5 ms·

"That's another thing we've learned from your Nation," said Mein Herr, "map-making. But we've carried it much further than you. What do you consider the largest

"That's another thing we've learned from your Nation," said Mein Herr, "map-making. But we've carried it much further than you. What do you consider the largest map that would be really useful?" "About six inches to the mile." ""Only six inches!"exclaimed Mein Herr. "We very soon got to six yards to the mile. Then we tried a hundred yards to the mile. And then came the grandest idea of all! We actually made a map of the country, on the scale of a mile to the mile!" "Have you used it much?" I enquired. "It has never been spread out, yet," said Mein Herr: "the farmers objected: they said it would cover the whole country, and shut out the sunlight! So we now use the country itself, as its own map, and I assure you it does nearly as well." (From Sylvie and Bruno Concluded by Lewis Carroll, first published in 1893.) I wonder whether the above is applicable to modeling the world and its behaviour in other ways; fully understanding everything of the complexity of the world would require the power of the world itself.

chatmasta 3y ago
It reminds me of virtualization. An emulated CPU in a hypervisor will never perform as well as the physical CPU that is hosting it.
- dekhn 3y ago
  virtualization doesn't emulate a CPU; instructions typically run natively. IO is trapped and handled exceptionally.
  - kazinator 3y ago
    Hardware virtualization can still emulate peripherals. If your virtual machine thinks it has an ethernet card that doesn't actually exist, it may be nice and fast for CPU operations, but networking will take a hit.
  - ChatGTP 3y ago
    They're talking about an "emulated CPU"...
- User23 3y ago
  That's not true. Some machines are faster for some workloads when virtualizing. This has been known for decades. I recall first reading about it around 20 years ago, but I can't find the reference I'm thinking of. Nevertheless you'll find plenty of hits for faster in virtualization if you search.
- vidarh 3y ago
  A cycle exact and semantically precise one, sure. One that is allowed to prune unobserved results, on the other hand could potentially just lazily evaluate or simulate approximate outcomes and skip whole chunks of the simulation. To make claims about the computational power needed to simulate something, we really need to first know at what level of precision, and whether there are e.g. any observable effects of taking shortcuts or not (e.g. if "outside time" are not observable "inside", then skipping anything that can be lazily evaluated only if actually referenced from something observable even if it makes computation slow might be fine)
dekhn 3y ago
Regarding your last sentence, "fully understanding everything of the complexity of the world would require the power of the world itself." maybe that's not true? In particular, maybe reality is highly redundant and can be modelled using highly compressed representations.
- NikkiA 3y ago
  You can take the Hari Seldon approach and abstract away the macro level 'crowds/nations' and simulate them when they're not in the observer's sphere of influence/vision using a (much) higher level of abstraction.
  - nox101 3y ago
    not really though. In the real world you can see the results of action over time. So, if you stop simulating what the user is observing, when they actually do observer it later, you're required to run the entire simulation to get that observed part of the world back to the state it should be in after time passed. That includes the influence of the butterfly on the other side of the world. It effectively adds up to computing the entire thing. To take a semi-long term example. If you go carve your name in a tree, when you come back 50 years later it better show your name distorted over those 50 years. If you cut open the tree. It better show a record of every weather event over those 50 years. Every piece of the world you inspect will need the simulation run and not just for it but for all the things that affected it and all the things that affected the things that affected it etc etc recursively until you've simulated every in the universe.
    - vidarh 3y ago
      You're assuming a simulation where you either care about accuracy for all elements, and/or where the observer can tell if you "cheat". Minecraft is an example of the latter: if you leave a chunk, mobs despawn and decay and growth stops. But a simulation need not work that way. E.g. instead of continuing to run a simulation, it can simulate macro-indocators, and continue to simulate micro-details with a strong bias towards reverting to a prediction from the macro-indicators, and each element that gets there can be discarded. To go back to the Minecraft example, you set a "decay rate" for mobs that reflects a believable rate of dispersal, or simulate changes to vegetation towards what your generating function will produce until they match. Then when the player re-enters at t+a_lot, you just run your generating function where time is one parameter, and apply whatever reduced delta is still relevant. Yes, you'd still need to simulate a lot, but you'd be able to prune most things. So the question is meaningless without defining your requirements.
harperlee 3y ago
And, inspired by that: "On Exactitude in Science", Jorge Luis Borges …In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the Empire, the entirety of a Province. In time, those Unconscionable Maps no longer satisfied, and the Cartographers Guilds struck a Map of the Empire whose size was that of the Empire, and which coincided point for point with it. The following Generations, who were not so fond of the Study of Cartography as their Forebears had been, saw that that vast Map was Useless, and not without some Pitilessness was it, that they delivered it up to the Inclemencies of Sun and Winters. In the Deserts of the West, still today, there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all the Land there is no other Relic of the Disciplines of Geography. — Suarez Miranda, Viajes de varones prudentes, Libro IV,Cap. XLV, Lerida, 1658
- shoubidouwah 3y ago
  All of you would love the "obscure cities" series of comics (https://en.wikipedia.org/wiki/Les_Cit%C3%A9s_obscures https://en.wikipedia.org/wiki/Les_Cit%C3%A9s_obscures), as well as some works by J. Abeille (https://en.wikipedia.org/wiki/Jacques_Abeille#Les_Jardins_statuaires_and_the_Cycle_des_Contr%C3%A9es https://en.wikipedia.org/wiki/Jacques_Abeille#Les_Jardins_st...)
falcor84 3y ago
> the farmers objected: they said it would cover the whole country, and shut out the sunlight! This is actually a solved problem now with Augmented Reality, whereby you can walk in some field and get an overlay with the additional layers you care about at that moment.
FrustratedMonky 3y ago
This is the problem. How good is a model compared to reality. I heard one argument against Climate Change being that it is 'just an estimate', that reality is more fine grained. How can you trust a model since the model is just an estimate of reality that leaves out a lot of details? They were calling into question all models, in order to debunk Climate Change. Not sure they realized how much of the technology is based on models.
corethree 3y ago
How many does it take to simulate an atom? What about multiple atoms? I believe with current computers the answer does not scale linearly. But like they did here you can always use one atom to simulate that same atom.
swader999 3y ago
This. Think in terms of the compute power and raw energy needed to accurately model climate. The best at the moment use cells that are about 3 miles on each side. Hopelessly crude. https://www.climatehubs.usda.gov/hubs/northwest/topic/basics-global-climate-models https://www.climatehubs.usda.gov/hubs/northwest/topic/basics...
- klysm 3y ago
  Is it hopelessly crude? I mean the model is definitely wrong by some high level behavior might be useful enough
  - FrustratedMonky 3y ago
    How do you know it is wrong? To be definitely wrong, wouldn't you need another more accurate model to compare to it, to disprove it?
    - swader999 3y ago
      Run it on past data to see how it predicts against known recent climate and watch for curve fitting.
      - FrustratedMonky 3y ago
        I guess you are saying that those failed? I doubt that. Since those types of runs are done all the time to improve accuracy. Or more to point, it isn't like there was one-run, we take that as gospel, then run on past data, and failed, so models are wrong forever. They are always being refined. And some of the longest range calculations, that were done decades ago, are matching. So what model are you specifically saying failed?
      - FrustratedMonky 3y ago
        ""The hallmark of good science, however, is the ability to make testable predictions, and climate models have been making predictions since the 1970s. How reliable have they been? Now a new evaluation of global climate models used to project Earth’s future global average surface temperatures over the past half-century answers that question: most of the models have been quite accurate."" https://climate.nasa.gov/news/2943/study-confirms-climate-models-are-getting-future-warming-projections-right/ https://climate.nasa.gov/news/2943/study-confirms-climate-mo...
kayo_20211030 3y ago
Would the "map" itself be shown at full scale in the "map"? This sounds like it's turtles all the way down - ad infinitum.

