QM: Interesting View - Get the Inside Scoop

[bhobba]

I recently came across the following lecture on what QM is:


I was shocked by how close it is to my view. What do others think?

Thanks
Bill

 

[physicsworks]

Idk, already the first slide (3rd minute of the video) threw me off. There he is reincarnating the wave-particle duality business and is very sloppily introducing Heisenberg uncertainty principle with the phrase "you can't simultaneously know exactly two properties of a quantum object". Immediately after he tops it off with "quantum objects can affect each other instantly over huge distances, this is so-called spooky action at a distance". Could not continue watching past that point. Maybe it gets better later though.

 

[.Scott]

His thoughts matched mine up to about the 29-minute mark.
But I am willing to entertain more "radical" resolutions to the Bell Inequality.

 

[bob012345]

Idk, already the first slide (3rd minute of the video) threw me off. There he is reincarnating the wave-particle duality business and is very sloppily introducing Heisenberg uncertainty principle with the phrase "you can't simultaneously know exactly two properties of a quantum object". Immediately after he tops it off with "quantum objects can affect each other instantly over huge distances, this is so-called spooky action at a distance". Could not continue watching past that point. Maybe it gets better later though.

But at 4:13 he then says;

Quantum Mechanics says none of these things...

 

[physicsworks]

@bob012345: oh, I see, so he was overdramatizing… well, then I will give it another try, thanks!

 

[bhobba]

Thanks for the comments. To be sure, like all interpretations or 'views', there is no 'correct' answer. They are ideas that, by discussing them, deepen one's understanding of the formalism everyone agrees on.

Thanks
Bill

 

[EPR]

He is labeling QM weird. I am going to go with Niels Bohr and say this speaker probably hasn't understood QM yet. The way he uses language and terms seems like he is somewhat surprised, not shocked.
Whereas, I would probably be screaming "We haven't been able to find anything to call 'fundamental' and on which to build our theories what this world is". So we have math at the bottom. And then suddenly chairs and tables. And almost nothing in between the math and tables and airplanes and stars and galaxies. This I find it not weird. I find it impossible to reconcile with what I classically observe as definite particles every day. I find it shocking, not weird. What is weird is choice of words. If there are trillions of universes created every second to account for this explanatory deficiency, it's also not weird. It's shocking. It's shocking that my brain with all its mental states can potentially be cloned in some other Universe preserving all of its internal structures and memories with no glitch...
I would use 'weird' in a conversation about the color of the neighbor's car or his clothes. The speaker's choice of words show lack of depth or a deliberate desire to keep things simple for the ignorant audience. The biggest issue I see with QM is that there is no recognizable fundamental stuff that everything else is made of in this apparently material world.

 

[bhobba]

I am going to go with Niels Bohr and say this speaker probably hasn't understood QM yet.

That is a lecture at the Royal Institute in the tradition of people like Faraday. You can take it as a given they know what they are talking about. You may disagree, which is fine, but their view is not based on limited understanding.

Thanks
Bill

 

[DennisN]

I recently came across the following lecture on what QM is (...) What do others think?

I've seen it and I liked it.
I've seen a number of lectures from the Royal Institution, e.g. one on Quantum Fields here: Quantum Fields - The Real Building Blocks of the Universe (and a Q&A here too). It's been a while since I saw those though, so I don't remember how well I liked it.

 

[vanhees71]

I just started to watch it. Indeed, Ball is right: There's physics and mathematics, which enables us to build an Apple notebook and there is "interpretation", which is confusing the clear and beautiful physics in mathematics, and which cannot be used for anything else than selling popular-science books about the weirdness of QT. So it's in fact not quantum theory that is weird but "interpretation", and here obviously "interpretation" means the metaphysics beyond the minimal interpretation, which latter gives the relation of the mathematical formalism to real-world objectively observable facts, while everything beyond it is metaphysics or even religion of individual physicists applying quantum theory.

 

[EPR]

That is a lecture at the Royal Institute in the tradition of people like Faraday. You can take it as a given they know what they are talking about. You may disagree, which is fine, but their view is not based on limited understanding.

