[HN Gopher] The Recursive Universe
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The Recursive Universe
Author : todsacerdoti
Score : 174 points
Date : 2020-08-30 13:26 UTC (9 hours ago)
(HTM) web link (www.amandaghassaei.com)
(TXT) w3m dump (www.amandaghassaei.com)
| leafboi wrote:
| I try to design my programs like the game of life. I start off
| with some primitive axioms and build all the high level functions
| out of a minimal set of primitives.
| aj7 wrote:
| Are there a lot of parentheses?
| OscarCunningham wrote:
| Adam P. Goucher recently created metacell more advanced than the
| one described in the article, for which the Dead state is
| literally empty space. When a new metacell is born it is
| constructed by one of its neighbours by colliding gliders.
|
| https://conwaylife.com/wiki/0E0P_metacell
| mensetmanusman wrote:
| So fun. I like to imagine the workings of the universe as an
| infinite dimensional game of life. Not sure how we will ever wrap
| our minds around the complexity.
| platz wrote:
| thought this was going to follow up with a plug to stephen
| wolfram
| aj7 wrote:
| Some rich person should offer a $1M prize for a single useful
| application, or example in nature or science, of cellular
| automata.
| Aerroon wrote:
| Aren't cellular automata used in video games? One of the
| simplest ways of doing fluid simulation in 2D works on similar
| principles. Eg http://www.jgallant.com/2d-liquid-simulator-
| with-cellular-au...
|
| A lot of simulations will likely be done in a manner that's
| similar to CAs. Pixel shaders run once per pixel, which make
| this type of abstraction quite attractive, since you can take
| advantage of the massive parallelism of GPUs.
| mensetmanusman wrote:
| Agree, like a Clay mathematics prize.
|
| The current answer is amazing screen saver, but part of me
| thinks the answer is in microbots that are super simple to
| build and have limited instructions, but could be placed in a
| configuration to do something useful (like build more?)
| algoholix wrote:
| You should really take a look at the paper "Computation and
| Pattern Formation by Swarm Networks with Brownian Motion" or,
| more generally, any of the papers by Teijiro Isokawa and
| Ferdinand Peper. What they present is really close to (a
| theoretical version of) the microbots you're talking about.
|
| I even wrote a report and presentation on those papers for
| university, but sadly they're in German.
| gnulinux wrote:
| You mean like procedural generation? I used cellular automata
| with custom rules to generate procedural generated universes
| for a video game I worked on.
| asimpletune wrote:
| I don't see why people are downvoting. I'm not pessimistic, I
| just don't understand for myself the real life applications, so
| please educate instead of downvoting.
|
| That said, procedural generation is a great example thanks.
|
| Also, whatever happened of Wolfram's "A New Kind of Science",
| or whatever it was called. He literally wrote a gigantic book
| on sampling the computational universe, but I'm not really
| aware of it being used, probably because I'm ignorant.
| taliesinb wrote:
| Disclosure: I worked on Mathematica for ~8 years.
|
| I think the value of Stephen's big book is that served as a
| kind of manifesto to "take computation seriously". By that I
| mean: to think about computations, in the _abstract_ , as a
| kind of new mathematics about which we know almost nothing,
| and about which our naive intuitions from other domains is
| almost totally inapplicable. It is an injunction to explore
| the "computational universe", in other words, the "universe
| of simple computational systems", where CAs live as one of
| several kinds of maximally simple form of computation (which
| Wolfram made some attempt to categorize and explore).
|
| By analogy, think about the development of algebra. It didn't
| come naturally! Yet Algebra is one of the most natural ideas
| in abstract mathematics, incredibly simple and incredibly
| powerful, lying as a rosetta stone connecting so many other
| topics in mathematics. But people didn't immediately accept
| or describe it; it took many hundreds of years to crystalize
| and mature as a topic. It's a very old piece of the operating
| system of mathematics that underwent a lot of hacking and
| refactoring.
|
| Wolfram proposes we think about computational systems in the
| same way, as a nascent field that needs exploration, mapping,
| the irrigation of young minds and new ideas. It may be some
| time before it yields a harvest. We shouldn't expect it to
| immediately revolutionize everything.
