Possible Worlds?

[Teh Ebil Snorlax]

Yes, but it's only logically identical from our subjective viewpoint, not from an objective viewpoint. All I have is a body of text in front of me you put together. Maybe Sentence 1 was put together because thought K lead to thought J lead to thought Q in your head, or maybe thought M lead to N lead to Q. It doesn't make a difference to me, and it won't create any difference in the future. To me, they are logically identical. But not objectively.

Since we can only know that which occurs in our world, a complete view of our world is the objective viewpoint. Since the whole point is that these other worlds cannot interact with our world in any way, then, yes, it is logically identical from an objective viewpoint. I don't even get what you're trying to say with the thought processes that put together what I said, I don't see what relevance it bears to what we're talking about.

No, that's not how it works. A lack of assumption that other worlds exist would mean being open to the idea, but not assuming it is true. Since "only one world exists" is not necessarily true, it's an assumption.

There's no reason in being open to an unfalsifiable hypothesis. Since the theory that other worlds which cannot in anyway interact with or influence our world in any way is completely impossible to falsify. A hypothesis that cannot be proven to me is just a thought experiment. When your hypothesis becomes falsifiable, then my alleged lack of open-mindedness turns "only one world exists" into an assumption. I am open to the idea as long as it can be demonstrated to me, but as long as "only one world exists" is the only logical conclusion one can reach in the question of "how many worlds exist?", that's the assumption that all my thoughts about this world are going to be predicated on.

My theory is still better than your theory if it can explain something yours doesn't. Occam's razor can only be used when two theories are equal in all other respects, so it doesn't apply here.

To be clear, Possible Worlds Theory assumes that other worlds exists, but I do not assume Possible Worlds Theory is true. Now then, as I said before, possible worlds theory makes a new assumption (other worlds exist) in order to explain something that wasn't explained before (why worlds exist in the first place). That is an okay thing to do.

The explanation of why worlds exist is only necessary if you already assume there indeed exists worlds and not just a singular world, i.e. your theory only explains something which needs to be explained for itself to be true, which is about as circular as logic can get. What exactly does your theory apparently explain about existence that makes it superior to "there is one world, created by the Big Bang"?

 

[Light]

Since we can only know that which occurs in our world, a complete view of our world is the objective viewpoint. Since the whole point is that these other worlds cannot interact with our world in any way, then, yes, it is logically identical from an objective viewpoint.

If other worlds exist, then there is a higher truth than your "objective" truth, which you limit to only describing our own world. Personally, I think "objective" should refer to the highest truth, which is, rather than "a complete view of our world", a complete view of everything. Why do you limit objective truth to what can be known from our own world? Nothing can be known in the first place.

I don't even get what you're trying to say with the thought processes that put together what I said, I don't see what relevance it bears to what we're talking about.

Okay, you said

Uh, actually, I'm sure you'll find I said they might as well not exist because they can't interact with us and vice versa. The point I was making is that even if they do exist, it doesn't make a difference, because they can influence or affect us or our world in anyway. Your "logical mirror" isn't a mirror at all - they can't do anything to us or our world that implies they might exist, so it doesn't really matter if they do, it's the same as if they didn't exist. What I'm saying is that since they can't interact with us on any level, if they exist, it's the same as if they don't and if they don't, it's the same as if they did i.e. what you're saying is the exact same statement in a different word order. It implies nothing my statement didn't, it's logically identical.

What I was trying to say was, for me, stating that you thought X -> Y -> Q versus J -> K -> Q is logically identical, but not for you. Thus, just because they are logically identical from a limited viewpoint does not mean one cannot imply something the other doesn't.

There's no reason in being open to an unfalsifiable hypothesis. Since the theory that other worlds which cannot in anyway interact with or influence our world in any way is completely impossible to falsify. A hypothesis that cannot be proven to me is just a thought experiment. When your hypothesis becomes falsifiable, then my alleged lack of open-mindedness turns "only one world exists" into an assumption. I am open to the idea as long as it can be demonstrated to me, but as long as "only one world exists" is the only logical conclusion one can reach in the question of "how many worlds exist?", that's the assumption that all my thoughts about this world are going to be predicated on.

Falsifiability is not some Holy Grail of truth. Perhaps knowledge, but not truth. Do you understand this concept or do I need to show it to you?

The explanation of why worlds exist is only necessary if you already assume there indeed exists worlds and not just a singular world, i.e. your theory only explains something which needs to be explained for itself to be true, which is about as circular as logic can get. What exactly does your theory apparently explain about existence that makes it superior to "there is one world, created by the Big Bang"?

You have obviously never pondered the nature of existence. The Big Bang only explains how, not why. Why did the Big Bang bang in the first place? And why was that? Etc's for infinity. Eventually you have to ask yourself, "why did something end up existing at all", because nothing ever had to. Seriously, why are people so enamored by Curiosity Stoppers?

 

[Teh Ebil Snorlax]

If other worlds exist, then there is a higher truth than your "objective" truth, which you limit to only describing our own world. Personally, I think "objective" should refer to the highest truth, which is, rather than "a complete view of our world", a complete view of everything. Why do you limit objective truth to what can be known from our own world? Nothing can be known in the first place.

