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MathMage comments on Harry Potter and the Methods of Rationality discussion thread, February 2015, chapter 109 - Less Wrong Discussion

5 Post author: Gondolinian 23 February 2015 08:05PM

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Comment author: MathMage 23 February 2015 09:41:56PM 14 points [-]

Prediction: Atlantis wasn't a catastrophe that the Mirror was too late to avert. Rather, the Mirror was completed, and the Atlanteans removed themselves to a realm of existence within the Mirror. Confidence: 5%.

Comment author: jimrandomh 23 February 2015 11:59:26PM 5 points [-]

Far more likely that there was a catastrophe, and the Mirror itself was the cause.

Comment author: MathMage 24 February 2015 12:11:18AM 2 points [-]

Yeah, that's a good way to turn all this "carefully designed not to destroy the world" stuff on its head.

Comment author: buybuydandavis 24 February 2015 02:28:32AM 0 points [-]

The narrative also serves to reinforce MIRIs basic premise, that AI could destroy the world.

Comment author: Bugmaster 23 February 2015 10:10:06PM 4 points [-]

Either that, or the world where HPMOR takes place is just one among many realms within the Mirror; i.e., the Simulation Argument is true, and the Atlanteans are the Matrix Lords. This explain the weird and inconsistent magic rules: they are just artificial constructs that the Atlanteans came up with on a lark.

Comment author: DanielLC 24 February 2015 02:19:19AM *  1 point [-]

Didn't Harry already point out that the time travel was not computable, and as a result it couldn't be a simulation? Although he didn't go to great lengths to prove that. He assumed that there was no force subtly manipulating events to make sure time travel is consistent. In fact, he is in a simulation run on the computer that is Eliezer's brain.

Comment author: Bugmaster 24 February 2015 02:21:13AM 2 points [-]

I don't know if he put it into exactly those terms, but a). Harry points out a lot of things that aren't true, like "you can't turn into a cat", and b). if the laws of reality are simulated, then they don't have to make sense; they could just be a giant "switch" statement somewhere in the Atlantean VM code.

Comment author: DanielLC 24 February 2015 03:29:14AM 0 points [-]

If the laws of reality are simulated, then they must be computable. A giant switch statement isn't going to let you figure out how to make time travel consistent. They couldn't easily check every possibility and see if it's consistent. Even if they did, that would mean they're simulating all of them, including the inconsistent ones, and there'd be no reason for Harry to find himself in a consistent one.

Comment author: Bugmaster 24 February 2015 03:55:11AM 3 points [-]

They couldn't easily check every possibility and see if it's consistent.

Why not ? It's not like the laws of our space-time apply to them or anything.

Comment author: Jost 24 February 2015 09:35:40AM *  12 points [-]

Atlantis-Human: “Where did you learn about computability, Harry?”

Harry: “… in the Matrix.”

A-H: “The Matrix tells elegant lies.”

Comment author: alienist 24 February 2015 06:00:37AM 1 point [-]

If the laws of reality are simulated, then they must be computable.

Depends on what they're being stimulated on.

Comment author: Astazha 24 February 2015 08:01:12PM 0 points [-]

The anthropic principle solves Harry finding himself in a consistent one nicely. We don't know about the paradoxical universes because time/magic destroys them. You could also propose that when paradox occurs time goes back to the point of paradox and makes changes, inserts prophecies, etc. (maybe even uses mind magic?) to attempt to correct, destroying only the portion of the time-stream that came after. In this version there is actually just one time stream, not many, and it loads from the last checkpoint so to speak whenever a paradox results.

Results like "DO NOT MESS WITH TIME" really imply an outside intelligence that is meddling to ensure consistent outcomes, rather than a universe that runs only on physical law. This isn't a reponse Harry would have thought of, it was inserted from somewhere external.

Regarding "computational difficulty":

1) We don't know what magic/time/the external universe is capable of, computationally. Magic does "impossible" stuff all the time. 2) It doesn't matter how difficult it is to compute or how long it takes. These things are transparent from an inside perspective. 1 second in-world could take a billion years to calculate, and it would still seem seamless from the inside.

Comment author: avichapman 24 February 2015 05:42:27AM 0 points [-]

It the simulation were infinitly parrallel and all simulations that weren't consistent crashed, the Harry that made the observation about the loop would necessarily be in a self-consistent simulation.

Comment author: kilobug 24 February 2015 09:44:39AM 0 points [-]

Time travel isn't fully computable, but that doesn't mean it can't be approximated, that you can't make hacks giving the impression of time travel to people inside the simulation.

It might even be possible that attempts to abuse time travel (like the one done by Harry at the beginning when he tried to factorize primes using the Time-Turner) raise an alert in the simulation, freezes the simulation until an operator manually inputs an acceptable solution ("don't mess with time" being the solution hand-crafted by the operator).

Comment author: garabik 24 February 2015 02:57:57PM 1 point [-]

Time travel isn't fully computable

Depends on what kind of time travel and what kind of universe. Heck, even classical newtonian real-valued physics is not computable (but is computable to arbitrary precision). If the information content of the universe is finite (like, it is a grid of finite many cells, each of them could be in only finite many states, and time is discrete as well), then time travel is computable - you just have to store the information for the past 6 hours and brute-force consistent stable loops.

Comment author: Benito 23 February 2015 10:49:16PM 3 points [-]

Thing is, on that line, this would sorta become a simulation fic, and Yudkowsky said it wasn't that.

Comment author: savedpass 24 February 2015 10:15:39AM 0 points [-]

Didn't he also say there wouldn't be AI in it?

Comment author: Benito 24 February 2015 10:31:09AM 1 point [-]

I think he said 'Harry won't create an AI' but I don't have the source.

Comment author: drethelin 24 February 2015 01:21:07AM 0 points [-]

I don't think it's really a simulation fic if simulations exist but the main story level isn't in one.

Comment author: Subbak 24 February 2015 12:43:12AM 0 points [-]

And changing the genre when the story is over 90% complete would be a questionable move.

Comment author: lerjj 23 February 2015 09:55:30PM 1 point [-]

This was what I thought as well. I doubt we'll get confirmation of that prediction though, unless Quirrell/Harry actually DOES try to destroy the world. In which case presumably the Atlanteans have to save the day (unsatisfying from a literary point of view, hence unlikely).