[ExI] Criticisms of Many Worlds Interpretation (MWI)

Tue Sep 26 02:26:47 UTC 2023

On Mon, Sep 25, 2023, 7:06 PM BillK via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Mon, 25 Sept 2023 at 23:39, Jason Resch via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:
> >
> <big snip>
> >
> > It tells us one thing quite clearly:
> > If relativity is true (i.e., nothing can travel faster than light) then
> measurements do not have single outcomes (i.e., there are many worlds).
> > So Aspect's result's are quite extraordinary. He proved that either
> relativity is false, or, that there are multiple universes.
> > This is because if experiments have multiple outcomes, there is no need
> for any effect to travel faster than light to explain the Bell
> inequalities. MW can explain all the observations via local interactions
> that travel at the speed of light or slower.
> >
> > Jason
> > _______________________________________________
>
>
>
> I asked several chatbots (that presumably have been trained on current
> quantum theory) and they all agree with Daniel that MWI is only one of
> several interpretations of quantum theory.
>

All the bots are trained to heavily weight what exists on Wikipedia, which
I think accounts for their common answers on these topics.

> One sample response was:
> Question:
> Does spooky action and violation of Bell's inequalities imply many
> worlds interpretation?
>

I don't think that's a good phrasing. MW holds that there is no spooky
action. It only seems that way because experiments have more than one
outcome (and we always find ourselves in a branch with consistent results).
The Bell inequalities only require spooky action under the condition that
experiments only have a single outcome.

I would instead ask the AI(a):

What interpretations of quantum mechanics are compatible with local
realism, that is, the property that there are no instantaneous faster than
light influences?

> Answer | GPT-3.5-Turbo Model
>
> The violation of Bell's inequalities does not necessarily imply the
> Many-Worlds Interpretation (MWI) of quantum mechanics.

The Bell inequalities together with Aspect's experimental confirmation of
them, only imply Many-Worlds if one holds relativity to be true, (and
therefore one believes relativity's principle tenet: that causality is
limited by the speed of light).

Bell's
> inequalities are mathematical constraints that describe the
> correlations between measurements on entangled particles. The
> violation of these inequalities indicates that the predictions of
> quantum mechanics cannot be explained by local hidden variables,

This is incomplete. See question 32 here, and it's answer:
https://anthropic-principle.com/preprints/manyworlds

"To recap. Many-worlds is local and deterministic. Local measurements split
local systems (including observers) in a subjectively random fashion;
distant systems are only split when the causally transmitted effects of the
local interactions reach them. We have not assumed any non-local FTL
effects, yet we have reproduced the standard predictions
of QM.

So where did Bell and Eberhard go wrong? They thought that all theories
that reproduced the standard predictions must be non-local. It has been
pointed out by both Albert [A] and Cramer [C] (who both support different
interpretations of QM) that Bell and Eberhard had implicity assumed that
every possible measurement -even if not performed - would have yielded a
*single* definite result. This assumption is called contra-factual
definiteness or CFD [S]. What Bell and Eberhard really proved was that
every quantum theory must either violate locality *or* CFD. Many-worlds
with its multiplicity of results in different worlds
violates CFD, of course, and thus can be local.

Thus many-worlds is the only local quantum theory in accord with the
standard predictions of QM and, so far, with experiment."

which
> are deterministic properties of the particles that are independent of
> the measurements made on them. The MWI is one interpretation of
> quantum mechanics that suggests the existence of parallel universes or
> multiple worlds to explain the probabilistic nature of quantum
> phenomena [10].
>

This is true but unrelated to the question you asked.

> The Copenhagen Interpretation of quantum mechanics, which is one of
> the oldest and most commonly taught interpretations, also takes into
> account the violation of Bell's inequalities. It rejects the
> assumption of counterfactual definiteness or "realism" and argues that
> quantum mechanics is as realistic as any theory of its scope and
> maturity can be [12]. The Copenhagen Interpretation emphasizes the
> indeterministic nature of quantum mechanics and the need to consider
> specific laboratory arrangements and complementary properties of
> quantum systems [12].
>

This is also irrelevant to your question. What is important here is that CI
assumes wave function collapse, and moreover requires that it be
instantaneous across any distance of space (and thus faster than light). So
measuring a particle on the other side of the galaxy immediately affects
the state of its entangled counterpart here in Earth.

Most who believe in CI will maintain that this is not a violation of
relativity, as it can't be used to send meaningful information. But to me,
this is clearly a violation of it. As Einstein (along with his co-authors)
wrote of the situation:
https://cds.cern.ch/record/405662/files/PhysRev.47.777.pdf

"This makes the reality of P and Q depend upon the process of measurement
carried out on the first system, which does not disturb the second system
in any way. No reasonable definition of reality could be expected to permit
this."

And in a 1947 letter to Max Born:
"I cannot seriously believe in [quantum theory] because it cannot be
reconciled with the idea that physics should represent a reality in time
and space, free from spooky actions at a distance."

Einstein saw QM (with it's assumption of instantaneous wave function
collapse) as fundamentally in conflict with the idea of there being a real
world out there, governed by local causal (speed-of-light obeying)
interactions.

> It is important to note that the interpretation of Bell's theorem and
> its implications for the nature of reality are still subjects of
> debate among physicists and philosophers.

That's true.

While the violation of
> Bell's inequalities suggests non-locality and challenges certain
> classical notions of reality, it does not necessarily imply the MWI or
> any specific interpretation of quantum mechanics [12].
>

The picture is this:

There are three explanations for the EPR paradox:
1. Local hidden variables
2. FTL influences (a.k.a. spooky action)
3. Non-contra-factual definiteness (a.k.a many-worlds)

Bell's inequalities rule out #1. That means , given Bell's theorem, either
#2 or #3 are the remaining possibilities.

Einstein was not aware of #3 as an option, and because he could not believe
in spooky action, believed #1. This option was disproven by Bell.

So if anyone wants to, in the spirit of Einstein, continue to believe the
speed of light means something, the only option left is #3.

Jason

> In summary:
> Violation of Bell's inequalities indicates that the predictions of
> quantum mechanics cannot be explained by local hidden variables.
> The Many-Worlds Interpretation is one possible interpretation of
> quantum mechanics that suggests the existence of parallel worlds, but
> the violation of Bell's inequalities does not necessarily imply this
> interpretation.
> The Copenhagen Interpretation is another widely taught interpretation
> that takes into account the violation of Bell's inequalities and
> emphasizes the indeterministic nature of quantum mechanics.
> The interpretation of Bell's theorem and its implications for the
> nature of reality are still subjects of debate among physicists and
> philosophers [10] [12].
> -----------------------------
>
> BillK
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