By your logic, there is no highest truth, since as long as we can speculate that more and more exists, there is more existence which we have to take into account before we can speculate. It's a self-creating, self-sustaining problem that makes no logical sense. The only thing that we can interact with is our world, so it should be the only thing we take into account in an objective view; after all, since the existence of possible worlds is unknowable, believing that they exist is a totally subjective opinion.

On the other hand, everyone can agree that, at the very least, the world they live in exists. Even if they believe that what we subjectively call "the world" is an illusion and doesn't accurately represent the actual world in which their consciousness exists, they can agree that the world they live in exists. Which, incidentally, demonstrates that your final assertion is completely wrong; we can, in fact, know that there is at least one world with at least one consciousness.

What I was trying to say was, for me, stating that you thought X -> Y -> Q versus J -> K -> Q is logically identical, but not for you. Thus, just because they are logically identical from a limited viewpoint does not mean one implies something the other doesn't.

But what does this have to do with the fact that since possible worlds can't interact with or influence our world in any way, their existence is just as probably and meaningless as their non-existence? I understand the sentences perfectly fine, I just don't get what they're supposed to mean or what relevance they have. Merely repeating yourself isn't going to make me understand, you need to elaborate on what you're actually saying.

Falsifiability is not some Holy Grail of truth. Perhaps knowledge, but not truth. Do you understand this concept or do I need to show it to you?

If a hypothesis cannot even theoretically be proven true or false, then it's meaningless. Your hypothesis is even worse, since it's not even possible to collect evidence of its truth. In fact, I retract my statements about Occam's Razor, since your hypothesis is clearly inferior.

You have obviously never pondered the nature of existence. The Big Bang only explains how, not why. Why did the Big Bang bang in the first place? And why was that? Etc's for infinity. Eventually you have to ask yourself, "why did something end up existing at all", because nothing ever had to. Seriously, why are people so enamored by Curiosity Stoppers?

You can kindly fuck off with any presumptions about what I've thought about. I've thought plenty about the nature of existence and I've reached a fairly simple conclusion; speculating about anything before the Big Bang is a waste of mental energy. What can you possibly say about something that came before the creation of the parameters in which we think and exist? Time started at the Big Bang and "before" denotes something at an earlier point in time, but there is no earlier point in time than the moment of the Big Bang. There is nothing meaningful we can say about "before" the Big Bang, such an idea defies definition.

 

[Light]

By your logic, there is no highest truth, since as long as we can speculate that more and more exists, there is more existence which we have to take into account before we can speculate. It's a self-creating, self-sustaining problem that makes no logical sense.

Just because you can't possibly contain the entirety of the details of all possible worlds doesn't mean it doesn't have a Highest Truth. It's Highest Truth is so attractive because of its simplicity: if it can exist, it does. It's a simple algorithm, and once you know how to use it you can determine whether any given state of affairs exists or not. It's like the graph of y = x^2. No matter how many times you plug in a new value to find a point that exists, you are no closer to having omniscient knowledge of the parabola. The parabola is infinite to either side of a point, and infinite in between any two points. That doesn't stop it from existing. It still has a Highest Truth: y = x^2.

Let me underscore the importance of this with a further clarification: the theory is not "all possible worlds exist". The theory is "things exist precisely because they can logically exist", and "all possible worlds exist" is a corollary.

The only thing that we can interact with is our world, so it should be the only thing we take into account in an objective view; after all, since the existence of possible worlds is unknowable, believing that they exist is a totally subjective opinion.

Still, possible worlds existing is either True or False. That makes it objective, unknowable fact.

On the other hand, everyone can agree that, at the very least, the world they live in exists. Even if they believe that what we subjectively call "the world" is an illusion and doesn't accurately represent the actual world in which their consciousness exists, they can agree that the world they live in exists. Which, incidentally, demonstrates that your final assertion is completely wrong; we can, in fact, know that there is at least one world with at least one consciousness.

"Nothing can be known"; "Basically nothing can be known". Pardon my sloppiness with words. It makes no difference to my argument in general.

But what does this have to do with the fact that since possible worlds can't interact with or influence our world in any way, their existence is just as probably and meaningless as their non-existence? I understand the sentences perfectly fine, I just don't get what they're supposed to mean or what relevance they have. Merely repeating yourself isn't going to make me understand, you need to elaborate on what you're actually saying.

Sorry, I worded it wrong, and ended up saying the opposite of what I meant. It's fixed. (The part of your argument it contradicts is bolded, by the way.)

There is a difference between irrelevant/ practically meaningless and actually meaningless.

If a hypothesis cannot even theoretically be proven true or false, then it's meaningless. Your hypothesis is even worse, since it's not even possible to collect evidence of its truth.

"Can't be theoretically proven true or false"? Are you kidding me? Easy. Something that is logically possible but does not exist would falsify it.

Just because something can't be theoretically tested, doesn't mean it can't be theoretically proven.

In fact, I retract my statements about Occam's Razor, since your hypothesis is clearly inferior.

