How Does Quantum Measurement Influence Reality Splitting in Many Worlds Theory?

[JamieSalaor]

TL;DR Summary

Can someone who know mwi well quickly tell me I have the right idea.

In many words a split occurs when a quantum measurement occurs, this split would then 'radiate' out into the universe.
So say a quantum measurement of an electron happens on the moon. The information from the measurement would travel to let's say some people. These people would then unknowingly become part of a branch where spin up was measured and another branch where spin down was measured.
This happens all the time whenever a measurement takes place so there a most likely a ludicrous amount of branches.

In regards to the metaphysical aspects we see consistency because we are part of the same branch.
(obviously branching occurs all the time so by 'we' I mean the other people who share the same set of Quantum outcomes as I do and you do)

Different versions of us exist in different branches.
But We all share the same histories of splitting. Hence all the agreement between us.

I saw an old thread where a guy was freaking out saying his family would all be copies.

But this isn't want mwi describes at all..
Our stream of consciousness doesn't notice a split. We are the ones who share this branch of the wavefunction.
Your stream of consciousness and mine exist in the same branch.
No weird solipsism no weird copies. Just streams of consciousness associated with a set of measurement outcomes.

Is this right.
Its terribly hard to write about this coherently but I'm sure someone will get my drift.
Also I'm blown away by the friendliness of people on this forum
You've all been very helpful
Cheers

 

[EPR]

If there 1 trillion universes created every second, there's 1 trillion you's in them. They are all 'you' in a sense(assuming your experience can be copied).
Or, some would consider only one's experience real and all other branches - theoretical/unknowable.

 

[JamieSalaor]

If there 1 trillion universes created every second, there's 1 trillion you's in them. They are all 'you' in a sense(assuming your experience can be copied).
Or, some would consider only one's experience real and all other branches - theoretical/unknowable.

But there's also a trillion yous split between those universes. No body is alone in experiencing a measurement outcome.

 

[JamieSalaor]

I have to say it's amazing how hard it is to talk about QM using the English language...

 

[Halc]

What you write in the OP is pretty accurate.
The friend need not freak out since those people in other worlds are not his family any more than the copies of himself are him.

The takeaway from MWI is that it assaults identity the same way as a cloning machine. I have a machine with 3 doors in a row. I walk into the middle one and a pair of identical people walk out the other two doors. Which is the original? The only thing freaky about the machine is that the clones can meet each other and need to decide who gets to keep the car (with the wife) in the parking lot.

So MWI has these splits yes, and there's no original/copy relationship to them. So there's no unique version that's actually you, which really stands against many religious ideas. Do they all go to heaven? Only some of them? Am I punished for deeds done in some other world? So the religious types tend to gravitate towards interpretations that maintain some sort of unique identity, which is probably one of the realist interpretations instead of one of the local ones.

 

[Halc]

@PeroK seems to be skeptical of my prior post. What part?
OK, you called my bluff. I don't actually have the cloning machine. It's in the shop right now...

 

[hutchphd]

You should have cloned it

 

[PeterDonis]

No weird solipsism no weird copies. Just streams of consciousness associated with a set of measurement outcomes.

Yes, that's what the MWI describes. Each time a measurement takes place, every stream of consciousness that observes that measurement "splits", in the sense that there are now multiple branches, one corresponding to each possible outcome of the measurement; but none of those streams of consciousness notice a split, each of them just experiences the measurement outcome that happens in their branch. But there is no "copying"; the overall wave function just undergoes unitary evolution.

 

[PeroK]

@PeroK seems to be skeptical of my prior post.

If we start taking religious ideas into account, then all of science (not just MWI) is called into question. And vice versa. Almost all scientific ideas call religious ideas into question.

 

[AlexCaledin]

Almost all scientific ideas call religious ideas into question.

- because they are trying to mend the Godshaped Hole in the QM)

 

[PeterDonis]

which really stands against many religious ideas. Do they all go to heaven? Only some of them? Am I punished for deeds done in some other world? So the religious types...

If we start taking religious ideas into account, then all of science (not just MWI) is called into question. And vice versa. Almost all scientific ideas call religious ideas into question.

