B Double slit experiment -- consciousness and information

[Viopia]

I am not a physicist but I am interested in the double slit experiment and would like a definitive answer, from a physicist, to my question as follows:. If the which path is just detected by a detector, without it flashing and bleeping at the same time, and without the detections being recorded for future reference, and without a consciousness observing these detections, will a two bar pattern still appear on the target screen?

 

[phinds]

I am not a physicist but I am interested in the double slit experiment and would like a definitive answer, from a physicist, to my question as follows:. If the which path is just detected by a detector, without it flashing and bleeping at the same time, and without the detections being recorded for future reference, and without a consciousness observing these detections, will a two bar pattern still appear on the target screen?

There is zero requirement that there EVER be a conscious observer. That's a mistaken point of view that was abandoned about 100 years ago but persists in pop-sci presentations. ANY white-path detection destroys the interference.

 

[DrClaude]

Hi Viopia,


You will have to post your questions in the proper forum. This one here is only for introducing yourself. But I can tell you already that no, consciousness is not needed. You will find many threads discussing this. For instance, at the bottom of this page, you will find a list of "Similar Discussions."

 

[phinds]

OOPS. Didn't realize when I responded that this was in the intro section.

 

[Viopia]

Hi Viopia,


You will have to post your questions in the proper forum. This one here is only for introducing yourself. But I can tell you already that no, consciousness is not needed. You will find many threads discussing this. For instance, at the bottom of this page, you will find a list of "Similar Discussions."

Thanks for the info. This being the case why is there so much current confusion over this, as demonstrated by the following YouTube link? I believe you are right, but the researchers who actually conduct the experiments also seem to be unsure about whether the which path information has to be recorded or not. Even Jim Al-Khalili's YouTube video shows the detector "flashing and bleeping" while detecting. Why does it need to "flash and bleep" if conscious observation is not required? Please take particular notice 6 minutes from the start of the video to see the complete confusion. Do you also know the answer to the first part of my question?

 

[phinds]

As I said in my post, the "confusion" ONLY persists in the minds of pop-science demonstrators. Physicists dumped the notion a century ago. The REAL question is, why don't pop-sci folks pay attention to actual science?

 

[Mentz114]

Why does it need to "flash and bleep"

Good question. It does not. A silent, black body detector would have the same effect. Polarizers in each path also affect the pattern. If they are wholely opposed there is no pattern.

 

[Nugatory]

This being the case why is there so much current confusion over this, as demonstrated by the following YouTube link?

Stuff like this is the reason why Physics Forums has its rules about acceptable sources. You won't find this confusion in the peer-reviewed literature where the real work is going on, and you won't find it in the first-year QM textbooks that aim to teach the real thing to people who are preparing to do real work in the field.

 

[Viopia]

Thanks. So the answer to the first part of my question is the which path detectors only have to detect without recording the information for future reference for a two bar pattern to appear.

 

[Nugatory]

Thanks. So the answer to the first part of my question is the which path detectors only have to detect without recording the information for future reference for a two bar pattern to appear.

In fact just about any substantial interaction will do the trick - it's an accident of history that we use the words "observation" and "detection" to describe these interactions.

Although not allowed sources under the PF rules (that is, you can't cite them as an authoritative source about what quantum mechanics really says - for that there is no substitute for a real textbook with the math and everything) there are two books that you may find more helpful than the random internet video:
Giancarlo Ghirardi: Sneaking a look at God's cards
David Lindley: Where does the wierdness go?

 

[Viopia]

Thanks for that. Perhaps the two Texas A&M PHd research physicists should also read these books, as well as the ex NASA physicist Tom Campbell. Also, do you think Professor Jim Al-Khalili should alter his YouTube video because the detectors do not need to flash and bleep and showing them flashing and bleeping gives people the impression that consciousness is required when it really is not.

 

[Viopia]

Just one last question. (It is easier for me to ask you than spending hours plowing through a textbook). There seems to be a consensus among physicists that detection "interaction" causing probability waves to become particles is very strange, especially in the delayed choice quantum erasor experiment where the particles historic pathway is created at the same time. Does the Quantum Field Theory address these issues by ignoring wave particle duality and suggesting that there are no particles, only waves. If so, does all the weirdness now have an explanation and is QFT part of mainstream science?

