[ExI] Criticisms of Many Worlds Interpretation (MWI)

[Jason Resch]

On Fri, Sep 15, 2023, 10:11 PM Keith Henson via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> Many worlds has the same problem that "are we living in a simulation?" has.
>
> From the inside, there is no way to tell.
>

This can be said of any theory: that because the only thing we can access
is our own subjectivity, and that could be in error, or designed to have no
correspondence to reality, then we cannot know anything. This predicament
is general, and no more specific to quantum mechanics than it is to gravity.

However, if we relax this supreme Cartesian doubt, and assume we aren't in
a fever dream or under control of an evil demon, then we can make
observations about reality and propose theories to account for them. When
we find these theories make accurate predictions we accept them.

As Leibniz writes: "Although the whole of this life were said to be nothing
but a dream and the physical world nothing but a phantasm, I should call
this dream or phantasm real enough, if, using reason well, we were never
deceived by it."

So if the evil demon, or simulation, or fever dream is reliable enough to
be described by an equation or formula, and one it never deviates from, we
might as well consider it a law.

This is what we have done for QM: we made a formula or equation, and it
works, so far we haven't been deceived by it, so we accept it as a
description of the reality we find ourselves in.

One implication of QM is that there's a multitude of other worlds out there
which only weakly make their existence known to us (through interference
effects). We regard these as real, because whatever dream or demon is
giving the appearance of all these worlds, must be modeling them all too.
Otherwise it wouldn't be able to give us factors of large numbers as a
quantum computer is able to.



> From Pigs in Cyberspace (Hans Moravec who used to post here)
>
> "The very moment we are now experiencing may actually
> be (almost certainly is) such a distributed mental event,
> and most likely is a complete fabrication that never happened
> physically.
>
> "Alas, there is no way to sort it out from our perspective: we
> can only wallow in the scenery."
>

One implication of ensemble theories is that QM must be true for all
observers, even simulated ones. That is, because every observer has
infinite instantiations, it is impossible "trap" their subjectivity in a
single world or in a single simulation. It will always escape/leak into
other neighboring possibilities, the possible continuations given
everything the observer can infer from their present scenery. So all
observers will experience fundamental unpredictability, even if one makes
an observer in a deterministic computer program (from their first person
view, the continuations of that observer's mind don't remain forever tied
to that simulation).

Jason
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