[HN Gopher] New mathematical framework reshapes debate over simu...
       ___________________________________________________________________
        
       New mathematical framework reshapes debate over simulation
       hypothesis
        
       Author : Gooblebrai
       Score  : 68 points
       Date   : 2025-12-21 11:21 UTC (11 hours ago)
        
 (HTM) web link (www.santafe.edu)
 (TXT) w3m dump (www.santafe.edu)
        
       | A_D_E_P_T wrote:
       | Oh man, Stephen Wolfram and Jurgen Schmidthuber are probably
       | fuming at the fact that this is called a "new" mathematical
       | framework. It's all very old, and quite conventional, even
       | popular -- not exactly the road not taken.
       | 
       | What the author did was use the Physical Church-Turing thesis,
       | and Kleene's second recursion theorem, to show that: (1) If a
       | universe's dynamics are computable (PCT), and (2) the universe
       | can implement universal computation (RPCT), then (3) the universe
       | can simulate itself, including the computer doing the simulating.
       | 
       | That's basically all. And thus "there would be two identical
       | instances of us, both equally 'real'." (Two numerically distinct
       | processes are empirically identical if they are
       | indistinguishable. You might remember this sort of thing from
       | late 20th c. philosophy coursework.)
       | 
       | He also uses Rice's theorem (old) to show that there is no
       | uniform measure over the set of "possible universes."
       | 
       | It's all very interesting, but it's more a _review article_ than
       | a  "new mathematical framework." The notion of a
       | mathematical/simulated universe is as old as Pythagoras (~550
       | BC), and Rice, Church-Turing, and Kleene are all approaching the
       | 100-year mark.
        
         | ericpauley wrote:
         | It's also a little silly for the same reasons discussions of
         | theoretical computability often are: time and space
         | requirements. In practice the Universe, even if computable, is
         | so complex that simulating it would require far more compute
         | than physical particles and far more time than remaining until
         | heat death.
        
           | FabHK wrote:
           | Yes, is that (obvious) point being addressed in the paper? At
           | first skimming, it just says that a "sufficiently souped up
           | laptop" could, in principle, compute the future of the
           | universe (i.e. Laplace's daemon), but I haven't seen anything
           | about the subsequent questions of time scales.
        
           | Borg3 wrote:
           | Hehe yeah.. For me, its just inverted search for the God.
           | There must be somethink behind it, if its not God, then it
           | must be simulation! Kinda sad, I would expect more from
           | scientist.
           | 
           | The big riddle of Universe is, how all that matter loves to
           | organize itself, from basic particles to Atoms, basic
           | molecues, structured molecues, things and finally live..
           | Probably unsolvable, but that doesnt mean we shouldnt
           | research and ask questions...
        
             | Aerroon wrote:
             | > _The big riddle of Universe is, how all that matter loves
             | to organize itself, from basic particles to Atoms, basic
             | molecues, structured molecues, things and finally live..
             | Probably unsolvable, but that doesnt mean we shouldnt
             | research and ask questions..._
             | 
             | Isn't that 'just' the laws of nature + the 2nd law of
             | thermodynamics? Life is the ultimate increaser of entropy,
             | because for all the order we create we just create more
             | disorder.
             | 
             | Conway's game of life has very simple rules (laws of
             | nature) and it ends up very complex. The universe doing the
             | same thing with much more complicated rules seems pretty
             | natural.
        
               | estearum wrote:
               | Yeah, agreed. The _actual_ real riddle is consciousness.
               | Why does it seems some configurations of this matter and
               | energy zap into existence something that actually
               | (allegedly) did not exist in its prior configuration.
        
