Maybe

How does this resolve if it turns out that physical realism is not the correct assumption or explanation of reality? it seems undecidable in that case, but maybe then the answer is no?

many-worlds is not determinisitc

@ItsMe It is deterministic.

Why would many worlds be random?

“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.)

@IsaacKing Fair :-)

"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.

You've stolen my last name

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.

Possible arbitrage opportunity?

@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.

Not only is it deterministic its predetermined and has already traveled every path.