Thanks
Bill

For the general audience, it's okay. I watched it and didn't learn anything new. I signed up here to learns new things. Progress will not be done or associated with the old thinking.
I guess you agree with him. It is fine.

 

[EPR]

I just started to watch it. Indeed, Ball is right: There's physics and mathematics, which enables us to build an Apple notebook and there is "interpretation", which is confusing the clear and beautiful physics in mathematics, and which cannot be used for anything else than selling popular-science books about the weirdness of QT. So it's in fact not quantum theory that is weird but "interpretation", and here obviously "interpretation" means the metaphysics beyond the minimal interpretation, which latter gives the relation of the mathematical formalism to real-world objectively observable facts, while everything beyond it is metaphysics or even religion of individual physicists applying quantum theory.

FAPP yes. I take it is obvious that progress is done by physicists who don't settle with the minimal body of available facts. Someone from those who work actively against the stalemate will break through. This is certain.

 

[EPR]

If we are dealing with "observable facts", this is a big opportunity to learn new things about how the world is not. And probably how it is?

 

[Quantumental]

While Phillip Ball is a relatively good presenter and writer, the problem with this kind of presentation is that it pretends to demystify and make sense of Quantum Mechanics from a philosophical point of view, without actually addressing any of the philosophical or metaphysical implications of X interpretation. It's literally equivalent to merely stating "The world as you perceive it won't change because we discovered quantum mechanics" which is tautological.

The real question lies in the true nature of QM.

 

[PeroK]

The real question lies in the true nature of QM.

The true nature of QM is mathematical.

 

[Quantumental]

The true nature of QM is mathematical.

Which just leads to an infinite loop of "is the math equivalent to reality" or "is the applied math real (collapse) or pure (everett) real?"

It's essentially a worthless question and subsequently presentation as it does not even touch on the only question people debate. Everyone knows that the math of QM works and we all utilize it identically, the entire debate stretching back 100 years is "what is actually going on in reality?"

 

[.Scott]

The real question lies in the true nature of QM.

You don't get to see the "true nature of QM" until you have a procedure for determining whether or not any given description of QM would qualify as its "true nature".

 

[robphy]

This reminds me of an old presentation with an interesting title by Ed Taylor
"Rescuing Quantum Mechanics from Atomic Physics"
https://www.eftaylor.com/pub/RescuingQM.pdf

 

[bhobba]

You don't get to see the "true nature of QM" until you have a procedure for determining whether or not any given description of QM would qualify as its "true nature".

To be specific, it is a mathematical model. The difference between it and other areas of physics is, while they too are mathematical models, we do not have direct experience with what they are modelling.

Thanks
Bill

 

[EPR]

To be specific, it is a mathematical model. The difference between it and other areas of physics is, while they too are mathematical models, we do not have direct experience with what they are modelling.

Thanks
Bill

It's not really a model, it's a tool(if it were, physics textbooks would be overflowing with information how the math relates to reality). We don't have direct experience with modeling Mars either. Yet, it's different from QM. Nothing on Mars seems to challenge obvious human assumptions about how the world works.

 

[bhobba]

It's not really a model, it's a tool(if it were, physics textbooks would be overflowing with information how the math relates to reality). We don't have direct experience with modeling Mars either. Yet, it's different from QM. Nothing on Mars seems to challenge obvious human assumptions about how the world works.

Physicists, applied mathematicians etc basically do not care how math relates to 'reality', whatever that is. The subject that worries about such things is philosophy. It has basically not gotten anywhere on the issue. For example, Turing attended Wittgenstein's lectures on it and soon lost interest because as he expressed it - if it was just a social convention, as Wittgenstein thought, bridges would fall down etc etc. That is just bye the bye, the philosophy of mathematics and its relation to reality is off-topic here.

Thanks
Bill

 

[.Scott]

Which just leads to an infinite loop of "is the math equivalent to reality" or "is the applied math real (collapse) or pure (everett) real?"