 

[dkotschessaa]

 

[weirdoguy]

by ignoring wave particle duality

Actually wave-particle duality is an outdated concept and as such it's "ignored" by every field of physics.

 

[bhobba]

Actually wave-particle duality is an outdated concept and as such it's "ignored" by every field of physics.

It was outdated at the end of 1926 when Dirac came up with his transformation theory which generally goes under the name QM today. Here is the history:
http://www.lajpe.org/may08/09_Carlos_Madrid.pdf

The wave particle idea was just an incorrect stepping stone to Schrodinger's wave equation (he even made a mistake in its derivation I will give a link about at the end) which later morphed and was combined with Matrix Mechanics by Dirac and others. It also included other ideas around at the time such as Dirac's Q numbers that Heisenberg described as much better than his own.

Here is the paper explaining what Schrodinger did, his mistake, and the modern view:
https://arxiv.org/abs/1204.0653

But please understand its purely of historical interest.

Thanks
Bill

 

[bhobba]

Thanks for that. Perhaps the two Texas A&M PHd research physicists should also read these books, as well as the ex NASA physicist Tom Campbell. Also, do you think Professor Jim Al-Khalili should alter his YouTube video because the detectors do not need to flash and bleep and showing them flashing and bleeping gives people the impression that consciousness is required when it really is not.

Post the peer reviewed literature of those people, and experts here will be only too happy to explain what's going on - its likely popularization's which, how to put it, are often way oversimplified to the point of downright lies for a lay audience.

But we can't comment until you post what they say, its source and just what concerns you.

It must also be said well respected textbooks are of course suitable references here, and some of the beginner ones of those sail close to - again how to put it - not quite kosha. But you must give the source and what worries you if we are to comment.

Thanks
Bill

 

[bhobba]

Just one last question. (It is easier for me to ask you than spending hours plowing through a textbook). There seems to be a consensus among physicists that detection "interaction" causing probability waves to become particles is very strange, especially in the delayed choice quantum erasor experiment where the particles historic pathway is created at the same time. Does the Quantum Field Theory address these issues by ignoring wave particle duality and suggesting that there are no particles, only waves. If so, does all the weirdness now have an explanation and is QFT part of mainstream science?

Opinions on if its strange or not varies. This is hardly surprising since 'being strange' is an emotional response. You don't need QFT to explain it.

To understand the 'real' fundamental issue(s) in QM you need to consult modern textbooks on interpretations, especially those dealing with what's called decoherence. The issue is, colloquially, why we get any outcomes at all, but that's by the by. I can't explain it at the lay level. THE standard text is:
https://www.amazon.com/dp/3540357734/?tag=pfamazon01-20

Its advanced however.

At your level I suggest the following textbook that has kindly been put out there for free. It uses math, but explains it as it goes along:
http://quantum.phys.cmu.edu/CQT/index.html

It has a whole chapter devoted to the delayed choice experiment, but you must take the time to read the entire book.

But its just a start. Once you start learning QM you never really stop.

Thanks
Bill

 

[bhobba]

That video is trash - discontinuity in reality - I mean - really. The possibility of collecting information - if a tree falls in forest does it make a sound if there is no one to hear it. Of course it does regardless of what people may prattle on about in an introductory philosophy class. If the detector doesn't record the information - same thing. QM is a theory about observations that occur in a common-sense classical world where observation is a very general thing.

I will not go into how consciousness entered this quantum thing - suffice to say it was due to a mistake made by the very great polymath Von-Neumann (he made a couple - but that in no way diminishes his greatness) in his classic - Mathematical Foundations Of QM. It was excusable at the time but we know more now and can easily see the mistake. Start a new thread if you want to delve into it.

Be very wary about the writings of the early pioneers such as Von-Neumann. They are of course acceptable sources, but things have moved on a lot.

To cut to the chase all the quantum eraser experiment does is show in simple cases decoherence can be undone. Its a matter of definition if decoherence so simple it can be undone is a real observation - normally its so complex it can't be undone. But as you probably have guessed I don't care about semantics - take any view you want - who cares - the answer is the same.

Thanks
Bill

 

[MrRobotoToo]

Even Eugene Wigner, who at one point was perhaps the most prominent proponent of the idea that consciousness causes collapse, eventually abandoned it after he learned of H. Deiter Zeh's pioneering 1970 paper on decoherence.

