Double slit experiment -- consciousness and information

[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

 

[low inhibition]

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

photons from CBMR are in the low freq radio spectrum, that's like saying we can make out the shape of a room and furniture in it using a radio goggle. I don't fully understand decoherence, but I'm pretty sure the mainstream view of why dust particles aren't teleporting around and have a definite position is due to decoherence, and not CBMR photons.

I'm not placing my weird views anywhere, how do u explain the youtube video i posted? The disappearance of interference occurred BEFORE the information of which slit it passed was obtained. This even suggest time travel might be possible lol.

 

[bhobba]

photons from CBMR are in the low freq radio spectrum, that's like saying we can make out the shape of a room and furniture in it using a radio goggle. I don't fully understand decoherence, but I'm pretty sure the mainstream view of why dust particles aren't teleporting around and have a definite position is due to decoherence, and not CBMR photons.

You are wrong and links to the professional literature explaining it has been given. Of course the CBMR is not the only thing affecting dust particles - but all by itself is enough to give it a definite position.

I'm not placing my weird views anywhere, how do u explain the youtube video i posted? The disappearance of interference occurred BEFORE the information of which slit it passed was obtained. This even suggest time travel might be possible lol.

Again its been explained in this thread. Its due to decoherence in simple cases can be undone.

I have given this link before, but will do it again:
http://quantum.phys.cmu.edu/CQT/index.html

It has a whole chapter devoted to the erasure experiment and variants:
http://quantum.phys.cmu.edu/CQT/chaps/cqt20.pdf

Here is the conclusion:
The analysis of the delayed choice paradox given above provides some useful lessons on how to
analyze quantum paradoxes of this general sort. Perhaps the first and most important lesson is
that a paradox must be turned into an explicit quantum mechanical model, complete with a set of
unitary time transformations. The model should be kept as simple as possible: there is no point in
using long expressions and extensive calculations when the essential elements of the paradox and the
ideas for untangling it can be represented in a simple way. Indeed, the simpler the representation,
the easier it will be to spot the problematic reasoning underlying the paradox. In the interests of
simplicity we used single states, rather than macroscopic projectors or density matrices, for the
measuring apparatus, and for discussing the outcomes of a quantum coin toss. A more sophisticated
approach is available, see Sec. 17.4, but it leads to the same conclusions.
A second lesson is that in order to discuss a paradox, it is necessary to introduce an appropriate
framework, which will be a consistent family if the paradox involves time development. There will,
typically, be more than one possible framework, and it is a good idea to look at several, since
different frameworks allow one to investigate different aspects of a situation.
A third lesson has to do with MQS states. These are usually not taken into account when stating
a paradox, and this is not surprising: most physicists do not have any intuitive idea as to what
they mean. Nevertheless, families containing MQS states may be very useful for understanding
where the reasoning underlying a paradox has gone astray. For example, a process of implicitly
(and thus unconsciously) choosing families which contain no MQS states, and then inferring from
this that the future influences the past, or that there are mysterious nonlocal influences, lies behind
a number of paradoxes. This becomes evident when one works out various alternative families of
histories and sees what is needed in order to satisfy the consistency conditions.

But you need to take the time to go through the whole book. It uses math, but its explained as you go along.

A question requiring an advanced answer for the full detail has been asked as a beginner - specifically you need knowledge of the difference between pure and mixed states plus decoherence. You simply have to accept some things at that level - it can't be explained in detail at the beginner level.

Thanks
Bill

 

[fresh_42]

The original post is answered and the discussion now is below our standard, which requires scientific textbooks and publications to be the base of discussion.

Thread closed.