Layman's questions regarding Measurement Problem

In summary: But it's not just atoms. We can also consider photons to be observers, and so on. So the measurement problem is really just a question of how we should define 'observer' and 'measurement'.B) If i were in the same room as the experiment while observing the electrons via an observation device then as i understand it the wave function collapse will occur. But, what would happen if i were one the other side of the planet, viewing the experiment through via data stream?The wave function collapse would not occur in either case.
  • #1
lauchlan
5
0
Not sure if anyone will be able to answer these questions but it would be good if someone would give it a shot.

A friend recently explained the measurement problem to me and i thought of a few questions which he was not able to answer.

A) Do animals count as observers, and can they cause wave function collapse?

B) If i were in the same room as the experiment while observing the electrons via an observation device then as i understand it the wave function collapse will occur. But, what would happen if i were one the other side of the planet, viewing the experiment through via data stream?

C) If i am controlling the experiment but not observing observing it, will the wave function collapse occur?

D) If a computer program that was sentient observed the experiment, would the collapse occur? I know that nobody actually knows the answer to this but some theories would be great.

Thank you in advance guys.

Sorry if these questions are lame but this has really intrigued me and i can't seem to find answers to my questions due to the fact that most papers i find on the subject are written in what may as well be Greek to me.
 
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  • #2
There have been no definite experiments done to rule out explanations on how collapse occurs. It MAY be animals collapse the wave function, it MAY be our consciousness does. That's all we can say right now.
 
  • #3
It may be animals, but I think it's highly unlikely because that gives special preference to things that, from nature's point of view, don't seem to be special. An electron is an electron, whether or not it is in an animal's brain. So, if it turned out that animals collapsed the wave function, that would be very bizarre, indeed, and there is certainly no reason to believe that that is the case. However, the phenomenon of consciousness is a mysterious one that seems, at least on the face of it, to be a manifestation of nature giving animals a preferred status, so I could be wrong.

For that matter, wave function collapse seems to me to be a mere procedure for predicting the results of experiments, with no clear relation to reality, as such. What is going on behind the scenes remains a mystery.
 
  • #4
I have read that some people argue, not only animals but all the matter around us is consciousness. This is to say that the reality existed even before the life appeared on earth.
 
  • #5
There is also Bohm Mechanics, which 'apparently' mimics quantum predictions, except reality exists at all times, without the need for a wave function collapse.
 
  • #6
I might also add decoherence is used by some to explain the measurement problem. Though there are many that argue decoherence does not lead to any solution of the problem.
 
  • #7
I found the following paper on conscious observer in quantum experiment, in the Journal of Cosmology, 2011.

http://journalofcosmology.com/Consciousness135.html

Hope you would find its interesting.
 
  • #8
lauchlan said:
A) Do animals count as observers, and can they cause wave function collapse?
Yes. Anything big enough collapses the wave function of a system observed by it.

But also a photodiode, or any other measuring device. These are far more reliable than animals,
whom to teach to measure something well is really difficult.

In physics, one usually chooses the simplest explaining set-up - so one doesn't complicate things by replacing a reliable device by something complex such as an animal or a human.

Computer programs are not observers, as the former are not material things. But if a program is in control of a measuring process the.the controlled measuring devices are observers.
 
  • #9
StevieTNZ,

Can you explain how does the reality exist all the time without wave function collapse according to Bhorm mechanics?
 
  • #10
Yes, animals collapse the wave function. I was talking about whether conscious creatures are the ONLY things that do so, which some people have argued for.
 
  • #11
The point is that it is possible to consider a measurement as just time evolution, provided that there's some other collapse later on. So, one idea is that maybe the cut-off point where the "real" collapse happens is with conscious observers.

Also, some people don't believe in collapse at all.
 
  • #12
rpt - I'm not sure if I'd consider something published in the Journal of Cosmology reputable. At all.

I'm uncomfortable with the idea that it requires a "consciousness" to collapse a wave-function. To me, that sounds more like pseudo-science than MWI. Photodiodes collapse wave functions, and unless your definition of consciousness is pretty broad, it's not going to include that.

The measurement problem is interesting, and I don't think it's solved by invoking consciousness.
 