 

[bhobba]

Even Eugene Wigner, who at one point was perhaps the most prominent proponent of the idea that consciousness causes collapse, eventually abandoned it after he learned of H. Deiter Zeh's pioneering 1970 paper on decoherence.

Indeed. I have zero doubt so would have Von-Neumann if he was still alive.

In relation to this these days a measurement is considered to have occurred after decoherence. Its purely quantum, nothing recorded etc etc. Even a dust particle can be decohered to have an actual position by a few stray photons from the CBMR. It can be interpreted as having position regardless of if anyone observes it, records it etc etc. We have made a lot of progress in understanding the measurement problem and why there is an objective reality out there in the common-sense everyday classical world.

Thanks
Bill

 

[oquen]

Indeed. I have zero doubt so would have Von-Neumann if he was still alive.

In relation to this these days a measurement is considered to have occurred after decoherence. Its purely quantum, nothing recorded etc etc. Even a dust particle can be decohered to have an actual position by a few stray photons from the CBMR. It can be interpreted as having position regardless of if anyone observes it, records it etc etc. We have made a lot of progress in understanding the measurement problem and why there is an objective reality out there in the common-sense everyday classical world.

Thanks
Bill

If one shields a metal pin from the CBMR using some form of container.. what kind of particle beam source can emit enough artificial CMBR or molecular disrupter that can overwhelm the position basis in the atomic structure of the metal pin enough to cause the whole metal pin to appear and vanish, etc. as the position basis and values are altered by the beam? and if this is impossible.. what would be the reason why?

 

[bhobba]

If one shields a metal pin from the CBMR using some form of container.. what kind of particle beam source can emit enough artificial CMBR or molecular disrupter that can overwhelm the position basis in the atomic structure of the metal pin enough to cause the whole metal pin to appear and vanish, etc. as the position basis and values are altered by the beam? and if this is impossible.. what would be the reason why?

You can't overwhelm the position basis as you call it. The reason objects are decohered to the position basis has to do with the radial nature of most interactions. But the detail is highly technical.

Thanks
Bill

 

[Viopia]

Indeed. I have zero doubt so would have Von-Neumann if he was still alive.

In relation to this these days a measurement is considered to have occurred after decoherence. Its purely quantum, nothing recorded etc etc. Even a dust particle can be decohered to have an actual position by a few stray photons from the CBMR. It can be interpreted as having position regardless of if anyone observes it, records it etc etc. We have made a lot of progress in understanding the measurement problem and why there is an objective reality out there in the common-sense everyday classical world.

Thanks
Bill

Yes, this seems to tie in with what Tom Campbell said in his YouTube video entitled "Tom Campbell in Calgary: Intro to MBT (Fri) 1/1" about 27m in when he says the photons or atoms could be replaced by electric toasters if the experiment could be scaled up enough. He seems to think that this is unlikely though. I would love to see two massive slits being bombarded by electric toasters crashing through, what a spectacle this would be. I did ask the RI if this could be done with something smaller, like sand particles being blasted into two slits, and I received a reply from a non-physicist member of staff who had asked members of the RI on my behalf. The reply was The grains of sand are too large/slow for the experiment. Apparently the largest particles that have ever shown an interference pattern are molecules hundreds of atoms across. Everything has a wave/particle duality (even people!, this is called the de Broglie wavelength), but the larger the thing, the smaller that wavelength and the harder it is to see. Sand is just too big to get an interference pattern with. Randomly sandblasting the two slits would result in two randomly sized piles of sand under the slits. Even though grains of sand are tiny to us, they are still massive in the world of quantum physics therefore any characteristics they display during experimentation will all adhere to the laws of classical physics e.g. Newton's three laws of motion, and we won't observe any quantum characteristics. It is interesting to note that the consensus appears to be that "everything has a wave/particles duality (even people)". I wonder why Tom Campbell's big TOE (Theory of Everything) has not been peer reviewed, after all he was a NASA physicist.

 

[Viopia]

There is zero requirement that there EVER be a conscious observer. That's a mistaken point of view that was abandoned about 100 years ago but persists in pop-sci presentations. ANY white-path detection destroys the interference.

Hi Viopia,


You will have to post your questions in the proper forum. This one here is only for introducing yourself. But I can tell you already that no, consciousness is not needed. You will find many threads discussing this. For instance, at the bottom of this page, you will find a list of "Similar Discussions."

