Question pertaining to the random distribution of many worlds

[g564321]

TL;DR Summary

Question on whether the many worlds interpretation produces every last conceivable outcome

Hi everyone,

I was having a conversation with my friend about the many worlds interpretation of quantum mechanics, and we couldn't figure out if many worlds implied every single last possible conceivable outcome, or if there were certain limitations that the system was confined to.

For example, there are things called synchronicities, moments where multiple facets of an individual event are highly connected, i.e. coincidences, but are supposed to hold some special inherent meaning for the observer. Just to make the question completely clear, would the many worlds interpretation allow for a life where one person lived nothing but synchronicities every day, i.e. a mass multitude of highly correlated and connected events, while the remainder of the people in this same specific world lived random lives, or is the many worlds interpretation always confined to some sort of random distribution?

 

[PeterDonis]

There is no randomness at all in the MWI. The wave function evolves deterministically at all times. In terms of measurement outcomes, any outcome that has a nonzero amplitude in the wave function occurs.

However, whether or not the wave function includes nonzero amplitudes for every possible "outcome" that you can imagine, such as this...

a life where one person lived nothing but synchronicities every day, i.e. a mass multitude of highly correlated and connected events

...is a different question, whose answer might well be "no".

 

[g564321]

There is no randomness at all in the MWI. The wave function evolves deterministically at all times. In terms of measurement outcomes, any outcome that has a nonzero amplitude in the wave function occurs.

However, whether or not the wave function includes nonzero amplitudes for every possible "outcome" that you can imagine, such as this...
...is a different question, whose answer might well be "no".

Thank you for your reply. Additionally, sorry for needing the extra clarification, but I've seen a few sources that have left whether or not there are infinite many worlds or a finite number of many worlds as an open ended question, i.e. it's not currently known. By "might well be no", do you mean that it's possible, but only just possible, that the outcomes aren't that varied, or that it's definitively known that this couldn't occur.

 

[PeterDonis]

I've seen a few sources that have left whether or not there are infinite many worlds or a finite number of many worlds as an open ended question

Please give specific references. We can't discuss unspecified "sources".

By "might well be no", do you mean that it's possible, but only just possible, that the outcomes aren't that varied

My statement about what outcomes have nonzero amplitudes in the wave function had nothing to do with whether the total number of worlds is finite or infinite. Even infinitely many worlds can still fail to realize all the possible "outcomes" that a particular person can dream up in their imagination. Your imagination is not a good guide to what outcomes actually have nonzero amplitudes in the wave function.

 

[g564321]

Please give specific references. We can't discuss unspecified "sources".
My statement about what outcomes have nonzero amplitudes in the wave function had nothing to do with whether the total number of worlds is finite or infinite. Even infinitely many worlds can still fail to realize all the possible "outcomes" that a particular person can dream up in their imagination. Your imagination is not a good guide to what outcomes actually have nonzero amplitudes in the wave function.

In terms of sources, this video sums up what I was referencing.



The part about infinite vs finite worlds starts at about the 3:50 mark.

Anyway, thank you for your clarification. I do understand what you're saying, but I'm not entirely sure as to why that's the answer still. I suppose where I'm missing the link is why exactly if each individual instance is possible independently, why isn't there an outcome where these possibilities are joined together as one if this is producing all possible outcomes.

I wonder if I'm taking the notion of being able to produce all outcomes too much at face value without properly taking into account certain constraints of the system, like spawning from past events or things of the sort. Are you aware of any literature, or specific subcategories of quantum, or any other sources, that you think may be helpful to completely clarify the situation?

 

[g564321]

Please give specific references. We can't discuss unspecified "sources".
My statement about what outcomes have nonzero amplitudes in the wave function had nothing to do with whether the total number of worlds is finite or infinite. Even infinitely many worlds can still fail to realize all the possible "outcomes" that a particular person can dream up in their imagination. Your imagination is not a good guide to what outcomes actually have nonzero amplitudes in the wave function.

Or maybe the better way to phrase this is that I understand what you’re saying is that not all outcomes are non-zero, i.e. certain outcomes just won’t come about, but what I don’t understand is that if this is just about where microscopic particles can go, and these microscopic aspects can support all of the macroscopic situations being fathomed, where is the breakdown occurring where certain macroscopic situations become impossible. Is it in certain constraints from the past history of the system, and if it is, why isn’t it looked at as if a new universe branches off at an earlier time to support that alternate history that would then support that additional outcome?

Once again, if you could provide any literature or additional sources that you think might help, it would be appreciated.

 

[PeterDonis]

if this is just about where microscopic particles can go

Basically, yes, since we're assuming that all other entities are "made of" these particles.

these microscopic aspects can support all of the macroscopic situations being fathomed

No; we don't know this, and we can't just assume it.

 

[g564321]

Basically, yes, since we're assuming that all other entities are "made of" these particles.
No; we don't know this, and we can't just assume it.