Uhm, inferior to what? I what I have is a hypothesis (explaining why things exist), and what you have is a lack of a hypothesis. ("Things exist precisely because they can logically exist".) Like I said before, the Big Bang doesn't explain why existence happened. When I brought this up you only responded by saying that thinking about anything more fundamental to existence than the Big Bang is a waste of energy:

You can kindly fuck off with any presumptions about what I've thought about. I've thought plenty about the nature of existence and I've reached a fairly simple conclusion; speculating about anything before the Big Bang is a waste of mental energy. What can you possibly say about something that came before the creation of the parameters in which we think and exist? Time started at the Big Bang and "before" denotes something at an earlier point in time, but there is no earlier point in time than the moment of the Big Bang. There is nothing meaningful we can say about "before" the Big Bang, such an idea defies definition.

Your "conclusion" is a lack of conclusion if I ever heard one. And did you even read the first paragraph of that link?

 

[Momo(th)]

A question of possible worlds; is there an alternative dimension for every little thing? If so, I don't even want to think of all the other potential worlds whenever it starts to rain. . .

 

[Light]

A question of possible worlds; is there an alternative dimension for every little thing? If so, I don't even want to think of all the other potential worlds whenever it starts to rain. . .

Yeah... One important thing with possible worlds is, the whole thing has to make sense together, down to the last detail. I think a lot of people might miss the impact that has. In a 100% deterministic system, that means with the starting laws/ equations, there is only going to be one output if the same initial configuration is used. So, for example, if the atmospheric configuration, down to the last atom, is a certain way before a storm, then all the laws governing the reaction, like condensation, air pressure, and resistance, are going to play out the same way.

The catch to this is Quantum Mechanics, where, as far as we currently know, reactions are not actually deterministic but are based partly on chance. According to one quantum mechanical theory, each possibility for every randomized decision is played out in a "parallel universe", a concept which physicists have started to take seriously. I tend to prefer a completely deterministic universe, where possible worlds would be different only on account of having different physical laws in the first place, but the parallel universe interpretation of quantum physics is interesting too.

 

[sovram]

I think I'm going to wander around in the dark a little here, because I'm bored and figure it couldn't really hurt. I'm just an (extremely) amateur (student) mathematician/computer scientist. Can't guarantee I'll say anything smart at all. Don't exactly have a reputation to worry about here so I'll have a shot. I'll warn you though, I'm going to be pretty finicky and it might be annoying. Oh and I will probably end up repeating someone, so I'm sorry.

First of all, I'm going to be taking MD's side when it comes to the use of "real". I poked around on Wikipedia -- I think what we're talking about is modal realism, and one of the main tenets is that "actual" is referential (edit: not sure if this is the word I'm looking for but I hope you understand), similar to "here" and "now", describing the world that the speaker experiences. I'm wondering: if speaker A in world X says "I'm here" and speaker B in world Y says "I'm here", then neither of them are wrong but the here of speaker A is meaningless to speaker B, yes? That's the feeling I get, anyway. So if speaker A in world X says "This world is real" and speaker B in world Y says "This world is real" ... what's different about this situation? Because speaker A is not in world Y, world Y is inherently unreal to em. And immediately I have reservations about similar claims to existence, but I'm not sure how to frame them.

A lack of assumption that other worlds exist would mean being open to the idea, but not assuming it is true. Since "only one world exists" is not necessarily true, it's an assumption.

Well, we have proof that at least one world exists. I find myself drawn to make an analogy with theism, though it may be woefully misinformed. I am an agnostic atheist and act as if zero gods exist. My claim isn't exactly baseless: I feel like we have plenty of evidence to suggest that our world is godless. Similarly, I have plenty of evidence to suggest that this world exists, so I act as if one world exists. My previous paragraph made it clear I have reservations about existence and actuality. The "existence" of other worlds by definition means they can't affect me in any way, so I feel safe in saying that there is no harm in acting as if there is only one world. It's not exactly an assumption because it's not baseless, and even if other worlds did exist, it wouldn't make any difference. I don't think that this saves me from making an "assumption" and I think you'll agree with me on that point, but I think that it does no harm to the one world argument. I'm still "open to the idea" but the very idea is meaningless because the worlds are necessarily separated. I think a very similar proposition was stated earlier in the thread. Phew, I hope some of that is at all digestible. Please be picky and point out the likely numerous problems with my jabber.

To be clear, Possible Worlds Theory assumes that other worlds exists, but I do not assume Possible Worlds Theory is true. Now then, as I said before, possible worlds theory makes a new assumption (other worlds exist) in order to explain something that wasn't explained before (why worlds exist in the first place). That is an okay thing to do.

I don't understand. I must admit I didn't digest very completely the Wikipedia article, but how does it explain why worlds exist? These possible worlds are basically devices to explain probability (among other things), right? So worlds exist to make up for possibilities in other worlds? But where does it all start? What world first had a (unfamiliar jargon coming through!) probability distribution that needed another world to explain it? Bah that's probably missing the point. In any case, it seems to open up many more questions than it actually answers. I don't know. I must admit I don't understand quantum mechanics as much as I'd like to. Please clarify all of this for me.

