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Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Bill S on 03/07/2018 23:14:21

Title: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 03/07/2018 23:14:21
One of the problems with brief, sporadic, visits to the forum is the risk of losing track of threads; so starting a new thread with thoughts I’ve had between visits is always a temptation.

The Copenhagen Interpretation of quantum theory holds that there is no reality at a quantum level, without observation.

Heisenberg, in developing his case for the uncertainty principle, used the example of “observing” an electron by hitting it with a gamma ray photon.  This act established the location of the electron, at the instant of contact, but gave no information about its velocity.

Bohr used this same example in defending complementarity; arguing that it supported the contention that “observation” created reality, in the quantum realm. The reasoning seemed to be that the electron had neither position, nor velocity, until an observation was made.

This must raise the questions: What was the gamma ray photon aimed at?  And, what did it hit, if the electron was not there before it was hit? 
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bogie_smiles on 04/07/2018 13:00:34
I think your understanding of the Copenhagen interpretation is pretty good.
...

This must raise the questions: What was the gamma ray photon aimed at?  And, what did it hit, if the electron was not there before it was hit? 

I would agree with that skepticism. The objective view is that a particle has location and momentum at all times, but that you cannot measure both at the same time. It is good logic to rationalize that a particle does not need to be observed in order to exist.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: jeffreyH on 04/07/2018 13:12:50
The biggest problem is that the measuring device cannot be independent of the object that it is measuring. It affects the object it is measuring. You can adjust a wavelength to detect either momentum or position but not both. If you want to determine momentum your wavelength has to be long so that multiple measurements disturb the system as little as possible. Shorter wavelengths measure position. This is a physical fact. Not just some esoteric idea.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 05/07/2018 01:44:04
Quote from: Bogie_smiles
It is good logic to rationalize that a particle does not need to be observed in order to exist.

Einstein would have been proud of you. :)

Trouble is that what our natural logic tells us is "obviously" the case, can break down very easily.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 05/07/2018 01:48:23
Quote from: Jeffrey
The biggest problem is that the measuring device cannot be independent of the object that it is measuring. It affects the object it is measuring.

Undoubtedly; but it doesn't say how one could aim at, or hit, an object that doesn't exist until it is hit.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bogie_smiles on 05/07/2018 02:19:23
Einstein would have been proud of you. :)

Trouble is that what our natural logic tells us is "obviously" the case, can break down very easily.
Maybe some would see a distinction between good logic that doesn't easily break down, and natural logic that can break down easily?

Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: jeffreyH on 05/07/2018 07:34:12
Quote from: Jeffrey
The biggest problem is that the measuring device cannot be independent of the object that it is measuring. It affects the object it is measuring.

Undoubtedly; but it doesn't say how one could aim at, or hit, an object that doesn't exist until it is hit.

Well then, the object has to exist. An indeterminacy relates more to our lack of understanding than to whether or not a particle exists. Quantum mechanics is a model. It approximates an underlying reality. We are taught to believe what our senses tell us but they are fallible.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bogie_smiles on 05/07/2018 10:33:58
Quote from: Jeffrey
The biggest problem is that the measuring device cannot be independent of the object that it is measuring. It affects the object it is measuring.

Undoubtedly; but it doesn't say how one could aim at, or hit, an object that doesn't exist until it is hit.

Well then, the object has to exist. An indeterminacy relates more to our lack of understanding than to whether or not a particle exists. Quantum mechanics is a model. It approximates an underlying reality. We are taught to believe what our senses tell us but they are fallible.
Sometimes a Devil's advocate position broadens the discussion, and so, though I don't invoke this thinking, the possible logic for the aiming and hitting an object that isn't there yet, is that there is an expectation that the particle will pass through a given space at a given time, and so the measurement attempt is made.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: jeffreyH on 05/07/2018 12:13:35
Well that leads nicely to the concept of an expectation value.
https://en.m.wikipedia.org/wiki/Expectation_value_(quantum_mechanics) (https://en.m.wikipedia.org/wiki/Expectation_value_(quantum_mechanics))
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bogie_smiles on 05/07/2018 13:10:07
Well that leads nicely to the concept of an expectation value.
https://en.m.wikipedia.org/wiki/Expectation_value_(quantum_mechanics) (https://en.m.wikipedia.org/wiki/Expectation_value_(quantum_mechanics))

Yes, and expectation value is certainly useful in quantum mechanics. When I say that under the Copenhagen interpretation that maybe just the expectation of the hit occurring is enough to cause it to occur is where I am playing the Devil's advocate.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 05/07/2018 20:33:44
Quote from: Jeffrey
Well then, the object has to exist. An indeterminacy relates more to our lack of understanding than to whether or not a particle exists. Quantum mechanics is a model. It approximates an underlying reality.