- because they are trying to mend the Godshaped Hole in the QM)

Everyone, religion is off topic for this forum. Please stick to the scientific topic of the thread.

 

[JamieSalaor]

https://www.physicsforums.com/threads/mwi-bugging-me.198571/

Has anyone read this thread. The original poster really obviously doesn't understand mwi... But almost everyone rather than clarifying what MWI says gives him really strange answers.
Really feel bad for the guy I hope he got his head straight...
Did people not really understand the philosophy of this interpretation in 2007?

Nobody jumps universe... The person you know now is the same person you've always known. They share the same measurements and have always shared the same measurements of you.
Its against mwi to interact with others in other worlds.

 

[PeroK]

The person you know now is the same person you've always known. They share the same measurements and have always shared the same measurements of you.

It's difficult or impossible to define someone at the level of elementary particles. People are complex organic systems that are changing all the time.

 

[JamieSalaor]

Yeah, I agree with that. I just feel sorry for the dude who made that post. People aren't really being helpful with it.
He goes on to ask whether his girlfriend is the same consciousness he's always know. No one outright just explains how it works. Many Worlds as put forward by Carrol and Deutsch would say yes. Her stream of consciousness would be the same one since when you first met, other versions of her exist in other worlds which are too arguably the same stream of consciousness as they both share consistent histories up until a point.
The point is that she would experience branching the same as you do. She (as in she in this branch) would feel as if she had just one stream of consciousness that followed one set of measurement outcomes.
He will never interact with other branches which contain versions of her with different histories to him
Again it's so hard to talk about this just using words lol..

Just kinda sad lol I hope he's ok now...

 

[Halc]

Nobody jumps universe...

The poster is assuming a classic identity for everybody and everything, and then trying to fit that premise in with MWI which indeed doesn't support it. If the replies (which I didn't read) don't point that out, then maybe they're not as helpful as they could be.

What he is saying is that he has measured + and another version of him has measured - and thus these two versions are in different worlds (which he mistakenly calls 'universes') so by definition they can't both be in the same world and by symmetry you are not the one special person that's always in the original world, therefore your world is not the original one, and thus you've 'jumped worlds'. But his classic notion of identity insists that only one of those worlds can possibly contain the original person, and it's unlikely to the one he's in, and this causes him strife.

The person you know now is the same person you've always known.

This depends on your definition of identity. I personally don't accept this as anything more than an assumption.

Its against mwi to interact with others in other worlds.

Per the paper I linked (ref 4 off the wiki):

• What Everett does NOT postulate: At certain magic instances, the the world undergoes some sort of metaphysical “split into two branches that subsequently never interact.

 

[JamieSalaor]

I agree it's an assumption. It's also about how you personally define identity.
I would say those in a different branch to me are no longer the people I know. As they no longer share a consistent history with me. Just as how the me in other branches is no longer me. I think in a way its relative. Because to the me in another branch would say the people he interacts with are his friends etc..

Those who I interact with, who will always share a consistent history with me are the people I would say I know. But its hard to talk about as me can have multiple meanings in MW

I think it's fascinating MWI but until there's any solid evidence for it I'm staying agnostic.
Thanks for your reply Halc! Appreciate all you've done one here for me.

 

[JamieSalaor]

I think Sean Carrol, David Deutsch and David Wallace all argue for separate metaphysical branches. Ill find some context

 

[JamieSalaor]

We might care about what happens to the versions of ourselves who live on other branches, but it’s not sensible to think of them as “us.” Imagine that you’re just about to perform a vertical-spin measurement on an electron you have prepared in an equal superposition of spin-up and spin-down. A random philanthropist enters your lab and offers you the following bargain: if the spin is up, they will give you a million dollars; if the spin is down, you give them one dollar. You would be wise to take the deal; for all intents and purposes, it’s as if you are being offered a bet with equal chances of winning a million dollars or losing just one dollar, even if one of your future selves will certainly be out a dollar.

But now imagine that you were a little quicker in your experimental setup, and you observed a spin-down outcome just before the philanthropist busts in. It turns out that they are a pushy deal-maker, and they explain that the version of you on the other branch is being given a million dollars, but you now have to give them one dollar in this branch.

