often overlooked.

 

[bhobba]

Yes, but also Tom Banks's arguments on locality and the classical limit of QM are very important and are often overlooked.

My views on quantum locality have recently changed a bit. Before, it concentrated on the cluster decomposition property of QFT. To make sense, it must preclude correlation. Also, normal QM is based on the Galeain Transformation so locality is not an issue - it assumes non-locality. The issue lies with relativistic QM. Now I think it is centred on the fact QM is a generalised probability theory and the difference between Parameter independence and Outcome independence:
https://plato.stanford.edu/entries/qm-action-distance/

See section 3.

Thanks
Bill