Reality exists when observed, but who is the observer?

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Hi,

Reading about quantum mechanics, the probability wave is so that a particle can be everywhere. But when observed, it's probability wave collapses and the particle has to take a definite state.

The example were given for Schrödinger's cat, which is either alive or dead only after we open the box to look at it. Other examples could be that the moon might not exist in the sky if no one look at it. Or a tree falling in the forest is not really falling if no one checks it.

What is the power of the observer to dictate a behavior to a quantum particle? In other words, why would the state of dead/alive of Schrödinger's cat materializes only when I look at it while the cover of the box was actually staring at it the whole time?

In the case of the moon, how come it materializes at the same position while there are billions of different of conscious observers? And on top of that, its position is even predictable.

Thanks for any clarification.
 

mathman

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You shouldn't take these examples too literally. What collapses a wave function is an interaction with something. The "looking" idea is meaningful in that it is necessary to shine a "light" on something to see it.
 
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The "looking" idea is meaningful in that it is necessary to shine a "light" on something to see it.
The solar cells on my house in no way changes the original or subsequent emission of photons from the sun itself.
"That's my story and I'm sticking to it.."
 

Drakkith

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Does a cat count as an observer? It does to me. As does all life. Even particles themselves are "observers" to me. I don't believe that there is something special that somehow makes us the masters of reality compared to the rest of the universe.
 
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Does a cat count as an observer? It does to me. As does all life. Even particles themselves are "observers" to me. I don't believe that there is something special that somehow makes us the masters of reality compared to the rest of the universe.
That is exactly what I wondered. Looking at something doesn't alter in any way the energy of the observed particle. And how does it know it is observed by someone or something? For example, a star distant at X light years away has no idea if it is observed.

BTW, the argument of shining light is not convincing. From Earth, no one can look at the dark side of the moon and there is plenty of light there. From the number of craters all over the moon, it did exist well before any one can look at it.

It is more probable that I didn't fully understand what I read. I really have hard time to see how the act of observing could transform a probable reality to a permanent and unalterable one.
 
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Dimensions = Direction of awareness. A 4th dimensional (spatial time) awareness exists on a 5 dimensional plane of possibilities. A 4th dimensional entity touches down into the 3rd dimension, swiping itself through time, whos awareness gets enveloped into the conscious beings that exist on the 3D plane giving a sense of "me" or "I" through the ego (self consciousness is awareness being drawn from outside, in). Manifestation and "free will" happen when the conscious being strongly wishes, urges or feels a certain way, swaying the 4th dimensional awareness to move through the 5 dimensional plane of possibility.

Everything exists always, there is a perceived beginning and end if perceiving time, however everything ever that is 3 dimensional exists on its plane of existence, through infinite timeless moments and paralleling timeless possibilities. the conscious observer as one is moving through time (at the same speed because it is one) thus we all have a reality to share in this "now" that is infinitely long and eternally fleeting. It doesnt matter if there is a conscious observer to see if something happens or not, if a conscious being happens to be there though, he sees the timeless moments strung together into a film to be observed as an experience through our brains neurons who reach threshold up to 100 times a second (one hundred conscious moments a second = average speed of 4th dimensional awareness through time) who is only aware of roughly 40 timeless moments per second unless awareness is heightened through adrenaline or drugs (this causes us to perceive time slower due to perceiving more timeless moments a second)
 

skippy1729

There is no universal agreement on the answers to your questions. If you are looking for a popular answer, you will not find it here. This is the one that works for me:

"In our description of nature the purpose is not to disclose the real essence of the phenomena but only to track down, so far as it is possible, relations between the manifold aspects of our experience" Niels Bohr

MY wavefunction of the cat is based on all the information I have about the classical experimental apparatus including MY knowledge of the preparation of the isotope used for the trigger &ct. I will calculate probabilities for cat-alive and cat-dead as functions of time. You may calculate YOUR wavefunction, based on all of YOUR information. It may or may not be identical to mine. You may have slightly different information. When I open the box I will acquire new information, namely cat-alive or cat-dead. I will use my new information to update MY wavefunction to a pure state |cat-alive> or |cat-dead>. If you happen not to be in the room YOUR wavefunction will not change. You might come into the room later and update YOUR wavefunction to a pure state. You might call me on the telephone and get new information. Based on this information you could update YOUR wavefunction to a pure state (if you trust me) or to a new mixed state (if you have reservations about my honesty).

