[ExI] Quantum Bayesianism (QBism)

[Darin Sunley]

The problem with these approaches is that interpretations of QM get
massively confused when you imagine the universe as a ginormous wave
function plus one or more "observers" that are an entirely different kind
of thing. Per hypothesis, the universe is not a ginormous wave function
plus n observers. It's just wave function all the way down. Observers
aren't actual things that exist. The entire point of many-worlds is that
observers are just factors within the wave function, like every other
observable subset of the universe. "Observation" occurs when any
identifiable factor of the wave function interacts with any other factor of
the wave function.

Maybe it's just the summary, but QBism kinda sounds like dualism with extra
steps. If you want to postulate the existence of souls/observers that are
ontologically different from the rest of the observable universe, just bite
the bullet and go full theist. It's a longstanding and time-honored
ontology, and has significant advantages in terms of internal consistency,
even if it runs unfashionably counter to the spirit of the age.

On Fri, Sep 8, 2023 at 9:57 AM BillK via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Fri, 8 Sept 2023 at 16:15, Jason Resch via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:
> > One thing I would like QBists to explain, is if there is no outer
> reality, only my "degrees of belief", then how is it that my "degrees of
> belief" are able to factor a 1000 digit semiprime, as happens in a quantum
> computer? Something external to me must be doing this, no?
> >
> > Jason
> > _______________________________________________
>
>
> Well, I am not a quantum theory expert. :)  Just an interested reader.
> But the technical article I referenced earlier says --
> A) QBism is still a work-in-progress (like most quantum theories) so
> perfection should not be expected. :)
> and
> B) In QBism, any observer, whether conscious or not, can update their
> beliefs upon making a measurement. There is no need for a special role
> of consciousness in the measurement process.
> --------
>
> I asked for an explanation of B) and AI said --
>
> To understand why this statement is important, let's first consider
> the Copenhagen interpretation of quantum mechanics, which posits that
> the act of measurement causes the wave function to collapse. In this
> view, the observer plays a fundamental role in the collapse of the
> wave function, as their consciousness is what brings about the
> collapse. However, this raises questions about the nature of
> consciousness and its relationship to the physical world.
>
> Qbism, on the other hand, offers a different perspective on the role
> of the observer in quantum mechanics. According to Qbism, the act of
> observation itself, rather than the consciousness of the observer, is
> what collapses the wave function. This means that the observer does
> not need to be conscious in order to bring about the collapse of the
> wave function. Instead, it is the act of observation, regardless of
> whether or not the observer is conscious, that is what matters.
> --------------
>
> To me, that reads as though we should expect the quantum computer to
> act as the observer in your example.
>
>
> BillK
>
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