The Multiverse - is there one, where is the line between science and metaphysics, and just how much stuff is there?

[Vastness]

Recently been reading a bit about the "multiverse" and the various theories (or rather, unprovable hypotheses, perhaps ) put forward by scientists to explain it's structure.

Anyone who needs to get up to speed should check out a couple of links - Multiverse on Wikipedia, good summary as ever, and for a slightly more mind-boggling look at some of the numbers involved, I enjoyed this article - Confronting the Multiverse: What 'Infinite Universes' Would Mean.

Theories of multiverse cosmology obviously have been gaining some traction for a long time, supposedly Stephen Hawking's last paper even approached the topic, I haven't read it and honestly don't have the scientific literacy to do so but supposedly it put some constraints on the size of the multiverse (scaling it down from potentially infinite to big but finite).

To be clear, I am most interested in scientific and/or logical approaches to the problem, although I have a lot of time for metaphysics, for the purposes of discussion I'm most interested in things about the multiverse that we could one day conceivably directly derive from observation and/or logical reasoning, rather than realisations that require either faith or a substantial monastic dedication to elevating one's consciousness (the objective reality of any such realisations or revelations notwithstanding).

I hope that clarifies the direction I was hoping to take this discussion in, but, that said, I recognise that almost nothing about any supposed multiverse theory is currently testable, so the line between science and metaphysics is somewhat blurred... the blurriness of this line, I think, is itself an interesting topic for discussion. For example, will it appear blurred forever, will our understanding of reality eventually reach a level that we cannot surpass, or will we eventually find ways to see beyond the Planck length, start to pin down elements of quantum uncertainty, or even devise ways to actually look into other dimensions, whether micro or macroscale, peering off the surface of our 3D universe into the hyperdimensional void...?

Obviously that question is impossible to answer right now, but anyway I digress slightly... something that is most interesting to me right now, probably partly because I think this is the only real tool we have to analyse the issue right now, is how exactly to apply logical reasoning to the question of whether there is or is not a multiverse - obviously it has implications for the Anthropic problem...

Anthropic principle
The concept of other universes has been proposed to explain how our own universe appears to be fine-tuned for conscious life as we experience it.

If there were a large (possibly infinite) number of universes, each with possibly different physical laws (or different fundamental physical constants), then some of these universes (even if very few) would have the combination of laws and fundamental parameters that are suitable for the development of matter, astronomical structures, elemental diversity, stars, and planets that can exist long enough for life to emerge and evolve.

The weak anthropic principle could then be applied to conclude that we (as conscious beings) would only exist in one of those few universes that happened to be finely tuned, permitting the existence of life with developed consciousness. Thus, while the probability might be extremely small that any particular universe would have the requisite conditions for life (as we understand life), those conditions do not require intelligent design as an explanation for the conditions in the Universe that promote our existence in it.

An early form of this reasoning is evident in Arthur Schopenhauer's 1844 work "Von der Nichtigkeit und dem Leiden des Lebens", where he argues that our world must be the worst of all possible worlds, because if it were significantly worse in any respect it could not continue to exist."

...and Occam's razor:

Proponents and critics disagree about how to apply Occam's razor. Critics argue that to postulate an almost infinite number of unobservable universes, just to explain our own universe, is contrary to Occam's razor.[72] However, proponents argue that in terms of Kolmogorov complexity the proposed multiverse is simpler than a single idiosyncratic universe.[59]

For example, multiverse proponent Max Tegmark argues:

[A]n entire ensemble is often much simpler than one of its members. This principle can be stated more formally using the notion of algorithmic information content. The algorithmic information content in a number is, roughly speaking, the length of the shortest computer program that will produce that number as output. For example, consider the set of all integers. Which is simpler, the whole set or just one number? Naively, you might think that a single number is simpler, but the entire set can be generated by quite a trivial computer program, whereas a single number can be hugely long. Therefore, the whole set is actually simpler... (Similarly), the higher-level multiverses are simpler. Going from our universe to the Level I multiverse eliminates the need to specify initial conditions, upgrading to Level II eliminates the need to specify physical constants, and the Level IV multiverse eliminates the need to specify anything at all... A common feature of all four multiverse levels is that the simplest and arguably most elegant theory involves parallel universes by default. To deny the existence of those universes, one needs to complicate the theory by adding experimentally unsupported processes and ad hoc postulates: finite space, wave function collapse and ontological asymmetry. Our judgment therefore comes down to which we find more wasteful and inelegant: many worlds or many words. Perhaps we will gradually get used to the weird ways of our cosmos and find its strangeness to be part of its charm.[59][73]
— Max Tegmark

So we get to the core of the issue I want to address. Is it more logical to assume that the multiverse does exist, or does not?