For all of you who know better, please comment on my understanding and analysis of the "reality" (or severe lack thereof) behind the Bell Inequality:
1) Each particle of an entangled particle pair follows a trajectory towards a detector. We presume information cannot be transmitted faster than light - and since we are looking to use this effect to keep the detectors from prematurely tipping off the particles about the measurement choices, we will use photons as our particles.
2) Upon reaching the detector, the detector makes a binary measurement - judging the photon to be in one of two states. It has no way of knowing that the photon is entangled and we select a detector/photon combination that almost always results in a detection and measurement (reducing that potential third "not detected" state to less than 1%).
3) After many photon pair measurements, made at different measurement orientations, we check the combined measurement statistics from both detectors and note that the measurement results at one detector are apparently tied to the orientation selection at the other detector.
4) For arguments sake, we will position the detectors far enough apart that it will take minutes for one detector to report its measurement orientations and results to the other detector. And we will position a human observer at one of these detectors.

The results agree with the QM arithmetic. But that arithmetic doesn't correspond to what humans expect of reality.

So if you insist on applying a neatly time-ordered cause and effect sequence to this experiment, I have listed some options that come to mind. I believe they all have some claim to being "true". In other words, I do not see these claims as contradicting each other.

A) You could hold that the photons in the pair become committed to measurement results as soon as they are formed. Thus, information about the future detector orientations was available to the photon pair when it formed. Either the experiment is cosmically "rigged" - in the sense that the universe is constrained to allow only experiments that "work"; or information about the future is routinely available whenever entangled particles are formed.

B) The photons commit to a measurement result en route. This may be the easiest one to swallow. Photons have a well-established "talent" for responding to "counter-factual" paths - places they have apparently never gone. When we say that a photon is emitted from a source, is reflected by mirror surfaces, and then strikes a target, what we really mean is that it was as if that path had been followed. We can have lasting evidence that energy from the photon is missing from the source and has appeared at the target with an appropriate time delay. But photons cannot be tracked like baseballs - and when examined closely do not follow such direct and simple paths. But for someone who is looking for a "true nature", it's easy to imagine a photon in flight using all information available from all its potential paths in a deterministic super-luminal computation of its final landing spot.

C) As nifty as the photon is, decoherence is tied to a measurement - the exchange of information between the photon and the measurement device and then the amplification of this measurement to human scale. Presumably, if the measurement device could isolate the result of its measurement from everything else, that result would remain in a superposition - although I have not seen this kind of experiment in the literature. So you could defer the measurement to the ultimate decoherence from the measurement process.

D) I'm not at all certain that this interpretation works - but why violate locality when you don't absolutely have to? At the cost of some serious entropy issues, you can defer the final measurement to whenever you can finally compare those measurements to the report from the other detector. You (and your immediate environment) get to be in a superposition of states until that report is received. The problem is that until you get the report, both you and the other detector get to broadcast "bad" information to the rest of the universe - information that would follow classical rather than quantum statistics. Eventually, that would all get cleaned up - but wouldn't that be too "ugly" to be "true"?

 

[vanhees71]

FAPP yes. I take it is obvious that progress is done by physicists who don't settle with the minimal body of available facts. Someone from those who work actively against the stalemate will break through. This is certain.

Einstein's quibbles with QT indeed triggered a great progress in our understanding of quantum theory through Bell's theoretical ideas about how to scientifically formulate these quibbles and make it testable to experiment. This triggered the experimental activity starting with Aspect et al and lead finally to new technology (quantum cryptography, quantum computing, and all that) today. The key point was that Bell turned the vague philosophical ideas of the EPR paper (which Einstein didn't like himself too much) into a scientifically decidable question testable by experiments in the lab.

 

[WernerQH]

Physicists, applied mathematicians etc basically do not care how math relates to 'reality', whatever that is.

Of course, physicists need not concern themselves with philosophers' "ultimate" reality. But they do need to think about better, more economic theories. If the basic concepts of the existing theories describe something "real" (are appropriate, necessary, useful), or should be replaced by something better. Think of what happened to Maxwell's ether. Most physicists would call Minkowski's formulation of electrodynamics a better theory than Maxwell's. And it doesn't need the ether.

