Is the Many-Worlds Interpretation truly deterministic?

[n01]

Thank you Bill,

I will try and buy the book if I find myself in a possible world where I have enough money to...

All kidding aside, isn't the most probable event the one that dictates the evolution/behavior of the wavefunction and thus presents us with this reality as opposed to any other (less probable, eg. one where I won the lottery)?

 

[secur]

Is Occam's Razor superseded or discredited by Everettian QM in explaining an infinitude of events?

No. Applied to theories Occam's doesn't call for fewer "real" objects, but fewer statements, axioms, or assertions. Which is simpler: "everything has property A", or "everything which is red, Belgian, with mass between 10 and 20 kg, has property A"? The first applies to "infinitely" more objects, but the second is much more complicated. Similarly, "every possible outcome becomes real" vs. "only one outcome becomes real, because of the wavefunction collapse, which means {long explanation omitted}". The first, MWI (or, "Everettian QM"), is (on the face of it) much simpler, even though it instantiates "infinitely" more "real" branches.

can the Church-Turing-Deutsch principle ever hope to amount to anything more than a theory? Can it be proved?

No, although it depends what you mean by "proved". With the normal, naive meaning, C-T can be proved because it's mathematics (or, formal logic). C-T-D can't be proved because it's physics, a statement about the "real" world. Judging by your avatar (Wittgenstein) I suppose you don't like Popper, but you could read him for more insight on this topic.

Under MWI, how is it that this reality (the sum total of logical relations between objects in the universe interacting with each other) is apparent (or real) as opposed to being none other than what it is itself?

No offense, but that doesn't actually make sense. And it will probably be hard to rephrase it so that it does.

 

[n01]

No, although it depends what you mean by "proved". With the normal, naive meaning, C-T can be proved because it's mathematics (or, formal logic). C-T-D can't be proved because it's physics, a statement about the "real" world. Judging by your avatar (Wittgenstein) I suppose you don't like Popper, but you could read him for more insight on this topic.

I don't understand why you use quotations when describing the "real" world.

I have read Popper; but, I subscribe to the notion that every physical law or physics can be understood through a formal system, eg. logic, and mathematics. This is a statement that I believe can either be "proved" to be true, false, undecidable if it fulfills or fails to fulfill the C-T-D principle. I'm kind of assuming the consequent; but, that is only due to not having enough information/knowledge on the matter.

No offense, but that doesn't actually make sense. And it will probably be hard to rephrase it so that it does.

Hypothetically, why haven't I won the lottery yet?

 

[bhobba]

isn't the most probable event the one that dictates the evolution/behavior of the wavefunction and thus presents us with this reality as opposed to any other (less probable, eg. one where I won the lottery)?

Its determined by some deep theorems found in the book.

Take for example going to two worlds. You may think it 50-50 what world you will experience. Now imagine in one of the worlds you do the same thing. So you have worlds - 50- 25 -25. Yet you have three worlds so you would think its 1/3, 1/3, 1/3. It consistency requirements like this that leads to the Born rule being the corrrect probability - its tied up with non-contextuality and Gleason's theorem - but that is for a whole new thread.

Thanks
Bill

 

[mfb]

Hypothetically, why haven't I won the lottery yet?

In MWI you have won in some branches, in those branches you ask why you won the lottery.

 

[secur]

I don't understand why you use quotations when describing the "real" world.

Because you're discussing philosophy (of science). Almost the whole point of this study is, precisely, to figure out what "real" means. So to use the word as though we already know what it means is to commit the fallacy of petition principii. Considering I'm dealing with people who respect someone like David Deutsch, you might ask, why bother to be accurate, to reason correctly - no one can tell the difference anyway. Actually, I've been wondering the same thing myself.

I have read Popper; but, I subscribe to the notion that every physical law or physics can be understood through a formal system, eg. logic, and mathematics.

There's no question that every physical law can be understood that way. A law is a limited, very finite statement written in a book. But the reality underlying that law is something else entirely. I perceive that you still think you can "figure out" life and reality. Have fun, but a word of advice: don't play the stock market! In particular, stay away from options trading.

Hypothetically, why haven't I won the lottery yet?

I don't know that you haven't.

 

[n01]

In MWI you have won in some branches, in those branches you ask why you won the lottery.

That much I understand.

I may be uneducated on the matter; but, why is this timeline where I'm asking these questions apparent to me and not any other? I'm not sure if I'm being clear enough.

Thank you.

 

[secur]

I may be uneducated on the matter; but, why is this timeline where I'm asking these questions apparent to me and not any other? I'm not sure if I'm being clear enough.

MWI says that your consciousness "splits" so that different versions of you exist on every timeline. You see one outcome of an experiment, while your "twin (s)" will see the other (s). The "split" is well-defined in QM math terms. The experimenter is entangled with the wave function, just like any other subsystem can be entangled. However the way consciousness does this, in detail, is not so well-defined.

Anyway, your "twin" right now is probably asking the same question, "why am I on this timeline?" - but it's a different branch he's asking about. According to MWI.

 

[n01]

MWI says that your consciousness "splits" so that different versions of you exist on every timeline.