Why do you limit objective truth to what can be known from our own world? Nothing can be known in the first place.

It seems to me that that is all that would be actually meaningful to us. And I don't really understand what you mean there. Like, "we cannot with absolute certainty say that x is true?"

Falsifiability is not some Holy Grail of truth. Perhaps knowledge, but not truth. Do you understand this concept or do I need to show it to you?

Can you show it to me, please? I have always closely correlated knowledge with truth and afaict the scientific method rests on falsifiability, and while I understand that it's not infallible, it seems pretty damn good to me.

Eventually you have to ask yourself, "why did something end up existing at all", because nothing ever had to. Seriously, why are people so enamored by Curiosity Stoppers?

I don't understand. Are you saying that possible worlds somehow answers this question? (And I think you're being a little condescending! Is "I don't know" a curiosity stopper? Because that's how I've always answered why?.)

Alright, I'm about to look severely naïve, so get ready.

Just because you can't possibly contain the entirety of the details of all possible worlds doesn't mean it doesn't have a Highest Truth.

Something about this doesn't sit well with me. If a dataset that contains perfectly the details of all possible worlds isn't coherent in the sense that it can't be contained entirely (that's what you seem to suggest -- please correct me if I am mistaken), how can you claim that it does have a Highest Truth? (Aside: I'm a bit wary of this "Highest Truth" because it feels like Platonism to me and I am not a Platonist. Again please clarify.) I am kind of struggling to think of something that this describes ... we're saying that these worlds are infinite in number, right? So the sum of their descriptions are probably infinite as well ... with exception of this Highest Truth. Sorry, I guess the entire concept is evading me.

It's Highest Truth is so attractive because of its simplicity: if it can exist, it does. It's a simple algorithm, and once you know how to use it you can determine whether any given state of affairs exists or not.

How do we determine if something can exist? Is this what you mean by "once you know how to use it"?

It's like the graph of y = x^2. No matter how many times you plug in a new value to find a point that exists, you are no closer to having omniscient knowledge of the parabola. The parabola is infinite to either side of a point, and infinite in between any two points. That doesn't stop it from existing. It still has a Highest Truth: y = x^2.

Naïvete incoming! Feels like Platonism again. Is that inherent to this theory? Because it's something I very much struggle to accept. In the context of this example, I gotta say that I am a humanist when it comes to mathematics. I don't believe there is "y = x^2" form hanging out somewhere that is invoked whenever we talk about parabolas. I think "y = x^2" is meaningless (or at least useless) outside of the context of our mathematical system and I'd be hard pressed to explain the concept without centuries of tradition behind me. Well, it does seem true to me (in context) that "y = x^2" describes an infinite object, the parabola, but the question of the existence of an infinite number of worlds, with a presumably infinitely complex description of the total, seems very different to the definition of a parabola. I wouldn't comfortably equate the two, I guess.

Sorry this is probably all incoherent!! But I'd appreciate any effort to look through it and advise me. (Incidentally, any LessWrong articles that talk about this?)

 

[Tarvos]

I keep hearing these things about Possible Worlds and things before the big bang.

Can someone explain to me in two sentences what these Possible Worlds actually are/represent?

Because when people talk about Possible Worlds it's like they just go on some incoherent rant and it ends up being Bla Bla Bla Bla Bla with no sort of form, condensed meaning, or anything.

In other words, could Light (or anyone else), please explain what they are actually on about?

No metaphysical essays, no moral implications, no bells and whistles. What is it exactly you're trying to say?

 

[Music Dragon]

I keep hearing these things about Possible Worlds and things before the big bang.

Can someone explain to me in two sentences what these Possible Worlds actually are/represent?

Because when people talk about Possible Worlds it's like they just go on some incoherent rant and it ends up being Bla Bla Bla Bla Bla with no sort of form, condensed meaning, or anything.

In other words, could Light (or anyone else), please explain what they are actually on about?

No metaphysical essays, no moral implications, no bells and whistles. What is it exactly you're trying to say?

Basically, the idea is that every outcome that is possible but didn't actually happen in our world instead happened in some other world (a possible world). Are you familiar with the many-worlds interpretation of quantum mechanics, or the "Schrödinger's cat" thought experiment?

 

[Dannichu]

Like that Doctor Who episode with the zeppelins :D

 

[Music Dragon]

Yes. Yes, exactly like that.

 

[Tarvos]

I don't watch Doctor Who, so that's a meaningless reference, but Schrödinger I know about, of course. But isn't the whole point that once we do open the box, we find out whether the cat has died? So that eventually leads to the simple conclusion that only one has actually happened.

The rest, in my view, is just a lot of what-if, and postulating that it could happen means about as much as postulating that I could grow organic yellow cucumbers in Siberia.

 

[sovram]

The rest, in my view, is just a lot of what-if, and postulating that it could happen means about as much as postulating that I could grow organic yellow cucumbers in Siberia.