Understanding quantum theory is still encumbered by strong habits of thought, and it hasn't been stripped of old metaphysical baggage. The formalism works just fine, but people can't even agree on whether or not wave function collapse is an essential part of the formalism. Why is that? Even if it's just "interpretation", it seems to have bad effects on our thinking.

 

[DennisN]

(...) please comment on my understanding and analysis of the "reality" (or severe lack thereof) behind the Bell Inequality

I've currently only got some comments on your points 1 - 4:

We presume information cannot be transmitted faster than light - and since we are looking to use this effect to keep the detectors from prematurely tipping off the particles about the measurement choices, we will use photons as our particles

"We presume information cannot be transmitted faster than light" Correct. Well, I presume the many of us presume it, at least. :)

Regarding the choice of photons as test objects:
The type of particle doesn't really matter. Other types of particles could in principle be used, but the experimental setup would of course be different. It is my understanding that photons are used because it is more easy to create entangled photon pairs (see "parametric down conversion").

Upon reaching the detector, the detector makes a binary measurement - judging the photon to be in one of two states.

The detector only detects a photon (or not) which implies the photon has passed the polarizer in front of the detector. So, yes, it's binary, since the photon either passes the polarizer or not.

For arguments sake, we will position the detectors far enough apart that it will take minutes for one detector to report its measurement orientations and results to the other detector.

You only have to place the detectors at a sufficient distance from each other that ensures there can be no communication between them faster than the speed of light.

And we will position a human observer at one of these detectors.

Why human? A computer will do the job just fine. :)

 

[.Scott]

Regarding the choice of photons as test objects:
The type of particle doesn't really matter. Other types of particles could in principle be used, but the experimental setup would of course be different. It is my understanding that photons are used because it is more easy to create entangled photon pairs (see "parametric down conversion").

If you want to have the detector choices isolated (space-like separation) from each opposite detectors, a fast particle makes things easier.

You only have to place the detectors at a sufficient distance from each other that ensures there can be no communication between them faster than the speed of light.

And make sure the measurement events are space-like separated - so roughly equal path lengths to the source.

The detector only detects a photon (or not) which implies the photon has passed the polarizer in front of the detector. So, yes, it's binary, since the photon either passes the polarizer or not.

In order to demonstrate the Bell inequality, you have to make sure that you account for all events - otherwise, I can show you how to simulate the particles with diodes and get the Bell inequality.
So, if you are only detecting one of the two spin states, you need to demonstrate that each detector is detecting the appropriate percent of what the other detector finds - and that that is not consistent with classical physics.
Couldn't you use a plate at the Brewster angle with four detectors?

Why human? A computer will do the job just fine. :)

I wanted to emphasize "ugly". What can be uglier than a human observer in a superposition?

 

[RUTA]

Of course, physicists need not concern themselves with philosophers' "ultimate" reality. But they do need to think about better, more economic theories. If the basic concepts of the existing theories describe something "real" (are appropriate, necessary, useful), or should be replaced by something better. Think of what happened to Maxwell's ether. Most physicists would call Minkowski's formulation of electrodynamics a better theory than Maxwell's. And it doesn't need the ether.

Understanding quantum theory is still encumbered by strong habits of thought, and it hasn't been stripped of old metaphysical baggage. The formalism works just fine, but people can't even agree on whether or not wave function collapse is an essential part of the formalism. Why is that? Even if it's just "interpretation", it seems to have bad effects on our thinking.

Your analogy between QM and SR can be taken further exactly as Ball advocates, i.e., by using quantum information theory. See this Insight, "How Quantum Information Theorists Revealed the Relativity Principle at the Foundation of Quantum Mechanics" https://www.physicsforums.com/insig...ciple-at-the-foundation-of-quantum-mechanics/

 

[WernerQH]

Your analogy between QM and SR can be taken further exactly as Ball advocates, i.e., by using quantum information theory.