Would be very interested to hear from any of you who are more deep into formal logic stuff. Obviously in natural language, I can suppose quite easily that once, the ocean was the edge of reality... soon after, it was the horizon... soon after that, the celestial dome with the stars printed on it... then the edge of the observable universe... and now, perhaps, some kind of ephemeral border in infinite-dimensional "Hilbert space"... :D But I am unsure if this line of reasoning actually stands up to scrutiny.

Assuming we can make any logical inferences about the multiverse's existence, can we make any inferences about it's size and properties? Mainly, is it infinite, or not?

Again, speaking in natural language terms, it seems conceivable that even going from a non-infinite multiverse such as one allowed by Stephen Hawking's last paper, we could keep peeling back more layers of reality indefinitely. But if the multiverse is infinite then the implications are mind-boggling... assuming for a moment that it is infinite obviously even infinity has some constraints, because, evidently, there are not an infinite number of pandimensional beings with the technology to traverse dimensions and time who invaded every single iteration of reality and enslaved the subjects... or perhaps there are, but just in another branch of the infinity-wavefunction... Even so, there must be some constraints to infinity. But does infinity even make sense? Or is infinity the most likely scenario or not? Is it possible to know, or even speculate?

Look forward to reading anyone's input.

 

[Xorkoth]

I'm not in a frame of mind right now to think up a rigorous response, but I had a couple of thoughts to get a reply in and maybe start this off as I think it's a fascinating and worthy topic. My first thought it a thought experiment I did as a kid. Imagine travel to the edge of the observable universe, and throwing a rock past it. It's gotta go somewhere, right? It's not going to just cease the exist, or freeze at the edge (I mean I don't think). From where we stand, we appear to be at the very center of the observable universe, just because light has been able to travel the length of time since the beginning from each direction, making it seem that there is a limited sphere around us. But every point in space experiences that same phenomenon. Given the incredible vastness of the cosmos that we can see, it seems like a strange leap of logic to assume that all we can see is what there is, or that there would be an edge at all.

Secondly, I like the idea of black holes being their own universes/big bangs. It's a bunch of light and matter that can never escape, a self-contained singularity. Seems an awful lot like our conception of our own universe.

My opinion on the matter is that the universe is a multiverse and it is infinite. It repeats on the macro and micro scales. Our perspective in it is meaningless because it fractallizes down or up to any level. True infinity, IMO. However I think all of it is mostly unreachable by the rest of it due to the distances involved even within a particular universe, let alone the seeming inability to survive entering a black hole to see a theoretical new universe within in existing one.

 

[Shady's Fox]

I think wormholes are more appropiate when comes to see new universes and OP think about life itself, what it's life? take out all your hobbies and you got nothing, simply a body and an energy within. What exactly do you want to find out about the multiverse, what page you want to read? Emotions, instinct and dreams, I think you are embedded in this type, what structure are you dependent on? Your life is bounded by the dream world and this also link the idea with energy and the wonderland. How does infinity looks like? Does it have a colour, it's simply a word? it's an idea/perspective, it's a definition of nothing, what could be and what's not yet? Or maybe a structure?. Repetition of the truth and you automatically choose hate because you want to be something in order to exist, basically the argument of time. Again, what your purpose with the multiverse and why you look towards it?

 

[Vastness]

I'm not in a frame of mind right now to think up a rigorous response, but I had a couple of thoughts to get a reply in and maybe start this off as I think it's a fascinating and worthy topic. My first thought it a thought experiment I did as a kid. Imagine travel to the edge of the observable universe, and throwing a rock past it. It's gotta go somewhere, right? It's not going to just cease the exist, or freeze at the edge (I mean I don't think). From where we stand, we appear to be at the very center of the observable universe, just because light has been able to travel the length of time since the beginning from each direction, making it seem that there is a limited sphere around us. But every point in space experiences that same phenomenon. Given the incredible vastness of the cosmos that we can see, it seems like a strange leap of logic to assume that all we can see is what there is, or that there would be an edge at all.

