[ExI] Quantum Bayesianism (QBism)

[BillK]

QBism seems to be becoming popular, with more articles appearing.

<https://theconversation.com/qbism-quantum-mechanics-is-not-a-description-of-objective-reality-it-reveals-a-world-of-genuine-free-will-200487>
Quote:
‘QBism’: quantum mechanics is not a description of objective reality –
it reveals a world of genuine free will   By: Ruediger Schack
Published: March 29, 2023

<https://medium.com/physics-philosophy-more/qbism-a-technical-discourse-34109e2b3c16>
Quote:
QBism — A technical discourse
Sanjay Basu, PhD     May 25, 2023
Unraveling QBism: A Deep Dive into Quantum Bayesianism


I asked AI to summarize and explain QBism:

QBism, also known as Quantum Bayesianism, is a philosophical
interpretation of quantum mechanics that combines elements of
subjective probability and Bayesian reasoning. It was developed by
physicist Christopher Fuchs and his colleagues in the early 2000s as a
response to the long-standing interpretational issues and paradoxes in
quantum theory.

At its core, QBism asserts that quantum mechanics is fundamentally
about an agent's personal beliefs or degrees of belief rather than
objective reality. It emphasizes the role of the observer and their
subjective experiences in understanding quantum phenomena. According
to QBism, the wave function, which describes the state of a quantum
system, represents an agent's personal probabilities or expectations
for different measurement outcomes.

In QBism, probabilities are understood as subjective degrees of belief
rather than objective frequencies or propensities. These probabilities
are updated using Bayesian inference, a mathematical framework for
updating beliefs based on new evidence. The agent's beliefs are
represented by a probability distribution over possible measurement
outcomes, and this distribution is updated using Bayes' theorem after
each measurement.

One key aspect of QBism is its rejection of the idea that quantum
systems have definite properties before they are measured. Instead, it
argues that these properties only exist in relation to an observer's
measurements and their subjective beliefs. This view is often referred
to as "participatory realism," as it suggests that reality is created
through the interaction between the observer and the observed system.

Another important concept in QBism is the notion of "quantum states as
personalist Bayesian agents." According to this idea, quantum systems
can be thought of as agents that update their own beliefs based on
their interactions with other systems. This perspective allows for a
more intuitive understanding of entanglement and non-locality in
quantum mechanics.

QBism also addresses the long-standing debate between wave-particle
duality and the collapse of the wave function. It suggests that these
concepts are not fundamental but rather emerge from an agent's
interactions with quantum systems. The wave function is seen as a tool
for making predictions about measurement outcomes, rather than a
physical entity.

Overall, QBism offers a new perspective on the interpretation of
quantum mechanics that places the observer and their subjective
beliefs at the center of the theory. It provides a framework for
understanding quantum phenomena in terms of personal probabilities and
Bayesian reasoning, challenging traditional notions of objective
reality.
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So, Many Worlds Interpretation is not required with QBism.

BillK