Resolves to physicists' best guess once we have a Theory of Everything and there don't seem to be any more unanswered questions that could in principle be answered.
This is about determinism in principle, not about what we observe. If the many-worlds interpretation of quantum mechanics is true, that counts as deterministic, even though we can't know what branch we're going to be in and it subjectivly seems random.
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“This is about determinism in principle, not about what we observe” I would say “this is about the consensus of the scientific community around the ontology implied by whatever physical theory is accepted at any given time”. It’s not impossible to have different interpretations for the same theory, as is now for quantum mechanics; whether this becomes more common as theories improve or the other way around I have no idea. If multiple interpretations for the theory of everything emerge, how will you resolve
@mariopasquato If there's serious doubt as to the correct answer, and it doesn't look like it's ever going to be resolved, I guess I'd have to resolve N/A. (Or leave the market open forever.)
"If the many-worlds interpretation of quantum mechanics is true, that counts as deterministic, even though we can't know what branch we're going to be in and it subjectively seems random."
"If libertarian free will and modal realism are both real, that counts as deterministic, even though we can't know which choice we will experience making and it is subjectively indeterminate."
Is there are any difference between these two?
If not, there seems to be some bias here in what counts as "deterministic."
@DavidBolin To be more explicit, I think it is obviously true that if the many-worlds interpretation of quantum mechanics is true, then determinism is false, the same way it is false with libertarian free will. Whether or not modal realism is true or opposite branches co-exist is irrelevant; in both cases there are two opposites and both are possible/real, so determinism is false.
@DavidBolin For determinism to be true, you need to have the next states of the universe to be completely determined by the previous ones, and this is the case in the the MWI.
That the different branches of the universe co-exist isn’t irrelevant at all for this question : If a program just print all the possible strings of 0 and 1, some of these strings will look or be random, but the program itself is as deterministic and simple as it could get.
Now, one thing about the MWI is that people can imagine they will end-up in only one branch instead on another after a measure, at random, but this is false: It would ask for something like a soul (or at least, something more than what the theory describes), and actual randomness. I think MWI just implies we should abandon the idea of a closed personal identity.
@dionisos But the next states of the universe are not completely determined by the previous ones, if you include all possibilities as the next states.
E.g. suppose you have a universe that starts out in state 1, and can move to state 2 or 3. Then there are two possible paths: 1-2, and 1-3.
I cannot make that universe deterministic simply by saying "both 1-2 and 1-3 happen, it's that simple."
They may both happen, but they are still two possibilities, so you still don't have determinism.
@DavidBolin
> But the next states of the universe are not completely determined by the previous ones, if you include all possibilities as the next states.
Then, yes, the next states are completely determined. There is absolutely nothing undetermined if all the possibilities happen.
If you think something would be undetermined in that case, then, please, tell what.
> I cannot make that universe deterministic simply by saying "both 1-2 and 1-3 happen, it's that simple.
This is actually that simple.
This would then just be two completely determined parts of the state of the universe.
@dionisos "If you think something would be undetermined in that case, then, please, tell what."
Which one will happen. "Both" is not one of them.
@DavidBolin But both will happen, none will be privileged in this interpretation, and this is what makes it determined.
I think I don’t get where you see a problem here, maybe you are expecting you will be in one in particular ?
@dionisos If there is any absolute meaning to “we are in this branch” and “the branch we end up being in is random” then there is something random (the place where “we” is put) happening, right? Unless “we” is completely interchangeable across branches
If there is any absolute meaning to “we are in this branch” and “the branch we end up being in is random”
Yes, this is true, and this is why this interpretation would not make a lot of sense.
Weirdly, I never see people talking about it, but the MWI sort of implies closed individualism is false. (you will not end-up in any particular branch)
I think it is false for other reasons, but when you bring the perfect continuous copies at a fundamental level of the physical world, I don’t see how you can keep the philosophical position of closed individualism.
If the many-worlds interpretation of quantum mechanics is true
Note that this means that this market isn't asking a physics question. All the interpretations of QM are empirically identical, and some of them are non-deterministic.
I agree it doesn’t really ask a physics question currently, but it could become one if we find another theory, which is not empirically identical to QM and do better predictions, and is clearly deterministic.
It could also resolve for philosophical reasons, if it becomes clear some interpretations of QM doesn’t really make sense (I think currently no interpretation really solve the measurement problem, they mostly just wave their hands at it, but it is actually still ill-defined, and an interpretation that actually solves it would be more correct than all we have now)
@ChristopherKing Sorry about the comment necromancy, but it's not the case that all the interpretations of QM are identical. MWI might, in principle, be testable. (Branches of the UWV aren't necessarily orthogonal, you can have interference between them. Maybe.) There's substantial debate over this. And there's some discussion over experiments for Bohmian Mechanics. Also, like, GRW, if you're a nerd.
