A Brief Explanation of Greg Egan’s Dust Theory • Hacker News Board

Re: A Brief Explanation of Greg Egan’s Dust Theory

#51

Post by aaron-santos » Sat, Sep 05, 2020, 5:41 PM UTC

croissants wrote: post #28

aaron-santos wrote: post #20

The article really ought to close the loop by tying it back to the final 10% of the book. The big point in the book is that you can craft arbitrary surjections and have an infinite set of justifications for your subjective experience. A physical substrate is just as good as a computational/mathematical substrate. In this sense you can bootstrap your simulated existence into the immortal world of forms.

The part I don't understand about this, which is the same as the part I don't understand about dust theory, is that it seems to ignore the distinction between an abstract representation of an object and the object itself. By the logic of dust theory, I can walk into a bank and say "give me the money, or else I'll throw this handful of sand into the air, and it might encode a universe where you're tortured for a billi…

You're right. To which the teller can reply, "I've crafted an encoding where you are tortured for billions of years."

The idea is more about swapping out the substrate of your current subjective experience than creating a new encoding of your current universe. The book has the convient liberty of actually jumping between simulations/encodings to illustrate this, but it's ancillary to the main idea.

Re: A Brief Explanation of Greg Egan’s Dust Theory

#52

Post by lachlan-sneff » Sat, Sep 05, 2020, 5:42 PM UTC

cmehdy wrote: post #44

sxp wrote: post #6

This article doesn't actually explain Dust Theory to someone who hasn't read the book. I haven't found a good standalone explanation of the theory that explains it in a compact manner so my recommendation to people is to read the book. Permutation City is among my top 5 favorite books because I found Dust Theory so mind blowingly amazing from a philosophical standpoint. I haven't seen it discussed elsewhere outside t…

I finished the book last night. It's not a long read in terms of pages, but in the first half particularly it took me quite a few stops to ponder about what had been laid in few sentences. Greg Egan is awesome. (Sort-of SPOILERS underneath) I can actually grasp the Dust theory thing pretty well as I followed Durham's realizations, however I somehow can't fathom the "more practical" TVC universe stuff, and perhaps you…

I read Permutation City a year or two ago, so bear with me.

I believe they run the computation on physical computers so that the people running in the simulation can, at any point, check if their reality is a descendant of the initial garden-of-eden configuration.

Re: A Brief Explanation of Greg Egan’s Dust Theory

#53

Post by MiroF » Sat, Sep 05, 2020, 5:42 PM UTC

ardy42 wrote: post #26

MiroF wrote: post #18

> This is sort of like the Boltzmann brain idea but even worse because it applies to any set of relations. According to Egan’s argument all possible experiences that can be computed by any sufficiently complex set of relations are in fact computed by them. This idea seems identical to the Boltzmann brain hypothesis and I don't understand how this paragraph differentiates it at all.

>> This is sort of like the Boltzmann brain idea but even worse because it applies to any set of relations. According to Egan’s argument all possible experiences that can be computed by any sufficiently complex set of relations are in fact computed by them. > This idea seems identical to the Boltzmann brain hypothesis and I don't understand how this paragraph differentiates it at all. I don't claim to totally underst…

> IIRC, the latter imagines a literally brain being formed briefly out of matter.

I see. FWIW I think that is a very narrow reading of the Boltzmann brain hypothesis and while it may have been true to when it was first presented, I think the general "brain as abstract relations that can be simulated by physical systems" Boltzmann brain is what most contemporary cosmologists are talking about.

Re: A Brief Explanation of Greg Egan’s Dust Theory

#54

Post by codethief » Sat, Sep 05, 2020, 5:44 PM UTC

throwaway_pdp09 wrote: post #49

codethief wrote: post #45

Earlier quoted context omitted.

Can anyone with GPT-3 beta access ask GPT-3 to give a summary of "Permutation City"? Given impressive examples like this one[0], I think GPT-3 might do better. [0] https://twitter.com/paraschopra/status/1284423233047900161

You call that roundabout word-salad concoction impressive?