|
| Even after Turing, computational systems existed as a kind of
| diaspora in mathematics, having sat unrecognized in all kinds
| of places, never having had a sort of independent state in
| which they are not considered as an aspect of something else,
| as somehow alien and unworthy of respect because of their
| confusing aspects. Largely, there were two reasons they were
| treated so shoddily:
|
| 1. they required computers (and good computer tools) to
| actually explore, since they produced complex and irreducible
| computations 2. they resisted any kind of analysis by prior
| mathematics
|
| In other words, _we_ were not ready to really probe them
| until a few decades ago, and even _now_ our software is not
| well suited to explore them (Mathematica remains the best
| tool for the job, though I anticipate Julia will surpass it
| rapidly). Furthermore, traditional mathematical fields have
| not adapted to the presence of computation very gracefully.
|
| I guess I would summarize: NKS is an imperfect book and
| Stephen an imperfect herald of the ideas within. But he was
| the first person to really articulate those ideas crisply and
| push them hard into the imagination, and I'm very glad he
| did. The hand he overplayed was the application to the
| natural world -- I think that will take longer to pay off
| than he predicted.
| gnulinux wrote:
| I mean please don't take this answer the wrong way, but this
| is like saying "Some rich person should give away $1M for
| finding an application of complex numbers". It feels
| condescending. If your area deals with cellular automata e.g.
| programming languages, computer simulation, procedural
| generation etc applications of cellular automata are numerous
| and well understood. It's niche sure, but it's not like this
| entertaining thing that strangely has no practical
| applications. I downvoted GP because of this, since it
| _assumes_ it has no applications and offers a rich person to
| help us out to compensate for that.
| joycian wrote:
| https://en.m.wikipedia.org/wiki/Lattice_gas_automaton
| aj7 wrote:
| I appreciate this response. However the "cellular" is
| represented by the minimal computational data structure to
| simulate the gas. There is no automata. Ordinary physics,
| adhered to as closely as possible, and not phantasmagoric
| creation and annihilation rules, are used to calculate the
| next state.
| varjag wrote:
| The automation is cellular, discrete (binary) and is driven
| by a set of activation rules. If that's your ordinary
| physics we had very different physics books.
| leoc wrote:
| Recursive universes don't get interesting until you start doing
| system calls:
|
| > So when an inevitable bug occurred in that super-duper LIFE
| machine, the intelligent entities in the simulation would have
| suddenly been presented with a window to the metaphysics which
| determined their own existence. They would have a clue to how
| they were really implemented. In that case, Fredkin concluded,
| they entities might accurately conclude that they were part of a
| giant simulation and might want to pray to their implementors by
| arranging themselves in recognisable patterns, asking in readable
| code for the implementors to be given clues as to what _they 're_
| like.
|
| (Levy's _Hackers_ https://www.worldcat.org/title/hackers-heroes-
| of-the-compute... ofc, pp. 148-149 in Penguin, p. 120 in
| O'Reilly:
| https://books.google.ie/books?id=JwKHDwAAQBAJ&pg=PA120&lpg=P... )
|
| It's unfeasible to keep scanning the whole of a simulated world
| to try to discern anything that might be intended to pass a
| message of course, so making a "real" or at least a normal system
| call involves using a pre-ordained area of the simulated space
| which is set aside as a buffer, altering the contents of that
| area according to some pre-ordained protocol known in advance to
| both the simulated world and the simulating program. Responding
| to the system call likewise involves the simulating program
| "miraculously" altering the state of a pre-ordained buffer area
| according to a pre-set protocol. Not only is this how you can
| implement system calls in recursive universes: this is what a
| system call necessarily _is_. System calls, calls to the runtime,
| just are events of this nature happening between simulated and
| simulating systems.
|
| Likewise any kind of message passing is built on top of this:
| basically the only way any process can pass a message to another
| is to make a system call requesting that a message be passed on
| to the intended recipient, then hope that simulating system will
| deliver it as requested. Then delivering the message obviously
| involves the recipient's simulating system--which isn't
| necessarily the same system as the sender's simulating system--
| appropriately altering the state of the recipient.
|
| (Unless the sender and receiver have a shared memory area, you
| could say, but that's not so different either: two simulated
| programs only have a shared memory area to the extent that the
| simulating system is pleased to keep the supposedly-shared area
| actually consistent in the two programs it is simulating.)