The "cover of the box" doesn't have a wavefunction as it is incapable acquiring and processing the information to build one.

MY wavefunction is about MY information. YOUR wavefunction is about YOUR information. THE wavefunction exists only as a mathematical abstraction in school-book exercises: "Given a hydrogen atom in the ground state, calculate....".

Advantages of this viewpoint:

1. Less sleepless nights dwelling on non-problems.

2. More sleepless nights dwelling on real problems.

3. If there are aspects of quantum theory which cannot be explained by this approach then they might contain a clue to the underlying physical phenomena.

4. There are no, in principle or in fact, unobservable metaphysical entities to cloud our picture of the world.

As for the moon, I agree with Von Weizsacker:

"What is observed certainly exists, about what is not observed we are still free to make suitable assumptions. This freedom is then used to avoid paradoxes."

I use my freedom to assume that the moon is there when I am not looking. So far, this has not lead to a paradox.

Skippy
 
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The simple answer to your question, is that reality exists even if it is not observed, but it is a probabilistic reality, so if no one observes it, no one can know what it is. If an amoeba observes it then that just isn't so great, since the amoeba can't create a subsequent macroscopic record like a paper on arXiv to explain its observation or even a discussion in starbucks.
 
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Observation does not collapse the wavefunction. It's various kinds of "interactions/setups" that collapse it.
 
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"Constrained" probability likely exists in reality.
Else a free-for-all would be present; which we do not see at all.
 
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another example how Copenhagen Int does more harm than good...
 

skippy1729

another example how Copenhagen Int does more harm than good...
Here is a 30 second discussion of CI that you will enjoy. It is a hoot!

 
Last edited by a moderator:
524
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There is no universal agreement on the answers to your questions. If you are looking for a popular answer, you will not find it here. This is the one that works for me:

"In our description of nature the purpose is not to disclose the real essence of the phenomena but only to track down, so far as it is possible, relations between the manifold aspects of our experience" Niels Bohr

MY wavefunction of the cat is based on all the information I have about the classical experimental apparatus including MY knowledge of the preparation of the isotope used for the trigger &ct. I will calculate probabilities for cat-alive and cat-dead as functions of time. You may calculate YOUR wavefunction, based on all of YOUR information. It may or may not be identical to mine. You may have slightly different information. When I open the box I will acquire new information, namely cat-alive or cat-dead. I will use my new information to update MY wavefunction to a pure state |cat-alive> or |cat-dead>. If you happen not to be in the room YOUR wavefunction will not change. You might come into the room later and update YOUR wavefunction to a pure state. You might call me on the telephone and get new information. Based on this information you could update YOUR wavefunction to a pure state (if you trust me) or to a new mixed state (if you have reservations about my honesty).

The "cover of the box" doesn't have a wavefunction as it is incapable acquiring and processing the information to build one.

MY wavefunction is about MY information. YOUR wavefunction is about YOUR information. THE wavefunction exists only as a mathematical abstraction in school-book exercises: "Given a hydrogen atom in the ground state, calculate....".

Advantages of this viewpoint:

1. Less sleepless nights dwelling on non-problems.

2. More sleepless nights dwelling on real problems.

3. If there are aspects of quantum theory which cannot be explained by this approach then they might contain a clue to the underlying physical phenomena.