Oh yeah for sure, that rock has to go somewhere. I don't know if you had a chance to check out that second article I linked but something that really fascinated me in it was the idea that rather than being "parallel" as in the common conception of parallel universes, there could be identical, or close to identical "Hubble volumes" even reachable through our current 3D space - just very, very, very far away. I can't remember the exact number but it was something like 10^14^14^14^14 ... something something someone estimated there could be reasonably expected to be a very close to identical hubble volume, with alternate versions of you, me, and everyone we've ever known...

Secondly, I like the idea of black holes being their own universes/big bangs. It's a bunch of light and matter that can never escape, a self-contained singularity. Seems an awful lot like our conception of our own universe.

I like this idea also, particularly I like the idea that black holes are the origin point for parallel universes with perpendicular timelines - but which I mean, the arrow of time in that particular universe is at a 90 degree angle to all 4 of the macro-dimensions we can perceive (3 space+1 time) - so the peak mass (I think) of the singularity defines the net total mass of this baby universe... Black holes really are fascinating enigmas in any case. Obviously whether macro-wormholes can exist in the universe is as yet an unanswered question, but if they can then given that a singularity is basically a one-ended wormhole apparently to nowhere it lends weight to the idea of some kind interdimensional energy exchange going on. I've butchered some of the science here no doubt but I think in this speculative context it's forgivable.

My opinion on the matter is that the universe is a multiverse and it is infinite. It repeats on the macro and micro scales. Our perspective in it is meaningless because it fractallizes down or up to any level. True infinity, IMO. However I think all of it is mostly unreachable by the rest of it due to the distances involved even within a particular universe, let alone the seeming inability to survive entering a black hole to see a theoretical new universe within in existing one.

I agree that most of this infinity is highly likely to be unreachable, there are a few ideas I like to think about though although I'm veering even further off my initially stated "scientific" avenue of discussion. The first is that the universe, at least this, one, maybe others, are in some sense "god machines", because if our current theories are anywhere close to being correct, in that several trillion years the stars will burn out, protons will decay, and inflation will increase exponentially until the zero-point energy of the universe is truly, infinitesimally close to zero... Any sentient intelligences that persist to the end of time and the cosmic freeze will be unfathomably powerful entities, borderline omniscient and omnipotent, some kind of hive mind of countless ancient civilisations that survived the struggles inherent with entering the real of true self-awareness from the messy violence of natural evolution, and persisted beyond the self destructive tendencies that (possibly) all intelligent life shares... and at this point, faced with slow extinction, and with a billion or even trillion year memory and accumulation of knowledge, itself the result of the personal struggles of countless zillians of minds, perhaps some of them will break the fundamental laws of physics and thermodynamics and venture elsewhere, or become something else...

I think this is a really interesting inversion of the traditional idea that the gods created the universe, when in fact it seems to me quite possible that the universe will create the gods. Although of course, both things can be equally true.

The second interesting concept I like to think about relies on a fairly materialistic conception of consciousness, I know this idea isn't everyone's cup of tea so to speak but I think most people can still appreciate the idea. If consciousness is an emergent property of sufficiently complex patterns, then in an infinite universe it's inevitable that the pattern giving rise to your conscious experience will spontaneously recur, somewhere, someplace, maybe many places, likely somewhere completely alien, and seamlessly continue from the destruction of the iteration of the sentience-awareness-fractal that some people might call a soul within our currently shared consensus reality.

Somewhat related, although IMO even more out there, I remember recently reading a theory that none of us ever actually experience our own death, infact we all traverse infinite branches of the quantum wavefunction which diverge from each other whenever conscious experience ceases... Obviously this requires some stretch of imagination when you consider the countless millenia of seemingly quite dead and unrecoverable humans prior to us even having the linguistic complexity to discuss such things... but, again, a fun idea to think about.

I think wormholes are more appropiate when comes to see new universes and OP think about life itself, what it's life? take out all your hobbies and you got nothing, simply a body and an energy within. What exactly do you want to find out about the multiverse, what page you want to read? Emotions, instinct and dreams, I think you are embedded in this type, what structure are you dependent on? Your life is bounded by the dream world and this also link the idea with energy and the wonderland. How does infinity looks like? Does it have a colour, it's simply a word? it's an idea/perspective, it's a definition of nothing, what could be and what's not yet? Or maybe a structure?. Repetition of the truth and you automatically choose hate because you want to be something in order to exist, basically the argument of time. Again, what your purpose with the multiverse and why you look towards it?

