# There is no Copenhagen interpretation of QM

#### WaveJumper

ytuab said:
the whole notion of classical continuous movement is an illusion. OK.
So you say that the electron's motions are an illusion, they don't radiate enegy in standard QM?

But How do you explain about the relativistic mass change of the electron?

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It is written as follows,
A nucleus with a large charge will cause an electron to have a high velocity. A higher electron velocity means an increased electron relativistic mass, as a result the electrons will be near the nucleus more of the time and thereby contract the radius for small principal quantum numbers.
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The relativistic mass change are bigger in Li++ He+ than hydrogen atom.
If you say the electrons are not actually moving, what cause the relativic mass change?
Or you are saying that even if the electrons are not actually moving, the relativistic mass change will occur?

I think your idea is contrary to the standard relativistic theory.
How do you think about it?

I am sure you are aware that your questions are touching foundational questions that are not resolved, namely - the problem of outcomes. Pure quantum states already represent a complete description of of the (physical) state of the system, and their evolution is given by the deterministic Scroedinger equation. Yet, there exists NO fundamental mechanism that would determine which particular outcome is realised in each measurement so that a 'realist' picture of the world we perceive and measure would appear. What matters to most physicists, i would say, is that, whenever there is a measurement there is a particle and observables can be derived and the value of that particluar observale is inline with the predictions of the theory.

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#### Demystifier

2018 Award
How does the existence of particles and waves point to continuous movement of the electrons, say in the Hydrogen atom(without radiating energy)?
The wave determines the quantum potential. The quantum potential determines the quantum force, due to which the electron and its electromagnetic field do not move classically. Radiation would occur if the motion was classical, but it is not classical and there is no radiation.

Is the de Broglie-Bohm view of the atom different from Bohr's?
Yes it is.

How is it not odd that an interpretation would assert that a quantum system does not have any properties before measurement, yet the Schroedinger equation gives us the exact probability of where an electron might land on the screen of the double slit experiment?
Well, it depends on what do you mean by a "property". If probability is a property, then yes, a system has a property before a measurement even in the Bohr's interpretation. But THAT property cannot be revealed by a SINGLE measurement on the system. So either that property is not a property of a single system, or that property is a hidden property (hidden variable) of a single system.

#### Fredrik

Staff Emeritus
Gold Member
What do you mean by "system"?
I mean the object on which we do a measurement. I don't think we need an operational or a mathematical definition here, but if you want to read about such things, see e.g. p. 75-76 in this book. I tried to link directly to page 75, but it didn't work. You'll have to search for the word "uneasiness", which only appears on page 75.

A comment about his notation: Every state vector $|\omega\rangle$ corresponds to a positive linear functional $A\mapsto\omega(A)\equiv\langle\omega|A|\omega\rangle$ on the set of observables. Note that two different normalized states that belong to the same ray (only differ by a phase factor) correspond to the same functional. When he talks about "the state" $\omega$, what he has in mind is this functional (or the corresponding equivalence class of state preparation procedures), not a state vector.

As I pointed out before there can be no physical theory that does not have some kind of ontology. What you probably have in mind is that CI does not ascribe beable status to the wavefunction. But the theory need to have some beables, the "system" you are referring to, the instrument readings, etc.?
A theory is defined by a mathematical model and a set of axioms that tells us how to interpret the mathematics as predictions about results of experiments. What I meant is that there's no need to interpret anything in the model ontologically. See also #135 in the other thread.

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#### Varon

Many physicists say that they prefer the "Copenhagen" interpretation of QM, but it does not mean that all these physicists prefer the same (or even a very similar) interpretation. There are at least 4 very different interpretations that are sometimes referred to as "Copenhagen":

1. Shut up and calculate - this is actually the interpretation that most practical physicists adopt.

2. Positivism - QM is only about the results of measurements, not about reality existing without measurements. (This is essentially the philosophy of Bohr.)

3. Collapse interpretation - when the measurement is performed, then the wave function collapses. (von Neumann)

4. Information interpretation - the wave function does not represent reality, but only the information about reality. (It is somewhat similar to 2., but still significantly different from it.)

What do you think?
I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".
This thread gives such a spectrum of insights and summarize each proponent (Fredrik, Dr. Chinese, Fra, etc.) position. After 2 years of analyzing it. Have you got additional to add or to alter the above 4 interpretations of Copenhagen? Pls. modify it based on your 2 years findings. Thanks.

#### A. Neumaier

whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".
This is no different than with other interpretations.

There is no SINGLE interpretation that may be called "the statistical interpretation".
There is no SINGLE interpretation that may be called "Bohmian mechanics".

What is meant is in each case in the eye of the beholder - with smaller subcommunities agreeing on a particular formulation, usually fixed by a particular reference.

#### Varon

This is no different than with other interpretations.

There is no SINGLE interpretation that may be called "the statistical interpretation".
There is no SINGLE interpretation that may be called "Bohmian mechanics".

What is meant is in each case in the eye of the beholder - with smaller subcommunities agreeing on a particular formulation, usually fixed by a particular reference.
In your formulation. I know you believe particles don't exist but they are just momentum of the field as told by Quantum field theory. Now I want to know is. Is there 100% proof and evidence that particles are really just momentum of the quantum field? Or is just a conjecture? This is supposed to be just a model for QFT. But is there solid proof that in a 430-atom buckyball when you send this off in a double slit, the buckyball quantum wave splits in the slits and splattered all over the detector. Meaning the 430-atom buckyball shatterred into many fragments in the detector as you believe. But rather than proving this. Just prove the general QFT idea that particles are just momentum of the field. Is there experiment that can distinguish this? If this can't be proven. Maybe this particular QFT model is just a temporary belief system to aid in the calculations. Someday. QFT may give rise to or superceded by a return to particles being primary and field just their emanations. Is this impossible? Why?

#### A. Neumaier

In your formulation. I know you believe particles don't exist but they are just momentum of the field as told by Quantum field theory.
Not momentum of the field (which is not even a well-defined notion), but localized concentrations of the field.
Now I want to know is. Is there 100% proof and evidence that particles are really just momentum of the quantum field? Or is just a conjecture?/QUOTE]
It is part of the traditional preparation procedure of particles, which may serve as their definition. One prepares them in a very localized source and lets them move in a very focussed direction. In a field theoric interpretation, it is these properties that give them the particle character.

But this is off-topic here; if you want to discuss it further, do it in the IR thread

#### yoda jedi

What do you think?

I am not asking you to say which interpretation do you find most appealing (we have many other topics on that), but to say whether you agree there there is no SINGLE interpretation that may be called "Copenhagen".

I Agree.