4. There are no, in principle or in fact, unobservable metaphysical entities to cloud our picture of the world.

As for the moon, I agree with Von Weizsacker:

"What is observed certainly exists, about what is not observed we are still free to make suitable assumptions. This freedom is then used to avoid paradoxes."

I use my freedom to assume that the moon is there when I am not looking. So far, this has not lead to a paradox.

Skippy
On a monday I thought of what you just described. But on a tuesday I entertain Many Worlds where the Wave function is literal and the cat being alive and dead really occurs. On a wednesday. I entertain Bohmian Mechanics where wave function has ontological reality but just informaiton... I'm so fickled minded when it comes to Interpretations. I can't seem to decide what to choose.

About what your describe above that it's just information of the observer. But there is interaction with the observed. For example. In the absence of measurement to determine its position, the electron has no position. And your information update of the wave function should be more complicated (than what you described) because it is interactive with something that appear only when observed. Incidentally, I read what you described is called the Ignorance Interpretations proposed at Solvay Congress 1927 and debunked by Dirac because of what I just mentioned.
 

Fredrik

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another example how Copenhagen Int does more harm than good...
I couldn't agree more.

(I'm assuming that we're defining the CI as "QM plus the assumption that a wavefunction is a complete description of all the properties of a single system", or something very similar to that).

People need to start thinking of QM as an assignment of probabilities to possible results of experiments, instead of as a description of what's actually happening. QM doesn't have a measurement problem. The CI, as defined above, does.
 
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I couldn't agree more.

(I'm assuming that we're defining the CI as "QM plus the assumption that a wavefunction is a complete description of all the properties of a single system", or something very similar to that).

People need to start thinking of QM as an assignment of probabilities to possible results of experiments, instead of as a description of what's actually happening. QM doesn't have a measurement problem. The CI, as defined above, does.
But accepting this QM as mere assignment of probabilities to possible results of experiments won't tell you why a particle can interfere with itself in the double slit. So your proposal is trying to suppress other information by focusing only on the primary one. It may work but this is incomplete physics.
 

Fredrik

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But accepting this QM as mere assignment of probabilities to possible results of experiments won't tell you why a particle can interfere with itself in the double slit. So your proposal is trying to suppress other information by focusing only on the primary one. It may work but this is incomplete physics.
There's no reason to think that QM contains an answer to the question of why a particle "interferes with itself". (Actually, I wouldn't say that a particle does interfere with itself. I would say e.g. that all the paths from the emitter to the detector must be included in the calculation of the total amplitude for detection. Your way of saying it suggests very strongly that we have identified the wavefunction with the actual particle, and that's exactly what I don't want to do, because that's the assumption that's causing most of the confusion about QM).

If you're going to make unjustified assumptions that change QM into something that does contain the answer, then what are you really accomplishing? This is like having a statement "B" that you're uncomfortable leaving unproved, and you know that "A implies B" is true, but you don't know if "A" is true, so you just assume that "A" is true and then claim that you have derived "B" as a theorem. How is it better to assume "A" instead of "B"?
 
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There's no reason to think that QM contains an answer to the question of why a particle "interferes with itself". (Actually, I wouldn't say that a particle does interfere with itself. I would say e.g. that all the paths from the emitter to the detector must be included in the calculation of the total amplitude for detection. Your way of saying it suggests very strongly that we have identified the wavefunction with the actual particle, and that's exactly what I don't want to do, because that's the assumption that's causing most of the confusion about QM).

If you're going to make unjustified assumptions that change QM into something that does contain the answer, then what are you really accomplishing? This is like having a statement "B" that you're uncomfortable leaving unproved, and you know that "A implies B" is true, but you don't know if "A" is true, so you just assume that "A" is true and then claim that you have derived "B" as a theorem. How is it better to assume "A" instead of "B"?
Let's this is how it can be scrutinzed.. by analyzing a one particle at a time double slit experiment. Instead of the particle also being wave and interfering with itself. You mentioned about "all the paths from the emitter to the detector must be included in the calculation of the total amplitude for detection", so instead of the particle turning into a wave. It literally takes all path and the final interference of the single particle is caused by this? This is even more bizarre than the particle turning into wave. If you'd say it is just mathematical. Pls. explain why it could be since an actual particle is emitted. Unless only measurement make sense because somehow the universe before measurement is in some processing unit in some distant surface boundary courtesy of the Holographic Principle.
 

