Position doesn't exist prior to measurement?

[Varon]

It is mentioned in the book "Quantum: Einstein, Bohr and the Great Debate about the Nature of Reality" the following:

"Once the momentum of particle A is measured, it is possible to predict accurately the result of a similar measurement of the momentum of particle B as outlined by EPR. However, Bohr argued that that does not mean that momentum is an independent element of B's reality. Only when an 'actual' momentum measurement is carried out on B can it be said to possesses momentum. A partilce's momentum becomes 'real' only when it interacts with a device designed to measure its momentum. A particle does exist in some unknown but 'real' state prior to an act of measurement. In the absence of such a measurement to determine either the position or momentum of a particle, Bohr argued that it was meaningless to assert that it actually possesed either."

How many here believe it is true, that position, momentum, etc. don't even exist in principle before measurement? How many disagree? And why?

 

[SpectraCat]

It is mentioned in the book "Quantum: Einstein, Bohr and the Great Debate about the Nature of Reality" the following:

"Once the momentum of particle A is measured, it is possible to predict accurately the result of a similar measurement of the momentum of particle B as outlined by EPR. However, Bohr argued that that does not mean that momentum is an independent element of B's reality. Only when an 'actual' momentum measurement is carried out on B can it be said to possesses momentum. A partilce's momentum becomes 'real' only when it interacts with a device designed to measure its momentum. A particle does exist in some unknown but 'real' state prior to an act of measurement. In the absence of such a measurement to determine either the position or momentum of a particle, Bohr argued that it was meaningless to assert that it actually possesed either."

How many here believe it is true, that position, momentum, etc. don't even exist in principle before measurement? How many disagree? And why?

I think that it fundamentally doesn't matter, because you can't frame the question in the form of an experimentally falsifiable hypothesis.

 

[Varon]

I think that it fundamentally doesn't matter, because you can't frame the question in the form of an experimentally falsifiable hypothesis.

I just want to have idea how many percentage believe in either. I'm sure Neumaier believes position still exist all the time because he is a realist like Einstein, Schroedinger. But for those anti-realists like Bohr. Position doesn't exist in principle.

Anyway. For those who believe they don't exist before measurement. Why do atoms don't disappear inside a substance that is not measured. Unless the mere existence of the nucleus is measuring the electrons around it and each atom is measuring the neighboring atom beside it. Is this the standard explanation for those group who believe position, momentum, charge, mass, etc. don't exist before measurements and why atoms don't just vanish?

 

[DrChinese]

Anyway. For those who believe they don't exist before measurement. Why do atoms don't disappear inside a substance that is not measured. Unless the mere existence of the nucleus is measuring the electrons around it and each atom is measuring the neighboring atom beside it. Is this the standard explanation for those group who believe position, momentum, charge, mass, etc. don't exist before measurements and why atoms don't just vanish?

No, the particle exists. According to Heisenberg Uncertainty Principle, there is a relationship between a particle's non-commuting properties. Knowledge of these can be traded off: more of one, less of the other (or vice versa). I think you could more accurately say that the nature of the particle's existence changes. But there is nothing to suggest that the particle itself does not exist at all times. The attraction between an electron and a nucleus would not have the effect of acting as an observation as long as it is a closed system.

 

[Varon]

No, the particle exists. According to Heisenberg Uncertainty Principle, there is a relationship between a particle's non-commuting properties. Knowledge of these can be traded off: more of one, less of the other (or vice versa). I think you could more accurately say that the nature of the particle's existence changes. But there is nothing to suggest that the particle itself does not exist at all times. The attraction between an electron and a nucleus would not have the effect of acting as an observation as long as it is a closed system.

Is it possible for an object to exist yet it doesn't have position even in principle? Bohr specifically said that prior to measurement, there is no position. He has this new idea after EPR. Prior to that. Bohr mentioned how disturbance of one measurement could affect it in the box thought experiment where HUP was scrutinized.

 

[tom.stoer]

I have an agnostic viewpoint because I do not even know what a particle is.

In order to say that the particle does exist with unknwon position I could e.g. say that there is a pointlike particle but 1a) that its position is unknown completely or 1b) that its position does not exist at all or 2a) that I do know its position but only with a certain delta x or 2b) that its position does exist but only with a certain delta x. These are just variations compatible with Copenhagen (which is not uniquely defined, I guess). The problem is that I do not even know what this particle is. I cannot say that it's a pointlike object; or that it's a wave function; I can switch between different representations (abstract Hilbert space, position space wave function, path integral, ... QFT ...) and in all representations the particle "is" something different.

So my conclusion is that I am not allowed to talk about a quantum object having a certain property as long as it is unclear whether this property can be attributed to a quantum object in every case (representation) and why we should agree on attributing this property to an object.

 

[Demystifier]

How many here believe it is true, that position, momentum, etc. don't even exist in principle before measurement? How many disagree? And why?

I believe that most quantities don't exist in an objective sense at all (before, after, or at the moment of measurement itself), but that at least one quantity always exists. Why? Because I believe that there is nothing special about measurements.

If you ask me WHICH quantity is the special one which always exists, my answer is that I don't know, but the particle position seems to be the best candidate.