There’s no reason for you to be happy about this (or to give up the dollar), even though the version of you on the other branch might be happy about it. You are not them, and they are not part of you. Post-branching, you’re two different people. Neither your experiences nor your rewards should be thought of as being shared by various copies of you on different branches. Don’t play quantum Russian roulette, and don’t accept losing bargains from pushy philanthropists.

Let’s say you have a choice to make: “Should I get pepperoni or sausage on my pizza?” (And let’s say you have too much restraint to give the obvious answer of asking for both on the same pizza.) You can fire up Universe Splitter, where you will see two text boxes, into which you can type “pepperoni” and “sausage.” Then hit the button, and your phone will send a signal through the internet to a laboratory in Switzerland, where a photon is sent toward a beam splitter (essentially a partially silvered mirror that reflects some photons and let's others through). According to the Schrödinger equation, the beam splitter turns the photon’s wave function into two components going left and right, each of which heads toward a different detector. When either detector notices a photon, it produces a readout that becomes entangled with the environment, quickly leading to decoherence and branching the wave function in two. The copy of you in the branch where the photon went left sees their phone flash with the message “pepperoni,” and in the one where it went right, they see “sausage.” If each one actually follows up with your plan to do what your phone advises, there will be one world in which a version of you orders pepperoni, and another in which a version of you orders sausage. Sadly, the two persons have no way of communicating with each other to share tasting notes afterward.

From Sean Carrols Something Deeply Hidden

 

[JamieSalaor]

So say I experienced getting the sausage answer for my pizza. I'd say that the people I know are people who share the sausage pizza, who experienced the same outcome to that quantum measurement. We share a branch

 

[EclogiteFacies]

The takeaway from MWI is that it assaults identity the same way as a cloning machine. I have a machine with 3 doors in a row. I walk into the middle one and a pair of identical people walk out the other two doors. Which is the original? The only thing freaky about the machine is that the clones can meet each other and need to decide who gets to keep the car (with the wife) in the parking lot.

I think, though I broadly agree with what you are saying.
I don't like the idea of the cloning machine, in the sense that it's not quite right.
As two out of three of those clones are 'new' in the sense that they would have fake memories imprinted into their brains during cloning. Only one coming out the other side would truly have experienced those things.
I think the way to think about it is like a cell dividing.
Both of copies following division came from exactly the same source and literally experienced the same life up until splitting. There is no original. Both are equally original, none are metaphysically special
They are 'extensions' of the original and share as its put here a 'consistent history' up until a point where they split.

Sean Caroll explains it below at 2:35 in the video below.



Also Halc I've seen some of your replies on here and you've got some pretty impressive knowledge!

 

[Halc]

I don't like the idea of the cloning machine, in the sense that it's not quite right.

You seem not to read me quite right though...

As two out of three of those clones are 'new' in the sense that they would have fake memories imprinted into their brains during cloning.

There's only the two that walk out of the side doors, no third one. That makes for no obvious 'original'. Walking in the middle door is synonymous with being about to take a measurement, and the exit doors are synonymous with having measured spin up and down respectively. Do you consider your memories 'fake' or 'imprinted'?

Only one coming out the other side would truly have experienced those things.

Which side is the 'other side'? Left or right? This happens in real life. I cut a starfish in half and now there are two starfish. Which is the original? You suggest a very asymmetrical view, not at all in line with what MWI says where there is no preferred 'actual' world.

I think the way to think about it is like a cell dividing.
Both of copies following division came from exactly the same source and literally experienced the same life up until splitting.

A human zygote is a fertilized egg. It quickly divides into a pair of blastomeres which on occasion become separated instead of sticking together (Disclaimer: Not a proper biological description of the actual process). In this way identical twins are formed. Which is the one that was truly the original zygote and which is the 'fake', as you put it? By your description with the cloning booth, one has the original DNA and the other a mere imprinted copy of it.

There is no original.

Now the story changes. You didn't say this above. I agree that there is no original, which is why I characterize MWI as 'assaulting' the common notion of continuous identity.