  • #13
Observation is not a matter of living things at all. In a quantum sense, think of observation more like 'interaction'. Atoms can interact with other atoms. Very simplistically, this is effectively an observation.
 
  • #14
I'm uncomfortable with the idea that it requires a "consciousness" to collapse a wave-function. To me, that sounds more like pseudo-science than MWI. Photodiodes collapse wave functions, and unless your definition of consciousness is pretty broad, it's not going to include that.

I don't like the idea, myself, but see, for example Sudbury's book Quantum Mechanics and the Particles of Nature, Chapter 5. He mentions this idea there. You don't have to include photodiodes because, as I said, you can actually incorporate any measurement into Schrodinger evolution, as Sudbery explains in his book. But the catch is that it just pushes the problem somewhere else, rather than solving the problem. So, the idea was to push the problem into consciousness. Probably, whoever put forth this idea would admit that it was speculative, at best.

I don't THINK collapse has anything to do with consciousness, and there is no reason to believe it does, but it's a vague possibility.
 
  • #15
homeomorphic said:
I don't like the idea, myself, but see, for example Sudbury's book Quantum Mechanics and the Particles of Nature, Chapter 5. He mentions this idea there. You don't have to include photodiodes because, as I said, you can actually incorporate any measurement into Schrodinger evolution, as Sudbery explains in his book. But the catch is that it just pushes the problem somewhere else, rather than solving the problem. So, the idea was to push the problem into consciousness. Probably, whoever put forth this idea would admit that it was speculative, at best.

I don't THINK collapse has anything to do with consciousness, and there is no reason to believe it does, but it's a vague possibility.

Wait, what? The entire point of the measurement problem is that it cannot be encoded into Schrodinger evolution! Do you have a paper on this subject?
 
  • #16
Wait, what? The entire point of the measurement problem is that it cannot be encoded into Schrodinger evolution!

Yes, and that's why I said, it doesn't solve the problem, just pushes it somewhere else. There is a collapse, eventually, but it may happen in a later experiment.

Do you have a paper on this subject?

The place where I read about this is Sudbery. That's the only reference I know. He's not claiming that you can incorporate measurement into Schrodinger evolution, exactly. Read it and you'll see.
 
  • #17
homeomorphic said:
Yes, and that's why I said, it doesn't solve the problem, just pushes it somewhere else. There is a collapse, eventually, but it may happen in a later experiment.

The place where I read about this is Sudbery. That's the only reference I know. He's not claiming that you can incorporate measurement into Schrodinger evolution, exactly. Read it and you'll see.

Then what is he claiming? I'm just going on what you claimed he said.

I don't much fancy tracking down a book just to see a proof. And anything can be written in a book. There must be a paper on the topic, surely. Does this interpretation have a name?
 
  • #18
e.bar.goum said:
Then what is he claiming? I'm just going on what you claimed he said.
If one goes back to Schrodinger's poor cat in the box, one can easily imagine putting the entire contraption in a sealed box with a camera that records whether the cat is alive or dead upon opening the inner box. But this just means there are two states inside the outer box - one where the box was opened and the camera imaged a live cat, and the other where the box was opened and the camera imaged a dead cat. You've collapsed a function but you've just pushed the problem outward one box.

You could observe the experiment, check the camera recording, which would collapse it into one state or the other - but what if someone put you and the contraption in a box and did not observe you? There'd be one state where you saw a camera that detected a dead cat, and another state where you didn't. It wouldn't collapse until you were let out of the box and observed.
 
  • #19
Well, maybe I will go check it out for you, and post when I have it figured out. It's been a while since I have thought about it.

Roughly, you consider the measuring device as some huge quantum mechanical system.

I'll have to post about it later when I have time to work it out/look it up. There must be some old papers that discuss these things. The fact that it is in a book doesn't really matter. He proves what he proves.

I don't know if it has a name.
 
  • #20
DaveC426913 said:
If one goes back to Schrodinger's poor cat in the box, one can easily imagine putting the entire contraption in a sealed box with a camera that records whether the cat is alive or dead upon opening the inner box. But this just means there are two states inside the outer box - one where the box was opened and the camera imaged a live cat, and the other where the box was opened and the camera imaged a dead cat. You've collapsed a function but you've just pushed the problem outward one box.

