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> 4. I wonder if Carroll's future work in philosophy will cause him to revisit the many-worlds interpretation of QM, which a fair share of philosophers believe

> 4. I wonder if Carroll's future work in philosophy will cause him to revisit the many-worlds interpretation of QM, which a fair share of philosophers believe carries too much metaphysical baggage. The idea of many worlds "existing" is a philosophical idea; it's not something you learn from studying physics. I think he would argue it carries the least metaphysical baggage as the worlds exist in the equations we have, unlike things posited by other interpretations.

vehemenz 5y ago
That is exactly what he argues. But I think it's a tough position, given that relational quantum mechanics also works "out of the box" and doesn't require ontological realism and a deeply speculative metaphysics. Sean Carroll discusses this with Carlo Rovelli in two separate Mindscape episodes.
- gliptic 5y ago
  Interesting, I'll have to listen to that. Sounds pretty much like QBism though.
- ithkuil 5y ago
  I don't grasp essential the difference between everettian and RQM. I'm both cases different observers observe different results. IIUC the "worlds" on the many worlds interpretation is just a convenient way to talk about the relationship between an observer and the possible states it can observe after the system and the observer have been entangled. The emergence of a world branch is not something that happens at some specific moment in time. This is also why branching can be viewed as happening at superluminal speeds, because it's not a physical phenomenon, just a shortcut for us to use to discard states that are no longer accessible to us. Whether that makes the many worlds interpretation more useful or less useful, it's a matter of context. However I have the impression that most people who oppose the view (e.g. citing how much more baggage it requires etc) fundamentally come from the mental trap of thinking that a conscious observer had a unique stream of consciousness and that anything that deviates from it would be inconceivable because "we don't experience it"
  - vehemenz 5y ago
    What you describe with respect to many worlds sounds more like possible worlds semantics. Someone not committed to the view might treat it as a formalism with no metaphysical baggage, but I don't think that is what the endorsors of many worlds believe. Carroll certainly believes in a universal wave function and actual many worlds. And there is definitely a difference between RQM: https://plato.stanford.edu/entries/qm-relational/#CompOtheInte https://plato.stanford.edu/entries/qm-relational/#CompOtheIn... I am sympathetic to the idea that no one interpretation is 100% correct and that we shouldn't be deeply attached to any of them. Each may have its usefulness in different contexts. Independent of that, some interpretations more accurately describe the quantum world than others, surely.
    - ithkuil 5y ago
      This was my interpretation of Carroll's interpretation of the may worlds interpretation :-) I'm an avid listener to mindscape podcast and read of his books, so I'm likely "indoctrinated", as I don't really know much of these things. But I had the distinct impression that Carrol believes that all there is is the wave function of the universe and everything else (including the many worlds) are emergent phenomena. In a way many worlds are "real" in the same way that "chairs" are real.
gpsx 5y ago
In the paper, Carrol goes through great pains to try reject people changing the laws of physics because they don't understand consciousness. This is exactly how I view people taking up the Copenhagen interpretation of quantum mechanics, where the wave function of the entire universe collapses when a random person makes an observation. Instead I take Schrodinger's equation (and the many worlds interpretation) as the rule and what we observe illuminates how _we_ work, or more specifically how the brain and consciousness work.

vehemenz 5y ago

That is exactly what he argues. But I think it's a tough position, given that relational quantum mechanics also works "out of the box" and doesn't require ontological realism and a deeply speculative metaphysics. Sean Carroll discusses this with Carlo Rovelli in two separate Mindscape episodes.

gliptic 5y ago
Interesting, I'll have to listen to that. Sounds pretty much like QBism though.
ithkuil 5y ago
I don't grasp essential the difference between everettian and RQM. I'm both cases different observers observe different results. IIUC the "worlds" on the many worlds interpretation is just a convenient way to talk about the relationship between an observer and the possible states it can observe after the system and the observer have been entangled. The emergence of a world branch is not something that happens at some specific moment in time. This is also why branching can be viewed as happening at superluminal speeds, because it's not a physical phenomenon, just a shortcut for us to use to discard states that are no longer accessible to us. Whether that makes the many worlds interpretation more useful or less useful, it's a matter of context. However I have the impression that most people who oppose the view (e.g. citing how much more baggage it requires etc) fundamentally come from the mental trap of thinking that a conscious observer had a unique stream of consciousness and that anything that deviates from it would be inconceivable because "we don't experience it"
- vehemenz 5y ago
  What you describe with respect to many worlds sounds more like possible worlds semantics. Someone not committed to the view might treat it as a formalism with no metaphysical baggage, but I don't think that is what the endorsors of many worlds believe. Carroll certainly believes in a universal wave function and actual many worlds. And there is definitely a difference between RQM: https://plato.stanford.edu/entries/qm-relational/#CompOtheInte https://plato.stanford.edu/entries/qm-relational/#CompOtheIn... I am sympathetic to the idea that no one interpretation is 100% correct and that we shouldn't be deeply attached to any of them. Each may have its usefulness in different contexts. Independent of that, some interpretations more accurately describe the quantum world than others, surely.
  - ithkuil 5y ago
    This was my interpretation of Carroll's interpretation of the may worlds interpretation :-) I'm an avid listener to mindscape podcast and read of his books, so I'm likely "indoctrinated", as I don't really know much of these things. But I had the distinct impression that Carrol believes that all there is is the wave function of the universe and everything else (including the many worlds) are emergent phenomena. In a way many worlds are "real" in the same way that "chairs" are real.

gpsx 5y ago

In the paper, Carrol goes through great pains to try reject people changing the laws of physics because they don't understand consciousness. This is exactly how I view people taking up the Copenhagen interpretation of quantum mechanics, where the wave function of the entire universe collapses when a random person makes an observation. Instead I take Schrodinger's equation (and the many worlds interpretation) as the rule and what we observe illuminates how _we_ work, or more specifically how the brain and consciousness work.