I know your post is meant somewhat figuratively but I must admit to having trouble parsing it. Particularly the part about choosing hate, which I do not believe I have chosen, at least not deliberately - quite the opposite, in fact - and I'm curious what makes you think otherwise.

Does there need to be a purpose? For what reason do human beings pursue any interest they might have? I do have a purpose however, my purpose is to gain a greater understanding of and appreciation for this incredible, technicolor, dreamlike, impossibly improbable reality in which I find myself incarnate, seemingly unbidden, of uncertain destination and uncertain origin, and perhaps none of either, or many of both. Why would you not look towards the multiverse? What greater, and more fundamental purpose can there be for anyone, or anything, than to gaze into infinity, to try to get in some small way, some tiny, tiny glimpse of the unfathomable, undeniable brilliance shimmering beneath this wispy veil of experiential reality?

 

[Xorkoth]

What greater, and more fundamental purpose can there be for anyone, or anything, than to gaze into infinity, to try to get in some small way, some tiny, tiny glimpse of the unfathomable, undeniable brilliance shimmering beneath this wispy veil of experiential reality?

Sometimes people ask me why I bother thinking about this stuff too because we can't possibly know, and I say much of the same thing as you do: because it's the most interesting thing I can possibly think about. Thanks for the thoughts. Thinking about our place in the infinity of the universe puts me in my place and helps me remember I am not important at all, except to myself. This helps me immeasurably in my life and it always has. My mom and I used to always talk about this kind of stuff from as young as I can remember.

 

[Shady's Fox]

There's a fundamental rule which is to psychological trick yourself into beliving the transformation of insights into implemented evolution, the scale are random but the selection isn't, what's your genetic question? What it's the difference between being different and being weird? it's the biological spirit of masculinity & feminity being built into a image created by you by whatever what hides behind, now the process of reflection into nothing and seeing everything it's metaphysical.

There are layers of realities, you belive in the artificial one. Ancients had the belief that dragonflys are gates to morals, ultimately the macro argument it's a statement but what does that mean exactly? There is a notion for pursuing and gazing into beyond it's a challange of courage, where's the evidence? now you tell me and everyone would probably say yes if asked but here's the idea, so imagine that you are a spirit, a God or maybe a mythos as you consider yourself, you have to come in terms with malevolence, that's the acceptation of the levels as the theatres presents as responsability.

 

[Vastness]

Sometimes people ask me why I bother thinking about this stuff too because we can't possibly know, and I say much of the same thing as you do: because it's the most interesting thing I can possibly think about. Thanks for the thoughts. Thinking about our place in the infinity of the universe puts me in my place and helps me remember I am not important at all, except to myself. This helps me immeasurably in my life and it always has. My mom and I used to always talk about this kind of stuff from as young as I can remember.

Hah, that's funny, I actually talk about this with my mum too! :giggle: I had a conversation about this topic shortly before or after starting this thread I think... she's a little more traditionally theistic than I am and I think finds some of the sheer scale of some of these concepts a little depressing, which I think is fairly common, it's hard for some people to get their head around the relative insignificance of everything that's important to anyone. I think I made a point that if you consider the mind boggling vastness of time and that if the universe will probably continue to spew stars and planets into the cosmos for another 100 trillion years... then really, on these kind of scales, what difference does it make what you get done and who lives and who dies? Really even if humankind can't get themselves on track to avoid self-annihilation, even if it takes a couple billion years for another torchbearing contender of sentient life to arise somewhere, someplace else... what does it matter? Time will keep on turning, possibly in more than one direction... I think some people find this a bit depressing, even frightening, but I find it quite the opposite - it's incredibly liberating if you can accept reality for what it is, and realise we are all ultimately just along for the ride.

There's a fundamental rule which is to psychological trick yourself into beliving the transformation of insights into implemented evolution, the scale are random but the selection isn't, what's your genetic question? What it's the difference between being different and being weird? it's the biological spirit of masculinity & feminity being built into a image created by you by whatever what hides behind, now the process of reflection into nothing and seeing everything it's metaphysical.

