Submitted by Azmisov t3_11qjmwp in philosophy
Azmisov OP t1_jc5ltqr wrote
Reply to comment by platoprime in A philosophical dive into “Everything Everywhere All at Once” by Azmisov
I didn't say the number of universes changes, so I don't know what you're commenting about
dolphin37 t1_jc6wtqo wrote
I think the confusion is that you referred to wave function collapse, which is essentially the scientific term for our singular universe being all there is after said collapse being triggered by measurement. In MWI the collapse doesn’t happen, so you’re not observing that, you’re observing one of the probabilities of the universal wave function. I think that’s really what you meant but the terms weren’t quite right.
I also am unsure with if the person who responded to you is right anyway. My understanding of MWI is not that all universes already exist. The process is literally called branching. To say that we’re branching on existing paths, to me, means that we would need to assume free will and entropy are not ‘real’, otherwise at a particular entropic point, some universes only exist mathematically, which is not the point of MWI. Would be interested in having that one explained.
platoprime t1_jc7oshe wrote
>I also am unsure with if the person who responded to you is right anyway. My understanding of MWI is not that all universes already exist.
They "branch" because they were coherent and identical before that.
The alternative is to suggest every time a measurement occurs an entirely new universe is created. Where do you imagine the energy required to create an entire universe comes from?
dolphin37 t1_jc7xxvx wrote
(My understanding:) In MWI, the universe is the wave function and each branch dilutes the energy. So if you have 1x energy and the universe branches, each 'world' contains 0.5x energy. We don't notice the change in energy because our entire world has got proportionally skinnier. That happens as part of decoherence.
Is this maybe a confusion between terms or something? The wave function/universe is one thing, the many worlds of which are created 'in to'... that kind of implies there is a thing they are in though, which is not necessarily the case. We can describe it as some kind of gigantic dimensional configuration space but as far as I'm aware that's not posited as a physical reality.
platoprime t1_jc7zfpr wrote
When an electron is in a superposition of two states it's the sum of two states. When it collapses it collapses to a single state. What happens to the other state? Is it gone and we don't need to worry about it(Copenhagen). Do both states happen in their own universes(MWI)?
So it's not totally incorrect to say 1 becomes two .5s but where in that description is a new universe created? The two states always existed. It sounds like a split when you reduce it to .5+.5=1 but in the superposition both states exist so it's more like .5+.5=(.5+.5). 1 isn't being cleaved in half. It's decohering into it's two states.
platoprime t1_jc809rm wrote
Sorry to reply twice but I didn't want to edit my other comment in case you missed it.
>as some kind of gigantic dimensional configuration space but as far as I'm aware that's not posited as a physical reality.
It is actually. There aren't really multiple universes strictly speaking. Instead there is a universal wave function that describes the entire multiverse created by decoherence in our universe. That universal wave function is our universe.
I specify our universe because there are other theoretically possible sources of multiverses like eternal inflation or extensions to the Penrose diagrams of black holes.
dolphin37 t1_jc8mw1o wrote
Reddit broke so I lost my whole post, will try to be shorter now and cover your second comment too.
Yeah I understand the above but my point was that I don’t think MWI posits that our universe is anything more than the wave function. The wave function is not a physical massive dimensional space, it’s just what the universe is. The wave function exists in hilbert space but that is just a mathematical abstraction not a physical space. The many worlds are the physical spaces. They aren’t existing or expanding in to something more than themselves
Regarding your electron, the issue I’m trying to get to is the superposition of a given electron or even all electrons or even all fields doesn’t describe every state of the environment at all points of entropy and with all interactions accounted for. If one electron exists now and all worlds exist for its superposition (you said this but branching is based off decoherence which is environmental entanglement not just superposition) what happens to an electron made one minute from now?
I’m not aware of MWI saying anything about time/entropy not being fundamental so this needs to be accounted for. For this to be accounted for in your scenario, the many worlds need to account for every current interaction and every past or future interaction at once. That means every possible event of decoherence has its own world that all start at t=0, when the universe was fully unentangled and entropy has yet to take effect. That doesn’t work if you remove entropy and making it work sounds like entropy is being proposed as emergent.
I can probably link to a dozen videos of theoretical physicists referring to branching and how often it happens. Sean Carroll has a common example he gives of how every radioactive decay in our body branches it, over time. I’m aware that sometimes these terms are used as human ways of understanding these concepts - but that is what we are and I’m not quite getting what you’re saying the abstracted alternative is?
platoprime t1_jc8re8a wrote
>Yeah I understand the above but my point was that I don’t think MWI posits that our universe is anything more than the wave function
Yes that's what I was referring to when I mentioned the universal wave function.
> The wave function is not a physical massive dimensional space, it’s just what the universe is.
Are you suggesting our universe isn't a massive dimensional space? That waves don't propagate and exist in a dimensional space?
