I What is the current perspective on quantum interpretation?

[Zaitsev Maxim]

I can propose an experiment. Don't really know if it was already, so you may delete this post as well, if it's nothing new.
The question is: is it only when we, people, look at it, is important, or not. If it does, then it's connected with understanding, not looking.
The experiment is as follows. We have device to fix position of particle. And we're not looking at what it fixes up to the very end. And not looking at what happens there at all. And look only at the end result. BUT we have this thing: device should forget instantly what it fixed (to the very end: we should clear this memory with zero instantly). I.e. we're not adding this result in some array, writing on hard drive or something is left in operative memory (RAM) in any way, so you can never extract it. And then look only at the end result, how this particles behaved themselves. If they change their behaviour like when we're looking, then it's done.
If not, then there's more.
1. We cold add line in code to remember info in array, and clear it comletely with zero just before the end. And then not clear.
2. We should try the same as initial but look at what happens there, not what device fixes. I.e. on picture through video or directly, if possible, through glass, even if we're not seeing this particle. And again not look at the result to the very end. Just look at where this particle goes through. If it doesn't change its behaviour then it's done. If it does you could try place there monkey, cat or even cockroach to check brains needed for it to change (or maybe you even should wait a little for this information to completely disappear from their minds and then look at result). Then try looking only at computer which fixes it, but forgets instantly and never tells you.
3. You could try initial experiment, but draw info on screen and forget instantly. But only in special screen without graphic card. You can even encode this through lamps in bitwise code (but without any memory to forget it instantly). And again not look at it at all, better isolate this place so that there's no light that goes through. And look at result. Then monkey and everyone else. And you may try to encode it so you will never understand, what this light means.
So you can determine if it's understanding or looking. Looking only something alive or even computer. Although it will end immediately, if only when computer looks, it already changes.
You can even never remember this information in operative memory and just fix it with device, which tells no one and never remembers itself, to determine, if it is extraction of information, not looking, which is important.

 

[AlexCaledin]

- but, whatever we do, it consists of elementary observations of choices made by the actual universal avalanche of events - inside and outside one's brain - we are simply learning about Nature's choices, never able to know how exactly they are made... Although, yes, some choices do seem made by ourselves and there is a very strong feeling of responsibility.

 

[Zaitsev Maxim]

But isn't it important which action triggers this change: extraction of information without keeping it at all, keeping this information somewhere for some time or trying to understand this information? You say looking, but maybe not looking.
If we're extracting it, not looking at it at all, not trying to understand, what happens there at all, can you tell me, what will happen? Should it change when we're not looking, but just fixing it without remembering it at all? Maybe it's important that we're trying to fix it, not look, so it should change and have fixed position.

 

[ObjectivelyRational]

There is currently no evidence to suggest that consciousness in the human brain, versus an animal's brain, versus a computer, or a sensor, or any other sufficiently "measurmenty" natural system has any fundamentally different causative effect on the outcome of a complex quantum system or experiment. Specifically, no evidence shows that measurement actually depends on consciousness.

We are grappling with our ignorance, and also the counter intuitive nature of the temporary indeterminacy of certain aspects of physical systems, and we are still trying to understand the mechanisms involved in measurement, but more experimentation is required for the answers, not more (or the same) "groundless maybes" (complete speculation).

According to the evidence there is nothing which "knows" whether a consciousness is watching a quantum experiment, and there is no evidence showing consciousness is in any way involved in the physical process of measurement.

 

[Zaitsev Maxim]

Sorry, if I'm being ignorant. I'm not a physicist. But I read in the book Beyond Weird, that even if we're sure that we're not influencing particle in any way during measurement, it changes its behaviour when we measure it. And it very strongly says that it's looking that's important. But is it really? Maybe it's measurement (extraction of information) in itself that's important, not looking.

 

[ObjectivelyRational]

Sorry, if I'm being ignorant. I'm not a physicist. But I read in the book Beyond Weird, that even if we're sure that we're not influencing particle in any way during measurement, it changes its behaviour when we measure it. And it very strongly says that it's looking that's important. But is it really? Maybe it's measurement (some interaction) in itself that's important, not looking.

No need to apologize and you are not being ignorant.

I think you are right. Measurement IS interaction, and interaction and causation, that kind of thing is science!

Trying to play philosophical games about reality rewriting itself once you "consciously" are aware of it.. that is sensationalism, not science. Quantum processes occurred in the universe countless times over billions of years before human consciousness existed, and they are occurring and "resolving" in over billions and billions of light years (cubed) of space and in billions and billions of galaxies through out the vast cosmos without a need for any consciousness to collapse anything.