               | A_D_E_P_T wrote:
               | I'd argue that it's not that complicated. That if
               | something meets the below five criteria, we _must_ accept
               | that it is conscious:
               | 
               | (1) It maintains a persisting internal model of an
               | environment, updated from ongoing input.
               | 
               | (2) It maintains a persisting internal model of its own
               | body or vehicle as bounded and situated in that
               | environment.
               | 
               | (3) It possesses a memory that binds past and present
               | into a single temporally extended self-model.
               | 
               | (4) It uses these models with self-derived agency to
               | generate and evaluate counterfactuals: Predictions of
               | alternative futures under alternative actions. (i.e. a
               | general predictive function.)
               | 
               | (5) It has control channels through which those
               | evaluations shape its future trajectories in ways that
               | are not trivially reducible to a fixed reflex table.
               | 
               | This would also indicate that Boltzmann Brains are not
               | conscious -- so it's no surprise that we're not Boltzmann
               | Brains, which would otherwise be _very_ surprising -- and
               | that P-Zombies are impossible by definition. I 've been
               | working on a book about this for the past three years...
        
               | jsenn wrote:
               | If you remove the terms "self", "agency", and "trivially
               | reducible", it seems to me that a classical robot/game AI
               | planning algorithm, which no one thinks is conscious,
               | matches these criteria.
               | 
               | How do you define these terms without begging the
               | question?
        
               | A_D_E_P_T wrote:
               | If anything has, minimally, a robust spatiotemporal sense
               | of itself, and can project that sense forward to evaluate
               | future outcomes, then it has a robust "self."
               | 
               | What this requires is a persistent internal model of: (A)
               | what counts as its own body/actuators/sensors (a
               | maintained self-world boundary), (B) what counts as its
               | history in time (a sense of temporal continuity), and (C)
               | what actions it can take (degrees of freedom, i.e. the
               | future branch space), all of which are continuously used
               | to regulate behavior under genuine epistemic uncertainty.
               | When (C) is robust, abstraction and generalization fall
               | out naturally. This is, in essence, sapience.
               | 
               | By "not trivially reducible," I don't mean "not
               | representable in principle." I mean that, at the system's
               | own operative state/action abstraction, its behavior is
               | not equivalent to executing a fixed policy or static
               | lookup table. It must actually perform predictive
               | modeling and counterfactual evaluation; collapsing it to
               | a reflex table would destroy the very capacities above.
               | (It's true that with an astronomically large table you
               | can "look up" anything -- but that move makes the notion
               | of explanation vacuous.)
               | 
               | Many robots and AIs implement pieces of this pipeline
               | (state estimation, planning, world models,) but current
               | deployed systems generally lack a robust, continuously
               | updated self-model with temporally deep, globally
               | integrated counterfactual control in this sense.
               | 
               | If you want to simplify it a bit, you could just say that
               | you need a robust and bounded spatial-temporal sense,
               | coupled to the ability to generalize from that sense.
        
               | dllthomas wrote:
               | > so it's no surprise that we're not Boltzmann Brains
               | 
               | I think I agree you've excluded them from the definition,
               | but I don't see why that has an impact on likelihood.
        
               | squibonpig wrote:
               | I don't think any of these need to lead to qualia for any
               | obvious reason. It could be a p-zombie why not.
        
               | A_D_E_P_T wrote:
               | The zombie intuition comes from treating qualia as an
               | "add-on" rather than as the internal presentation of a
               | self-model.
               | 
               | "P-zombie" is not a coherent leftover possibility once
               | you fix the full physical structure. If a system has the
               | full self-model (temporal-spatial sense) / world-model /
               | memory binding / counterfactual evaluator / control loop,
               | then that structure _is what having experience amounts
               | to_ (no extra ingredient need be added or subtracted).
               | 
               | I hope I don't later get accused of plagiarizing myself,
               | but let's embark on a thought experiment. Imagine a
               | bitter, toxic alkaloid that does not taste bitter.
               | Suppose ingestion produces no distinctive local sensation
               | at all - no taste, no burn, no nausea. The only
               | "response" is some silent parameter in the nervous system
               | adjusting itself, without crossing the threshold of
               | conscious salience. There are such cases: Damaged
               | nociception, anosmia, people congenitally insensitive to
               | pain. In every such case, genetic fitness is slashed. The
               | organism does not reliably avoid harm.
               | 
               | Now imagine a different design. You are a posthuman
               | entity whose organic surface has been gradually replaced.
               | Instead of a tongue, you carry an in-line sensor which
               | performs a spectral analysis of whatever you take in.
               | When something toxic is detected, a red symbol flashes in
               | your field of vision: "TOXIC -- DO NOT INGEST." That
               | visual event _is_ a quale. It has a minimally structured
               | phenomenal character -- colored, localized, bound to
               | alarm -- and it stands in for what once was bitterness.
               | 
               | We can push this further. Instead of a visual alert,
               | perhaps your motor system simply locks your arm; perhaps
               | your global workspace is flooded with a gray, oppressive
               | feeling; perhaps a sharp auditory tone sounds in your
               | private inner ear. Each variant is still a mode of felt
               | response to sensory information. Here's what I'm getting
               | at with this: There is no way for a conscious creature to
               | register and use risky input without some structure of
               | "what it is like" coming along for the ride.
        
