4 ms·

Two somewhat-related-pointers for people who decide that they're curious about these things: * a light and nice read: https://www.frc.ri.cmu.edu/~hpm/project.a

by wfn 12y ago

Two somewhat-related-pointers for people who decide that they're curious about these things: * a light and nice read: https://www.frc.ri.cmu.edu/~hpm/project.archive/general.articles/1998/SimConEx.98.html https://www.frc.ri.cmu.edu/~hpm/project.archive/general.arti... (an oft-cited article) * the madness of Max Tegmark: http://arxiv.org/abs/grqc/9704009 http://arxiv.org/abs/grqc/9704009 , http://arxiv.org/abs/0704.0646 http://arxiv.org/abs/0704.0646 (cliff's notes: "The [...] postulate in this theory is that all structures that exist mathematically exist also physically, by which we mean that in those complex enough to contain self-aware substructures (SASs), these SASs will subjectively perceive themselves as existing in a physically ``real'' world." Which means: take http://xkcd.com/505/ http://xkcd.com/505/ , and abstract it enough times so that you decide that the rocks themselves are not needed anymore.) -> if anyone has any comments about the MUH, would be interested to hear them. My head is kinda-still-aching from the last time I tried to decide how seriously I should take his ideas.

cscheid 12y ago
Scott Aaronson's review of the Tegmark's book is pretty great: http://www.scottaaronson.com/blog/?p=1753 http://www.scottaaronson.com/blog/?p=1753
- wfn 12y ago
  Will very much read it. Thanks for the link! (Also, that blog is kind of a big deal. Good stuff.)
  - dvanduzer 12y ago
    I'd say the best decision Scott made was naming his blog. (See also https://en.wikipedia.org/wiki/Dunbar's_number https://en.wikipedia.org/wiki/Dunbar's_number)
    - sjy 12y ago
      I still don't really get it. Brains are optimised to maintain friendships with approximately the population of a shtetl, but is there a connection to the blog's subject matter? I've been wondering this for years!
      - dvanduzer 12y ago
        As a layman, I find it easy to think about the poetry of a computational oracle rather than the math of it. A bunch of rabbis wandering around the village teaching each other what they can't learn individually, but reaching a consensus as a group.
deleted 12y ago
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picomancer 12y ago
Wow. This is epic. I totally had this exact idea a few years ago -- that every mathematically possible universe physically exists, with some probability distribution. I was thinking maybe the probability of finding yourself in a given universe is related to the length of the computer program that runs that universe. And also, of course, to the probability of intelligent life evolving in that universe (a formalization of the anthropic principle). It's always neat when you discover you've independently invented an idea proposed by someone famous :) Although, to be fair to Tegmark, he goes further than I ever did: "The predictions of the theory take the form of probability distributions for the outcome of experiments, which makes it testable." This is a natural consequence of the form of the theory, but I didn't really think in that direction -- but now that Tegmark's pointed it out, it seems like an obvious direction in hindsight.
- wfn 12y ago
  I totally know what you mean! I've been recommending this book left and right around these parts, but can't hurt to say it again: you should probably read "Permutation City."[1] As far as literature, character development and style goes, there is nothing much to it. As far as (hard-ish) scifi goes, it's a big deal. In a way, what MT calls MUH Egan calls "dust theory" (roughly). It's a very interesting exploration of the whole idea, and it involves cellular automata, etc etc. There's also a short story of his, "Wang's Carpets" (which you can read online[2]) - it was later incorporated (as a chapter) into his book "Diaspora"[3] (which is also a great read that I've thoroughly enjoyed.) > Although, to be fair to Tegmark, he goes further than I ever did: "The predictions of the theory take the form of probability distributions for the outcome of experiments, which makes it testable." I wonder, though, if this is not a bit of a stretch. I certainly understand what he (and you) mean by probability distributions, but it seems to be there because he really wants to be able to call it a "scientific theory," which requires it to be falsifiable (<=> testable.) But, yeah, it's pretty neat! > I was thinking maybe the probability of finding yourself in a given universe is related to the length of the computer program that runs that universe. Now, can some of those programs run a (say, finite-tape-version-of) Turing machine[4] (can some of them not run it)? Does this have any implications (re: / in relation to the halting problem, for example)? I don't have the faintest idea. Tegmark has a thing to say about mathematically incomplete (in the Godel sense) universes, but again, I'm not sure how much of it is just him having fun. ;) (which is the best way of having fun, as far as I'm concerned.) ...anyway. Good stuff! Let's try and not go insane within our heads with these things. Then again, some insanity is always a good thing, imo. edit P.S. there's also http://plato.stanford.edu/entries/computation-physicalsystems/ http://plato.stanford.edu/entries/computation-physicalsystem... editedit P.P.S. if you haven't, maybe also read the (very) short story of Borges, "The Library of Babel."[5] It's basically an articulation of the idea that a "description" of a universe is that universe. And a "description" can very well be thought of as a program. And if you imagine a multidimensional "computational-symbol-space," a "path" to that program/description (first choose this symbol/predicate, then that one..) is that program (and, by extension, "kinda-is" that particular universe.) These ideas are not new in themselves in the very least. e.g. I'm still yet to try and honestly delve into Kant's "Critique of Pure Reason," which actually addresses some of that stuff (in its own very particular vocabulary and context.) Also, lots of stuff to read from the theoretical CS side of things. And mathematics (Yoneda lemma in category theory, and other things which I like to pretend to understand!) [1]: http://en.wikipedia.org/wiki/Permutation_City http://en.wikipedia.org/wiki/Permutation_City [2]: http://bookre.org/reader?file=222997 http://bookre.org/reader?file=222997 [3]: http://en.wikipedia.org/wiki/Diaspora_(novel) http://en.wikipedia.org/wiki/Diaspora_(novel) [4]: a good read (and/or rehash) on this: http://plato.stanford.edu/entries/turing-machine/ http://plato.stanford.edu/entries/turing-machine/ [5]: http://jubal.westnet.com/hyperdiscordia/library_of_babel.html http://jubal.westnet.com/hyperdiscordia/library_of_babel.htm...