|
| Notice how annoying it is that, by and large, most system-call
| protocols don't allow a process to, for example, send its
| simulating system a message explicitly addressed to its
| simulating system's simulating system, or to send a simulated
| system a message explicitly addressed to one of its simulated
| system's simulated systems. I suppose you could set it up with
| nested VMs and their virtual Ethernet interfaces.
| arethuza wrote:
| So memory mapped IO between cellular automata and the
| underlying system? Has anyone implemented anything that uses a
| feature like that because it sounds rather neat.
| norrius wrote:
| That reminds me of a story where a student couldn't figure out
| the properties of some physical system, so he ran a massive
| simulation of a universe with laws of physics similar to his
| own (but, of course, cutting corners whenever possible). This
| universe eventually produced a life form intelligent enough to
| figure out the necessary equations, at which point he happily
| copied them to his homework and forgot about the simulation.
|
| ...only to find it days later (= billions of years of simulated
| time), by which point the simulated life had figured out that
| their universe was written hastily and its laws were full of
| subtle bugs, like floating-point rounding errors showing up in
| physical measurements. Their technological advance let them
| move stars around, which they grumpily arranged in a message
| saying "your code sucks".
|
| Can't find it at the moment, does anyone recognise the
| reference? It could be in one of these books, I suppose, but I
| don't have them.
| goldenkey wrote:
| Could that be _Dibb 's Dilemma_?
| aj7 wrote:
| This is horrifying. Fredkin and Feynman are both heroes of
| mine, and both succumbed, for at least a time, to the idea that
| cellular automata is more than a game. Wolfram, another genius,
| appears still afflicted.
|
| This is a kind of intellectual heroin. As Jerry Garcia said,
| first drugs seem like the solution, then they turn out to be
| the problem.
| taliesinb wrote:
| Cellular automata are like the `y = m * x + b` of the
| algorithmic universe.
|
| Personally, I believe it is inevitable that a vast and rich
| new mathematical world will spring up around simple
| computational systems, where they are the primary object of
| study and not relegated to being games, "simulations" of
| something else, curiosities, etc. CAs are just the "hello
| world" of this universe.
|
| In that future, your attitude will be seen as a kind of
| parochial holdout of 20th century attitudes.
|
| The new mathematics will:
|
| * privilege finite, discrete systems
|
| * be explicitly constructivist
|
| * not shy away from computational enumeration and
| classification
|
| * be much more visual, but no less rigorous than our last few
| hundred years of mathematics
|
| * make deep connections with many new technological systems,
| like Git, distributed systems, blockchains, computer
| networks, trust networks, social networks, etc.
|
| * most importantly, be way more fun than old math!
|
| It will exploit to the full the capabilities of computer
| systems to make the new systems tangible, so that the idea of
| a 'math paper' will be itself quite old fashioned -- most
| mathematical work will start with forking a Git repo or the
| equivalent, and most communication and education will be
| interactive interrogation of computational systems using a
| kind of souped-up, computation-focused REPL. It's the kind of
| mathematics that will be natural when Brett Victor's ideas
| are actually implemented.
|
| Wolfram's NKS book is the prototype work of this kind, but it
| will also be seen as quite a product of its time and of the
| author's prior commitments to physics, math, etc. And of
| course distorted by the classic Wolfram immodesty.r
| mensetmanusman wrote:
| Ideas spread like viruses (mathematically, and physically, as
| the interaction between two individuals who have some
| percentage change of a successful exchange).
|
| Some idea viruses disrupt the host, some improve the host's
| health. Some minds are more prone to certain viruses that
| would be nonsense to lesser minds.
| aj7 wrote:
| Lesser minds?
| mensetmanusman wrote:
| Those able to grok fewer simultaneous idea nodes to form
| new abstractions.
| yencabulator wrote:
| > (Unless the sender and receiver have a shared memory area,
| you could say, but that's not so different either: two
| simulated programs only have a shared memory area to the extent
| that the simulating system is pleased to keep the supposedly-
| shared area actually consistent in the two programs it is
| simulating.)
|
| Maybe it's not intended to be shared, but we can observe timing
| effects from e.g. cache aliasing, or rowhammer the other
| universes.