There are layers of realities, you belive in the artificial one. Ancients had the belief that dragonflys are gates to morals, ultimately the macro argument it's a statement but what does that mean exactly? There is a notion for pursuing and gazing into beyond it's a challange of courage, where's the evidence? now you tell me and everyone would probably say yes if asked but here's the idea, so imagine that you are a spirit, a God or maybe a mythos as you consider yourself, you have to come in terms with malevolence, that's the acceptation of the levels as the theatres presents as responsability.

I'm sorry but I just have no idea what you are trying to say. I can discern I think that you believe sensory experience to be an illusion. You may well be right, but in that case what "layer of reality" do you consider to be more real?

Ultimately everything we can perceive is part of our own inner sensory world, what we consider to be the external included, so I really don't see whatever distinction you are trying to draw here. Whether it's ultimately illusory or not, words and concepts we use to describe our material world still have relevance and meaning in the context of human lives.

I mean I'm guessing that in your life, you've travelled to a new location once or twice, probably explored a little to get your bearings, see what is around, both for your own convenience and just out of interest. I'm really not doing anything differently here, I'm just exploring the place that I live on a grander scale. Necessarily the exploration is a little more conceptual, of course.

 

[Shady's Fox]

Yeah not much philosophy overall and just curiosity even though it killed the cat but the satisfaction brought it back haha, same, i'm fascinated by everything around me especially by dark winds over the water. Layers of reality? well as you may know if not it's perfectly okay to ask sometimes, there are indeed few of them and with a simple Google search you can verify that, we currently live in a empirical reality which has ontology as base. As you and maybe more people I like to live in my own head, I really love to travel through my brain till I get lost into the void. Time machine for e.g work on Brahman.

 

[Xorkoth]

There are layers of realities, you belive in the artificial one.

Are you trying to say you don't believe the external universe is real? Who are you to say what is real and what isn't? Anyway this is just speculation on a topic, none of us knows what is and isn't real, but many people find it really fascinating to think about and discuss the universe.

Hah, that's funny, I actually talk about this with my mum too! :giggle: I had a conversation about this topic shortly before or after starting this thread I think... she's a little more traditionally theistic than I am and I think finds some of the sheer scale of some of these concepts a little depressing, which I think is fairly common, it's hard for some people to get their head around the relative insignificance of everything that's important to anyone. I think I made a point that if you consider the mind boggling vastness of time and that if the universe will probably continue to spew stars and planets into the cosmos for another 100 trillion years... then really, on these kind of scales, what difference does it make what you get done and who lives and who dies? Really even if humankind can't get themselves on track to avoid self-annihilation, even if it takes a couple billion years for another torchbearing contender of sentient life to arise somewhere, someplace else... what does it matter? Time will keep on turning, possibly in more than one direction... I think some people find this a bit depressing, even frightening, but I find it quite the opposite - it's incredibly liberating if you can accept reality for what it is, and realise we are all ultimately just along for the ride.

Haha weird, my mom is also traditionally theistic (though in a very open-minded and loving way), and I also find the vastness of it all to be liberating. To realize none of this matters at all except for the purpose of our own experience means that you can go through life taking experiences in as they come and not get too wrapped up in ego traps. Whatever experiences you have, they're part of a vast whole whose scale is beautifully massive and majestic.

Man, think about that... 100 trillion more years of new creation, on top of the overwhelming amount that exists now. We're having a discussion in CEPS in a thread about whether or not there is life outside of Earth. How could it possibly be that the probability of life forming on a planet would be precisely, exactly 1 in however many planets there are (trillions of trillions)? And if you bring in the idea of a multiverse, and past and future trillions of year periods... it seems so strange to me to think that all of this exists with only us on this little rock to observe it.

 

[alasdairm]

is there a universe in the multiverse where there's no possibility of a multiverse?

how does that work?

alasdair

 

[Shady's Fox]

Well it could be a frame if I imagine that the evolutionary process to organize the structure and you know matter and dark matter, both are made from atom & molecules. What's time? a illusion which allows changes, the ingredient by itself it's out there but if I handed you a molecule of water you wouldn't be able to phantom the scale about the relationship between the baring and warmholes, time could be same and so the experience of a universe being not fundamental and being rejected by time it's possible. If we can't bend it with time then we can't see the future only the past same as we experience things with space. If we discover dark matter we could reveal some hidden universes and fuck me if I know what those hides and man take the black hole example. I think you can travel into the future with it now how do you get back to the past? I dunno we didn't uncovered that edge yet where the laws of psyhics breaks. So yeah there could be a universe, somehow, it's just an irony of itself, you can rule out that, at least for the available options that we have now.