by wfn 12y ago

cscheid 12y ago

Scott Aaronson's review of the Tegmark's book is pretty great: http://www.scottaaronson.com/blog/?p=1753 http://www.scottaaronson.com/blog/?p=1753

wfn 12y ago
Will very much read it. Thanks for the link! (Also, that blog is kind of a big deal. Good stuff.)
- dvanduzer 12y ago
  I'd say the best decision Scott made was naming his blog. (See also https://en.wikipedia.org/wiki/Dunbar's_number https://en.wikipedia.org/wiki/Dunbar's_number)
  - sjy 12y ago
    I still don't really get it. Brains are optimised to maintain friendships with approximately the population of a shtetl, but is there a connection to the blog's subject matter? I've been wondering this for years!
    - dvanduzer 12y ago
      As a layman, I find it easy to think about the poetry of a computational oracle rather than the math of it. A bunch of rabbis wandering around the village teaching each other what they can't learn individually, but reaching a consensus as a group.

deleted 12y ago

[deleted]

picomancer 12y ago

Wow. This is epic. I totally had this exact idea a few years ago -- that every mathematically possible universe physically exists, with some probability distribution. I was thinking maybe the probability of finding yourself in a given universe is related to the length of the computer program that runs that universe. And also, of course, to the probability of intelligent life evolving in that universe (a formalization of the anthropic principle). It's always neat when you discover you've independently invented an idea proposed by someone famous :) Although, to be fair to Tegmark, he goes further than I ever did: "The predictions of the theory take the form of probability distributions for the outcome of experiments, which makes it testable." This is a natural consequence of the form of the theory, but I didn't really think in that direction -- but now that Tegmark's pointed it out, it seems like an obvious direction in hindsight.

wfn 12y ago
I totally know what you mean! I've been recommending this book left and right around these parts, but can't hurt to say it again: you should probably read "Permutation City."[1] As far as literature, character development and style goes, there is nothing much to it. As far as (hard-ish) scifi goes, it's a big deal. In a way, what MT calls MUH Egan calls "dust theory" (roughly). It's a very interesting exploration of the whole idea, and it involves cellular automata, etc etc. There's also a short story of his, "Wang's Carpets" (which you can read online[2]) - it was later incorporated (as a chapter) into his book "Diaspora"[3] (which is also a great read that I've thoroughly enjoyed.) > Although, to be fair to Tegmark, he goes further than I ever did: "The predictions of the theory take the form of probability distributions for the outcome of experiments, which makes it testable." I wonder, though, if this is not a bit of a stretch. I certainly understand what he (and you) mean by probability distributions, but it seems to be there because he really wants to be able to call it a "scientific theory," which requires it to be falsifiable (<=> testable.) But, yeah, it's pretty neat! > I was thinking maybe the probability of finding yourself in a given universe is related to the length of the computer program that runs that universe. Now, can some of those programs run a (say, finite-tape-version-of) Turing machine[4] (can some of them not run it)? Does this have any implications (re: / in relation to the halting problem, for example)? I don't have the faintest idea. Tegmark has a thing to say about mathematically incomplete (in the Godel sense) universes, but again, I'm not sure how much of it is just him having fun. ;) (which is the best way of having fun, as far as I'm concerned.) ...anyway. Good stuff! Let's try and not go insane within our heads with these things. Then again, some insanity is always a good thing, imo. edit P.S. there's also http://plato.stanford.edu/entries/computation-physicalsystems/ http://plato.stanford.edu/entries/computation-physicalsystem... editedit P.P.S. if you haven't, maybe also read the (very) short story of Borges, "The Library of Babel."[5] It's basically an articulation of the idea that a "description" of a universe is that universe. And a "description" can very well be thought of as a program. And if you imagine a multidimensional "computational-symbol-space," a "path" to that program/description (first choose this symbol/predicate, then that one..) is that program (and, by extension, "kinda-is" that particular universe.) These ideas are not new in themselves in the very least. e.g. I'm still yet to try and honestly delve into Kant's "Critique of Pure Reason," which actually addresses some of that stuff (in its own very particular vocabulary and context.) Also, lots of stuff to read from the theoretical CS side of things. And mathematics (Yoneda lemma in category theory, and other things which I like to pretend to understand!) [1]: http://en.wikipedia.org/wiki/Permutation_City http://en.wikipedia.org/wiki/Permutation_City [2]: http://bookre.org/reader?file=222997 http://bookre.org/reader?file=222997 [3]: http://en.wikipedia.org/wiki/Diaspora_(novel) http://en.wikipedia.org/wiki/Diaspora_(novel) [4]: a good read (and/or rehash) on this: http://plato.stanford.edu/entries/turing-machine/ http://plato.stanford.edu/entries/turing-machine/ [5]: http://jubal.westnet.com/hyperdiscordia/library_of_babel.html http://jubal.westnet.com/hyperdiscordia/library_of_babel.htm...