Well, yes, it does seem to be a lot of what-if. Seeing as how they would be completely isolated from us, it seems to me that it would utterly make no difference in how we would live or act. And it doesn't answer any questions to me. "Choices/probability are explained by an infinite number of possible worlds" does seem to be equal in all respects to "Things only happen in one way according to probabilities" and Occam's Razor does seem appropriate.

Note that I really have zero mastery over quantum mechanical concepts but I don't see the need for other worlds to explain probability. It might help that I am a hardcore determinist.

 

[Music Dragon]

I don't watch Doctor Who, so that's a meaningless reference, but Schrödinger I know about, of course. But isn't the whole point that once we do open the box, we find out whether the cat has died? So that eventually leads to the simple conclusion that only one has actually happened.

The rest, in my view, is just a lot of what-if, and postulating that it could happen means about as much as postulating that I could grow organic yellow cucumbers in Siberia.

Once you do open the box, the cat is either in the "dead" state or the "alive" state, but prior to opening the box, the cat existed in a superposition of both states - at least according to the laws of physics as we understand them today.

The problem is that nobody knows what that even means. What does it mean that the cat is partly in the "dead" state and partly in the "alive" state, and what is it that happens when you open the box, causing the wave-function to collapse (or not, depending on who you ask)? There are various interpretations, and one of them is that the "cat is alive" scenario plays out in one world/timeline while the "cat is dead" scenario plays out in another.

Keep in mind, this isn't just number-crunching mumbo jumbo, either. The wave function gives us a probability distribution that we can use to calculate where a particle - say, an electron - is likely to be found. However, this isn't as simple as "we're not sure where the electron really is, but it's probably here"; it's way weirder than that. There is a phenomenon known as "quantum tunnelling" in which particles, say electrons, are able to escape potential wells that they classically couldn't, because there's a tiny probability that they're actually outside that well. Allow me to illustrate:

If you were to use the wave function to calculate the probability of my hand being on the moon right now, it would be ridiculously small, but it would be non-zero. And this literally means that my hand could disappear and end up on the moon (then hopefully come back here...). Of course, the frequency with which my hand is on the moon is low enough that we'll never actually observe this happening, but it's physically possible. That's because my hand doesn't detach from my body and fly to the moon at faster-than-light speed; it is, in a sense, already on the moon!

This is a real phenomenon, with real applications. One example of quantum tunnelling is radioactive decay, which is very much real. Tunnelling is also one of the factors that limit how small electronics can be made (because once you reach a certain scale, electrons start leaking out, causing all sorts of problems).

So yeah, quantum tunnelling demonstrates quite neatly that particles really do exist in a superposition of states, and this means more than just "we don't know which the real state is"; somehow, particles exist in multiple places at the same time, and that sometimes allows them to inexplicably teleport through walls and other crazy shit.

The same applies in the case of Schrödinger's cat. The wave function gives us a probability distribution that tells us how likely the cat is to be dead at any given moment. But this doesn't just mean "we don't know if the cat is alive or dead"; just like with quantum tunnelling, it has to be something more than that. And yet, when you open the box and look at the cat, it's either dead or alive, not "70% dead and 30% alive". It's just one or the other. So what exactly is it that happens in-between? When does a system stop being a superposition of states and become just one state?

A lot of people don't know this, but variations on the Schrödinger's cat experiment have actually been performed in real life - not with actual cats, of course, but with (relatively) large-scale systems of other kinds. Here's an example. So in theory, that cat really could exist as a superposition of mutually exclusive states, as counterintuitive as that may seem.

Schrödinger's cat basically ties quantum superposition to macroscopic systems, at which point we start freaking out because what the laws of physics tell us flies in the face of intuition and common sense - but then again, wasn't that the case with the whole "speed affects time" thing as well?

 

[Light]

First of all, I'm going to be taking MD's side when it comes to the use of "real". I poked around on Wikipedia -- I think what we're talking about is modal realism, and one of the main tenets is that "actual" is referential (edit: not sure if this is the word I'm looking for but I hope you understand), similar to "here" and "now", describing the world that the speaker experiences. I'm wondering: if speaker A in world X says "I'm here" and speaker B in world Y says "I'm here", then neither of them are wrong but the here of speaker A is meaningless to speaker B, yes? That's the feeling I get, anyway. So if speaker A in world X says "This world is real" and speaker B in world Y says "This world is real" ... what's different about this situation? Because speaker A is not in world Y, world Y is inherently unreal to em. And immediately I have reservations about similar claims to existence, but I'm not sure how to frame them.

Eh, if you don't wanna call other worlds that are separated from our own "real", it doesn't bother me. It's not important really. I'm not sure what you're getting at with existence, though. I think at least that word should be reserved for description of unsubjective reality.