It seems to have become a popular idea, but I don't think information is physical. It's a feature of our descriptions of Nature, and physical only indirectly, because we hope that our theories describe reality. I can't think of information without an underlying substrate. Call me old-fashioned, if you like. :-)

 

[RUTA]

It seems to have become a popular idea, but I don't think information is physical. It's a feature of our descriptions of Nature, and physical only indirectly, because we hope that our theories describe reality. I can't think of information without an underlying substrate. Call me old-fashioned, if you like. :-)

I also don't take information to be "physical," but the information-theoretic reconstructions don't require that information be "physical." To continue the analogy with SR, Lorentz produced his transformations assuming the existence of a luminiferous aether, but the Lorentz transformations hold and are invaluable for physics whether the aether exists or not. Likewise, the information-theoretic principle of "Information Invariance & Continuity: The total information of one bit is invariant under a continuous change between different complete sets of mutually complementary measurements" maps to the relativity principle applied to the invariant measurement of Planck's constant at the kinematic basis of QM regardless of whether or not information is "physical." So, the motivation for producing the information-theoretic reconstructions of QM does not bear on their validity or value one way or another.

 

[EPR]

I can't think of information without an underlying substrate

I signed up here to get new ideas about what this substrate might be.
I am studying neurobiology as a side hobby and the relationship between dopamine levels in the brain and cognition. Dopamine production is a precursor of how we see and experience the world - altered, abnormal levels quickly trigger a number of mental disorders, visions and experiences. These are newer findings from the last decade or so. How our 'healthy' brains operate is directly tied to how we perceive the reality, as just about everything we perceive is constructed in the brain with variable degrees of accuracy from this alleged "substrate".

 

[WernerQH]

So, the motivation for producing the information-theoretic reconstructions of QM does not bear on their validity or value one way or another.

Agreed. The quantum formalism is flawless, and it's nice that you have found a neater (more economical) presentation. But the question remains what it is that Q(F)T describes. To my mind it's absurd to talk about "quantum objects" that can exist in different states with different properties (observables) at the same time, and that these properties become "real" when "measured". At bottom, QFT describes the correlations between events, and "particle" or "field" are just names we give to special patterns of events in spacetime.

 

[WernerQH]

How our 'healthy' brains operate is directly tied to how we perceive the reality, as just about everything we perceive is constructed in the brain with variable degrees of accuracy from this alleged "substrate".

The brain is another kind of substrate, as is a book, or a computer screen. All can be built from just 92 different kinds of atom. I don't expect neurobiology or "consciousness" to have any bearing on quantum theory.

 

[EPR]

The brain is another kind of substrate, as is a book, or a computer screen. All can be built from just 92 different kinds of atom. I don't expect neurobiology or "consciousness" to have any bearing on quantum theory.

Newton's conception of the world was a terrible misunderstanding.

 

[RUTA]

Agreed. The quantum formalism is flawless, and it's nice that you have found a neater (more economical) presentation. But the question remains what it is that Q(F)T describes. To my mind it's absurd to talk about "quantum objects" that can exist in different states with different properties (observables) at the same time, and that these properties become "real" when "measured". At bottom, QFT describes the correlations between events, and "particle" or "field" are just names we give to special patterns of events in spacetime.

A principle account doesn't say anything about ontology. That's where SR is today and QM reconstructions have gotten QM to the same place. Whether or not some consensus constructive counterpart to the relativity principle applied to the invariant measurement of c and h is ever created remains to be seen. No one has much interest in doing that for SR anymore. We'll see about QM once everyone realizes it rests on the same principle as SR.

 

[artis]

To my mind it's absurd to talk about "quantum objects" that can exist in different states with different properties (observables) at the same time, and that these properties become "real" when "measured".

I don't expect neurobiology or "consciousness" to have any bearing on quantum theory.

I'm not saying I don't agree with your first assessment but truth be told since we are the only known conscious beings and we developed quantum theory , I'd say consciousness has a lot to do with everything not just QT