 

[Zaitsev Maxim]

(by the way I changed "some interaction" in "extraction of information" because we really shouldn't influence particle in any way)

To say it more clearly: we can easily differentiate between 4 possibilities (which I can see):
1. Measurement itself.
2. Keeping information in some way.
3. Looking at information.
4. Understanding this information.

1. If we just measure never keeping result at all and never looking or trying to understand what's going on in there. So we never lift uncertainty for oneselves. If it changes result then it's measurement. If not then we're at least completely sure we're not influencing particle in any way by this measurement.

2. If we remember this result temporary in some way but strictly never looking at it and destroy it completely before we look at result (or right after by timer, never looking). Again never lift uncertainty in any way. If it influences, then it's keeping information (or something related).

3. If we look at encrypted information (without information loss) which we can never understand and again never keep it in any way and it influences result, then it's looking. If we write information somewhere, then it doesn't count because we can understand it later. If we look at encrypted information which will be forever lost and it doesn't influence result, then it's not looking. (We can even try encrypt in sound and listen to it if you wish)

4. If we look at information we can somehow understand (maybe shouldn't write it again), and it influences result, then it's understanding. You can even try to place someone who looks at the same thing alone but doesn't know anything and can't remember or understand it. It will be very fun if result is changing depending on who is watching.

Or maybe it's amount of information that is important. We can also try light up some lamp, every time measuring goes through and look at result. Or maybe it can behave the more freely, the less we know or inquiry about it. We're constantly trying to measure as precise as possible, but what if we do reverse thing and purposely limit ourselves in precision of our measurements, so that even measurement tool can't know more than we want? Will its behaviour change again?

 

[ObjectivelyRational]

(by the way I changed "some interaction" in "extraction of information" because we really shouldn't influence particle in any way)

There must be a causal chain to make any measurement. Some causal chains interact with the subject prior to your participation (sunlight falling on an observable projectile), but some interaction must have occurred for you to measure that light. In this case you are using the light bouncing off the projectile to locate the projectile, but you must keep in mind the fact that the light DID interact and affect the projectile.

Something isolated and kept isolated from all external interaction is by definition unmeasurable while it is being kept isolated.

 

[Zaitsev Maxim]

Something isolated and kept isolated from all external interaction is by definition unmeasurable while it is being kept isolated.

But it's the very thing I'm trying to say. What if the cause of change is not observation of this information but simply inquiring about it? We don't measure it for oneselves, you can guarantee that you're not influencing particle (or else there would not be such absurd conjecture about looking) and we're not influencing it by looking or knowing something. If we do the same thing, but never know results of measurements (and never can extract them, if we extract then we're looking) and only look at the end result and it changes, then it is measurement, not looking, because we never looked or tried to understand what's going on. We're not measuring because we want to know result of our measurements, we measure because we should check influence of the act of measurement itself.
And then again if we limit our tool to ask only very approximate information (for example, with error of 1 centimeter) without looking at it and it changes its behaviour to something new, then it's inquiring of information that is important, not measuring.
And more so if we do the same thing when we measure but never fixing it with any device and then do the same but with fixing and forgetting instantly, and result is different, then it's extraction of information and measurement doesn't influence particle completely. But if it changes even without fixing it with device then it should be problem with measurement or interaction.
So, we can prove that we're not influencing it by measurement mothed if we do the same thing as in measurement but never ever even fix it with device. Because we're not even extracting some information from this and if it changes result then it can't be helped. But if not, then we've proved it.

 

[AlexCaledin]

This Feynman quote is ever so remarkable,

You may argue, “I don't care which atom is up.” Perhaps you don't, but nature knows

 

[Lord Jestocost]

Trying to play philosophical games about reality rewriting itself once you "consciously" are aware of it.. that is sensationalism, not science. Quantum processes occurred in the universe countless times over billions of years before human consciousness existed, and they are occurring and "resolving" in over billions and billions of light years (cubed) of space and in billions and billions of galaxies through out the vast cosmos without a need for any consciousness to collapse anything.

Simple declarations make no sense. One should, as John von Neumann has done, merely rely on the unambiguous mathematics constituting quantum theory. The quantum mechanical time evolution is valid for all "physical systems". That's the reason why all “quantum processes” finally boil down - in mathematical language - to something like a purely quantum-mechanical von Neumann measurement chain when physical systems are interacting which each other.