 

[Foreigner]

I don't think humans are evolved enough to really understand this. We are too material. That said... I will try to answer.

Why should the universe have a beginning or an end? It's assumed that because of our laws of thermodynamics - that is, that the universe is expanding and cooling - that it had an original dense point. However, that's specious reasoning because we can't see the edge of the universe. We also don't know if expansion is limitless or cyclical. Maybe after 20 billion years it will start contracting, then expand again. There may not be an alpha and omega, we are just projecting one onto it because humans are a physical, linear species.

We also don't understand dark matter very well, and it makes up more of our universe than visible matter. I don't buy the notion that space has a fabric, only that certain phenomena warp perception of space-time. For example I don't think black holes go anywhere, they are just super objects so dense that they look like a hole. In science class, gravity is explained as a "well"... like when you put a marble on a piece of fabric, it makes a dent in the fabric. However there's no evidence that gravity is doing this to space. Our mathematical explanation of gravity, according to our perception, looks concave, but the explanation is insufficient. We still don't know what gravity is, exactly. When they describe gravity as a "well", it drives me crazy.

Cosmology is like a religion. Some of the things they say just make me shake my head. At the same time, our consciousness knows, on some level, that this physical universe is not all there is. It's why we keep trying to come up with rules to circumvent it, in order to move beyond it. Meanwhile, with the human capacity for something like astral projection, you can go from one point in the universe to any other instantaneously (with some limits). So called space-time is irrelevant.

I think our biggest problem is that we're looking at the universe through a physical body, which on its own is very limiting. We can probably figure out much more about the universe by doing more inner inquiry about the nature of consciousness. We should do both the physical and metaphysical investigations, but because of how science arose in the west as a counter to religion, it is devoid of spirit. As a consequence, all material reductionists will acknowledge is the mechanical universe. With science only looking at the material, it's going to take us forever to become a cosmic level species.

 

[Vastness]

^ You make a lot of good points but I just want to address one thing which I disagree with, material reductionist that I am.

With science only looking at the material, it's going to take us forever to become a cosmic level species.

The problem is, immaterial stuff, for whatever reason, just doesn't appear well suited to scientific scrutiny. It's not like no-one has ever tried to investigate metaphysical phenomena in a scientific way, people have tried since probably before the scientific method was even properly understood.

It just seems that, for whatever reason, all attempts to bring such immaterial phenomena out of the shadows have failed. Whether you believe this is because a lot of metaphysical ideas just wilt under the harsh light of rigorous scientific enquiry, or because the engineers behind the game of life, so to speak, just want to keep people a little confused, lest they unlock some kind of cheat code for reality... and our human capacity for self-delusion is great. I don't consider myself a scientific fundamentalist and can accept that science doesn't have all the answers right now, but as far as systems of thought go for getting a deeper understanding of how the world works... well, it's a pretty good system for sure. And I think it's important to remember that a bunch of stuff that historically would be considered science (well, first magic or witchcraft, depending how far back you go) is now common sense.

Scientists are trying, and I have known a few, believe me, it's just that no one, scientist or otherwise, in the history of the human species has yet come up with a better way to use science to make life better for everyone, hence they focus on the material, which is something that we collectively have some kind of a handle on and a fairly clear path to move forward. Anything else would just be stumbling around in the dark.

Astral projection is something that very much interested me when I was younger, but as I've become more cynical I'm pretty skeptical of this too. I remember some of the stuff I read just sounded utterly fantastical though. Is this something you've practised yourself?

By any chance, have you considered using this skill to perform some indisputably magical feats? Perhaps contacted some researchers so that other people can benefit from this hidden knowledge?

If there truly is a layer of reality much closer and more accessible than most of us think, then anyone who has access to this should surely do their utmost to bring this secret knowledge to the world. IMO, the delay to us becoming a cosmic species isn't a collective lack of effort on the part of science, it's the apparently endless reluctance of those who do understand the immaterial to share it in any truly significant way!

