# Does valid interpretations of quantum mechanics always reduce to trivial arguments about the equations? [closed]

This is the editted 'short' version of the question :)

Interpretation is very important in physics, but physics is governed by equations. With bare equations, physics would be just mathematics. Physics relies on the experiments, and the underlying theory and consistent experimental agreement verifies the theory. A physical phenomenom is bound to be explained by known laws of physics or not at all or not yet.

There are many kinds of interpretations, for example regarding particle/wave nature of electrons, the measurement problem and virtual particles. Interpretations evolve over time as understanding grows. With 'valid interpretations' in caption, I mean such interpretations which are scientifically sound and contain a minimum amount of postulates required. The decoherence explanation of the 'measurement problem' required no additional postulates, and thus was reduced.

What confuses me, is that admittedly, the early interpretations of quantum mechanics puzzled the people in Copenhagen, but how come they still puzzle in university classes. For example, 'collapse of the wave function' does no longer need additional postulates of wave function collapse as it did before, but it can be explained with decoherence arising directly from including the environment to Schrödniger equation. We find that lack of knowledge led to these seemingly hard to understand interpretations, but when clarified, they reduced back to the QM mathematics world.

Weird things are being said, like 'Electron is a particle when measured', 'Electron has both particle and wave nature' and 'Electron is a wave until it collapses to a particle in the measurement device' or 'Waves are not objects. Only particles are physical objects'. A well educated interpreter knows, that the whole apparent paradox of the particle-wave duality just arises, when classical terms are being assigned to things in the QM mathematics world. Thus, almost if increased understanding of interpretation quantum mechanics has suddenly diverted interpretation ball back to QM mathematics world for explanation.

Thus, I feel that given any experiment, it is always possible to formulate the appropriate equations, transition matrix element etc., to describe this experiment and the interpretation is needed i) to give names to terms being used in equations. ii) To discuss effects happening in these equations. Thus, I feel that all sound quantum mechanical interpretations can be reduced so that i) equations describe the process fully ii) absolute minimal interpretation is required (such as naming things, and definitions so that people can discuss about reality).

Now the question is: Do you feel that same way about interpretation of quantum mechanics, or what counter arguments you can come up against my argumentation? As a bonus, I would be interested in links to sound scienficic research into interpretations of quantum mechanics (this would be qualitative research, philosophy of science etc.? ).

Here is some more text about 'interpretation of virtual particles':

I believe that some of you may agree with me so far, but I will now push harder. What about virtual particles? They are called virtual in the interpretation world. To distinguish them from 'real' particles? Here is a direct quote from wikipedia "They appear to be able to violate basic laws of physics. Regular particles of course never do so." If something appears to be violating basic laws of physics, perhaps it's interpretation in which it 'appears' is completely wrong. Instead of relectrons and velectrons, let's go back to the equations. I will not do QED for simplicity, but just our 1D electron with a external field.Here is a Feynman-like diagrams, describing how a free electron would move in a potential:

===>=== = --->--- + --->---*--->--- + --->---*--->---*--->--- ...
|                 |       |
V(t1)             V(t1)   V(t2)


Now, there are lots of electrons being created and annihilated within these diagrams, that are by definition virtual. Now let's assert that virtual and real particles are indistinguisable (i.e. there are no virtual particles). What are the implications? There just aren't any. And you know what happends to statements without implications in science? Only thing which distinguishes virtual and real particles, are that virtual particles are inside a diagram by definition (describing the mathematical propagator object). This is always in a context of a particular set of diagram, and that is just a definition. Thus, a closer look into interpretation once again reduced to trivial arguments about the equations. And what about the apparent violation of laws of physics by virtual particles but not real. Let's consider photon here for a while, since the law in the Wikipedia text might refer to that light speed in vacuum is c, and matter and information cannot travel faster than c. Firstly, light speed is in vacuum c, as predicted by QED, when those superluminal propagators are plugged in. Secondly, the reason why we won't observe 'off mass shell' virtual particles is that our measuring devices are incapable of to do so (see Scharnhorst effect where light speed is predicted >c). QED is historically mostly used to describe particle collisions with well defined momenta states, and this has created the terminology. A measurement is always an entanglement of the measuring device to the quantum system. It is increasingly hard to couple it in such spatial and temporal scales with the system do display off shell effects. In conclusions, there are no 'magic' interpretations needed even for virtual particles, but they are just propagators of QM equations. Experiments can be well understood keeping all the particles as real as it gets.

## closed as unclear what you're asking by DanielSank, user36790, Kyle Kanos, ACuriousMind♦, Sebastian RieseDec 1 '15 at 14:41

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This is an interesting and valid point of view.

It goes beyond "Shut up and calculate!". That "motto" says that's not relevant for science to care about reality, as long as we have a theory that's works well to predict outcomes of experiments.