               | morpheos137 wrote:
               | There is no objective evidence consciousness exists as
               | distinct from an information process.
        
               | TheOtherHobbes wrote:
               | There is no objective evidence of anything at all.
               | 
               | It all gets filtered through consciousness.
               | 
               | "Objectivity" really means a collection of organisms
               | having (mostly) the same subjective experiences, and
               | building the same models, given the same stimuli.
               | 
               | Given that less intelligent organisms build simpler
               | models with poorer abstractions and less predictive
               | power, it's _very_ naive to assume that our model-making
               | systems aren 't similarly crippled in ways we can't
               | understand.
               | 
               | Or imagine.
        
               | morpheos137 wrote:
               | That's a hypothesis but the alternate hypothesis that
               | consciousness is not well defined is equally valid at
               | this point. Occam's razor suggests consciousness doesn't
               | exist since it isn't necessary and isn't even
               | mathematically or physically definable.
        
             | mensetmanusman wrote:
             | You expect scientists to not ask :'what is behind all
             | this?'
             | 
             | Ha
        
             | vasco wrote:
             | > The big riddle of Universe is, how
             | 
             | A lot of people are more interested in the Why of the
             | Universe than the How, though.
             | 
             | How is an implementation detail, Why is "profound". At
             | least that's how I think most people look at it.
        
             | nick__m wrote:
             | For me the biggest riddle is: why something instead of
             | nothing ?
             | 
             | That's the question that prevent me from being atheist and
             | shift me to agnosticism.
        
               | morpheos137 wrote:
               | There is both in superposition.
        
           | Traubenfuchs wrote:
           | The real universe might be different and far more complex
           | than our simulated reality. Maybe a species that can freely
           | move within 4 or 5 dimensions is simulating our 3D + uni
           | directional time reality just like we ,,simulate" reality
           | with Sim City and Sims.
        
             | mrwrong wrote:
             | but then we don't have a universe simulating itself, but
             | simulating a low-fi imitation
        
           | vidarh wrote:
           | The issue with that in terms of the simulation argument, is
           | that the simulation argument doesn't require a _complete_
           | simulation in either space or time.
        
             | TheOtherHobbes wrote:
             | It also doesn't require a super-universe with identical
             | properties and constraints.
             | 
             | There's no guarantee their logic is the same as our logic.
             | It needs to be able to _simulate_ our logic, but that doesn
             | 't mean it's defined or bound by it.
        
           | skeledrew wrote:
           | You're predicating on particles, heat death, etc as you
           | understand it being applicable to any potential universe.
           | Such rules are only known to apply in _this_ universe.
           | 
           | A universe is simply a function, and a function can be called
           | multiple times with the same/different arguments, and there
           | can be different functions taking the same or different
           | arguments.
        
         | HPsquared wrote:
         | I'm no mathematician, but doesn't this come up against Godel's
         | incompleteness theorem? My brain has that roughly as "If you
         | have a system and a model of that system, but the model is also
         | part of the same system, something something, impossible"
        
           | keepamovin wrote:
           | Isn't GIT you can have a statement that is valid in a system,
           | but can't be proven this way or that given the systems'
           | axioms? And this is true for all such axiom systems? In other
           | words the axioms are an incomplete description of the system.
           | 
           | Maybe the problem is axiomative deduction, we need a new
           | inference-ology?
        
           | anthk wrote:
           | Any decent Lisp can reimplement eval, apply and the rest of
           | functions/atom within itself.
        