>They aren’t existing or expanding in to something more than themselves
Exactly. At no point is anything new created the wave function simply changes.
>what happens to an electron made one minute from now?
What do you mean? If there are two outcomes for that electron then it will be created in two universes and both outcomes will happen.
> That means every possible event of decoherence has its own world that all start at t=0, when the universe was fully unentangled and entropy has yet to take effect. That doesn’t work if you remove entropy and making it work sounds like entropy is being proposed as emergent.
Yes, but when did I suggest removing entropy?
>I’m not quite getting what you’re saying the abstracted alternative is?
The actual model instead of imagining a branching tree of multiverses which is not what MWI is. These are identical universes that are entangled and decohere. I'm not sure where you got the idea entanglement contradicts what I said or implies the creation of new universes. When two particles become entangled they do it through interaction not creation of particles.
dolphin37 t1_jc9txzg wrote
At t=0 there is no entanglement and entropy has not yet occurred right? Nothing has occurred. For lack of a better term, entropy then creates a sequential nature to events from that point. There being no entanglement means that there is no decoherence, which means there is no branching. So at the point in your suggestion that every single world must be created, no decoherence or branching is happening. No physicist I have ever heard says that all superpositions create branches by themselves, it’s when they entangle with another quantum system. As soon as entropy makes sequence 1 happen, the wave function changes and then it’s theoretically possible to predict the rest of the universe, although I still don’t think it makes physical sense for all variations to be created at that point but that is what it is.
The fact that the wave function has to evolve over time/entropy, means reality is evolving too i.e. branching. What you’re proposing would mean every world where this evolution is happening was already created at a point in time before any evolution has begun. That’s not making sense to me
Are you able to link me to any resource that says no branches are created beyond inception? I’m looking everywhere and I can’t find anybody saying it
Edit: notice the language you used about the electron, you said ‘if there are two outcomes’, the electron ‘will be’ created in two universes then outcomes ‘will happen’. If what you’re saying was correct the language should be that those universes already have been created and the interaction effectively already has happened because the wave function must have fully determined the life of the universe as the wave function is reality and all of reality has already been created according to you
platoprime t1_jccqlk0 wrote
We don't even know that there was a t=0 and if there was we don't know what it was like. It's ridiculous to make these assumptions about t=0. Also there was almost certainly entropy at t=0. Entropy is a property of system so unless the universe wasn't a system at t=0 it had a value for it's entropy.
>If what you’re saying was correct the language should be that those universes already have been
I said the electrons will be created not the universes. You need to read my comments more carefully and consider answering my questions. Repeatedly shoving the word branching into your comment doesn't show that universes are being created. You're arguing about physics using a third hand analogy and are fixating on the word branching because you don't understand what's happening. It's like two people(universes) holding hands(coherent) taking different paths(decohering). No new person was created the two people just followed the same path until the branch.
> interaction effectively already has happened because the wave function must have fully determined
Absolutely not. The wave function describes a "moment" of time and as that function changes time moves forward. All you're saying is "if we have the starting conditions of the universe we can calculate the future conditions". That's called determinism.
dolphin37 t1_jccrn9j wrote
I’ve already asked if you can link to anything that can explain what is happening as I’m not connecting with your attempts to explain it and I can’t find anybody saying what you’re saying. I just get overwhelmed with physicists talking about instances of branching occurring over time. I don’t really see that you are making any points that I haven’t responded to but perhaps I’m also just not understanding those. The only questions of yours I ignored were ones I commented on previously and I’m not resorting to telling you to read more carefully for failing to address half of my previous comment, so you can keep that kinda language to yourself.
I tell you what, I’ll ask Sean Carroll in a couple of weeks and will get him to explain his view. I’ll write back and link you his response then and maybe that will help me understand and help you explain it better.
Edit: Some of your post appeared after I responded, dunno if you edited but doesn’t matter. Just wanted to say I don’t know why you talk down to me with stuff like ‘that’s called determinism’, like yeah, I know, I literally used the word determined in the quote. You did the same thing before where you tell me my understanding of the full universe is wrong only to agree with me and tell me that’s what you said. It makes me view you as a lot less credible.
platoprime t1_jccw9ey wrote
Let me try again then. Do me a favor and stop thinking about t=0 or when the universal wave function was created or when entropy started. Or even entropy at all. All of that is a separate and irrelevant question.
I don't want to source every sentence but if I say anything in the following comment that you don't accept then I would be happy to source it.
In quantum mechanics we have things called states. You can add, or superpose, any states together as much as you want. It's similar to how you can just add up waves and their interference. This sum of two states is called the superposition. Eventually though something in a superposition of more than one state will eventually interact with something causing it to resolve to one of it's base states. Unfortunately we cannot determine which state the superposition will collapse into. We can only describe it probabilistically.
We need to explain why this is and what happened to the other states. One solution is the Many Worlds Interpretation. In MWI the other states of the superposition don't just disappear. Instead, in another universe, the superposition resolved to the "lost" state.