Isn't this what the Copenhagen Interpretation says is not the case?
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: chiralSPO on 06/07/2018 04:28:35
Heisenberg, in developing his case for the uncertainty principle, used the example of “observing” an electron by hitting it with a gamma ray photon.  This act established the location of the electron, at the instant of contact, but gave no information about its velocity.

Bohr used this same example in defending complementarity; arguing that it supported the contention that “observation” created reality, in the quantum realm. The reasoning seemed to be that the electron had neither position, nor velocity, until an observation was made.

This must raise the questions: What was the gamma ray photon aimed at?  And, what did it hit, if the electron was not there before it was hit? 

As far as I understand it, the problem with this line of reasoning is that electrons aren't actually particles, and neither are gamma rays (and neither of 'em are waves either!) None of these phenomena have any macroscopic analog that offers an intuitive and accurate way of thinking about them--that's how we get into trouble!

Instead of trying to think about a discrete point particles, consider two intersecting infinite (but not evenly distributed) blobs that are going to interact somewhere within their intersection. "Before" the interaction occurs, the best we can do is offer up a probability distribution of where the most likely times and places of the interaction will be, based on information we have about the histories or environments of these blobs. The "time" and "location" of this interaction do not mean that two point particles collided at that precise time and place. No, it merely means that this is when and where the two blobs interacted--no more, no less.

I know this isn't that much more satisfactory than the "shut up and calculate" philosophy, but I think it is very important to remember that subatomic particles aren't mysterious because they are magical--they are mysterious because we are simple creatures that can only understand things by experience, and we really can't experience anything remotely close to the reality of this scale.

Some of QM does kinda boil down to epistemology: we can imagine tiny particles whizzing around at (nearly?) infinite speed, guided by some waveform that only becomes apparent when multiple observations can be made. And maybe this is "actually" how it is. But I doubt it. Even if a ridiculous model ends up making excellent predictions, and lines up well with observations, that doesn't mean that the ridiculous (untestable) parts are true too--those are just there so we have something to imagine.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Colin2B on 06/07/2018 08:43:46
I agree with @chiralSPO it is our attempt to rationalise the quantum world which gets us into trouble. We try to find mental hooks to hang ideas on so we say that because a wave’s energy can be counted in integer units and because it carries momentum it has particle properties (and we end up forgetting that other waves can carry momentum). We also talk about tunneling, but no one suggests that the particle/wave digs a little hole!
I view Copenhagen as a set of rules for using a methodology that gives amazingly accurate answers, but like most analogies and methodologies these rules can be overextended to give even greater confusion.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 06/07/2018 16:50:37
Quote from: ChiralSPO
I know this isn't that much more satisfactory than the "shut up and calculate" philosophy,

I have to disagree with that.  It's the best explanation of the (possible) situation I've seen.  People have written books and said less that is meaningful to "hitch-hikers" than that.

Colin's addition is the icing on the cake.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: chiralSPO on 06/07/2018 17:18:18
Quote from: ChiralSPO
I know this isn't that much more satisfactory than the "shut up and calculate" philosophy,

I have to disagree with that.  It's the best explanation of the (possible) situation I've seen.  People have written books and said less that is meaningful to "hitch-hikers" than that.

Colin's addition is the icing on the cake.

Well, thank you!
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: alancalverd on 06/07/2018 18:03:08
The Copenhagen Interpretation of quantum theory holds that there is no reality at a quantum level, without observation.
And there's the problem. You start with an undefined and probably undefinable concept "reality" then add an equally undefined "observation". That's OK if you want to build a mathematical model in which the undefined variables cancel each other and you end up with a testable prediction, but you can't take the axioms too seriously. It's a bit like "aether" and "conventional current" - helpful but ultimately meaningless!

It's generally preferable to begin with experimental observations, e.g. light is quantised, and work out how these relate to other experimental observations like atomic spectra.