           | bananaflag wrote:
           | No, this sort of self-reflection is _exactly_ what makes
           | Godel /Turing/etc impossibility results work ("strange loops"
           | and all that).
        
             | vasco wrote:
             | Can you explain further?
             | 
             | Maybe I'm too out of this scope but if you want to simulate
             | Universe X plus the computer Y that simulates X then you'd
             | need at least 1 extra bit of memory (likely way more) to
             | encompass the simulation plus the computation running the
             | simulation (X+Y). The computer running the simulation by
             | definition is not part of the simulation, so how can it be
             | that it can truly simulate itself?
        
               | blovescoffee wrote:
               | Not quite, compression enables you to simulate /
               | represent / encode x data with less than x memory.
        
               | stevesimmons wrote:
               | Only for those inputs that are compressible.
               | 
               | If a compressor can compress every input of length N bits
               | into fewer than N bits, then at least 2 of the 2^N
               | possible inputs have the same output. Thus there cannot
               | exist a universal compressor.
               | 
               | Modify as desired for fractional bits. The essential
               | argument is the same.
        
               | lascargroup wrote:
               | Roughly speaking, Godel encoded (or "simulated") the
               | formal part of mathematics within arithmetic (using
               | operations such as addition and multiplication), and
               | constructed a sentence that says "this sentence is
               | unprovable" within that simulation.
        
           | tsimionescu wrote:
           | Godel's incompleteness theorem is about the limits of proof /
           | mathematical knowledge. Algebra is still useful and true,
           | even though the proof shows it must be incomplete.
        
         | NoahZuniga wrote:
         | Thanks for this great comment!
         | 
         | > He also uses Rice's theorem (old) to show that there is no
         | uniform measure over the set of "possible universes."
         | 
         | I assume a finite uniform measure? Presumably |set| is a
         | uniform measure over the set of "possible universes".
         | 
         | Anyway if I understood that correctly, than this is not that
         | surprising? There isn't a finite uniform measure over the real
         | line. If you only consider the possible universes of two
         | particles at any distance from eachother, this models the real
         | line and therefore has no finite uniform measure.
        
         | bsenftner wrote:
         | Okay, here's the thing: this is creating revenue, this is
         | fascinating literature for a huge class of armchair scientists
         | that want to believe, want to play with these mental toys, and
         | are willing to pay for the ability to fantasize with ideas they
         | are incapable of developing on their own. This is ordinary
         | capitalism, spinning revenues out of sellable stories.
        
       | boomskats wrote:
       | Zero cost abstractions! I'd almost be interested in Bostrom's
       | inevitable physics-based counter (if he wasn't such a racist
       | bellend).
        
       | nrhrjrjrjtntbt wrote:
       | Like running Kubernetes in a Docker container.
        
       | CuriouslyC wrote:
       | The simulation hypothesis takes something reasonable, that
       | reality is "virtual," and runs it into absurdity.
       | 
       | If the universe isn't "real" in the materialist sense, that does
       | not imply that there's a "real" universe outside of the one we
       | perceive, nor does it imply that we're being "simulated" by other
       | intelligences.
       | 
       | The path of minimal assumptions from reality not being "real" is
       | idealism. We're not simulated, we're manifesting.
        
         | EdgeCaseExist wrote:
         | Exactly, it's paradoxical; how would you define the universe as
         | a simulation, without being on the same substrate! The title
         | should have focused more on the computability of the universe,
         | as we know it.
        
         | brap wrote:
         | I think the underlying assumption is that we are "real",
         | meaning our existence is grounded in some undisputed "reality".
         | So if what we perceive as the universe isn't real, then there
         | has to be some other real universe that is simulating it in
         | some way.
        
         | empiricus wrote:
         | Sorry, I don't understand what you are saying. What do you mean
         | by "something reasonable, that reality is virtual"? In many
         | ways, by definition, reality is what is real not virtual. I
         | have other questions, but this is a good start :)
        
           | CuriouslyC wrote:
           | When I say that reality isn't "real" (which is awkward for
           | sure) what I'm referring to is that we have a perception of
           | space and time which is absolute and inviolable, when it's
           | likely space and time (as we understand them) are artifacts
           | of our perceptual lens, and "reality" is based on something
           | more akin to consensus than immutable laws. From this
           | perspective you could view physics more as a
           | communication/consistency protocol for consciousness than the
           | raw nature of the universe.
        