Fra

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There's no reason to think that QM contains an answer to the question of why a particle "interferes with itself".
...
If you're going to make unjustified assumptions that change QM into something that does contain the answer, then what are you really accomplishing?
This is the issue again of "pure interpretations". I agree that at the end of the day these pure interpretations makes no difference.

But if we think QM needs modification and generalisation in order to solve the open issues of QG and unification, then I think there is something to accomplish. But it's not evident as long as the discussions stays at the "interpretation-only" level.

IMHO, there is one very SIMPLE way to actually understand what interfering with yourself means:

In my tweaked version of the information interpretation, the action of an observing system depends on the systems own EXPECTATIONS of the future. This is a little bit like the master always says to the student in old martial arts movies :) "The enemy is not in front of you, he is in your head". This is actually partly true, because your own actions really ARE influence by your OWN expectations of your environmen. You can CHANGE the behaviour of a system, simply by chancing it's expectations of you.

This is how I think of this, and self-interference makes good sense.

Then what difference it makes, is I think not obvious at this point but this is the only way I've found to try to generalize measurment theory to one that is intrinsic and applies also to cosmological scale scenarios.

/Fredrik
 
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This is the issue again of "pure interpretations". I agree that at the end of the day these pure interpretations makes no difference.

But if we think QM needs modification and generalisation in order to solve the open issues of QG and unification, then I think there is something to accomplish. But it's not evident as long as the discussions stays at the "interpretation-only" level.

IMHO, there is one very SIMPLE way to actually understand what interfering with yourself means:

In my tweaked version of the information interpretation, the action of an observing system depends on the systems own EXPECTATIONS of the future. This is a little bit like the master always says to the student in old martial arts movies :) "The enemy is not in front of you, he is in your head". This is actually partly true, because your own actions really ARE influence by your OWN expectations of your environmen. You can CHANGE the behaviour of a system, simply by chancing it's expectations of you.

This is how I think of this, and self-interference makes good sense.

Then what difference it makes, is I think not obvious at this point but this is the only way I've found to try to generalize measurment theory to one that is intrinsic and applies also to cosmological scale scenarios.

/Fredrik
Translate this to a single particle double slit experiment. So the observing system is the detector. And you said "the action of an observing system depends on the systems own EXPECTATIONS of the future." You make it sound like the particle is alive. Just explain how the particle can form destructive interference after million of single hits. The devil is at the details as they say. So you are like saying "the action of the detector depends on the particle own EXPECTATIONS of the future"?? So in your view, a particle can think? You didn't make much sense.
 

Fra

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Translate this to a single particle double slit experiment. So the observing system is the detector. And you said "the action of an observing system depends on the systems own EXPECTATIONS of the future." You make it sound like the particle is alive. Just explain how the particle can form destructive interference after million of single hits. The devil is at the details as they say. So you are like saying "the action of the detector depends on the particle own EXPECTATIONS of the future"?? So in your view, a particle can think? You didn't make much sense.
With particles EXPECTATIONS and the detectors EXPECTATIONS I mean what's implicit in the physical STATE of the particle and the detector.

I'm using the analogy with humans to illustrate the principle only. No I don't suggest observers "think". The particles action is completely random. From the inside view I think the partilces just does a "random walk", it does not think at all of course. But, the random walk takes place relative to the system of mictrostructures that defines the particle itself.