Consciousness has reared its ugly head again. I looked at a YouTube video entitled "Delayed choice eraser experiment explained" which was published in 2014. 6.34 in it said that the only difference between the two (D1 and D3) is what we, the conscious observer, know about the system. Even John Wheeler himself said "it begins to look as if we, ourselves, by a last minute decision, have influence on what a photon will do when it has already accomplished most of its doing. We have to say that we ourselves have an undeniable part in shaping what we have always called the past".

 

[Viopia]

Opinions on if its strange or not varies. This is hardly surprising since 'being strange' is an emotional response. You don't need QFT to explain it.

To understand the 'real' fundamental issue(s) in QM you need to consult modern textbooks on interpretations, especially those dealing with what's called decoherence. The issue is, colloquially, why we get any outcomes at all, but that's by the by. I can't explain it at the lay level. THE standard text is:
https://www.amazon.com/dp/3540357734/?tag=pfamazon01-20

Its advanced however.

At your level I suggest the following textbook that has kindly been put out there for free. It uses math, but explains it as it goes along:
http://quantum.phys.cmu.edu/CQT/index.html

It has a whole chapter devoted to the delayed choice experiment, but you must take the time to read the entire book.

But its just a start. Once you start learning QM you never really stop.

Thanks
Bill

Thanks for the links. There are some strange things though. For instance I have heard that Shrodinger's Car is neither alive or dead until the box is opened. What is this all about? It's not exactly what you would call normal "belt and bracer or bricks and mortar" type of stuff.

 

[Nugatory]

For instance I have heard that Schrodinger's Cat is neither alive or dead

That is one of the more common pieces of misinformation you'll hear. It's not true, and you will find a number of older threads here with the correct explanation. (You've mentioned another common piece of misinformation in another post above - "wave-particle duality" isn't what you've been told it is, and if you want to understand quantum mechanics you should make a serious effort to forget that you ever heard about it).

I've already mentioned the Physics Forums rule about acceptable sources. We have this rule because so much of what is out there in YouTube videos, popular books, and internet articles is either so oversimplified as to be misleading or just plain wrong.

 

[bhobba]

Everything has a wave/particle duality (even people!, this is called the de Broglie wavelength)

Nothing has a wave particle duality - its an outdated idea - see post 15.

Everything however is quantum. How the classical world emerges is still an area of active research, although much progress has been made to the point many would say its largely solved. But some key theorems are still not yet done. You will find a discussion here:
https://www.amazon.com/dp/0691004358/?tag=pfamazon01-20

Thanks
Bill

 

[bhobba]

What is this all about?

It was proposed by Schrodinger to highlight an issue with the Copenhagen interpretation as to what point the quantum classical cut is to be made. Its now solved via our better understanding of decoherence.

There is no substitute for studying an actual textbook. I think I already mentioned the Consistent Histories one:
http://quantum.phys.cmu.edu/CQT/index.html

It will take time to study it, and your thinking cap must be on, but really its the only way.

Thanks
Bill

 

[DrChinese]

Consciousness has reared its ugly head again. I looked at a YouTube video entitled "Delayed choice eraser experiment explained" which was published in 2014. 6.34 in it said that the only difference between the two (D1 and D3) is what we, the conscious observer, know about the system. Even John Wheeler himself said "it begins to look as if we, ourselves, by a last minute decision, have influence on what a photon will do when it has already accomplished most of its doing. We have to say that we ourselves have an undeniable part in shaping what we have always called the past".

Wheeler's statement has nothing to do with consciousness in this case. In any delayed choice experiment, the future appears to influence the past. You can take human choice out of the equation and the results are unchanged.

 

[Viopia]

Thanks for all your comments. I am grateful you have taken the time to direct me to the proper sources of information. I am surprised how much incorrect information is out there regarding this subject. I have used YouTube for many things, like for DIY tasks, music composition and computer operating tutorials etc. and I have usually found it to be an excellent source of information. I believe it when you say consciousness is not required, but for me to prove all the things you say from textbooks would be difficult, to say the least, because of my poor mathematical abilities. I am still interested in physics however, and may ask you to verify some things from time to time to make sure I understand these things correctly.