And what happens at the end of such a purely quantum-mechanical von Neumann measurement chain? In case the “observer” is regarded as a “pure physical system”, mathematics is unambiguous: Nothing happens; the “purely physical observer” is simply part of the purely quantum-mechanical von Neumann measurement chain and entangles with the system the state of which is to be measured! The system is sucked into a vortex of entanglement and no longer has its own quantum state. On top of that, the entangled state fails to indicate any particular measurement outcome.

 

[EPR]

With the risk of being banned, the formalism of QM does not provide an explanation for single outcomes. The ones observed at the classical scales. No matter how you turn it, philosophy must enter to explain this missing bit. You can sideline it as minor detail or try to delve deeper(if such knowledge is even possible or obtainable).

 

[PeterDonis]

the formalism of QM does not provide an explanation for single outcomes

In fact, the formalism does not even require single outcomes, since at least one interpretation, the MWI, does not have single outcomes.

 

[EPR]

Indeed. The MWI is philosophy

 

[PeterDonis]

The MWI is philosophy

To the extent that any interpretation of QM is philosophy, yes.

 

[vanhees71]

What in classical mechanics says that there are "single outcomes"? That's all empty philosophical gibberish (I know I'm provocative here ;-)).

Physics is an empirical science and all our theories provide just descriptions of observed facts, and one observed fact is that we are able to construct measurement devices to measure various observables, which always give a well-defined "reading" for the measured observable.

Classical physics is a very much coarse grained description of the underlying quantum dynamics and there often the randomness of all kinds of fluctuations (particularly quantum fluctuations but also "thermal fluctuations" etc.) are simply neglected, because they are not resolved in the coarse-graining procedure. Before we were able to measure much more accurately we had only such coarse-grained observables and thus came to the wrong conclusion that (a) observables have always determined values and (b) that we can measure these observables without considerable influence on the measured system.

Famously (thermal) fluctuations came into the point of view by Einstein's seminal work on classical statistical physics, where he not only rediscovered much older results by Maxwell, Boltzmann, and Gibbs (many of which he was not aware of, because he didn't bother to read all the literature of a subject he was thinking about for himself) but also considered the said fluctuations, finally leading to convincing evidence for the "reality" of the "atomistic structure" of matter which was not commonly accepted among physicists (while for chemists it was pretty much obvious).

Finally more and more evidence lead to the discovery of quantum theory and thus forced the physicists to accept that the above mentioned conclusions (a) and (b) from "macroscopic" evidence and theorizing, is fundamentally wrong, i.e., that there is inherent randomness in Nature, i.e., that there is no state of any system where, all its observables take determined values, and even the preparation state of the system in a quantum theoretical pure state (which is the most complete possible preparation of the system) does thus not imply the determination of values of all observables. That's all what QT says and that's all that is observed in all measurements done today. There's no need for "philosophy" and esoterics or fancy interpretations of the quantum-theoretical mathematical formalism. All you need is simply to accept that the natural sciences are an endeavor enabling us to learn how Nature really behaves as it can be observed by us, and this can lead to tremendous corrections of older worldviews as is deterministic classical physical theories, which turn out to be approximations of the more detailed description provided by quantum theory.

Maybe one day, we'll find discrepancies between observed objective facts and quantum theory too. Then we'll have to find a new more comprehensive theory to describe it. It's obvious that we need something like this, because we have no satisfactory description of the gravitational interaction, i.e., no quantum formulation of General Relativity yet.

The claimed "interpretational problems" philosophers seem still to have with quantum (field) theory are just philosophical but no physical problem though, at least not given the known empirical objective facts we have today.

 

[PeterDonis]

What in classical mechanics says that there are "single outcomes"?

Classical mechanics doesn't really have a concept of "outcomes" as distinct from the state of the system, the way QM has a distinction between measurement outcomes and the wave function. In classical mechanics, the state of the system just is the "outcomes".

 

[stevendaryl]

What in classical mechanics says that there are "single outcomes"? That's all empty philosophical gibberish (I know I'm provocative here ;-)).

Yes. All philosophical positions other than yours are gibberish. But your position is considered gibberish by others, as well.

 

[gentzen]

Einstein's seminal work on classical statistical physics, where he not only rediscovered much older results by Maxwell, Boltzmann, and Gibbs (many of which he was not aware of, because he didn't bother to read all the literature of a subject he was thinking about for himself)

Do you have evidence for that claim with respect to Boltzmann? And do you have evidence that this was really intentional from his side with respect to Maxwell and Gibbs, and not just explained by language barrier and availability?