In contrast to the OP it's at least intelligible?

Re: A Brief Explanation of Greg Egan’s Dust Theory

#55

Post by _xerces_ » Sat, Sep 05, 2020, 5:44 PM UTC

sxp wrote: post #6

This article doesn't actually explain Dust Theory to someone who hasn't read the book. I haven't found a good standalone explanation of the theory that explains it in a compact manner so my recommendation to people is to read the book. Permutation City is among my top 5 favorite books because I found Dust Theory so mind blowingly amazing from a philosophical standpoint. I haven't seen it discussed elsewhere outside t…

How about this explanation? Simulation, Consciousness, Existence Hans Moravec, 1998

https://outline.com/JHCE77

Re: A Brief Explanation of Greg Egan’s Dust Theory

#56

Post by db48x » Sat, Sep 05, 2020, 5:47 PM UTC

codethief wrote: post #48

db48x wrote: post #46

Earlier quoted context omitted.

Not all computation is subjective, but some computations have a subjective viewpoint. We would say that those computations are sapient, or sentient, or self aware, or otherwise describe them as people.

> Not all computation is subjective, but some computations have a subjective viewpoint. No, you're interpreting them as such. Computation is objective. The only thing is that obviously your outputs depend on your inputs.

This is a theme which is explored in several different ways in the book. Another commenter has already related the tale of the man who ran an automatic optimizer on a copy of his own program. The optimizer noticed that the copy of the program had no inputs and no outputs, so it optimized it to an empty program. The man was understandably dissatisfied, because the empty program has no subjective experiences, while the man does. You might say that he made the mistake of optimizing a program with no inputs or outputs, but he would say that the designer of the optimizer made the mistake of not considering the subjective experience of the software to be valuable. It's certainly true that you can have a worthwhile life even if you stop talking to other people. At the very least, there have been hermits who have thought that they were having a worthwhile life, and who are we to argue?

The author of the brief "explanation" errs, I think, in simply using the phrase "computation is […] subjective". He should have instead said that sapient computations have a subjective experience. But if you don't believe that minds are software running on a funny kind of Turing machine, then even that statement might be nonsense.

Re: A Brief Explanation of Greg Egan’s Dust Theory

#57

Post by 3pt14159 » Sat, Sep 05, 2020, 5:47 PM UTC

sxp wrote: post #6

This article doesn't actually explain Dust Theory to someone who hasn't read the book. I haven't found a good standalone explanation of the theory that explains it in a compact manner so my recommendation to people is to read the book. Permutation City is among my top 5 favorite books because I found Dust Theory so mind blowingly amazing from a philosophical standpoint. I haven't seen it discussed elsewhere outside t…

Almost a decade ago I independently invented the same idea. Discussion was here:

https://news.ycombinator.com/item?id=2727750

It's a pretty simple theory, which I ultimately reject even to this day. If it were true, however, the expanse of existence is truly terrifying.

This theory leads to any possible existence existing, short of maybe self-contradiction[0]. Well, so if that is true, then there exists a relation of beings where one of the beings is both powerful and has motives that are purely antithetical to the others. Think "I Have No Mouth, and I Must Scream" kinda bad, only armed with Knuth's up notation and applied to pain and suffering. A hell that's truly beyond comprehension.

If this theory is correct, then all beings eventually find themselves in this hell. Note that this isn't argumentum ad consequentiam. I'm not saying that since this is such a horrific outcome that it's clearly false. I'm saying that if it is true, it is a horror beyond all horrors.

Though I suppose there is always a chance that a being that found themself in such a situation could always randomly pop out into some other, better existence by sheer chance.

Thinking about it is useful, but ultimately there are too many degrees of freedom to come to any practical conclusions.

[0] An existence arising that stops the existence of the vast randomness leading to all existences, for example.