You could observe the experiment, check the camera recording, which would collapse it into one state of the other, but what if someone put you and the contraption in a box and did not observe you? There'd be one state where you saw a camera that detected a dead cat, and another state where you didn't. It wouldn't collapse until you were let out of the box and observed.

Right. Thanks. I've seen that before, it's rather obvious in formal notation. It certainly doesn't solve anything though, unless you're fond of MWI. (Which I kind of am. I blame my advanced theoretical physics lecturer for that)

homeomorphic - it's fine, DaveC has explained his argument, I've seen it before.
 
  • #21
You could observe the experiment, check the camera recording, which would collapse it into one state of the other, but what if someone put you and the contraption in a box and did not observe you? There'd be one state where you saw a camera that detected a dead cat, and another state where you didn't. It wouldn't collapse until you were let out of the box and observed.

Yeah, that's pretty much what he says, but he does the math that says that.
 
  • #22
homeomorphic said:
Yeah, that's pretty much what he says, but he does the math that says that.
If one accepts the premise of the Schrodinger experiment in the first place then this "Russian doll" escalation of the experiment is a logically inescapable outcome - but having a mathematical proof doesn't hurt. :smile:
 
  • #23
homeomorphic said:
Yes, animals collapse the wave function. I was talking about whether conscious creatures are the ONLY things that do so, which some people have argued for.

Well, a photodiode may be considered to be consious of what it observes. Then the answer is yes. If consciousness refers to the kind humans (and animals?) enjoy, the answer is clearly No.
 
  • #24
homeomorphic said:
The point is that it is possible to consider a measurement as just time evolution, provided that there's some other collapse later on. So, one idea is that maybe the cut-off point where the "real" collapse happens is with conscious observers.

Also, some people don't believe in collapse at all.

There is universal agreement that collapse is _observable_ in open systems; it is an intrinsic part of the way theses systems are commonly modeled.

What is debatable is only whether it occurs in closed systems. But this is a moot question, as an observed system is never closed.
 
  • #25
DaveC426913 said:
Observation is not a matter of living things at all. In a quantum sense, think of observation more like 'interaction'. Atoms can interact with other atoms. Very simplistically, this is effectively an observation.

No, not according to standard usage. A measurement/observation requires that the measurement result is irreversibly recorded (at least for some macroscopic time interval).
 
  • #26
Well, a photodiode may be considered to be consious of what it observes. Then the answer is yes. If consciousness refers to the kind humans (and animals?) enjoy, the answer is clearly No.

Not clear in the sense that I was using. I was making a distinction between "real" collapse and other collapses, which are just procedures. Of course, in this sense, it is also not clear that collapses caused by animals are "real".

It's a moot point for me because I consider collapse to be a mathematical procedure, only, so there's no "real" collapse at all. Or maybe there is a "real" collapse, but I don't care because I'm mainly concerned with predicting the results of experiments (unless I want to speculate on interpretation, just for the fun of it).
 
  • #27
There is universal agreement that collapse is _observable_ in open systems; it is an intrinsic part of the way theses systems are commonly modeled.

But we're talking about interpretation, rather than modeling. From a modeling point of view, there may be lots of collapses. But from an interpretational point of view, the question is open as to which of these, if any, are the "real" collapses.
 
  • #28
homeomorphic said:
But we're talking about interpretation, rather than modeling. From a modeling point of view, there may be lots of collapses. But from an interpretational point of view, the question is open as to which of these, if any, are the "real" collapses.

A real collapse is an observable collapse, and that happens all the time in real, open systems.

Closed systems are not observable from the outside, hence it is both irrelevant and undecidable whether or not there is a collapse.

The interpretational problems only appear if one tries to treat an observed, hence open system as a closed system, and then wonders why there are apparent problems arising from taking an idealization for the real thing.

The description by von Neumann's (who introduced consciousness into the interpretational debate) applies only to observations from outside, not to observations from inside a system, as it must be when one assumes as given a closed system, described by the Schroedinger equation. Thus the usual discussions already start from an inconsistency of the descriptions.

On the other hand, nobody seems to have a useful framework for interpreting how to observe a quantum system from inside. Thus there is currently no consistent framework to discuss the question.
 