> "the action of the detector depends on the particle own EXPECTATIONS of the future"

I think the INSTANT action of the detector depends on the DETECTORS expectations of the particle. The finite action of the detector depends on the full "interaciton" between particle and detector. I think the "potentialities" for the interference is there always in a single particle, due to the idea that the system responds to it's own expectations (instantly or infinitesimally), but it's still true that in order for use to see it, we need many particles. But this is no more weird that the fact that you need to throw a dice several times to see it's prior. One or two throws does not reveal. But the potentialities is still in the single dice.

All I was commenting is that I personally doe not have any problems to conceptualize what "self-interference" means.

With Expectations I do not refer to thinking particles. I think of it as random walks. But the random walks is relative to the observer, this is why while I am doing a random walk (on step at a time; thinking I follow the easiest path forward) an outside observer can see that I am following a curved path. Here with path I mean a generalizaion from spacetime and path can mean a path in a general state space.

/Fredrik
 
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With particles EXPECTATIONS and the detectors EXPECTATIONS I mean what's implicit in the physical STATE of the particle and the detector.

I'm using the analogy with humans to illustrate the principle only. No I don't suggest observers "think". The particles action is completely random. From the inside view I think the partilces just does a "random walk", it does not think at all of course. But, the random walk takes place relative to the system of mictrostructures that defines the particle itself.

> "the action of the detector depends on the particle own EXPECTATIONS of the future"

I think the INSTANT action of the detector depends on the DETECTORS expectations of the particle. The finite action of the detector depends on the full "interaciton" between particle and detector. I think the "potentialities" for the interference is there always in a single particle, due to the idea that the system responds to it's own expectations (instantly or infinitesimally), but it's still true that in order for use to see it, we need many particles. But this is no more weird that the fact that you need to throw a dice several times to see it's prior. One or two throws does not reveal. But the potentialities is still in the single dice.

All I was commenting is that I personally doe not have any problems to conceptualize what "self-interference" means.

With Expectations I do not refer to thinking particles. I think of it as random walks. But the random walks is relative to the observer, this is why while I am doing a random walk (on step at a time; thinking I follow the easiest path forward) an outside observer can see that I am following a curved path. Here with path I mean a generalizaion from spacetime and path can mean a path in a general state space.

/Fredrik
Why are you making it much more complicated. Why not just accept the Copenhagen explanation that after the particle is emitted, it doesn't have any position even in principle.. and it morphs into a wave and upon exiting the slits, the wave reconstitute into a particle after it reached the detector. What's wrong with this picture? You don't accept it? Which part don't you accept and why?

Or maybe you accept that the wave function is just the knowledge of the person doing the experiment? This doesn't make sense because it implies the particle didn't turn into a wave when unobserved. It just avoids the question of what happens to the electron.

Btw.. you keep mentioning about observers. In the double slit. Is the observer the detector or the person performing the experiment?
 

Fra

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> Why are you making it much more complicated. Why not just accept the Copenhagen explanation that after the particle is emitted, it doesn't have any position even in principle.. and it morphs into a wave and upon exiting

The reason I complicate it, is because I'm aiming at more than just an interpretation. I'm aiming to understand the origin of the interactions themselves (ie. what is usually put in manually as an hamiltonian och lagrangian) and this ultimately suggest a generalisation of QM. In order to do that, I am looking for the simply inside view. Then the more complex eternal view (usually encoded as a lagrangian etc) should be inferrable from the inside view, by means to evolving the theory to a more complex scale.

Ie. Rather than starting from a classical lagrangian, and then "quantize" (in which case you can not explain/understand the interactions and in particular no unification in terms of inference), I am trying to understand all interactions in terms of what I call "rational action" which is the action you get when you make a random walk in the INSIDE VIEW. This random walk takes place in the inferred state space, This ultimately views ALL interactions as emergent as per an entropic construction. From the inside view, all there is are random walks. The more complex (certainl not random ones) are what you see when a second observer, rationally infers the action from another perspective.