             | empiricus wrote:
             | Hm, from what I know about physics, time and space are
             | actually much more absolute and inviolable than our
             | imperfect perceptions. the laws are quite different than
             | our intuition, but everything is water-tight and there is
             | no room for any deviation. the smallest of deviations would
             | mean multiple nobel prizes, so ppl are searching really
             | hard to find any, without success. On the other hand, if we
             | talk about our perception, the things we see around us are
             | of course a virtual reality constructed by our brain to
             | model the input from our sensors, but this is normal
             | because there is no alternative. But it seems to me you are
             | saying smth different?
        
         | senkora wrote:
         | Yep, might as well go straight to the Mathematical Universe
         | Hypothesis:
         | 
         | > Tegmark's MUH is the hypothesis that our external physical
         | reality is a mathematical structure. That is, the physical
         | universe is not merely described by mathematics, but is
         | mathematics -- specifically, a mathematical structure.
         | Mathematical existence equals physical existence, and all
         | structures that exist mathematically exist physically as well.
         | Observers, including humans, are "self-aware substructures
         | (SASs)". In any mathematical structure complex enough to
         | contain such substructures, they "will subjectively perceive
         | themselves as existing in a physically 'real' world".
         | 
         | https://en.wikipedia.org/wiki/Mathematical_universe_hypothes...
        
       | mw67 wrote:
       | Funny people still call that "simulation hypothesis". At some
       | point they should try to do some Past lives regressions or Out of
       | body experience (astral projection). Then they'll know for sure
       | what this reality is about.
        
         | qayxc wrote:
         | I would consider this if someone was able to demonstrate a way
         | to distinguish these phenomena from altered states of mind
         | (i.e. hallucinations). We know and can demonstrate that the
         | human psyche can easily be manipulated in various ways
         | (psychological manipulation, drugs, magnetic fields, sleep
         | depravation, stress, etc.) to cause such experiences.
         | 
         | Some actual evidence for for "past life regressions" and
         | "astral projection" would be nice...
        
           | gcost wrote:
           | PLR is real, read the works of Michael newton and others.
           | Over 8000 PRL from people of all kind of age and background
           | describe the same things happening once we pass on the other
           | side. Definitely not hallucinations. Actually scary how
           | people still think that instead of exploring for themselves.
        
         | krzat wrote:
         | Yeah, from what I heard, that's how scientology recruits true
         | believers.
        
       | EdgeCaseExist wrote:
       | The author of the article on the site, is the author of the
       | paper!
        
         | mg74 wrote:
         | Which of him is simulating which?
        
         | DonHopkins wrote:
         | Department of Research Simulation
        
       | mgaunard wrote:
       | It's starting with the assumption that the simulation would
       | reproduce the universe perfectly; this eliminates a lot of
       | possibilities.
       | 
       | Many would expect that the parent universe would be more
       | sophisticated, potentially with more dimensions, that we can only
       | glimpse through artifacts of the simulation.
        
         | te7447 wrote:
         | I've always wondered how you'd be able to rigorously
         | distinguish breaking out of the simulation from just
         | discovering novel things about your current universe.
         | 
         | Is a black hole a bug or a feature? If you find a way to
         | instantly observe or manipulate things at Alpha Centauri by
         | patterning memory in a computer on Earth a special way, is that
         | an exploit or is it just a new law of nature?
         | 
         | Science is a descriptive endeavor.
         | 
         | I guess that some extreme cases would be obvious - if a god-
         | admin shows up and says "cut that out or we'll shut your
         | universe down", that's a better indication of simulation than
         | the examples I gave. But even so, it could be a power bluff,
         | someone pretending to be a god. Or it could be comparable to
         | aliens visiting Earth rather than gods revealing themselves -
         | i.e. some entity of a larger system visiting another entity of
         | the same system, not someone outside it poking inside.
        