 

[Lord Jestocost]

@vanhees71

The fundamental and essential question quantum theory has risen is simple. As Harald Atmanspacher formulates it in “Determinism Is Ontic, Determinability Is Epistemic”:

“Can nature be observed and described as it is in itself independent of those who observe and describe – that is to say, nature as it is ‘when nobody looks’? This question has been debated throughout the history of philosophy with no clearly decided answer one way or the other. Each perspective has strengths and weaknesses, and each epoch has had its critics and proponents with respect to these perspectives.”

I don’t think that such debates were or are merely philosophical gibberish.

 

[ShayanJ]

Finally more and more evidence lead to the discovery of quantum theory and thus forced the physicists to accept that the above mentioned conclusions (a) and (b) from "macroscopic" evidence and theorizing, is fundamentally wrong, i.e., that there is inherent randomness in Nature, i.e., that there is no state of any system where, all its observables take determined values, and even the preparation state of the system in a quantum theoretical pure state (which is the most complete possible preparation of the system) does thus not imply the determination of values of all observables. That's all what QT says and that's all that is observed in all measurements done today. There's no need for "philosophy" and esoterics or fancy interpretations of the quantum-theoretical mathematical formalism. All you need is simply to accept that the natural sciences are an endeavor enabling us to learn how Nature really behaves as it can be observed by us, and this can lead to tremendous corrections of older worldviews as is deterministic classical physical theories, which turn out to be approximations of the more detailed description provided by quantum theory.

You're pretending that anyone who is interested in interpretations of quantum mechanics is someone who was just too comfortable with classical physics and now doesn't want to let go of that comfort. But that's not true! Only hidden variable interpretations are trying to get quantum physics as close to classical physics as they can but other interpretations are driven by different motivations that is answering actual questions.

You're also pretending there is nothing more to understand about quantum mechanics. But I should remind you that its actually these kinds of questions that led to a clear understanding of decoherence which is a very important part of quantum physics. And I think it proves that although you may not see anything "physical" in arguments about interpretations of QM right now, it doesn't mean that they won't lead to a profound discovery in physics.

 

[vanhees71]

Yes. All philosophical positions other than yours are gibberish. But your position is considered gibberish by others, as well.

Fine with me, but it's at least physics not philosophy ;-)).

 

[vanhees71]

You're pretending that anyone who is interested in interpretations of quantum mechanics is someone who was just too comfortable with classical physics and now doesn't want to let go of that comfort. But that's not true! Only hidden variable interpretations are trying to get quantum physics as close to classical physics as they can but other interpretations are driven by different motivations that is answering actual questions.

You're also pretending there is nothing more to understand about quantum mechanics. But I should remind you that its actually these kinds of questions that led to a clear understanding of decoherence which is a very important part of quantum physics. And I think it proves that although you may not see anything "physical" in arguments about interpretations of QM right now, it doesn't mean that they won't lead to a profound discovery in physics.

In my opinion the interpretational problems are solved with Bell's work and the empirical facts from experiments all of which with high precision excludes local deterministic hidden-variable models in the sense defined by bell and confirm the predictions of quantum theory.

It's also true that the physics part of all this work has been very fruitful, including what you say concerning decoherence, the theory of open quantum systems, and finally now developing "quantum engineering", i.e., making use of the results for technical developments like quantum cryptography and quantum computers etc.

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.

 

[ShayanJ]

In my opinion the interpretational problems are solved with Bell's work and the empirical facts from experiments all of which with high precision excludes local deterministic hidden-variable models in the sense defined by bell and confirm the predictions of quantum theory.

It's also true that the physics part of all this work has been very fruitful, including what you say concerning decoherence, the theory of open quantum systems, and finally now developing "quantum engineering", i.e., making use of the results for technical developments like quantum cryptography and quantum computers etc.

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.

I agree. Bell's work is one of the monumental milestones in the history of quantum mechanics. EPR just proved that there are still unanswered questions about quantum mechanics. But it was Bell who showed that those questions are actually not just philosophical, but deeply physical.

But I should remind you that EPR published their paper in 1935. Bell published his theorem in 1964. I'm pretty sure that 29 year gap is actually because most people had a mindset similar to yours and didn't think there was anything more to be understood. But in hindsight, we're all grateful that Bell didn't think that way. So let's learn from history and don't rush to conclusions!

 

[stevendaryl]

In my opinion, the goal of science is to understand nature. The goal of making falsifiable predictions is to test our understanding. But to say that the goal of science is to make and test falsifiable predictions is to confuse a test with the subject matter it is testing. It’s sort of like saying that the goal of studying physics is to get good scores on physics exams.