Well, we have proof that at least one world exists. I find myself drawn to make an analogy with theism, though it may be woefully misinformed. I am an agnostic atheist and act as if zero gods exist. My claim isn't exactly baseless: I feel like we have plenty of evidence to suggest that our world is godless. Similarly, I have plenty of evidence to suggest that this world exists, so I act as if one world exists. My previous paragraph made it clear I have reservations about existence and actuality. The "existence" of other worlds by definition means they can't affect me in any way, so I feel safe in saying that there is no harm in acting as if there is only one world. It's not exactly an assumption because it's not baseless, and even if other worlds did exist, it wouldn't make any difference. I don't think that this saves me from making an "assumption" and I think you'll agree with me on that point, but I think that it does no harm to the one world argument. I'm still "open to the idea" but the very idea is meaningless because the worlds are necessarily separated. I think a very similar proposition was stated earlier in the thread. Phew, I hope some of that is at all digestible. Please be picky and point out the likely numerous problems with my jabber.

There is of course nothing wrong with acting as if only one world exists, since that would be the same as acting as if other worlds did exist! And that's because other worlds don't affect us in our daily lives. I can act as if aliens exist on invisible planet Yashlverge, or I can act as if they don't, and I will be acting exactly the same either way, because it makes no difference. Yet they either exist or not. And that is what makes the idea not meaningless despite being necessarily separated from our scope of knowledge. Of course, Occam's razor comes into play in this case since invisible aliens don't explain anything, but even then only to say they are extremely unlikely to exist. Possible Worlds on the other hand do explain something which I have mentioned in previous posts, and will get to in a second.

I don't understand. I must admit I didn't digest very completely the Wikipedia article, but how does it explain why worlds exist?

Worlds exist, precisely because they can exist, goes the explanation. So if a world can (logically) exist, it does exist. Which gives rise to an infinite number of possible worlds.

Basically, it answers the fundamental question of reality "why does the universe exist" by going, "Why? Why not!" :D

These possible worlds are basically devices to explain probability (among other things), right? So worlds exist to make up for possibilities in other worlds?

Worlds exist in order to make up for possibilities, period. Why do you need other worlds to have possibilites to begin with? Can't possibilites exist within empty nothingness? (Sorry if not making lots of sense... we're getting pretty theoretical to be talking about what kind of abstractions can exists within concrete nonexistence)

But where does it all start? What world first had a (unfamiliar jargon coming through!) probability distribution that needed another world to explain it? Bah that's probably missing the point. In any case, it seems to open up many more questions than it actually answers. I don't know. I must admit I don't understand quantum mechanics as much as I'd like to. Please clarify all of this for me.

Even without quantum mechanical indeterminism, Possible Worlds still has powerful explanatory ability, and even more fundamental to reality. Like why the laws of physics were the way they were, and why the universal constants had the values they did, and why spacetime is 4 dimensional. Each possible universe with its own distinct set of laws gets played out in a separate world.

It seems to me that that is all that would be actually meaningful to us. And I don't really understand what you mean there. Like, "we cannot with absolute certainty say that x is true?"

How 'bout this. The universe is basically made up of clusters (solar systems), and clusters of clusters (galaxies), and clusters of these clusters, and so on and so forth. It comes to a point where it's all everything we know, but there could always be other "clusters" like this big one too far away for us to even detect. If there is more to the universe that is too far away for us to detect, isn't that meaningful in a sense, even if we can't know for certain about it?

Can you show it to me, please? I have always closely correlated knowledge with truth and afaict the scientific method rests on falsifiability, and while I understand that it's not infallible, it seems pretty damn good to me.

Consider a blue beetle with yellow spots. We do not know whether or not such a thing exists in the universe, but it either does or doesn't. The statement "there is a blue beetle with yellow spots somewhere at sometime in the universe" is not falsifiable because there is no possible way to search every point in the universe at every point in time for such a thing. It's of course affirmable; finding a blue beetle with yellow spots would make the statement true, but it can never be falsified if one is not found.

So truth either says there's a blue bettle or it says there's not a blue beetle, depending on whether there is, of course. Human knowledge, on the other hand, cannot make the claim that "there is not a blue beetle".

Is "I don't know" a curiosity stopper? Because that's how I've always answered why?.

"I don't know" is a perfectly fine answer to unanswered questions; the best, actually. It acknowledges the fact that there is indeed an unanswered question, and does nothing to discourage looking for an answer.

Something about this doesn't sit well with me. If a dataset that contains perfectly the details of all possible worlds isn't coherent in the sense that it can't be contained entirely (that's what you seem to suggest -- please correct me if I am mistaken), how can you claim that it does have a Highest Truth? (Aside: I'm a bit wary of this "Highest Truth" because it feels like Platonism to me and I am not a Platonist. Again please clarify.) I am kind of struggling to think of something that this describes ... we're saying that these worlds are infinite in number, right? So the sum of their descriptions are probably infinite as well ... with exception of this Highest Truth. Sorry, I guess the entire concept is evading me.

What I was getting at I think was that something can be infinite and still be real.

Perhaps this is Platonism, which I'm not really familiar with. I guess I need to do a bit of research on that front.

Are you familiar with fractals?

How do we determine if something can exist? Is this what you mean by "once you know how to use it"?

It can exist if it is logically consistent.