Now notice how I said we need to explain where the "lost" state went? Well we need to explain it because the state existed before the collapse and we want to know where it went. The collapse of the superposition does not create a new universe and it does not create a new state. Instead these two states decohered from one another. Nothing new is created.
dolphin37 t1_jcdej3i wrote
You’re just mostly describing the basics of QM. That’s not the issue here. The topic is MWI and when the other worlds start existing. I already understand why they need to. It’s disconcerting that you’re using the language of collapse when talking about MWI as the wave function doesn’t collapse in MWI but I can just assume you’re describing the observation of our branch of the wave function after decoherence.
What you need to explain is why all of the many worlds must exist, all of which will be identical copies until their own event of decoherence happens. Each of these, at a point in time, having the same wave function as there’s no entanglement? It needs to be clear why it cannot be the case that we start from a position of one world, which then upon an event of decoherence, creates two worlds. Both of these worlds exist in the same hilbert space as before, but they are now relatively ‘skinnier’.
So if you can explain why all worlds, which will ever feature every event of decoherence, always exist, in a succinct way, then I’ll put that to Sean as the point of debate and he can hopefully help me get it!
platoprime t1_jcdhl2g wrote
>Each of these, at a point in time, having the same wave function as there’s no entanglement?
They are each a part of the same universal wave function. Of course they are entangled. If you know the outcome in one universe you know the outcome in the other.
>Both of these worlds exist in the same hilbert space as before, but they are now relatively ‘skinnier’.
Yes when they decohere they are "smaller" than when they are together. Nothing new is created two things that were coherent became two things that are decoherent. A division of existing space is not the creation of new space.
>So if you can explain why all worlds, which will ever feature every event of decoherence, always exist, in a succinct way, then I’ll put that to Sean as the point of debate and he can hopefully help me get it!
You're saying yourself that one "thick" thing becomes two "thinner" things. That isn't the creation of anything.
>It’s disconcerting that you’re using the language of collapse when talking about MWI
The entire point of MWI is to explain collapse.
dolphin37 t1_jcdrbnz wrote
MWIs ‘explanation’ for collapse is that it doesn’t collapse. You’re just using the wrong language when referring to a collapse that’s all.
I’m still just not seeing anything that explains why all must exist at all times vs them beginning to exist only at a point in time. It’s just not intuitive to start from a position of a potentially infinite number of identical copies. I get why it’s neater from a conservation perspective because everything has its own energy already before docehering but I need to hear something that explains why that can’t be split at the moment of decoherence instead, with the pre-decohered state containing all of the energy within one world.
I think I’ll leave it here as if there were a clearer explanation for this it probably would have come out by now. But I at least understand the position so can ask the question.
platoprime t1_jcdzczr wrote
>(“spin is up” + “spin is down” ; apparatus says “ready”) (1)
>[...]
>(spin is up ; apparatus says “up”) + (spin is down ; apparatus says “down”). (2)
>[...]
>We wouldn’t think of our pre-measurement state (1) as describing two different worlds; it’s just one world, in which the particle is in a superposition. But (2) has two worlds in it. The difference is that we can imagine undoing the superposition in (1) by carefully manipulating the particle, but in (2) the difference between the two branches has diffused into the environment and is lost there forever.
When you have a superposition of two states each state is it's own world.
>You’re just using the wrong language when referring to a collapse that’s all.
The only time I used the word collapse in the comment you're replying to is to say MWI's purpose is to explain apparent collapse. Saying it doesn't happen is still an explanation. You're getting tangled in the weeds with this one.
dolphin37 t1_jceuu3l wrote
Yes in that example you already have entanglement/decoherence in (2), at which point I’ve already said the multiple worlds must now exist. Sean’s language in that very article uses terms like ‘we expect the apparatus to become quickly entangled’ and ‘once our quantum superposition involves macroscopic systems’ and ‘proceed to evolve’ and ‘it is as if they have become distinct worlds’. They ‘come in to being’. They ‘occur’. All of the terminology implies the actions are happening over time.
Saying the possibility for all of the worlds is always there is not the same as saying all the worlds are always there. If that’s what is meant, the language should be clearer. Which I will find out.
And yes you were trying to explain ‘apparent collapse’ but you didn’t use that terminology, like the terminology Sean does in the article linked, you just described collapse multiple times, which isn’t happening. I was just pointing out that it’s not ideal and already stated what I assumed you meant, which is exactly what you apparently meant, but you are again doing the thing where you default to telling me I’m wrong when you actually completely agree with me but have an inability to accept your own fault. Kinda tiring tbh.
Edit: It just occurred to me that you said my objection is that there are too many universes. I didn’t realise you still don’t understand my point this far in 😩
platoprime t1_jchbtln wrote
> It’s just not intuitive to start from a position of a potentially infinite number of identical copies.
You did say this after all.
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