Why or how was it decided to stick to the Copenhagen interpretation of quantum mechanics?

Prishon

In Copenhagen it was decided to stick to the Copenhagen view that QM is inherently probabilistic, as apposed to deterministic. Of couurse does the wave function evolves deterministically but the determinism I refer to is the determinism in relation to the motion of particles. They don't posses precisely defined positions and momenta at the same time. These are undetermined and obey a probabilistic law. They have all positions and momenta at the same time (depending on the state of the system). The deterministic view states that at any time the particles have precise positions and momenta.

Now in these times there weren't yet means to exclude or include one of them (as there arent yet today though it can be decided before not too long by measuring arrival times).

What or who or how it was decided to stick to ïndeterminism? Could history had evolved differently? (though for the application of the theory it wouldn't have made a big difference)

Was it simply decided at the Copenhagen conference? Then how it was decided? By majority? By ballot, which is how many things in a democracy are decided which doesn't say much about the reality of the proposal though. Thousand people can vote for things to fall up...

Why was it decided there to stick to the purely probabilistic interpretation and make that the official view? de Broglie's wave made just as much sense. Of course did Born's rule also apply in that case (the square of the de Broglie's wave value gives the probability of an outcome) but the rule is normally associated with the purely probabilistic interpretation. I think the very rule contributed to this interpretation. But I can be wrong.

To put it differently, why do almost all think that Einstein (inherent determinism) was wrong and Bohr (inherent probability) was right?

Andrew M

To put it differently, why do almost all think that Einstein (inherent determinism) was wrong and Bohr (inherent probability) was right? — Prishon

I suspect for pragmatic reasons. Copenhagen was seen as the minimalist interpretation. It left the math alone (with the exception of the collapse postulate). That appealed to physicists who just wanted to link experiments with observations (i.e., shut-up-and-calculate).

Many other interpretations change or extend the math (e.g., objective collapse, de Broglie–Bohm), adding complexity and other undesirable features (e.g., non-locality, hidden variables).

As David Wallace has noted:

Call these strategies "change the philosophy" and "change the physics", respectively.

Famous examples of the change-the-philosophy strategy are the original Copenhagen interpretation, as espoused by Niels Bohr, and its various more-or-less operationalist descendents. Many physicists are attracted to this strategy: they recognise the virtues of leaving quantum mechanics — a profoundly successful scientific theory — unmodified at the mathematical level. Few philosophers share the attraction: mostly they see the philosophical difficulties of the strategy as prohibitive. In particular, attempts to promote terms like “observer” or “measurement” to some privileged position in the formulation of a scientific theory are widely held to have proved untenable.

Famous examples of the change-the-physics strategy are de Broglie and Bohm’s pilot-wave hidden variable theory, and Ghirardi, Rimini and Weber’s dynamical-collapse theory (see the discussions in chapters X and X of the current volume). Many philosophers are attracted to this strategy: they recognise the virtue of holding on to our standard picture of scientific theories as representations of an objective reality. Few physicists share the attraction: mostly they see the scientific difficulties of the strategy as prohibitive. In particular, the task of constructing alternative theories which can reproduce the empirical successes not just of non-relativistic particle mechanics but of Lorentz-covariant quantum field theory has proved extremely challenging.[5] — The Everett Interpretation - David Wallace, 2010

DeScheleSchilder

other undesirable features — Andrew M

Why are these undesirebale? Isn't the unitarity problem, in the MWI, shifted to the branching points?

Andrew M

Why are these undesirebale? — DeScheleSchilder

Non-local theories need to be reconciled with relativity. Hidden variables are constrained by no-go theorems (e.g., Bell's theorem).

Isn't the unitarity problem, in the MWI, shifted to the branching points? — DeScheleSchilder

What is the unitarity problem?

DeScheleSchilder

What is the unitarity problem? — Andrew M

Sorry! I thought you would understand. You seem to know about it. I mean the non-unitary collapse of the wave function. The MWI of Everett does away with this. But at the points where a split into two worlds finds place, it seems that a comparable thing to collapse happens.

Bell constrains but not forbids. There even has been proposed an experiment to distiguish between pure, clean chance and dterminism.

Andrew M

I mean the non-unitary collapse of the wave function. — DeScheleSchilder

OK, you mean the measurement problem - I wasn't sure.

The MWI of Everett does away with this. But at the points where a split into two worlds finds place, it seems that a comparable thing to collapse happens. — DeScheleSchilder

Yes - the difference is that unitary evolution continues and so doesn't require a change to the math.

Bell constrains but not forbids. There even has been proposed an experiment to distiguish between pure, clean chance and dterminism. — DeScheleSchilder

What experiment is that?

theRiddler

Probabalism was a way to try and force determinism onto a mystery, IMO. The maths add up...until they don't.

theRiddler

Some people just can't accept that it's a mystery, a dead space of reason, pure illogic underlying everything. But we must. We must embrace mystery and move forward from there.

TheMadFool

To put it differently, why do almost all think that Einstein (inherent determinism) was wrong and Bohr (inherent probability) was right? — Prishon

My hunch is Einstein was saying something that the math in QM didn't support while Bohr's position was true to the math of QM.

What I find most intriguing is how the math in QM could, in a sense, utter/say something that doesn't make logical sense? It basically means math and logic diverge at the quantum level of reality - what's mathematically cogent is illogical and what's logical is mathematically unsound. The puzzling bit is math is the embodiment of logic. :chin:

Why or how was it decided to stick to the Copenhagen interpretation of quantum mechanics?

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