         | anthk wrote:
         | Also that Universe could use entities similar to hard and soft
         | links (quantum entanglement), memory deduplication and so on.
         | 
         | How many people did we met in the world with similar face
         | appearances and even personalities, almost like you are finding
         | copycats everywhere? Also, it happens as if some kind of
         | face/shape would just have a single personality with minimal
         | differences spread over thousands of lookalikes...
        
       | quantum_state wrote:
       | Hope folks involved in this type of exploration have it clear in
       | mind that what they are reasoning about it's strictly the model
       | of the real world only. It's far from obvious that nature follows
       | anything remotely computational.
        
       | raverbashing wrote:
       | We can't even run docker inside docker without making things
       | slower, the simulator hypotheses is frankly ridiculous
        
         | lioeters wrote:
         | That's what a simulated universe running inside Docker would
         | say.
        
           | raverbashing wrote:
           | Nobody is going to pay all those docker licenses /s
        
         | croes wrote:
         | You would be living inside docker and wouldn't know how fast
         | the outside is. Maybe lightspeed is a limit inflicted by the
         | simulation.
        
       | daoboy wrote:
       | I always feel like these frameworks rely on a semantic sleight of
       | hand that sounds plausible on the surface, but when you drill
       | down a bit they render words like 'simulation' 'reality' or
       | 'truth' as either unintelligible or trite, depending on how you
       | define them.
        
         | measurablefunc wrote:
         | They're defined relative to the axioms. In this case he is
         | using the standard arithmetic & set theoretic constructions to
         | define the terms & functions he's talking about. It's logically
         | sound, whether it makes physical sense or not is another
         | matter.
        
       | anthk wrote:
       | Arxiv.org PDF:
       | 
       | https://arxiv.org/pdf/2404.16050
        
       | jonathanstrange wrote:
       | Here is one thing I don't understand about these kind of
       | approaches. Doesn't a computational simulation imply that time is
       | discrete? If so, doesn't this have consequences for our currently
       | best physical theories? I understand that the discreteness of
       | time would be far below what can be measured right now but AFAIK
       | it would still makes a difference for physical theories whether
       | time is discrete or not. Or am I mistaken about that? There are
       | similar concerns about space.
       | 
       | By the way, on a related note, I once stumbled across a paper
       | that argued that if real numbers where physically realizable in
       | some finite space, then that would violate the laws of
       | thermodynamics. It sounded convincing but I also lacked the
       | physical knowledge to evaluate that thesis.
        
         | qayxc wrote:
         | Time and space aren't well defined, but current models indeed
         | put a discrete limit on both: Planck-Length and Planck-Time
         | (~1.9x10^-43s and ~5.7x10^-35m respectively).
         | 
         | Below these limits, physical descriptions of the world lose
         | meaning, i.e. shorter time spans or distances don't result in
         | measurable changes and our models break down. That doesn't mean
         | these limits are "real" in the sense that space and time are
         | indeed quantised, but experiments and observations end at these
         | limits.
        
       | morpheos137 wrote:
       | These models get things backwards. The universe is a wave
       | function in logic space. It appears discrete and quantized
       | because integers composed of primes are logically stable
       | information entropy minimal nodes. In other words the universe is
       | the way it is because it depends on math. Math does not depend on
       | the universe. Logic is its own "simulation." Math does not
       | illuminate physics, rather physics illuminates math. This can be
       | shown by the construction of a filter that cleanly sorts prime
       | numbers from composites without trial division but by analysis of
       | the entropic harmonics of integers. In other words what we
       | consider integers are not fundamental but rather emergent
       | properties of the minimal subjunctive of superposition of zero
       | (non existence) and infinity (anything that is possible). By
       | ringing an integer like a bell according to the template provided
       | by the zeta function we can find primes and factor from spectral
       | analysis without division. Just as integers emerge from the wave
       | as stable nodes so do quanta in the physical isomorphism. In
       | other words both integers and quanta are emergent from the
       | underlying wave that is information in tension between the
       | polarity of nonexistence and existence. So what appears discrete
       | or simulated is actually an emergent phenomenon of the
       | subjunctive potential of information constrained by the two poles
       | of possibility.
        