Heisenberg's indeterminacy is mathematically obvious, and no more than a correct formulation of Zeno's paradox. Speed is Δx/Δt, position is x. The larger we make  Δx and Δt, the more precisely we can measure their ratio, but the less meaning we can assign to either x or t. The clever bit is mixing in mass, then guessing that ΔpΔx ≥ h, so whilst we might have a very good idea of the position of a cannonball at any given moment, it becomes very difficult to locate an atom or an electron as m decreases. Ultimately this explains why the hydrogen atom has a finite (but fuzzy) diameter instead of collapsing, and to everyone's surprise h turns out to be a universal constant.

The key to quantum physics is, I think, to accept and use it as a series of statements about what actually happens and not to attempt to derive or "interpret" it from common sense, philosophy, or classical physics.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: jeffreyH on 06/07/2018 19:13:21
I think the idea that 'reality' is a bad starting point is very important. Observation and experiment tell us what happens and not why. Ignore my statement above about an underlying reality. It was just wrong.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 06/07/2018 19:38:46
Quote from: Jeffrey
  It approximates an underlying reality.

If this is what you want us to ignore; I would like to propose, for consideration, the following:

It links a possibly underlying reality, which we cannot perceive directly, to an apparent reality in which we exist, and which we must therefore be able to perceive. 
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: alancalverd on 06/07/2018 22:06:32
Quantum mechanics is nothing more or less than a mathematical description of what we have observed to date. Its value is in its apparent predictive power and universality.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bogie_smiles on 07/07/2018 20:14:26
Interpreting the observations and postulates of QM is as fun as it gets in quantum mechanics, :)
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 08/07/2018 18:44:28
Quote from: Jeffrey
I think the idea that 'reality' is a bad starting point is very important.

Would it be fare to paraphrase/extend this to say something like:

     “Reality” is not the best starting point for thinking about the quantum world.  This would not be because the quantum world is “unreal”, but because our concept of reality is founded in our perception of the macroscopic Universe. 
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 08/07/2018 19:04:51
Quote from: Chiral
Instead of  trying to think about a discrete point particles, consider two intersecting infinite (but not evenly distributed) blobs that are going to interact somewhere within their intersection. "Before" the interaction occurs, the best we can do is offer up a probability distribution of where the most likely times and places of the interaction will be, based on information we have about the histories or environments of these blobs. The "time" and "location" of this interaction do not mean that two point particles collided at that precise time and place. No, it merely means that this is when and where the two blobs interacted--no more, no less.

I’m impressed.  Even I can visualise this.  I’m struggling with one aspect, though.  It has a ring of familiarity to it. 

By “infinite blobs” do you mean:

1. They occupy the entire Universe, or
2. They might occupy the entire Universe, but we don’t know, until an observation is made?

If 1, do we run into the problem of FTL communication when an observation is made?
If 2, do we not have the same problem of mutual location that we had with particles, just on a different scale?

Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 08/07/2018 19:16:36
Quote from: Colin
I view Copenhagen as a set of rules for using a methodology that gives amazingly accurate answers, but like most analogies and methodologies these rules can be overextended to give even greater confusion.
Would you consider that maintaining that the Copenhagen interpretation holds that there is no “reality” before observation is an “overextension”?   It seems to have been fundamental to Bohr’s original concept.

Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 08/07/2018 19:31:49
Quote from: Alan
Heisenberg's indeterminacy is mathematically obvious, and no more than a correct formulation of Zeno's paradox. Speed is Δx/Δt, position is x. The larger we make  Δx and Δt, the more precisely we can measure their ratio, but the less meaning we can assign to either x or t. The clever bit is mixing in mass, then guessing that ΔpΔx ≥ h, so whilst we might have a very good idea of the position of a cannonball at any given moment, it becomes very difficult to locate an atom or an electron as m decreases. Ultimately this explains why the hydrogen atom has a finite (but fuzzy) diameter instead of collapsing, and to everyone's surprise h turns out to be a universal constant.

Heisenberg’s example of the photon hitting the electron seems to suggest that it is the inadequacy of the measuring device that “creates” the uncertainty.  My understanding is that uncertainty is more fundamental to QM, and that however much we might improve our measuring instruments, we will never achieve "certainty".  Would I be right in interpreting your post as agreeing with that?

Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: chiralSPO on 08/07/2018 19:55:52
Quote from: Chiral
Instead of  trying to think about a discrete point particles, consider two intersecting infinite (but not evenly distributed) blobs that are going to interact somewhere within their intersection. "Before" the interaction occurs, the best we can do is offer up a probability distribution of where the most likely times and places of the interaction will be, based on information we have about the histories or environments of these blobs. The "time" and "location" of this interaction do not mean that two point particles collided at that precise time and place. No, it merely means that this is when and where the two blobs interacted--no more, no less.

I’m impressed.  Even I can visualise this.  I’m struggling with one aspect, though.  It has a ring of familiarity to it. 

By “infinite blobs” do you mean:

1. They occupy the entire Universe, or
2. They might occupy the entire Universe, but we don’t know, until an observation is made?

If 1, do we run into the problem of FTL communication when an observation is made?
If 2, do we not have the same problem of mutual location that we had with particles, just on a different scale?



I would say statement 1 is more in line with my understanding. I suspect that statement 2 runs afoul of "hidden variables," which have been shown to be highly improbable by several experiments, known collectively as Bell tests (https://en.wikipedia.org/wiki/Bell_test_experiments).

I don't think that we need to worry about FTL communication, though... the information gained from the interaction will propagate no faster than c.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 08/07/2018 20:22:59
Quote from: Chiral
I don't think that we need to worry about FTL communication, though... the information gained from the interaction will propagate no faster than c.

If the "blobs" occupy the entire Universe until they interact.  Then, at the instant of impact, they cease to occupy the entire Universe, how does the distant part know that it should no longer occupy that space?

Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: guest4091 on 09/07/2018 18:24:24
Some of these points were mentioned, but I'll elaborate.

Quote
The Copenhagen Interpretation of quantum theory holds that there is no reality at a quantum level, without observation
.
---
This is true at all levels of observation.
---
Quote
Heisenberg, in developing his case for the uncertainty principle, used the example of “observing” an electron by hitting it with a gamma ray photon.  This act established the location of the electron, at the instant of contact, but gave no information about its velocity.

Bohr used this same example in defending complementarity; arguing that it supported the contention that “observation” created reality, in the quantum realm. The reasoning seemed to be that the electron had neither position, nor velocity, until an observation was made.
---
Back to basics for a minute. Position and velocity are not properties of a particle. They are relations/descriptions used in human observations for the purpose of understanding the behavior of the world we inhabit, in terms of the model the mind has formed. I.e. they are part of perception, reality confined to the mind. Determining velocity requires two observations to establish a time and space interval, for calculation. One observation gets you an historical position, with no velocity information. The second observation gets you a 2nd historical position. The velocity calculation is made. Now you know where the particle was, and what the velocity was.

There must be a distinction made between a thing as it exists in the physical world, and the perception of that thing, just as with Claude and an image of Claude. The mind is an  image processing system. Looking at the rings of Saturn through a telescope, we know we aren't 'really' that close, but the images have been manipulated to simulate being closer.
There must also be a distinction made between a thing as it exists in the physical world, and our knowledge of that thing. At the moment, I don’t know with certainty if the Eiffel Tower is still standing, unless the media informs me of a terrorist plot to bring it down. Our knowledge is always historical and with a degree of uncertainty.

I would expect the predictive accuracy of quantum physics to be accurate, since it's based on actual historical events or statistics. Similar to what the weather people do.
---
Quote
This must raise the questions: What was the gamma ray photon aimed at?  And, what did it hit, if the electron was not there before it was hit?
---
These type of experiments involve selective targeting of samples. You can research CERN, which has multiple projects in process.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 09/07/2018 23:58:08
Quote
Quote
The Copenhagen Interpretation of quantum theory holds that there is no reality at a quantum level, without observation.

This is true at all levels of observation.

Are you saying that without observation, there is nothing there; or that without observation there is no way of knowing what, if anything, is there?

Quote
Back to basics for a minute. Position and velocity are not properties of a particle. They are relations/descriptions used in human observations for the purpose of understanding the behavior of the world we inhabit,
Should this be interpreted as saying that Heisenberg was not justified in drawing the conclusion he did from his analogy?
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: alancalverd on 10/07/2018 06:03:12
Heisenberg’s example of the photon hitting the electron seems to suggest that it is the inadequacy of the measuring device that “creates” the uncertainty.  My understanding is that uncertainty is more fundamental to QM, and that however much we might improve our measuring instruments, we will never achieve "certainty".  Would I be right in interpreting your post as agreeing with that?