Re: A Brief Explanation of Greg Egan’s Dust Theory

#58

Post by KerrickStaley » Sat, Sep 05, 2020, 5:51 PM UTC

Here is an explanation of Dust Theory from Wikipedia:

"[Dust theory states that] there is no difference, even in principle, between physics and mathematics, and that all mathematically possible structures exist, among them our physics and therefore our spacetime...The dust theory implies that all possible universes exist and are equally real, emerging spontaneously from their own mathematical self-consistency."

I think this does a pretty good job of summarizing the concept: the universe is simulatable, but there is nothing doing the simulation; it just exists as a pure mathematical object. All other possible universes that are simulatable (i.e. follow some mathematical model) are equally as real as ours.

Re: A Brief Explanation of Greg Egan’s Dust Theory

#59

Post by ryukafalz » Sat, Sep 05, 2020, 5:59 PM UTC

cmehdy wrote: post #44

sxp wrote: post #6

This article doesn't actually explain Dust Theory to someone who hasn't read the book. I haven't found a good standalone explanation of the theory that explains it in a compact manner so my recommendation to people is to read the book. Permutation City is among my top 5 favorite books because I found Dust Theory so mind blowingly amazing from a philosophical standpoint. I haven't seen it discussed elsewhere outside t…

I finished the book last night. It's not a long read in terms of pages, but in the first half particularly it took me quite a few stops to ponder about what had been laid in few sentences. Greg Egan is awesome. (Sort-of SPOILERS underneath) I can actually grasp the Dust theory thing pretty well as I followed Durham's realizations, however I somehow can't fathom the "more practical" TVC universe stuff, and perhaps you…

It has admittedly been a long time since I've read the book, so my recollection of it may be a bit hazy, but:

> Why would a few minutes of compute offer Durham any more relief than a second of it, a theoretical proof of it, or a billion years of it? Since they are even in a position to kickstart something computable, it mathematically exists, therefore by the Dust theory they don't even need to start it in order for everything in the book to happen. Admittedly, that makes for a much shorter book (or a billion trillion other scenarios and then some, whatever floats one's boat)

I'd guess for "flesh" Durham's assurance that the simulation worked as well as he thought it would. It's one thing to be pretty sure it'll work in theory, but I'd imagine it'd be quite a bit more reassuring to see it in action.

Of course, TVC-Durham gets to see that it works subjectively, but from outside the TVC universe the only way you can verify that it's working is to run the simulation and observe the result.

I don't think they had enough compute power to run a billion years of the simulation, and a few seconds is too short to e.g. see people interacting within it.

Re: A Brief Explanation of Greg Egan’s Dust Theory

#60

Post by cmehdy » Sat, Sep 05, 2020, 6:04 PM UTC

lachlan-sneff wrote: post #52

cmehdy wrote: post #44

Earlier quoted context omitted.

I finished the book last night. It's not a long read in terms of pages, but in the first half particularly it took me quite a few stops to ponder about what had been laid in few sentences. Greg Egan is awesome. (Sort-of SPOILERS underneath) I can actually grasp the Dust theory thing pretty well as I followed Durham's realizations, however I somehow can't fathom the "more practical" TVC universe stuff, and perhaps you…

I read Permutation City a year or two ago, so bear with me. I believe they run the computation on physical computers so that the people running in the simulation can, at any point, check if their reality is a descendant of the initial garden-of-eden configuration.

I think I can see it: they write the software without having a clear proof (that, say, it is mathematically inconsistent and will crash). Then they execute it for long enough for its self-test phase(s) to be reasonably validated (with all the resources they can get in the "normal" world), therefore practically reassuring themselves that there's a mathematically valid outcome (in a "formal verification" sense), which ensures at least one configuration existing with their wishes (the Garden-of-Eden one).

It does have the side effect of ensuring the reality that exists also has a way to know the Garden of Eden configuration (provided the people scanned are/were made aware of it prior to the scan, since it's made clear that there's no guaranteed way to know what happened to the "flesh person" after a scan when you're "reborn virtual".