Why is there no consensus about the meaning of probability in MWI?

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Discussion Overview

The discussion revolves around the lack of consensus regarding the meaning of probability within the Many-Worlds Interpretation (MWI) of quantum mechanics, particularly in the context of deterministic models. Participants explore theoretical implications, interpretations, and the challenges of defining probability in this framework.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants argue that in a deterministic model, there is no fundamental probability, suggesting that probabilities arise from ignorance of all influencing factors or chaotic dynamics.
  • Others propose that in MWI, probabilities emerge from the branching of worlds, where observers split into separate realities, leading to a lack of knowledge about all possible outcomes.
  • A participant questions why an observer would perceive a higher probability for certain outcomes if the world splits into two, suggesting that a binary tree model does not accurately represent the probabilities observed in repeated measurements.
  • Some participants express skepticism about the ability of MWI to explain probabilities, arguing that it fundamentally rejects randomness and that probabilities are merely a reflection of ignorance.
  • There are mentions of various attempts to derive the Born rule within MWI, including approaches by David Deutsch, Hilary Greaves, David Wallace, Wojciech H. Zurek, Charles Sebens, and Sean M. Carroll, with criticisms of these methods being circular or lacking clarity.
  • One participant notes that the lack of consensus may stem from disagreements over terminology and the absence of a universally accepted explanation for the Born rule in MWI.
  • Another participant highlights that the differences between interpretations of MWI and other theories, such as Bohmian mechanics or superdeterminism, are not sharply defined, leading to further confusion.

Areas of Agreement / Disagreement

Participants generally do not agree on a single interpretation of probability within MWI, with multiple competing views and unresolved questions remaining throughout the discussion.

Contextual Notes

Participants express uncertainty regarding the definitions and implications of probability in MWI, noting that existing models and explanations may not adequately address the complexities involved.

  • #271
May I ask - If one entertains the notion of "multiple worlds" that does not interact, why do we care about consensus between them? It seems it's not a problem as long as they don't interact.

What is wrong with the more obvious: We have "many observers" in the same world, but that DO interact. And the quest is to understand how.

QM as we know, does not describe interacting observers. This why therer is a "problem" whenever we put a "classical measurement device" as part of the "quantum side".

I say lets solve the real problem, I dont see how then many worlds concept is constructive in any direction? How does it help?

/Fredrik
 
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  • #272
Fra said:
I say lets solve the real problem, I dont see how then many worlds concept is constructive in any direction? How does it help?

/Fredrik
It doesn't. It's not even a well-defined concept. It's primarily a name given to an interpretation, where things which it would be reasonable to call "worlds" emerge from the model and scare the living hell out of us. They also invite a catchy, if somewhat misleading, name for the interpretation. But these worlds are not used in the arguments of the model as far as I know, and they are certainly not postulated a priori.
 
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  • #273
kered rettop said:
It doesn't.
I think this all the consensus I need.

/Fredrik
 
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  • #274
Fra said:
I think this all the consensus I need.

/Fredrik
Really? You must be the only person on PF who regards my opinions as being a sufficient consensus. Even I take them with a very large pinch of salt!
 
  • #275
Fra said:
QM as we know, does not describe interacting observers.
How do we "know" this?
 
  • #276
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  • #277
After moderator review, the thread will remain closed.
 
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