Not "inadequacy" but  an entirely inescapable consequence of measurement. Actually I'm not sure this example is correctly attributed to WH, whose appreciation of indeterminacy was a lot deeper.

Certainty is undefined. What we know (with absolute certainty!) is that either ΔpΔx ≥ h, or the universe would collapse to a singular point. It hasn't, and we have a pretty good idea of the value of h. 
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 10/07/2018 18:24:36
Quote from: Alan
Actually I'm not sure this example is correctly attributed to WH, whose appreciation of indeterminacy was a lot deeper.

Your doubts may be well founded.  I understand it was Bohr who brought this to "public" attention at a Physics Conference in about 1928.  Bohr was notoriously easily misunderstood, so the whole thing may be apocryphal.   

Quote
Certainty is undefined. What we know (with absolute certainty!) is that either ΔpΔx ≥ h, or the universe would collapse to a singular point. It hasn't, and we have a pretty good idea of the value of h. 


Thinks for clarifying that.  All I have to do now is work out why the Universe would collapse.  :)
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: guest4091 on 10/07/2018 19:54:50
Bill S;
Quote
Are you saying that without observation, there is nothing there; or that without observation there is no way of knowing what, if anything, is there?
Knowledge is dependent on sensory input which is analyzed by the brain/mind. Sensory input is predominately visual. Photons are often referred to as 'messenger particles'  since that is one role they play on behalf of the observer. Observation does not cause a material object to exist, but It does make you aware of it's presence. 
Quote
Should this be interpreted as saying that Heisenberg was not justified in drawing the conclusion he did from his analogy?
No scientist should expect to get velocity information from one observation/probe. That is basic physics.
When lasers reflect off the moon, informing them it is creeping away at 1 inch/year, the observation does not alter the state of the moon in any significan/detectable manner.
At the quantum scale of events, the energy of the probes is on an equivalent scale as the object being probed. Like swinging at a baseball with a bat vs a fly swatter The reality he speaks of is our knowledge of the state. The particle has a state, no one knows what it is.
It's not confined to the quantum level.
When you insert a thermometer into a liquid, the device temperature adjusts to the liquid.
Flip a coin. In the air it's H and T, until it lands and becomes H or T. You still have to look to know the outcome.
The uncertainty is not in Schrodingers cat, but in the radioactive sample.
I added that because it seems there is a confusion between things and the perception of things. Science is moving toward more abstract ideas.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 10/07/2018 22:44:02
Quote from: Phyti
Flip a coin. In the air it's H and T, until it lands and becomes H or T. The coin has the “qualities” of H & T, throughout.

  Are you saying that, for example, an electron has position and momentum before observation?

This has some interesting things to say about wave/particle duality and the role of observation, which may be relevant to this thread.

https://www.sciencealert.com/reality-doesn-t-exist-until-we-measure-it-quantum-experiment-confirms
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: PmbPhy on 11/07/2018 02:50:34
There are two things to consider here (1) what does a measurement consist of and (2) what does the system being observed consist of.

Things like Compton scattering are often treated classically so there's no wave function or worry about when a measurement is made or what state the system is in. And when you do use quantum mechanics you have to use quantum electrodynamics.

The other thing to consider is what an observation/measurement is. An observation is made when a microscopic system interacts with a macroscopic system, the results of which can be recorded on/by the macroscopic system.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: yor_on on 11/07/2018 23:07:03
Enjoy reading you Phyti
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: guest4091 on 12/07/2018 15:58:34
The coin has the “qualities” of H & T, throughout.

That is not part of my post
.
If we assume an object persists unless it's destroyed (conservation principle) then it's somewhere, and has a position IF we choose measure it.
If it's not somewhere, the conservation principle is violated.
It still reduces to our knowledge about the object.

As to the article you cited, What is the definition of 'reality'?
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?p
Post by: alancalverd on 12/07/2018 18:04:12
Quote from: Alan
Certainty is undefined. What we know (with absolute certainty!) is that either ΔpΔx ≥ h, or the universe would collapse to a singular point. It hasn't, and we have a pretty good idea of the value of h. 