@duck_master There's no arbitrage here, Olivia's market is uncoupled from reality, and the title has no relevance to its resolution. Its correct probability is 50% until it starts becoming known what the whales are going to do to it right before close.
I planned on responding to several of the comments, but I'd be repeating many points so I'll state them here.
For those of you citing the Copenhagen Interpretation, I'd challenge you to define what exactly you mean, as the interpretation is ill-defined... Not even Bohr and Heisenberg, the fathers of what is now called the Copenhagen Interpretation, agreed on an interpretation of QM. As a result, there are schisms within the interpretation (see the debate on what constitutes an observer/measurement and whether or not there is a primacy of consciousness within the formalism) (1). Bohr asserted that wavefunctions were symbolic representations rather than a physical reality (2), and yet we have a litany of experimental results that disprove this notion, such as photons in a "[schrodinger's] cat state" (3).
My second point could be seen merely as a language game (and it might be, I don't know), but wave functions evolve according to the Schrodinger Equation. Even assuming that the Copenhagen Interpretation is true, the possible states upon collapse and their associated probabilities are fully determined by this equation. The actual outcome is probabilistic, but I don't see this as much of an argument for global indeterminacy given that the possible outcomes are causally determined.
The possibilities for physical collapse models continue to dwindle as more experiments are conducted (4). While this doesn't mean that wavefunctions don't collapse, as posited in the Many Worlds Interpretation, but there is sufficient evidence to rule out some collapse models.
Lastly, I don't consider polls on what interpretations physicists favor as strong evidence for (or against) the validity of any particular interpretation. As someone who studied physics, my professors never discussed the philosophical implications of QM. It was treated similarly by my textbooks, rarely earning more than the occasional footnote. The prevailing narrative at my university was to "shut up and calculate" and leave the rest to philosophers.
I'm not sure which is correct and am open to being convinced, though I find the simplicity of how the Many Worlds Interpretation treats the Schrodinger Equation to be more compelling than the sort of anti-realist approach provided by the Copenhagen Interpretation.
@JonLamb It's true that many physicists don't care about the metaphysical implications of their work ("shut up and calculate"), but this market cares about the ones that do ("Resolves to physicists' best guess..."). What physicists currently are willing to say, even if many aren't willing to say it, is probably the best available data on what they will eventually think the answer to this question is.
@whenhaveiever I think the "...once we have a theory of everything" is doing a lot of heavy lifting here. The implications of our hypothetical "theory of everything" may be radically different from those of QFT/Core Theory. This is true despite the fact that any underlying theory will have to subsume QFT (in the same way QFT encompasses classical mechanics but has very different implications).
I also don't think the study you linked is very supportive of the idea that "what physicists are currently willing to say... is our best available data" on this subject. In fact, I think the study suggests something much different: many of the physicists who participated haven't put much thought into interpretations of QM.
The majority were:
not familiar with the measurement problem
incorrect about violations of Bell's Inequality excluding hidden variables interpretations (it only excludes local hidden variables)
not familiar with the features of the Many World's interpretation (aside from the Many Worlds it implies), nor with those of Bohm's Pilot Wave interpretation
Moreover, the authors implore readers to "be very cautious in extrapolating the answers from the participants of the survey, to represent the whole of the physics community" given the massive disparity between the number of participants (149) and the number of individuals with at least a Master's in Physics.
Like the authors, I don't think this survey should be taken as evidence for what a majority of physicists think. Furthermore, I don't think this study is the best available (or even good) data on "what physicists will eventually think". I'd take the opinions of physicists would have thought deeply about foundations of quantum mechanics over a general poll any day.
@whenhaveiever I thought about this some more and I agree with what I think your sentiment is. Consensus is important in science, so in many cases a survey of the attitudes of scientists should count for something. However this specific poll isn’t representative of the whole and shows more of a lack of understanding from participants than a consensus. I suspect the lack of awareness is because asks about the interpretation and philosophical implications of a theory rather than an actual scientific theory. I’m sure they know more about physics than I do.
@JonLamb I think you may be misunderstanding what 'determinism' is in a philosophical context - it means that every event is fully determined by previous events, and could never have happened otherwise. If any event happens at all which could have happened otherwise given all previous events, then the universe is not fully deterministic (though it may be mostly so). It is impossible for any event in a fully deterministic universe to have a probability other than 0 or 1. As the question is formulated, any probabilistic outcome would indeed inevitably imply a 'no' answer.