 

[Aeon Psyche]

there are no multiverses. that's BS. This one is perfect so no other pure spirit who completed their cycle would create another one, for what purpose? Where are you going to put your universe? next to this one? lol. people get your dimensionology correct.

 

[Vastness]

^ In ancient times people would have said much the same thing about the Earth!

 

[Jabberwocky]

i have a masters in mathematical logic and a phd in quantum computing but i've rotted my brain with drugs and am a bit rusty... i'll try to answer some of these questions from my point of view. firstly, i should point out i am an adherent of the everettian (many universes) interpretation of quantum mechanics. and as far as i am concerned, the probabilities in quantum mechanics constitute evidence of other universes.

my choice of interpretation is pragmatic, its the best way i could reason about quantum mechanical systems precisely enough to do original research in that area.

iirc they quantified the everettian multiverse as uncountably infinite, but there may be some debate. there are different levels of infinity that are provably bigger than one another.

a hilbert space is just a vector space with a norm it doesn't have a notion of border.

to me, this version of the multiverse doesn't imply any spiritual mumbo jumbo, or anything about cosmology, because those are outside the remit of quantum mechanics. there are other notions of the multiverse- the inflationary then collapsing, i'm not sure how we would get any idea about things 'outside' our universe, rather than in the truly parallel universes hypothesised by everett. i'm sure i read somewhere that dark matter might be the influence of alternate universes (in some non quantum mechanical sense because the parallel universes are causally separated after splitting in that case) on our universe but i don't know how much traction that theory has.

 

[Vastness]

Very interesting! Thanks for responding!

I wonder if you could clear up my layman's understanding of quantum computers (at least, whatever rudimentary experiments in quantum computing have been done so far). I've read/heard/interpreted in some way that basically when multiple calculations are done simultaneously, essentially one could say that what is happening is that these computations are occurring in parallel versions of the computer, or perhaps just the qubit, and somehow the parallel computations collaborate to output the correct answer (presumably in each possible universe). As someone who has studied quantum computing, does that sounds roughly accurate?

 

[Jabberwocky]

ha, why yes i could, its my favourite subject!

physically, any quantum mechanical system that we can control sufficiently precisely could act as a quantum computer. in practise, at least by the time i finished my phd, there was no proof that we can control enough quantum mechanical systems to provide useful computing power in the way needed, cos they need to be in as close to a true vacuum as possible, which is hard.

each qubit is a superposition of a classical bit, so its both 1 and 0 at the same time, with a certain probability of 'collapsing' into either 1 or 0 upon measurement (which in a many universe interpretation is the universe forking so in one universe you get a 1 and in the other universe you get a 0, cos on the scale of the multiverse the wave function never collapses). you are right that this does offer massive parallelism, you basically get to test each possibility in one computation.

the price of the parallelism is that your output is probabilistic so you need to rerun your computation a sufficient number of times to get the probability distribution, so it does not always output the right answer, unless the probability of doing so is equal to one.

quantum mechanical algorithms work by controlling interference between different basis states of the qubit (i.e. the bit that's in the 1 state and the bit that's in the 0 state) so that they behave in a certain manner under certain conditions. until measurement, the computation is completely deterministic so we know exactly what is going on.

does that make sense?

i've just reread your thread title- i think as discoveries in physics progress, the line between metaphysics and science is blurring. in my research, i simply couldn't reason about the systems i was studying without picking an interpretation, and taking the wave function at face value (which is what many universes does) was the easiest way, so it was necessary for me to take a metaphysical stance. to me this is a large part of the division between maths and science. physicists HAVE to pick an interpretation otherwise we get no where. for logical reasons, there is nothing in the mathematical structure of physics that says electrons exist, and there cannot be, but to reason, we have to think electrons, or more precisely disturbances in the electron field, exist. its possible to do maths without an interpretation, but great physicists have strong physical intuition, and for that you need an interpretation, and for that you need metaphysics.

 

[Aeon Psyche]

electrons are not a part of the physical, as in the way I see it, electrons are what combines our material world to the spiritual world. Our own very souls consist of electrons as they store our intelligence inside and is what makes a soul give light outside the physical body. Offcourse electrons exist. Our whole universe exists out of vibrations, ever considered or noticed that?

 

[Ganjcat]

Sounds interesting I've bookmarked this to read later on