 

[Viopia]

Wheeler's statement has nothing to do with consciousness in this case. In any delayed choice experiment, the future appears to influence the past. You can take human choice out of the equation and the results are unchanged.

Has this now been proved, that the future influences the past? If there were no particles, only waves of energy, could the energy transfers between EM waves and standing waves imitate particles at their points of interaction making the influence of the past unecessary?

 

[DrChinese]

Has this now been proved, that the future influences the past?

At first glance, it is pretty compelling. But the answer is NO, it is actually interpretation dependent.

 

[Viopia]

Is there an alternative interpretation?

 

[DrChinese]

Is there an alternative interpretation?

Actually, they are all alternatives:

https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics

 

[Viopia]

Actually, they are all alternatives:

https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics

Thanks for the link. I particularly like the "Many Worlds" (parallel universe level 3) interpretation which seems to suggest the universe could keep splitting trillions of times per second. Really! Don't you think it is more likely that there are no particles, only waves of energy, and the transfers of energy between EM waves and standing waves imitate particles at their points of interaction making the influence of the past unecessary?

 

[Nugatory]

Thanks for the link. I particularly like the "Many Worlds" (parallel universe level 3) interpretation which seems to suggest the universe could keep splitting trillions of times per second. Really!

There is something not to like about every interpretation, and this extravagant multiplication of worlds is the thing not to like about MWI. However, until you have a solid understanding of the mathematics behind quantum mechanics there's little reason to pay attention to MWI - you need the math to understand the problem that it does solve. While you're learning that math you will be better off working with the minimal statistical interpretation, also known as "shut up and calculate" - the thing not to like about that interpretation is that it refuses to answer your questions about what is "really" happening under the covers, and you don't need that to learn and understand the math.
(If it were a half-century ago, the advice might be to work with a collapse interpretation. These are easy to reason about and will easily see you through your first year or so of study, but are confusing when applied to some more modern theoretical and experimental developments).

Don't you think it is more likely that there are no particles, only waves of energy, and the transfers of energy between EM waves and standing waves imitate particles at their points of interaction making the influence of the past unecessary?

Without the math that's not an idea, it's just a bunch of sciency-sounding words strung together to produce something that sounds cool. However, your intuition is steering you in the right general direction here - the word "particle" as used in quantum physics means something very different from the ordinary English-language notion of a small thing moving around in space. So you can reasonably be thinking that there "are no particles" in the ordinary English-language sense of the word... but for a proper understanding of what quantum particles are you'll need quantum electrodynamics for EM waves and quantum field theory. These were developed during the 1940s and 1950s and unfortunately are far beyond the scope of a B-level thread.

Many posts back I suggested two books. Have you tried them yet?

 

[Viopia]

There is something not to like about every interpretation, and this extravagant multiplication of worlds is the thing not to like about MWI. However, until you have a solid understanding of the mathematics behind quantum mechanics there's little reason to pay attention to MWI - you need the math to understand the problem that it does solve. While you're learning that math you will be better off working with the minimal statistical interpretation, also known as "shut up and calculate" - the thing not to like about that interpretation is that it refuses to answer your questions about what is "really" happening under the covers, and you don't need that to learn and understand the math.
(If it were a half-century ago, the advice might be to work with a collapse interpretation. These are easy to reason about and will easily see you through your first year or so of study, but are confusing when applied to some more modern theoretical and experimental developments).
Without the math that's not an idea, it's just a bunch of sciency-sounding words strung together to produce something that sounds cool. However, your intuition is steering you in the right general direction here - the word "particle" as used in quantum physics means something very different from the ordinary English-language notion of a small thing moving around in space. So you can reasonably be thinking that there "are no particles" in the ordinary English-language sense of the word... but for a proper understanding of what quantum particles are you'll need quantum electrodynamics for EM waves and quantum field theory. These were developed during the 1940s and 1950s and unfortunately are far beyond the scope of a B-level thread.

Many posts back I suggested two books. Have you tried them yet?