 

[EclogiteFacies]

Yes I did misread you sorry!
I don't think there is an original in many worlds. Both have equal claim.
This is the opinion of most Many Worlders.
There is no fake, both have equal claim to the title of original.
They both experienced the same history up until the split as one person then a split occurs and they are two.
None is the original. If anything you could say they are both copies, this is how David Wallace puts it.

Sorry for misunderstanding!
I think we agree on what we are saying lol

Thank you

 

[EclogiteFacies]

Sorry if I was not clear before!

 

[EclogiteFacies]

My notions of one with implanted memories was an idea formed from misunderstanding of your cloning machine abaollgy.
I do not believe one has false memories and the other does not. They both truly experience the same history as one.

 

[Halc]

Yes I did misread you sorry!
I don't think there is an original in many worlds. Both have equal claim.
This is the opinion of most Many Worlders.
There is no fake, both have equal claim to the title of original.

MWI does not support the meaningfullness of that title at all. There is no original. It's not that nobody can know it. 'The original' carries no meaningful distinction from 'copy' or 'not-original', so the interpretation simply does not support such a notion.

If anything you could say they are both copies, this is how David Wallace puts it.

Better. I'm not an official spokesperson, so my opinions don't matter. MWI isn't even my preferred interpretation, but I suppose it was for a while. I'm more of an RQM guy now which solves the problem of any realist interpretation like MWI.

 

[EclogiteFacies]

I'm also an RQM guy! It's less nutty feeling than QBism but more simple than MWI.
I think it was when i understood how it tackles Shrodingers Cat. Relative to the cat it is either dead/alive but is not defined relative to me. It prevents Many Worlds, and also prevents a dead / alive scenario.

Big fan of all of Rovelli’s work. I read Helgoland just last month to practice my Italian. I did not know it would win me over to RQM...

 

[JamieSalaor]

My notions of one with implanted memories was an idea formed from misunderstanding of your cloning machine abaollgy.
I do not believe one has false memories and the other does not. They both truly experience the same history as one.

I think this is what I was trying to say when I said that the people who I interact with would be the same people as always.
Though they just like me can be defined as copies. We under MWI would all feel as if we had only lived in one world. The consciousness I interact with therefore would be the same stream of consciousness I have always interacted with, those in my branch would experience life like I do, just feeling as if they have always been part of one single world.
It's not like someone else from another branch joins my branch and replaces my friends... We will always share the same measurement outcomes and always feel like we have lived in one branch alongside each other. Again it links to definitions of identity. Am I the same me as I was last week? Well, I have experienced a consistent stream of consciousness since then, so yes I suppose so... As has everybody else around me...

Also I'm excited for Helgoland to come out in English! Jealous you have read it!

 

[EclogiteFacies]

Though they just like me can be defined as copies. We under MWI would all feel as if we had only lived in one world. The consciousness I interact with therefore would be the same stream of consciousness I have always interacted with, those in my branch would experience life like I do, just feeling as if they have always been part of one single world.
It's not like someone else from another branch joins my branch and replaces my friends... We will always share the same measurement outcomes and always feel like we have lived in one branch alongside each other. Again it links to definitions of identity. Am I the same me as I was last week? Well, I have experienced a consistent stream of consciousness since then, so yes I suppose so... As has everybody else around me...

Yes that is what MWI implies. I think before you were clearly confused on how you were personally defining identity. MWI states that those around you share the same measurement outcomes as you, and therefore share a branch. From their POV they have always been part of the same branch as you. But to another copy in another branch with another you they would think the same thing. Therefore saying that you're with the same person you've always known is relative to the individuals in each branch.
But yes, the person you are with has experienced a continuous stream of consciousness alongside you within these branches. If that's what you are asking here?
No interpretations other than maybe Von Neuman/ Wigner implies anything different.
Up to you if you think consciousness has anything to do with QM. But I know where I stand.

Which is the original in MWI? There isn't one. You are on equal metaphysical footing.

 

[Drakkith]

Which is the original in MWI? There isn't one. You are on equal metaphysical footing.

A bit like watching a cell divide and then asking, "Which is the original cell?"

 

[AlexCaledin]

- who in the multiverse is watching a branch divide??

 

[PeterDonis]

who in the multiverse is watching a branch divide??

Nobody. It's not something that can be "watched".