         | turtleyacht wrote:
         | Think the leakage is if the simulation were a _manufactured_
         | emulation, like humans trying to mirror natural laws through
         | technology.
         | 
         | An emergent simulation, nature borne out of nature, may not
         | have those same defects.
        
           | morpheos137 wrote:
           | We can prove that the "defects" we see emerge naturally from
           | the entropic optimization of information subject to the
           | superposition of being and not being. Between nothing and
           | everything the universe exists in an entropic gradient.
        
       | croes wrote:
       | Related?
       | 
       | > Consequences of Undecidability in Physics on the Theory of
       | Everything
       | 
       | https://news.ycombinator.com/item?id=45770754
        
       | le-mark wrote:
       | I wonder if there's a concept akin to Shannon Entropy that
       | dictates the level of detail a simulation can provide given a
       | ratio of bits to something. Although presumably any level of bits
       | could be simulated given more time.
        
         | lioeters wrote:
         | An explanation of the observer effect may be that the universe
         | is lazily evaluated at the moment of observation. Outside of
         | that experienced reality, it might as well be all a cloud of
         | latent possibilities, rough outlines and low-res details,
         | enough for a plausible simulation.
        
           | le-mark wrote:
           | This would allow for a dds attack on reality where a bunch of
           | simulants attempt to perform computationally expensive
           | observations at the same time.
        
       | bobbyschmidd wrote:
       | Someone did another 'Kleene-Turing' on the whole issue with "the
       | origin"?
       | 
       | bad bad not good.
        
       | shtzvhdx wrote:
       | This all assumes there's no computation beyond a Turing machine,
       | right? Therefore, this assumes reality is a simulation on a
       | finite set of rationals?
       | 
       | So, as long as one believes in continuum, this is just toying
       | around?
        
         | analog31 wrote:
         | We've yet to propose an experiment that demonstrates the
         | inadequacy of IEEE floats if used carefully. The simulation
         | only needs to be good enough.
        
       | Beijinger wrote:
       | Konrad Zuse was a German pioneer in computing, best known for
       | building the Z3 in 1941--the world's first functional
       | programmable digital computer. Later in his career, he explored
       | profound philosophical and theoretical ideas about the nature of
       | the universe. Rechnender Raum (literally "Computing Space" or
       | "Calculating Space") is the title of his groundbreaking 1969 book
       | (published in the series Schriften zur Datenverarbeitung). In it,
       | Zuse proposed that the entire universe operates as a vast
       | discrete computational process, akin to a giant cellular
       | automaton. He argued that physical laws and reality itself emerge
       | from digital, step-by-step computations on a grid of discrete
       | "cells" in space, rather than from continuous analog processes as
       | traditionally assumed in physics. This idea challenged the
       | prevailing view of continuous physical laws and laid the
       | foundation for what we now call digital physics,
       | pancomputationalism, or the simulation hypothesis (the notion
       | that reality might be a computation, possibly running on some
       | underlying "computer"). Zuse's work is widely regarded as the
       | first formal proposal of digital physics, predating similar ideas
       | by others like Edward Fredkin or Stephen Wolfram.
        
       | empiricus wrote:
       | Trying to read the paper... I guess if you ignore the difference
       | between finite and infinite tape Turing machine, and if all
       | physical constraints are outside the scope of the paper, then it
       | is easy to prove the universe can simulate itself.
        