If someone is happy with starting with a classical system and then quantize ok fine, but I am not. I'm trying to do more than just "interpret QM" for small subsystems, because to me, the questions are related.

I have nothing to add to the pure interpretational discussion. Some people try to "interpret QM" without going too deep, and without trying to think that the problems of unification and QG has anything todo with the foundations of QM. I think they do.

> Or maybe you accept that the wave function is just the knowledge of the person doing the experiment? This doesn't make sense because it implies the particle didn't turn into a wave when unobserved.

No I don't think the wavefunction refers to human knowledge. I agree it makes no sense.

> Btw.. you keep mentioning about observers. In the double slit. Is the observer the detector or the person performing the experiment?

The observer is not unique, and if you change the observer, the description of the measurement changes. Each experiment can be described by different angles (observers). In my view, there are "many observers" which are interacting, not many worlds or ensembles.

Interactions in general are then EXPLAINED as "interactions" between different observers. This is MY view. And it's aims to explain much more than just old CI.

But to not complicate things: what I mean with "observer" above is the entire measurement apparatous. Ie. detector, slits etc. If you change the slits, the measurement devices changes.

Although it's true that there may be also a human observer, but since the human-measurement devices interaction is purely classical (ie reading a gage or a counter or plate) it is "trivial"(ie classical) in the analysis since we can disregard it.

Classical<->classical communication is commutative, and is thus "trivial" at least in this discussion.

/Fredrik
 

Fredrik

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Instead of the particle also being wave and interfering with itself. You mentioned about "all the paths from the emitter to the detector must be included in the calculation of the total amplitude for detection", so instead of the particle turning into a wave. It literally takes all path and the final interference of the single particle is caused by this?
No. I didn't say that the particle takes all paths, because QM doesn't say that it does. The whole point of saying what I said instead of saying that the particle interferes with itself is to avoid making claims that QM doesn't. I'm just saying that those paths are a part of the calculation of the amplitude for detection. I'm not saying anything about what "actually happens".

If you'd say it is just mathematical. Pls. explain why it could be since an actual particle is emitted.
As I said yesterday in one of these threads, there are only two kinds of answers to questions about reality: Answers given by theories, and BS. I assume that you don't want a BS answer, so I can only explain "why it could be" if there's a theory that provides an answer. Do you know any such theory? I don't.

Unless only measurement make sense because somehow the universe before measurement is in some processing unit in some distant surface boundary courtesy of the Holographic Principle.
If this is not a crackpot interpretation, then you should at least reference an article in a peer-reviewed physics journal that explains it. I can't promise you that I would read it, but I do promise that I won't discuss anything that looks like a crackpot interpretation.
 
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No. I didn't say that the particle takes all paths, because QM doesn't say that it does. The whole point of saying what I said instead of saying that the particle interferes with itself is to avoid making claims that QM doesn't. I'm just saying that those paths are a part of the calculation of the amplitude for detection. I'm not saying anything about what "actually happens".
So it's possible that nothing actually happens? And only the calculations make sense? Thinking about particle physics gauge theory and all those symmetries. It's in the math too and nothing newtonian actually happens. Is this what you are saying that can also happen to our garden variety non-relativistic QM?

As I said yesterday in one of these threads, there are only two kinds of answers to questions about reality: Answers given by theories, and BS. I assume that you don't want a BS answer, so I can only explain "why it could be" if there's a theory that provides an answer. Do you know any such theory? I don't.
Interesting thoughts. Do you have a web site or some article or something about this?


If this is not a crackpot interpretation, then you should at least reference an article in a peer-reviewed physics journal that explains it. I can't promise you that I would read it, but I do promise that I won't discuss anything that looks like a crackpot interpretation.
I just read about it in Brian Greene The Hidden Reality although he used the word "Simulation" but I think we must not use the word "simulation" because it denotes "conspiracies" which can only turn off serious scruntiny of the principle. So let's ignore about this simulation thing for now. Our reality now is much more interesting than it.
 

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