chatmasta 3y ago

It reminds me of virtualization. An emulated CPU in a hypervisor will never perform as well as the physical CPU that is hosting it.

dekhn 3y ago
virtualization doesn't emulate a CPU; instructions typically run natively. IO is trapped and handled exceptionally.
- kazinator 3y ago
  Hardware virtualization can still emulate peripherals. If your virtual machine thinks it has an ethernet card that doesn't actually exist, it may be nice and fast for CPU operations, but networking will take a hit.
- ChatGTP 3y ago
  They're talking about an "emulated CPU"...
User23 3y ago
That's not true. Some machines are faster for some workloads when virtualizing. This has been known for decades. I recall first reading about it around 20 years ago, but I can't find the reference I'm thinking of. Nevertheless you'll find plenty of hits for faster in virtualization if you search.
vidarh 3y ago
A cycle exact and semantically precise one, sure. One that is allowed to prune unobserved results, on the other hand could potentially just lazily evaluate or simulate approximate outcomes and skip whole chunks of the simulation. To make claims about the computational power needed to simulate something, we really need to first know at what level of precision, and whether there are e.g. any observable effects of taking shortcuts or not (e.g. if "outside time" are not observable "inside", then skipping anything that can be lazily evaluated only if actually referenced from something observable even if it makes computation slow might be fine)

dekhn 3y ago

Regarding your last sentence, "fully understanding everything of the complexity of the world would require the power of the world itself." maybe that's not true? In particular, maybe reality is highly redundant and can be modelled using highly compressed representations.