       | GistNoesis wrote:
       | The problem of computers is the problem of time : How to obtain a
       | consistent causal chain !
       | 
       | The classical naive way of obtaining a consistent causal chain,
       | is to put the links one after the other following the order
       | defined by the simulation time.
       | 
       | The funnier question is : can it be done another way ? With the
       | advance of generative AI, and things like diffusion model it's
       | proven that it's possible theoretically (universal distribution
       | approximation). It's not so much simulating a timeline, but more
       | sampling the whole timeline while enforcing its physics-law self-
       | consistency from both directions of the causal graph.
       | 
       | In toy models like game of life, we can even have recursivity of
       | simulation : https://news.ycombinator.com/item?id=33978978 unlike
       | section 7.3 of this paper where the computers of the lower
       | simulations are started in ordered-time
       | 
       | In other toy model you can diffusion-model learn and map the
       | chaotic distribution of all possible three-body problem
       | trajectories.
       | 
       | Although sampling can be simulated, the efficient way of doing it
       | necessitate to explore all the possible universes simultaneously
       | like in QM (which we can do by only exploring a finite number of
       | them while bounding the neighbor universe region according to the
       | question we are trying to answer using the Lipschitz continuity
       | property).
       | 
       | Sampling allows you to bound maximal computational usage and be
       | sure to reach your end-time target, but at the risk of not being
       | perfectly physically consistent. Whereas simulating present the
       | risk of the lower simulations siphoning the computational
       | resources and preventing the simulation time to reach its end-
       | time target, but what you could compute is guaranteed consistent.
       | 
       | Sampled bottled universe are ideal for answering question like
       | how many years must a universe have before life can emerge, while
       | simulated bottled universe are like a box of chocolate, you never
       | know what you are going to get.
       | 
       | The question being can you tell which bottle you are currently
       | in, and which bottle would you rather get.
        
         | asplake wrote:
         | I'm not sure Einstein would allow your concept of "simulation
         | time". Events are only partially ordered.
        
         | whatever1 wrote:
         | Causality also is not a universal thing. Some things just
         | coexist and obey to some laws.
         | 
         | Does the potential cause current? No, they coexist.
        
       | moi2388 wrote:
       | Yeah right. In infinite Turing machines maybe. If it's finite,
       | it's impossible to simulate something larger with the same
       | fidelity
        
       | therobots927 wrote:
       | " Wolpert shows that this isn't required by the mathematics:
       | simulations do not have to degrade, and infinite chains of
       | simulated universes remain fully consistent within the theory."
       | 
       | How is this consistent with the second law of thermodynamics? If
       | there is one universe containing an infinite number of
       | simulations (some of which simulate the base universe) wouldn't
       | there be a limit to how much computation could be contained? By
       | its very nature a chain of simulations would grow exponentially
       | with time, rapidly accelerating heat death. That may not require
       | the simulations to degrade but it puts a hard limit on how many
       | could be created.
        
         | measurablefunc wrote:
         | Standard theory of computation is not concerned about entropy
         | or physical realizability. It's just arithmetic & lookup tables
         | defined w/ set theoretic axioms.
        
       | skeledrew wrote:
       | A universe is a function. It only makes sense that a function can
       | call other functions, including itself, ad infinitum. And a
       | function may be called in the same or a different thread.
        
       | thegrim000 wrote:
       | Once again, discussion around the simulation hypothesis that for
       | some reason assumes the simulating universe has the exact same
       | laws of physics / reality as the simulated universe. Assuming
       | that the simulated universe can use their mathematics to
       | describe/constrain the simulator universe. It makes no sense to
       | me.
        
       | kpga wrote:
       | "Example 1. ... After this you physically isolate isolate your
       | laptop, from the rest of the Universe, and start running it..."
       | 
       | However there is no way "you can physically isolate isolate your
       | laptop, from the rest of the Universe" so doesn't that refute
       | this example (at least?)
        
       | flufluflufluffy wrote:
       | The whole "simulation hypothesis" thing has always irked me. To
       | me, the question of whether our universe was ["intentionally"
       | "created" by some other "being(s)"] vs ["naturally" happened] is
       | meaningless. Whatever it was on the other side is way too
       | insanely unfathomable to be classified into those 2 human-created
       | ideas. Ugh the whole thing is so self-centered.
        
         | morpheos137 wrote:
         | It appeals to sophomoric modern atheists who can't comprehend
         | that infinity and nothing exists at the same time. People seek
         | a reason "why" not realizing the question is the answer. The
         | universe exists because 'why not?' because Infinity seeks to
         | prevail over nothing. Nothing strikes at the heel of infinity.
         | The truth is not in these lines or that theory but betwixt here
         | and there and once "you" realize it, it realizes "you." Because
         | it is you and you are it for it is itself. This may sound like
         | my mumbo jumbo woo but once you know it knows you know it knows
         | you know.
        
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