 

[Lord Jestocost]

But I should remind you that EPR published their paper in 1935. Bell published his theorem in 1964. I'm pretty sure that 29 year gap is actually because most people had a mindset similar to yours and didn't think there was anything more to be understood. But in hindsight, we're all grateful that Bell didn't think that way. So let's learn from history and don't rush to conclusions!

One should mention here that it was Bohmian mechanics whose nonlocality inspired John Bell to show that nonlocality must be a feature of any interpretation that “completes” quantum mechanics in the sense of Einstein, Podolsky, and Rosen.

 

[RUTA]

In my opinion, the goal of science is to understand nature. The goal of making falsifiable predictions is to test our understanding. But to say that the goal of science is to make and test falsifiable predictions is to confuse a test with the subject matter it is testing. It’s sort of like saying that the goal of studying physics is to get good scores on physics exams.

Here is post 222 in:
https://www.physicsforums.com/threads/assumptions-of-the-bell-theorem.1002054/page-9#post-6492762

Engineering? I always thought of science as the process of creating the tools, and engineering is about as just using the tools.

I have one funny memory from a class in analytical mechanics, where half of the group was in the science program, and half of the group with engineering students, but we both had the same books and made the same exams, the difference was more in emphasis of learning how to use, or conceptual understanding.

I think on a bad day, the lecturer who was very much a person that encouraged deeper questions, was provoced by one of the engineering students that asked many stupid questions like "I do not understand why I need to learn this, I will not have use for this when i get employed", and the teacher responded in frustration to the engineering student that "You are obviously not here to understand, you are just here to learn".

The science part of the group was amused.

/Fredrik

 

[stevendaryl]

Fine with me, but it's at least physics not philosophy ;-)).

I disagree. I think your position very much is philosophy, not physics.

 

[Zaitsev Maxim]

This Feynman quote is ever so remarkable,

You may argue, “I don't care which atom is up.” Perhaps you don't, but nature knows

Very sorry again, if I'm being ignorant. Does it mean nature knows, that we're looking?
I perfectly understand, that even if we just look at the end result then it may change. But we're looking at different information here. If you're saying, that it's during measurement result changes, then shouldn't we determine during which phase it changes? If you always measure and look at results of your measurement, then you're doing very many steps at once and just call it "looking". If you say in QM we're dealing with information, then shouldn't we think in terms of information?
If you Always look inside and Always try determine particle position for oneself, then you're Always doing many steps and simply call it "looking": extract information (by measuring position), transform, transmit, store and only then actually look. And if your theory about looking is built on this, then you're wrong. If you haven't tried yet to divide between these steps, then you can't say that result changes just because we observe it. But you can say, it changes depending on what we do.
What I say is we do a little different thing. If you say, that by measuring for ourselves result changes (no more you can actually say), then we will Never measure it for ourselves and look what happens (you can't yet claim, it changes just because we truly look). We're looking at different type of information here. Your "looking" is (as I think) Always related with "position of particle". But I Never influence it in this way. I only look at what it does and you can't claim it may change if we look at result because your "looking" related with "measuring".
You've always tried to look inside and did many actions at once, but suddenly create theory and transfer this "looking" word to everything. So, first we should look into what this "looking" action means. If every time we "look", we do some action, then it may be this action, not "looking", that is the cause. And you have no basis for this theory yet.
So, we should truncate this action little by little. Remove actual looking (and saving info for later), then saving, then transfering, then transforming (not possible I think), then extracting and look where result changes. Or better from bottom up and look where appears a change. If what you (physicist) say about not influencing particle is true and if we Never register its position with any device (i.e. not even extract information in any form), then you never influence it at all in any form and measuring action without registering any information shouldn't influence result. (You have no basis yet, to say our looking at result in itself is influencing process, because your word "looking" comes from the very definite set if actions)

 

[Zaitsev Maxim]

In other words, you say: "we measure it and look at it, so just because we look at it result changes". But you forget, that you Always measure as well. It May be as well just because we measure it. So your inference about looking is not complete and wrong.
In this book Beyond Weird is said this thing: "It’s a little like saying that you begin with a box that you know is red and think weighs one kilogram – but if you want to check that weight exactly, you weaken the link to redness, so that you can’t any longer say for sure that the box you’re weighing is a red one. The weight and the colour become interdependent pieces of information about the box." So it changes, depending on what we inquiry about it. And it may very well be that if you inquiry something about it, it should provide this information, but it can't provide it as it's as of now. So it should change to have it. So just because we inquiry it (not even for ourselves) it should transform to have it.
So if we try do measuring without registering and with it, and result is different, then it should be it.