Thinks for clarifying that.  All I have to do now is work out why the Universe would collapse.  :)

Easy. If ΔpΔx = 0, every electron will spiral in to the nucleus of its atom, emitting a continuous spectrum of electromagnetic radiation as it does so. That's just classical electrostatics and  electrodynamics, and is the Achilles heel of  the classical Bohr atom.

As h > 0, there are finite solutions to the Schrodinger equation and thus nonzero orbital dimensions and shapes, with quantised energy differences between them. Hence a noninfinitesimal universe, the hydrogen bond, stereochemistry, and us. Though the existence of politicians, philosophers and priests still baffles me. What are they for?
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 16/07/2018 00:10:57
Quote from: Spiral SPO
Instead of trying to think about a discrete point particles, consider two intersecting infinite (but not evenly distributed) blobs that are going to interact somewhere within their intersection. "Before" the interaction occurs, the best we can do is offer up a probability distribution of where the most likely times and places of the interaction will be, based on information we have about the histories or environments of these blobs.

I like your "blobs", but have some questions.

According to Copenhagen; do they exist before you observe them?
If they don't; what is there to observe?
If they do; how do you know, if you have not observed them?
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: chiralSPO on 16/07/2018 01:52:17
My understanding is that they exist, they are just undefined (you don't have information about them).

I don't believe that anyone with a firm understanding of physics would claim that the universe ceases to exist when we close our eyes to it. Similarly, it is not that matter goes into and out of existence depending on whether we have our instruments turned on. But it is at least somewhat reasonable to claim that a particle is not located anywhere if there are no ongoing interactions with which to locate it.

Another important point, that has been mentioned in this thread, but not explicitly focused on is this: Nothing can ever be known exactly--there is always some uncertainty. And it is also rare that there is zero information available about something. So asking about the existence of something in the case in which nothing is known about it, is really an extreme case.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 16/07/2018 15:57:32
Quote from: Chiral
.... Nothing can ever be known exactly--there is always some uncertainty. And it is also rare that there is zero information available about something....

 Wouldn't it be true to say that if nothing can ever be known exactly; it would not be "rare" to have "zero" information about something, as that would leave no room for uncertainty?

Pedants of the world, unite!  [:)]
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: chiralSPO on 16/07/2018 16:23:37
Quote from: Chiral
.... Nothing can ever be known exactly--there is always some uncertainty. And it is also rare that there is zero information available about something....

 Wouldn't it be true to say that if nothing can ever be known exactly; it would not be "rare" to have "zero" information about something, as that would leave no room for uncertainty?

Pedants of the world, unite!  [:)]
Indeed. I wanted to say it was impossible to have zero knowledge about something--on the other hand, my experience indicates that it is entirely possible for people (not you) to have zero knowledge...
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 17/07/2018 00:31:36
Quote
...it is entirely possible for people (not you) to have zero knowledge...

I appreciate the "not you", but there are times when I would be inclined to argue with it.  :)

Having not read a book since I was in Hosp in Nov 2016, I'm trying to restructure my routine to do something about that.  I'm about to have a go at Adam Becker's "what is Real".  Does anyone know if it's worth the effort?
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: Bill S on 26/07/2018 21:51:53
I’ve had a quick look at this and think it is relevant to this thread. 

https://www.quantamagazine.org/pilot-wave-theory-gains-experimental-support-20160516/

I understand that Bohm may, at some point, have said that the pilot wave idea might not work.  I have long suspected that this may have had more to do with political and other pressures than to his own doubts.  This article suggests that he kept working on it until his death.
Title: Re: How real is (my understanding of) the Copenhagen Interpretation?
Post by: alancalverd on 27/07/2018 00:14:25
Another important point, that has been mentioned in this thread, but not explicitly focused on is this: Nothing can ever be known exactly--there is always some uncertainty.
It is absolutely crucial to distinguish between uncertainty - the confidence limits of a measurement - and indeterminacy - the fact that ΔpΔx ≥ h.

We can measure the density or x-ray diffraction pattern of solid hydrogen and thus deduce the effective diameter dH of a hydrogen atom with an uncertainty of, perhaps, ± 0.1% But the fact that  dH >> dproton is due to the indeterminacy of the electron.