Sorry if I come across as pressing the issue, but I’m still not entirely clear on your answer.

By support all of the macroscopic situations, I meant theoretically, not in actuality. I figured I would clarify this because if the particles can support the life instances that they already support, I don’t see how there could be a difference in other situations when microscopically they are the same. For instance, a situation without a coincidence has to be the same microscopically as a situation with a coincidence.

So what I was trying to ask is why even though certain aspects are theoretically identical from the start microscopically, what’s occurring that’s causing certain situations to become impossible while still allowing others to be possible?

The takeaway that I had walked away with earlier was that you were saying that my original question was impossible, but now I’m not sure if you’re just saying that it can’t be assumed, which I completely understand. Still, can it be ruled out?

Additionally, thank you for your help.

 

[PeterDonis]

a situation without a coincidence has to be the same microscopically as a situation with a coincidence.

No, it won't be. If there is any difference at all, there must be a microscopic difference. The question is what kind of microscopic difference. See below.

even though certain aspects are theoretically identical from the start

They aren't. That's the whole point. There are many different theoretically possible wave functions, but only one of them is the actual wave function. If you are imagining some scenario which differs from the reality you actually observe in any respect, no matter how small, you have no way of knowing whether the difference you are imagining is included in the actual wave function--just in another branch of it, which the MWI says will exist--or if the difference you are imagining is not included at all in the actual wave function, but only in some other theoretically possible wave function that is different from the actual one. Many discussions of the MWI implicitly assume that all possible differences you can imagine are included somewhere in the actual wave function of our actual universe, but there is no theoretical justification for that assumption.

 

[g564321]

No, it won't be. If there is any difference at all, there must be a microscopic difference. The question is what kind of microscopic difference. See below.
They aren't. That's the whole point. There are many different theoretically possible wave functions, but only one of them is the actual wave function. If you are imagining some scenario which differs from the reality you actually observe in any respect, no matter how small, you have no way of knowing whether the difference you are imagining is included in the actual wave function--just in another branch of it, which the MWI says will exist--or if the difference you are imagining is not included at all in the actual wave function, but only in some other theoretically possible wave function that is different from the actual one. Many discussions of the MWI implicitly assume that all possible differences you can imagine are included somewhere in the actual wave function of our actual universe, but there is no theoretical justification for that assumption.

Ok, I think I understand then where the constraints are then. I've seen many places where the point is expressed that many worlds is simply taking the wave-function and applying it to the entire macroscopic scale without any additional aspects. That view is even expressed in the video that I posted before. So, I suppose the constraints come from the fact that the wave-function in it's most basic form doesn't actually carry all possibilities in the first place, just much more than one possibility, and so when this is applied to a macro scale, it produces many possibilities, but not absolutely all of them, and in not producing absolutely all of them, this conception is impossible for the many worlds interpretation to realize. Would you say that this appears to be an accurate understanding?

 

[PeterDonis]

the wave-function in it's most basic form doesn't actually carry all possibilities in the first place

Not if "all possibilities" means "all possibilities that anyone can imagine", no.

However, many discussions of the MWI implicitly conflate this meaning of "all possibilities" with another meaning, which is "all possibilities that have nonzero amplitudes in the actual wave function of our actual universe". And then they use the second meaning to draw conclusions, but forget they switched meanings and talk as if those conclusions are valid for the first meaning, which they aren't.

in not producing absolutely all of them, this conception is impossible for the many worlds interpretation to realize

If you mean the MWI, using the actual wave function of our actual universe, will not predict that all possibilities that anyone can imagine will be realized, yes, I think this is true.

 

[g564321]

Based off of your reply in my other thread, I figured that it was appropriate to post my question as a follow up here as opposed to create a new thread. Sorry if that isn't actually the right thing to do.

As a related follow up question to this post, I've been reading about multiverses, and I was wondering if the many-worlds interpretation was the only multiverse theory that had the ability to have direct consequences on our life. Yes, the other multiverse theories would have implications for reality as a whole, but with my understanding, they wouldn't be able to have any direct impact on our lives specifically.

To provide my understanding of the differences between the types of multiverses through analogy, if you were to think of our universe as a single tree, I see the many worlds interpretation as producing many branches on that one tree, while I think of the other multiverse theories as a vast amount of different trees with each one being independent from the others. As a result, if the other multiverse theories would have the different universes represented as entirely different trees, than there is no way that they could influence our tree, or universe, and then no way that they could influence our lives as a result.

Meanwhile, in reading about this, I've seen that Max Tegmark has a theory of four different types of multiverses, while Brian Greene has a theory of nine different types of multiverses, so I wanted to make sure that I was accounting for them all.

So to reiterate, my question is that if the many worlds interpretation is the only multiverse theory that could influence our lives directly.

 

[PeterDonis]

my question is that if the many worlds interpretation is the only multiverse theory that could influence our lives directly.

This question is too vague to be answerable.

Thread closed.