There is something not to like about every interpretation, and this extravagant multiplication of worlds is the thing not to like about MWI. However, until you have a solid understanding of the mathematics behind quantum mechanics there's little reason to pay attention to MWI - you need the math to understand the problem that it does solve. While you're learning that math you will be better off working with the minimal statistical interpretation, also known as "shut up and calculate" - the thing not to like about that interpretation is that it refuses to answer your questions about what is "really" happening under the covers, and you don't need that to learn and understand the math.
(If it were a half-century ago, the advice might be to work with a collapse interpretation. These are easy to reason about and will easily see you through your first year or so of study, but are confusing when applied to some more modern theoretical and experimental developments).
Without the math that's not an idea, it's just a bunch of sciency-sounding words strung together to produce something that sounds cool. However, your intuition is steering you in the right general direction here - the word "particle" as used in quantum physics means something very different from the ordinary English-language notion of a small thing moving around in space. So you can reasonably be thinking that there "are no particles" in the ordinary English-language sense of the word... but for a proper understanding of what quantum particles are you'll need quantum electrodynamics for EM waves and quantum field theory. These were developed during the 1940s and 1950s and unfortunately are far beyond the scope of a B-level thread.

Many posts back I suggested two books. Have you tried them yet?

Thank you for your advice. I have not had chance to look at the books you recommended yet, but I will try to do so and try to increased my knowledge of mathematics.

There is something not to like about every interpretation, and this extravagant multiplication of worlds is the thing not to like about MWI. However, until you have a solid understanding of the mathematics behind quantum mechanics there's little reason to pay attention to MWI - you need the math to understand the problem that it does solve. While you're learning that math you will be better off working with the minimal statistical interpretation, also known as "shut up and calculate" - the thing not to like about that interpretation is that it refuses to answer your questions about what is "really" happening under the covers, and you don't need that to learn and understand the math.
(If it were a half-century ago, the advice might be to work with a collapse interpretation. These are easy to reason about and will easily see you through your first year or so of study, but are confusing when applied to some more modern theoretical and experimental developments).
Without the math that's not an idea, it's just a bunch of sciency-sounding words strung together to produce something that sounds cool. However, your intuition is steering you in the right general direction here - the word "particle" as used in quantum physics means something very different from the ordinary English-language notion of a small thing moving around in space. So you can reasonably be thinking that there "are no particles" in the ordinary English-language sense of the word... but for a proper understanding of what quantum particles are you'll need quantum electrodynamics for EM waves and quantum field theory. These were developed during the 1940s and 1950s and unfortunately are far beyond the scope of a B-level thread.

Many posts back I suggested two books. Have you tried them yet?

Thanks for your advice. I have not had chance to read the books you have recommended but I will look at them and try to increase my mathematical knowledge. I wondered if there is any other way I can logically think about physics rather than having to learn all this complicated mathematics. Even Feynman himself used diagrams as well as pure math(s) to make things simpler. Also, am I right in thinking that if the math has no errors then it must be true and this MUST be the way reality works, or could the math work on a blackboard but have nothing to do with reality itself? If the latter is true we could be leading ourselves up the garden path with theories like the "Many worlds" theory. I am glad you think my words sound "cool", but they actually stem from what little understanding I have of the Quantum Field Theory. Incidentally, the math associated with QFT is supposed to be terribly complicated and so what chance do I stand of fully understanding it? Anyway, thanks for you comments and helpful suggestions.

 

[Karolus]

The question is very interesting. If between the two plates there is a detector, capable of detecting if the particle has passed through the slit 1 rather than the slit 2, there is no interference, (absence of alternating light and dark bands), regardless of the fact that there is a human observer, otherwise it is inexplicable that the laws of physics, quantum apply equally well before humans. However the issue is highly controversial

 

[Karolus]

actually the MQ has introduced the concept of "observable" . But because the MQ recourse to "Observable" ?, perhaps in classical physics the speed was not observable or detectable if you prefer? The fundamental reason is that velocity and position according to classical physics were absolute values, independent observer who measured. They existed in itself. Not as things go in MQ, where the observer when making a measurement will influence the result, so it is itself, in a way, part of the experimental apparatus

 

[phinds]

The question is very interesting. If between the two plates there is a detector, capable of detecting if the particle has passed through the slit 1 rather than the slit 2, there is no interference, (absence of alternating light and dark bands), regardless of the fact that there is a human observer, otherwise it is inexplicable that the laws of physics, quantum apply equally well before humans. However the issue is highly controversial

First you point out that it is an established fact (which it is) and then you say it is controversial (which it is not). Why do you think it is controversial?