I know I'm repeating myself; but, I am only aware of one timeline and not others. The wavefunction seems to evolve in a deterministic fashion in that I am experiencing this timeline and not another. How come?

 

[bhobba]

I know I'm repeating myself; but, I am only aware of one timeline and not others. The wavefunction seems to evolve in a deterministic fashion in that I am experiencing this timeline and not another. How come?

That is the assumption of MW.

What you are talking about is a history. In MW all histories happen but you experience just one - by assumption.

Thanks
Bill

 

[n01]

but you experience just one

Can you tell me why do I experience just one? Quite curious.

 

[bhobba]

Can you tell me why do I experience just one? Quite curious.

Its an assumption from the definition of a history - that's why.

The theory assumes that all histories occur and each is a separate world. By the definition of a history you only experience it.

In science some things are assumed - this is one of them. No reason - its just assumed. You have versions of MW where you experience all at once - but your brain only is aware of one. That's called many minds interpretation:
https://en.wikipedia.org/wiki/Many-minds_interpretation

Thanks
Bill

 

[n01]

Its an assumption from the definition of a history - that's why.

The theory assumes that all histories occur and each is a separate world. By the definition of a history you only experience it.

In science some things are assumed - this is one of them. No reason - its just assumed. You have versions of MW where you experience all at once - but your brain only is aware of one. That's called many minds interpretation:
https://en.wikipedia.org/wiki/Many-minds_interpretation

Thanks
Bill

So, the fact that I, or I think I can use the word 'we' without assuming anything, experience the same history means that we are experiencing a super deterministic world as opposed to a less probably one. I've just got it stuck in my head that the most probably stochastic event is what dictates the evolution of 'this' (the one we are both experiencing) world/reality.

 

[bhobba]

So, the fact that I, or I think I can use the word 'we' without assuming anything, experience the same history means that we are experiencing a super deterministic world as opposed to a less probably one. I've just got it stuck in my head that the most probably stochastic event is what dictates the evolution of 'this' (the one we are both experiencing) world/reality.

No.

MW is mathematically very beautiful. You should study the math - not try to semantically analyse it.

Thanks
Bill

 

[PeterDonis]

Can you tell me why do I experience just one?

Because the physical thing in which your experiencing happens is entangled with the physical things you are experiencing. In different branches ("worlds"), these entangled systems are in different states, so the copy of you in those branches experiences different things. But in each individual branch, the entangled systems are each in some particular state, and so you have a certain experience and the things you are experiencing are in the state that is consistent with that experience.

 

[n01]

Because the physical thing in which your experiencing happens is entangled with the physical things you are experiencing. In different branches ("worlds"), these entangled systems are in different states, so the copy of you in those branches experiences different things. But in each individual branch, the entangled systems are each in some particular state, and so you have a certain experience and the things you are experiencing are in the state that is consistent with that experience.

The state space we both occupy (since you are entangled in some manner by replying to this post by me) is evolving non-stochastically? Or are we literally evolving in different state spaces?

 

[n01]

I don't see anything deterministic about the wavefunction evolving in an infinite amount of ways.

If every reality is real then that makes the world "reality" lose its meaning and becomes a vacuous existential (or universal?) quantifier denoting nothing in reality.

 

[PeterDonis]

The state space we both occupy (since you are entangled in some manner by replying to this post by me) is evolving non-stochastically?

The state space doesn't evolve at all. In the usual formulation of the MWI, the evolution of the quantum state, which is a particular vector in the state space, is unitary, hence information-preserving and deterministic. The description in terms of different "worlds" comes from picking a particular basis in which the state vector is a superposition of terms, and viewing each term as a separate world.

Or are we literally evolving in different state spaces?

No. See above.

If you have not spent any time studying the actual math underlying the MWI (and QM in general), I would strongly suggest that you do so. Even better, study several different treatments of it from different viewpoints.

 

[n01]

I would strongly suggest that you do so. Even better, study several different treatments of it from different viewpoints.

If you can recommend any particular books on the matter, I would appreciate for satisfying my curiosity on the matter.

Thank you.

 

[PeterDonis]

If you can recommend any particular books on the matter,

I have found Ballentine to be a good treatment.

https://www.google.com/search?q=ballentine+quantum+mechanics&oq=ballentine+quantum+mechanics

Others here can no doubt suggest other references.

 

[vanhees71]

Well, doesn't this entire debate show, how nonsensical the many-world interpretation (as most other interpretations that go beyond the minimal interpretation) are from a scientific point of view? There may be some people whose mind/consciousness split all the time, particularly those who think "interpretation" is a scientifically relevant topic , but I think that the majority of people, particularly physicists who haven't already lost contact to experiments and observations in the "real world", cannot confirm such experiences with any objective confidence. We do experiments and make observations and always find one outcome (modulo uncertainties of any measurement/observation). There's nothing splitting in branches, and the only thing QT provides are probabilities for the outcome of these unique observations and measurements (unique of course always within the uncertainties any measurement has of course, and most of the experimental work is to provide adequate and objective estimates of statistical and systematic errors!). That's it. There's nothing more concerning "interpretation", and so far there's not a single observation that contradicts this point of view but to the contrary QT is confirmed with an amazing significance.

 

[PeterDonis]

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