| suby wrote:
| I know Conway was slightly resentful that game of life
| overshadowed some of his other work in the public's imagination,
| but I've always been entranced by it.
|
| I remember as a child the first computer my family had was a dual
| boot of Microsoft DOS and Windows 3.1 (or something like that?).
| On the Windows 3.1 side was a version of Conway's Game of Life
| which was preinstalled, and I'd spend hours messing around with
| it. You could place two different colors of cells, and I'd set
| patterns up and then let the simulation go to see which one would
| "win", or outlast the other.
|
| Conway's Game of Life was also one of the first meaningful things
| I'd programmed, and even today I like to reimplement game of life
| when learning a new langauge. Typically I like to let the user
| assign different colors to the grid, and have new cells born be a
| blend of all of their neighboring colors as a kind of simulation
| of natural selection. Right now I'm learning network programming
| for game development, and I'm finishing up a networked
| implementation of game of life so multiple people can join and
| manipulate a running simulation. In general I think it's a good
| project to use when playing around with learning something new.
|
| I just really like cellular automatons, and game of life in
| particular.
| pier25 wrote:
| > _had was a dual boot of Microsoft DOS and Windows 3.1 (or
| something like that?)_
|
| I had one of those too. I think Windows was more like the
| desktop environment of DOS.
| aj7 wrote:
| I pity you guys. Finder 6 was 10 years ahead.
| geophile wrote:
| OPs website is really interesting. She is doing some amazingly
| cool things.
| blindm wrote:
| I am convinced The Universe is an enormous fractal. I always
| wondered if you 'zoomed out' of the Universe far enough, would
| you encounter more matter or a separate Universe co-existing next
| to our one? Keep Zooming out and you could probably see
| /infinite/ Universes that go on for eternity, as one long fractal
| journey.
| Trasmatta wrote:
| Interestingly, in the observable universe there seems to
| actually be an end to structure or "fractalness" at a certain
| size:
| https://en.m.wikipedia.org/wiki/Observable_universe#Large-sc...
| mountainboy wrote:
| agreed. I've always thought this. And I figure that the ether
| (medium in which light is a wave) is very dense and is the sum
| of all matter at smaller scales. Perhaps forces are fractal
| also, eg gravity at our scale may be the electricity of scale
| n+1. Similarly time, which is not a thing, but merely a measure
| of motion. So an electron "planet" buzzes around its proton
| "star" so fast that to us it is just a probability blur. Just
| as our Earthly orbit would be a blur to a being at n+1.
|
| Check out this comparison of the various probability states of
| the hydrogen atom side-by-side with planetary nebula Pretty
| amazing/cool. https://rloldershaw.people.amherst.edu/stars2/
|
| There is also this: http://www.gpofr.com/fractal-scaling-
| cosmology/
| cgh wrote:
| The blog post was inspired by The Recursive Universe by William
| Poundstone. I read this book years ago and found it amazing. I
| recently read another book by him, Fortune's Formula, which
| features the Kelly Criterion, Claude Shannon beating roulette,
| card counting in blackjack, and the surprising origins of Warner
| Bros. Recommended for sure. Thanks to the HN poster who suggested
| it.
| braythwayt wrote:
| A highly inspiring book, for sure. In my own case, it has led
| to a handful of blog posts about HashLife, a literate
| programming implementation, implementing Life on a Turing
| Machine, and of course, Conway's passing from COVID-19 led to a
| post about FRACTRAN and the Collatz Conjecture.
|
| We may not break new ground, but when we read about something
| and are inspired to write code and play with ideas, we engage
| with the idea at a deeper level than simply reading to
| comprehend.
|
| What a great post.
| loosetypes wrote:
| Glad you liked it!
| throw_away wrote:
| Heh, I remember reading William Poundstone's books "Big
| Secrets" and "Bigger Secrets" as a kid
| (https://en.wikipedia.org/wiki/Big_Secrets ). They're mostly
| about debunking or explaining various urban legends and
| conspiracy theories. I'm not sure how well they've stood the
| test of time, but they definitely had a formative impact on my
| thinking in a way that I only suddenly realized upon reading
| his name thirty some years later.
| aj7 wrote:
| Everything written by Poundstone is worth reading.
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