 

[Karolus]

The text of John Bell "speakable and unspeakable in quantum mechanics", for example, poses many problems in this respect, on the MQ interpretations. So I think that there are open questions, though, there is no doubt on the scientific results and the scientific success of the MQ

 

[Karolus]

For example, always returning the double-slit experiment, surely you need not be an observer in the flesh, yet we always think in terms of observation, although hypothetical. Now a measure or observation pretends to be done by someone ... and by whom?
alternatively follow Feynman admonition: "Shut up and calculate!", but the problem is put under the carpet, and sooner or later the chickens come home to roost

 

[bhobba]

Now a measure or observation pretends to be done by someone ... and by whom?

What an observation means in QM has always been well known and has nothing to do with the meaning in a colloquial sense. In modern times its once decoherence has occurred.

This is a beginner level thread. Unfortunately the full answer is advanced and found in standard texts at that level eg:
https://www.amazon.com/dp/3540357734/?tag=pfamazon01-20

Thanks
Billl

 

[Karolus]

I have good reason to think that the theory of "quantum decoherence" is at present only an attempt to overcome the problems such as the collapse of the wave function by an act of measurement that still overshadow quantum mechanics

 

[DrChinese]

For example, always returning the double-slit experiment, surely you need not be an observer in the flesh, yet we always think in terms of observation, although hypothetical. Now a measure or observation pretends to be done by someone ... and by whom?
alternatively follow Feynman admonition: "Shut up and calculate!", but the problem is put under the carpet, and sooner or later the chickens come home to roost

Plenty of effort has been exerted to learn more. Meanwhile, not many chickens have returned to roost.

At any rate: the double slit is an example of an experiment in which consciousness can be demonstrated not to play a factor. The pattern can be made to appear or not without any conscious observer (or photographic device or similar) knowing the slightest about which slit information.

 

[Karolus]

not the presence or absence of light and dark bands which implies the existence of an observer, but the device must see that the electron that passes through one or the other slit. In fact, this device must be able to detect whether an electron has passed through the slit or not, in other words assumes a hypothetical observer who understands if the electron is passed or not, regardless of the fact that this observer was present in the flesh. . I think this is the crucial role played by the observer.

 

[bhobba]

I think this is the crucial role played by the observer.

In the sense you mean observer you are wrong.

It can be done by computer, results stored to computer memory, and the results viewed by someone decades later. Millions of copies of those results can even be made - are you saying the first person to look at a copy is what causes the interference pattern?

If so that's simply 'silly' and virtually everyone would reject it as that, but could be made into a coherent world view - an overly complicated one for no gain, but possible.

I suspect you have been overly influenced by pop-sci junk.

Thanks
Bill

 

[low inhibition]

certainly u don't need a conscious observer. But knowing the information, whether it's by a computer or real person, seems to affect reality



I'm not a physicist so i don't know what to make of this. It seems everything in QM is affected by whether the information is known or not (by non conscious computers or otherwise), and this is VERY creepy.

Nature seems to be conscious itself, and is playing a major conspiracy against us.

 

[low inhibition]

For example, always returning the double-slit experiment, surely you need not be an observer in the flesh, yet we always think in terms of observation, although hypothetical. Now a measure or observation pretends to be done by someone ... and by whom?
alternatively follow Feynman admonition: "Shut up and calculate!", but the problem is put under the carpet, and sooner or later the chickens come home to roost

I agree. It's just like the foundational issues in math, no one knows if the current foundation ZFC is consistent. This issue just died down over the decades, and mathematicians adopted the shut up and calculate mentality, instead of finding a different type of formal system (not based on first order logic due to its deficiencies). But sooner or later it's going to come back to bite us in the ass, mark my words.

 

[bhobba]

certainly u don't need a conscious observer. But knowing the information, whether it's by a computer or real person, seems to affect reality

That's untrue as well.

For example a few stray photons from the CBMR will give a dust particle a definite position - whether knowing that position or not. Von-Neumann ages ago showed the quantum classical cut can be placed anywhere. Don't make life hard for yourself by placing it at places that lead to rather absurd views. Place it just after decoherence - it resolves all the issues you seem to be struggling with - its the modern view.

What leaves me scratching my head is where are people getting this from. Sure you can make a coherent interpretation from such views, but why do you want things that weird? Its not required.

If you want to find out about QM come here and ask questions - don't jump to conclusions.

Thanks
Bill