  • #29
A. Neumaier said:
There is universal agreement that collapse is _observable_ in open systems

Could you please give a reference?

Thank you
 
  • #30
akhmeteli said:
Could you please give a reference?

In quantum optics, one routinely observes and analyzes quantum jumps, the most conspicuous experimental demonstrations of collapse. See, e.g.,
RG Hulet, DJ Wineland, JC Bergquist, WM Itano
Precise test of quantum jump theory
Phys. Rev. A 37, 4544 - 4547 (1988)
or
N Gisin, PL Knight, IC Percival, RC Thompson, and DC Wilson
Quantum State Diffusion Theory and a Quantum Jump Experiment
Journal of Modern Optics 40, 1663 (1993)
A much-cited paper is
MB Plenio, PL Knight
The quantum-jump approach to dissipative dynamics in quantum optics
Rev. Mod. Phys. 70, 101 - 144 (1998).

The Lindblad equations, universally used to describe the dynamics of (mixed) states of open systems have dissipative terms, which are the leftover of collapse when averaged over the quantum jumps.
 
  • #31
Greetings lauchlan:

If I understand the original question, human beings or any others that I know of can not observe individual electrons directly. It requires some kind of instrumentality, and it is that instrumentality by its very nature of being able to observe the electrons causes the collapse of the wave function, not a person, life form, or apparatus, that receives the data from the instrumentality.

Therefore:

A) Do animals count as observers, and can they cause wave function collapse?

No.

B) If i were in the same room as the experiment while observing the electrons via an observation device then as i understand it the wave function collapse will occur. But, what would happen if i were one the other side of the planet, viewing the experiment through via data stream?

No, and no effect.

C) If i am controlling the experiment but not observing observing it, will the wave function collapse occur?

Possible if you are controlling the observing instrumentality, otherwise no.

D) If a computer program that was sentient observed the experiment, would the collapse occur? I know that nobody actually knows the answer to this but some theories would be great.

Again no. Only the actual observing instrumentality can cause the collapse all others would only being seeing the data from the observing instrumentality. Interpretations thereof would depend on that which was receiving the data.
 
  • #32
OMG OMG OMG!


The universe really wanted me to have an answer to this question. Let me explain.

I posted this question a few days ago. I have never met a quantum physicist in my entire life and then yesterday, as i am a gas engineer, i worked in David Deutsch's house...

David Deutsch laid the foundations of the quantum theory of computation, and has subsequently made or participated in many of the most important advances in the field, including the discovery of the first quantum algorithms, the theory of quantum logic gates and quantum computational networks, the first quantum error-correction scheme, and several fundamental quantum universality results. He has set the agenda for worldwide research efforts in this new, interdisciplinary field, made progress in understanding its philosophical implications (via a variant of the many-universes interpretation) and made it comprehensible to the general public, notably in his book The Fabric of Reality.

Basically he told me that if you subscribe to the single universe idea then you could believe that consciousness collapses the wave function. But, if you subscribe to the multi universe theory then all you are seeing is a single slice of the pie, and hence one of the outcomes of the many available to the electron. Kind of like it is spread out over all the universes, but you can only see one outcome. I think that is what he meant.

Anyway, for those of you debating this and who are interested in his answer to it, you should read his book, apparently this topic is discussed at length in chapter two. Can't wait to have some time off i Jan to get through it.

Still can't believe my luck. Seriously, what are the chances, i do live in Oxford, but still. Do hope he invests in a new boiler though because the one he has is probably going to end end his life in this universe.

Thanx again for all the replies guys :)
 
  • #33
A. Neumaier said:
In quantum optics, one routinely observes and analyzes quantum jumps, the most conspicuous experimental demonstrations of collapse. See, e.g.,
RG Hulet, DJ Wineland, JC Bergquist, WM Itano
Precise test of quantum jump theory
Phys. Rev. A 37, 4544 - 4547 (1988)
or
N Gisin, PL Knight, IC Percival, RC Thompson, and DC Wilson
Quantum State Diffusion Theory and a Quantum Jump Experiment
Journal of Modern Optics 40, 1663 (1993)
A much-cited paper is
MB Plenio, PL Knight
The quantum-jump approach to dissipative dynamics in quantum optics
Rev. Mod. Phys. 70, 101 - 144 (1998).