Naïvete incoming! Feels like Platonism again. Is that inherent to this theory? Because it's something I very much struggle to accept. In the context of this example, I gotta say that I am a humanist when it comes to mathematics. I don't believe there is "y = x^2" form hanging out somewhere that is invoked whenever we talk about parabolas. I think "y = x^2" is meaningless (or at least useless) outside of the context of our mathematical system and I'd be hard pressed to explain the concept without centuries of tradition behind me. Well, it does seem true to me (in context) that "y = x^2" describes an infinite object, the parabola, but the question of the existence of an infinite number of worlds, with a presumably infinitely complex description of the total, seems very different to the definition of a parabola. I wouldn't comfortably equate the two, I guess.

Actually, I don't really think the two are that different, because there is a simple function for the existence of points on each of them. The test for possible worlds existing is whether it logically can or not. If we graphed this, it would look like the whole graph was filled in black, -infinity to +infinity. No imaginary numbers. Of course, this would be more that a 2-dimensional graph; it would have infinite dimensions as well. (Fractals can be infinite dimensions.) In fact, this might be the precise mathematical representation of all of existence, or "Highest Truth" if you will, of Possible Worlds Theory.

I keep hearing these things about Possible Worlds and things before the big bang.

Can someone explain to me in two sentences what these Possible Worlds actually are/represent?

Because when people talk about Possible Worlds it's like they just go on some incoherent rant and it ends up being Bla Bla Bla Bla Bla with no sort of form, condensed meaning, or anything.

In other words, could Light (or anyone else), please explain what they are actually on about?

No metaphysical essays, no moral implications, no bells and whistles. What is it exactly you're trying to say?

MD did a great job, and I would add that every possible set of Laws of Physics that could govern a universe got played out in another Possible World.

 

[Tarvos]

Dude, I know about the quantum mechanics. I just don't see how that makes Possible Worlds theory any more than a load of nonsense.

 

[Music Dragon]

Dude, I know about the quantum mechanics. I just don't see how that makes Possible Worlds theory any more than a load of nonsense.

Honestly, I think you're contradicting yourself here. If you do know about the quantum mechanics, then you also know that Schrödinger's cat most decidedly does not merely lead to a single immediately obvious conclusion that "only one has actually happened", and you also know that the many-worlds interpretation is relatively mainstream and not necessarily just a "load of nonsense".

 

[sovram]

Eh, if you don't wanna call other worlds that are separated from our own "real", it doesn't bother me. It's not important really. I'm not sure what you're getting at with existence, though. I think at least that word should be reserved for description of unsubjective reality.

Very well. I guess that is reasonable.

There is of course nothing wrong with acting as if only one world exists, since that would be the same as acting as if other worlds did exist! And that's because other worlds don't affect us in our daily lives. I can act as if aliens exist on invisible planet Yashlverge, or I can act as if they don't, and I will be acting exactly the same either way, because it makes no difference. Yet they either exist or not. And that is what makes the idea not meaningless despite being necessarily separated from our scope of knowledge. Of course, Occam's razor comes into play in this case since invisible aliens don't explain anything, but even then only to say they are extremely unlikely to exist. Possible Worlds on the other hand do explain something which I have mentioned in previous posts, and will get to in a second.

Worlds exist, precisely because they can exist, goes the explanation. So if a world can (logically) exist, it does exist. Which gives rise to an infinite number of possible worlds.

Basically, it answers the fundamental question of reality "why does the universe exist" by going, "Why? Why not!" :D

Eh. I'm having trouble swallowing this. It just fails to answer the question for me. "Why not!" doesn't mean anything more to me than "I don't know!". The qualification for existence, in this case, is logical consistence -- incidentally it feels like we've been using this a bit fuzzily. What does it mean? Immediately I think of conditions like "causality must be respected/preserved", "the world's natural laws must not be violated", et cetera. "Our understanding of our world's natural law set is incomplete. I propose that all possible gods which do not violate, have not violated, and will not violate our set of natural laws exist. This explains why our world exists AND the whole of human religion." I know, it's a bit of a stretch and likely has more assumptions (that I can't detect), but it feels like the same thing, and it answers two questions! :D

In short, it just seems unnecessary.

Worlds exist in order to make up for possibilities, period. Why do you need other worlds to have possibilites to begin with? Can't possibilites exist within empty nothingness? (Sorry if not making lots of sense... we're getting pretty theoretical to be talking about what kind of abstractions can exists within concrete nonexistence)

Well, that's kind of a can of worms. I was reading something the other day which suggested that nothingness can't actually be nothingness without somethingness ... a bit of a yin yang thing. Kind of interesting. Anyway, no, I don't think possibilities can exist within nothingness. Actually, someone (in the same thread) suggested that you could enumerate the natural numbers with the empty set, e.g. {0}; {{0}}; {{{0}}, {{0}}} ... but this presupposes logic, or at the very least, sets -- which aren't nothingness. Here's a quote:

That same compulsion to define nothing along with 'something' (however incorporeal logic as a 'something' is) attracts me to the Eastern philosophies of pratitya samutpada, or interdependent co-arising, where the basis of reality are mutually interdependent opposites which generate each other. Eastern philosophies take this a further step and suppose that logic exists as a function of consciousness and conclude thereby that consciousness + nothing forms the basis of reality.