NikkiA 3y ago
You can take the Hari Seldon approach and abstract away the macro level 'crowds/nations' and simulate them when they're not in the observer's sphere of influence/vision using a (much) higher level of abstraction.
- nox101 3y ago
  not really though. In the real world you can see the results of action over time. So, if you stop simulating what the user is observing, when they actually do observer it later, you're required to run the entire simulation to get that observed part of the world back to the state it should be in after time passed. That includes the influence of the butterfly on the other side of the world. It effectively adds up to computing the entire thing. To take a semi-long term example. If you go carve your name in a tree, when you come back 50 years later it better show your name distorted over those 50 years. If you cut open the tree. It better show a record of every weather event over those 50 years. Every piece of the world you inspect will need the simulation run and not just for it but for all the things that affected it and all the things that affected the things that affected it etc etc recursively until you've simulated every in the universe.
  - vidarh 3y ago
    You're assuming a simulation where you either care about accuracy for all elements, and/or where the observer can tell if you "cheat". Minecraft is an example of the latter: if you leave a chunk, mobs despawn and decay and growth stops. But a simulation need not work that way. E.g. instead of continuing to run a simulation, it can simulate macro-indocators, and continue to simulate micro-details with a strong bias towards reverting to a prediction from the macro-indicators, and each element that gets there can be discarded. To go back to the Minecraft example, you set a "decay rate" for mobs that reflects a believable rate of dispersal, or simulate changes to vegetation towards what your generating function will produce until they match. Then when the player re-enters at t+a_lot, you just run your generating function where time is one parameter, and apply whatever reduced delta is still relevant. Yes, you'd still need to simulate a lot, but you'd be able to prune most things. So the question is meaningless without defining your requirements.

harperlee 3y ago

And, inspired by that: "On Exactitude in Science", Jorge Luis Borges …In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the Empire, the entirety of a Province. In time, those Unconscionable Maps no longer satisfied, and the Cartographers Guilds struck a Map of the Empire whose size was that of the Empire, and which coincided point for point with it. The following Generations, who were not so fond of the Study of Cartography as their Forebears had been, saw that that vast Map was Useless, and not without some Pitilessness was it, that they delivered it up to the Inclemencies of Sun and Winters. In the Deserts of the West, still today, there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all the Land there is no other Relic of the Disciplines of Geography. — Suarez Miranda, Viajes de varones prudentes, Libro IV,Cap. XLV, Lerida, 1658

shoubidouwah 3y ago
All of you would love the "obscure cities" series of comics (https://en.wikipedia.org/wiki/Les_Cit%C3%A9s_obscures https://en.wikipedia.org/wiki/Les_Cit%C3%A9s_obscures), as well as some works by J. Abeille (https://en.wikipedia.org/wiki/Jacques_Abeille#Les_Jardins_statuaires_and_the_Cycle_des_Contr%C3%A9es https://en.wikipedia.org/wiki/Jacques_Abeille#Les_Jardins_st...)

falcor84 3y ago

> the farmers objected: they said it would cover the whole country, and shut out the sunlight! This is actually a solved problem now with Augmented Reality, whereby you can walk in some field and get an overlay with the additional layers you care about at that moment.

FrustratedMonky 3y ago

This is the problem. How good is a model compared to reality. I heard one argument against Climate Change being that it is 'just an estimate', that reality is more fine grained. How can you trust a model since the model is just an estimate of reality that leaves out a lot of details? They were calling into question all models, in order to debunk Climate Change. Not sure they realized how much of the technology is based on models.

corethree 3y ago

How many does it take to simulate an atom? What about multiple atoms? I believe with current computers the answer does not scale linearly. But like they did here you can always use one atom to simulate that same atom.

swader999 3y ago

This. Think in terms of the compute power and raw energy needed to accurately model climate. The best at the moment use cells that are about 3 miles on each side. Hopelessly crude. https://www.climatehubs.usda.gov/hubs/northwest/topic/basics-global-climate-models https://www.climatehubs.usda.gov/hubs/northwest/topic/basics...

klysm 3y ago
Is it hopelessly crude? I mean the model is definitely wrong by some high level behavior might be useful enough
- FrustratedMonky 3y ago
  How do you know it is wrong? To be definitely wrong, wouldn't you need another more accurate model to compare to it, to disprove it?
  - swader999 3y ago
    Run it on past data to see how it predicts against known recent climate and watch for curve fitting.
    - FrustratedMonky 3y ago
      I guess you are saying that those failed? I doubt that. Since those types of runs are done all the time to improve accuracy. Or more to point, it isn't like there was one-run, we take that as gospel, then run on past data, and failed, so models are wrong forever. They are always being refined. And some of the longest range calculations, that were done decades ago, are matching. So what model are you specifically saying failed?
    - FrustratedMonky 3y ago
      ""The hallmark of good science, however, is the ability to make testable predictions, and climate models have been making predictions since the 1970s. How reliable have they been? Now a new evaluation of global climate models used to project Earth’s future global average surface temperatures over the past half-century answers that question: most of the models have been quite accurate."" https://climate.nasa.gov/news/2943/study-confirms-climate-models-are-getting-future-warming-projections-right/ https://climate.nasa.gov/news/2943/study-confirms-climate-mo...

kayo_20211030 3y ago

Would the "map" itself be shown at full scale in the "map"? This sounds like it's turtles all the way down - ad infinitum.