The Lindblad equations, universally used to describe the dynamics of (mixed) states of open systems have dissipative terms, which are the leftover of collapse when averaged over the quantum jumps.

Thank you very much for the references. I'm still not sure though. Those references do not seem to have wordings similar to what you offer: "There is universal agreement that collapse is _observable_ in open systems" . Furthermore, everybody emphasizes that the transition from one state to another is fast, but continuous (so theoretically there is always a superposition); therefore, the only thing one can say is that under some conditions collapse can be a good approximation. No authors of your references seem to claim any experimental deviations from unitary evolution. On the other hand, unitary evolution directly contradicts strict collapse, as defined in the projection postulate. So I tend to accept the Schlosshauer's conclusion (M. Schlosshauer, Annals of Physics, 321 (2006) 112-149)):

"no positive experimental evidence exists for physical state-vector collapse"
 
  • #34
A real collapse is an observable collapse, and that happens all the time in real, open systems.

But what does it mean for a collapse to be "observable"?

I don't know if it is the collapse itself that is observable. I would tend to think it was more like the result of the collapse. So, I see the collapse as more of a mathematical black-box, and the measurement itself (say, position of the electron is between x and y), as the "real" thing.
 
  • #35
Wouldn't an open system still be described fundamentally by the Schrodinger equation, hence superpositions all the way?
 
<h2>What is the measurement problem in science?</h2><p>The measurement problem refers to the philosophical and scientific debate surrounding the nature of measurement and the reliability of scientific measurements. It questions whether measurements can accurately capture the true nature of reality and whether there is a single, objective reality that can be measured.</p><h2>Why is the measurement problem important?</h2><p>The measurement problem is important because it challenges the foundation of scientific knowledge and the validity of scientific experiments and theories. It also raises questions about the role of human perception and interpretation in the scientific process.</p><h2>What are some proposed solutions to the measurement problem?</h2><p>Some proposed solutions to the measurement problem include the idea of multiple realities, where different measurements can be valid in different contexts, and the concept of complementarity, where different measurements reveal different aspects of reality. Other solutions involve incorporating consciousness and observer effects into the measurement process.</p><h2>How does the measurement problem relate to quantum mechanics?</h2><p>The measurement problem is often associated with quantum mechanics because it challenges the traditional understanding of measurement in this field. Quantum mechanics suggests that the act of measurement can affect the outcome of an experiment, leading to uncertainty and multiple possible outcomes.</p><h2>Is the measurement problem still a topic of debate in the scientific community?</h2><p>Yes, the measurement problem continues to be a topic of debate in the scientific community, particularly in the field of quantum mechanics. While some scientists believe that the problem has been solved, others argue that it remains a fundamental challenge in understanding the nature of reality and the role of measurement in science.</p>

What is the measurement problem in science?

The measurement problem refers to the philosophical and scientific debate surrounding the nature of measurement and the reliability of scientific measurements. It questions whether measurements can accurately capture the true nature of reality and whether there is a single, objective reality that can be measured.

Why is the measurement problem important?

The measurement problem is important because it challenges the foundation of scientific knowledge and the validity of scientific experiments and theories. It also raises questions about the role of human perception and interpretation in the scientific process.

What are some proposed solutions to the measurement problem?

Some proposed solutions to the measurement problem include the idea of multiple realities, where different measurements can be valid in different contexts, and the concept of complementarity, where different measurements reveal different aspects of reality. Other solutions involve incorporating consciousness and observer effects into the measurement process.

How does the measurement problem relate to quantum mechanics?

The measurement problem is often associated with quantum mechanics because it challenges the traditional understanding of measurement in this field. Quantum mechanics suggests that the act of measurement can affect the outcome of an experiment, leading to uncertainty and multiple possible outcomes.

Is the measurement problem still a topic of debate in the scientific community?

Yes, the measurement problem continues to be a topic of debate in the scientific community, particularly in the field of quantum mechanics. While some scientists believe that the problem has been solved, others argue that it remains a fundamental challenge in understanding the nature of reality and the role of measurement in science.

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