Here's the thread.

Even without quantum mechanical indeterminism, Possible Worlds still has powerful explanatory ability, and even more fundamental to reality. Like why the laws of physics were the way they were, and why the universal constants had the values they did, and why spacetime is 4 dimensional. Each possible universe with its own distinct set of laws gets played out in a separate world.

I mean, I see what you're getting at here, but it doesn't that powerful to me! It might explain "why do we have these laws?" -- well, we have these because the other worlds don't. But it doesn't explain to me how, which seems like the bigger and more important question. Insert noncommittal grunt here.

How 'bout this. The universe is basically made up of clusters (solar systems), and clusters of clusters (galaxies), and clusters of these clusters, and so on and so forth. It comes to a point where it's all everything we know, but there could always be other "clusters" like this big one too far away for us to even detect. If there is more to the universe that is too far away for us to detect, isn't that meaningful in a sense, even if we can't know for certain about it?

In a sense, I suppose?? I guess I just have an apathy about it. My "truth" describes our world. I think it boils down to whether we should pursue truth for the sake of truth or for application (not necessarily practical!). If the deepest truth, i.e. that which describes ALL worlds (because it seems to me if each world has a truth, then surely there must be a description of what all of these worlds in turn exist within??), can't actually be processed or understood in an appropriate context (since we are restricted to our own world), it seems ... pointless. I think all of the parentheses and question marks indicate that this is getting a little too metaphysical than what I bargained for, ha.

What I was getting at I think was that something can be infinite and still be real.

Perhaps this is Platonism, which I'm not really familiar with. I guess I need to do a bit of research on that front.

Are you familiar with fractals?

Oh, definitely. I'm not technically a mathematician (at least, not yet), but I'm passingly familiar with Cantor and his work with the infinite. Just very basic concepts with infinity. Infinite series and the like.

If I had to explain Platonism (since I'm not much of a philosopher), I'd say that it's basically that our world is populated with images of Forms, which are the most perfect and truest representations of concepts. What we know as cows are actually imperfect models of the Cow Form, that is ethereal and hanging out somewhere in the heavens or something like that.

And I'm passing familiar with fractals too, yes. Actually, I'm reading a book on chaos right now and much has been devoted to the subject. Kind of familiar with the Sierpienski (sp?) gasket, Mengel (sp?) sponge, Cantor middle third set, etc.

Actually, I don't really think the two are that different, because there is a simple function for the existence of points on each of them. The test for possible worlds existing is whether it logically can or not. If we graphed this, it would look like the whole graph was filled in black, -infinity to +infinity. No imaginary numbers. Of course, this would be more that a 2-dimensional graph; it would have infinite dimensions as well. (Fractals can be infinite dimensions.) In fact, this might be the precise mathematical representation of all of existence, or "Highest Truth" if you will, of Possible Worlds Theory.

Explain to me where you get this visualisation of this "logical consistence function". I don't see where this image is coming from! Of course "y = x^2" seems very simple to verify, but "logical consistence" seems much more complicated, and my intuition tells me that it couldn't really be encoded in a finite way. It kind of feels like, "This is the 'hexagon function', which tells you if a shape is a hexagon or not. If it is, the graph is all filled in." It seems very simple, but there are a lot of details that you're cheating your way out of by encoding it in "is it a hexagon or not". Does this make sense? I think I might just be misinterpreting you.

I didn't know that fractals could be of infinite dimension! Not immediately, anyway. Knew that they can be non-integer. I feel like I've heard of infinite topological dimension, but I might be imagining that.

 

[Tarvos]

Honestly, I think you're contradicting yourself here. If you do know about the quantum mechanics, then you also know that Schrödinger's cat most decidedly does not merely lead to a single immediately obvious conclusion that "only one has actually happened", and you also know that the many-worlds interpretation is relatively mainstream and not necessarily just a "load of nonsense".

I get the first and the second bit, but what's the link?

 

[Butterfree]

The multiverse theory has nothing to do with the many-worlds interpretation of quantum mechanics, and I can't help but find it misleading to talk about quantum many-worlds as if it means "all possible worlds" exist, because quantum amplitudes aren't probabilities and what we think of as being "possible" doesn't have much to do with quantum superpositions.

Like, we think of it as being "possible" that we could have made some other decision than we did at some point in time... but in reality, the decision we made was determined by the state of our brain at the time, which was determined by various psychological and biological factors. The fact we were there as conscious beings making a decision didn't create a special universe for each possible decision we feel like we could have made, which is the naïve, intuitive way to interpret "all possible worlds exist".

So "possible" worlds that we can hypothetically imagine are not in any way implicated to exist by quantum mechanics, and I don't see how we can possibly debate the existence of such worlds because... we don't know. There is no possible way that anyone can know, or even have evidence bearing on the matter. It's like trying to stage a debate about whether a randomly generated bit that we can't see is zero or one; we have zero access to information that could tell us anything about whether possible worlds exist in any interesting sense, so debating about it cannot possibly be meaningful. Unless you decide to define existence in some uninteresting sense that renders the question trivial.