If I understand correctly your question, you state that the equations are good, and problems only arise when you try to "interpret" them. This is physical realism, and saying that physical reality is the universale wave fonction. Or, if you want to avoid a too strong statement : there is a physical reality and quantum physics equations is the most accurate view we have on it.

However, as long as you says that "wave fonction collapse" is explained by putting environment (and observer) in the Schrödinger equation, you are exactly in the Everett interpretation. So even if you may want to avoid choosing an interpretation, you are very near to this one.

• Thanks. Also the term 'physical realism' was new to me. That will be a good keyword to search with. I am not in field of 'philosophy of science' or anything, which makes it hard to formulate even the question. – Mikael Kuisma Dec 1 '15 at 11:56

The most important thing to remember is that waves are not objects. Only particles are physical objects. A wave is a name we give to a specific type of process where particles toss photons to each other. You can never touch a wave. When you touch a 'wave' the best you can do is touch a particle participating in a wave.

There is no wave/particle duality.

A photon or electron is a particle.

Always has been and always will be.

EDIT: I got this insight from watching Bill Gaede's videos. Most of his videos and his theory are, ahem, amusing, but he does raise some valid points along the way about reification in physics.

Does valid interpretations of quantum mechanics always reduce to trivial arguments about the equations?

No. It reduces to a very important issue of understanding. We do physics to understand the world. Shut up and calculate is just not good enough.

There are many kinds of interpretations, for example regarding particle/wave nature of electrons, the measurement problem and virtual particles. Interpretations evolve over time as understanding grows. With 'valid interpretations' in caption, I mean such interpretations which are scientifically sound and contain a minimum amount of postulates required.

Make sure you look at weak measurement and work by Aephraim Steinberg et al and work by Jeff Lundeen et al. See this in Jeff's semi-technical explanation:

"With weak measurements, it’s possible to learn something about the wavefunction without completely destroying it. As the measurement becomes very weak, you learn very little about the wavefunction, but leave it largely unchanged. This is the technique that we’ve used in our experiment. We have developed a methodology for measuring the wavefunction directly, by repeating many weak measurements on a group of systems that have been prepared with identical wavefunctions. By repeating the measurements the knowledge of the wavefunction accumulates to the point where high precision can be restored. So what does this mean? We hope that the scientific community can now improve upon the Copenhagen Interpretation, and redefine the wavefunction so that it is no longer just a mathematical tool, but rather something that can be directly measured in the laboratory".

Weird things are being said, like 'Electron is a particle when measured', 'Electron has both particle and wave nature' and 'Electron is a wave until it collapses to a particle in the measurement device' or 'Waves are not objects. Only particles are physical objects'...

It isn't weird when you've looked at the optical Fourier transform, see Steven Lehar's web page.

A photon has an E=hf wave nature. Ditto for an electron. The wave goes through both slits and interferes with itself. But when you detect it at the screen you perform something akin to the optical Fourier transform on it, and it's converted into something pointlike so you see a dot on the screen. Or if you detect it at one of the slits you perform something akin to the optical Fourier transform on it, and it's converted into something pointlike so it goes through that slit only. Then there's no interference. No mystical waves of probability are required, and nor is any many-worlds multiverse.

Do you feel that same way about interpretation of quantum mechanics, or what counter arguments you can come up against my argumentation?

I'm not sure whether I share your view. But whatever: I will not accept quantum physics surpasseth all human understanding.

As a bonus, I would be interested in links to sound scientific research into interpretations of quantum mechanics

Read the physicsworld article In Praise of Weakness.

I believe that some of you may agree with me so far, but I will now push harder. What about virtual particles?

They are virtual. They aren't real. They don't pop in and out of existence like magic. That's a popscience myth. It's like what anna v said in this answer. Virtual particles exist only in the mathematics of the model.

If something appears to be violating basic laws of physics, perhaps its interpretation in which it 'appears' is completely wrong.

Electrons and protons don't throw photons at one another. Hydrogen atoms don't twinkle. Virtual photons aren't short-lived real photons popping in and out of existence like magic, and they aren't the same thing as vacuum fluctuations. Instead they're "field quanta". It's like you divvy up an electromagnetic field into little chunks, and say each is a virtual photon. Then when the electron and the proton attract one another, they exchange field, such that the resultant hydrogen atom doesn't have much of an electromagnetic field at all. Hence you can see the underlying correctness of the exchange idea and why QED "works". However when two hydrogen atoms attract each other gravitationally, they don't exchange field. Instead of the two fields (almost) cancelling one another, they're additive. So whole concept of virtual gravitons being exchanged just doesn't fly.

Now, there are lots of electrons being created and annihilated within these diagrams, that are by definition virtual...

That's virtual as in not real. For some reason a strange cargo-cult myth has grown up which claims virtual particles are short-lived real particles. They aren't.The notion that they is is just a "lies to children" fairy tale. Only it would seem that some physicists have grown up believing it.