Harry Potter and the Methods of Rationality discussion thread, February 2015, chapter 109

Dumbledore isn't in the mirror. Harry and Voldemort are. The trap triggered, stuck them in a time-dilated mirror plane. Which is, of course, the only reasonable way to deal with an immortal serial killer. This even counts as fulfilling the darn prophecy, doesn't it? Definitely if Dumbledore can extract Harry, because that way naught but a remnant will exist in the same world, and yes, it does count as Harry defeating him. He talked him into stepping into that trap, after all. Bravo.

Harry had applied the Charm he'd learned for battles that made his eyeglasses stick to his face, regardless of how his head moved.

(Chapter 104)

The first thing Harry had to do was strip off all his clothes, and his shoes, and everything else he was wearing except his glasses; without his wand, Harry couldn't unstick his glasses from his own forehead, and neither could Professor Quirrell because of the magical resonance.

(Chapter 109)

Just pointing out: Hermione's body is probably Harry's glasses.

I show not your face but your coherent extrapolated volition

I got shivers when I read that and realized what the Mirror was. Another thing that ought to have been obvious, in hindsight.

I'm having trouble making sense of the Mirror. Atlantean-MIRI built a CEV-viewer to guide the massively powerful optimization they were planning to unleash, sure.

But it's not just a viewing device; you can put things in and take them out. Why? Unsatisfactory answer: So you can step inside and live out your life in the room of your heart's desire. Unsatisfactory because you might want more than one room.

Also, every viewer doesn't get a freshly minted instance of their CEV; it's possible for them to see the effects of someone else's prior interactions with the world. Why? Answer 1: Because storing things in the mirror was an intended use. But why? Answer 2: People whose CEV dictates they live together, with the real versions of one another and not convenient copies, need the same instance of the same world.

If the Mirror is the source of phoenixes, then the mirror can be used to create things. Maybe the idea was to produce the singularity within the mirror and take it out? The world doesn't look like this happened, and I doubt EY's ending is that no one really wanted a singularity, but maybe there's some limitation that prevented this. Say, the Mirror piggybacks off the user's brainpower, so it can't extrapolate its way to a much Friendlier singularity than the user could have designed. I do take the mirror's performance so far as evidence it doesn't extrapolate very aggressively.

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%.

BTW, not related to the plot much at all, but I think I get the point of the dungeonrun first year students can beat.

The mirror is set to show students their CEV, which Harry dismissed as "Themselves in some very desirable situation". Is dismissed the right word? Eh, anyway, I don't think the people Harry talked to quite managed to convey the magnitude of it to him.

Slytherin's core insight, the thing his house if founded on, is that people become who they are supposed to be by pursuing their ambitions, or at least that is the opinion of Quirrel the teacher-persona. I don't actually care if he truly believes that, because it just strikes me as an important truth.

The mirror tailors good and sound ambitions for people. Or at least it does for any student which has a CEV which could conceivably be achieved via their own efforts. And they are, after all, witches and wizards.

Putting it behind an obstacle course makes people value and pay attention to what it gives them. It is a really impressive piece of pedagoguery.

So basically, the entire thing isn't about Voldemort at all. It's about teaching. Wonder how much of slytherin house did this run? Because it obviously is the house that would benefit the most from it.

So, is that really the stone? Was "triumphant Dumbledore" enough to get the mirror to coff it up, or is that a trap of some kind?

My thinking is trap. Dumbledore doesn't believe he can best Voldemort, he thinks Harry will, due to prophecy. He's set up the mirror to give him a false Stone if he appeared in front of it thinking that he'd won, because he believes that if that was the cases he'd have been deceived.

Further guess, the mirror's actual condition for giving up the stone is that it will give the stone to a phoenix.

Dumbledore has argued that death is good. We have all assumed that this meant he thought death is good. I'm beginning to question that assumption. Dumbledore's stated belief has given him access to the Philosopher's Stone, and resulted in Voldemort going to the Mirror with a specific state of mind. Both of those are very useful conditional on Dumbledore considering death to be bad.

Admittedly, he probably didn't predict the second one, but it's entirely possible that Dumbledore had been claiming that death was great for his whole life in hopes that one day the holder of the Philosopher's Stone would give it to him for safe keeping.

I'm not quite sure how to interpret the end of the chapter. Option 1 is that real!Dumbledore is within the mirror, option 2 is that Riddle!Dumbledore is within the mirror (and about to interact with Tom in the way Tom always wanted him to), option 3 is that real!Dumbledore is outside the mirror and Harry can see him reflected in it.

Hypothesis: The mirror (or the whole room) connects universes. More specifically, there is only one mirror, stable in the multiverse (quantum, mathematical, magical or whatever) of compatible universes. A compatible universe is such an universe where the mirror exists, i.e. most probably the one that did not branch off before the end of Atlantis (or boltzmanned into existence a moment ago).

Looking into the reflection, your (magical) brain picks the image from a different universe, the one that matches your CEV most closely.

Nothing can hurt the mirror, unless the measure of the universes the action is performed in is a "significant portion" of the multiverse - otherwise it just dissipates.

The map shows gibberish, because, well, there is everybody and nobody in the last room...

I am confused. Quirrell's plan to get the Stone out of the Mirror while eluding Dumbledore's traps is: go to the Mirror with Harry, then brainstorm ideas together for how to get the Stone from the Mirror, and then try the riskiest idea that Harry came up with?

It's a pity we didn't get to see what Harry would see if he looked into the mirror. I half-expected to see the scene where Harry looks into the mirror and sees himself transcend his humanity, becoming an immortal intelligence running on a Matryoska brain, then uses his newfound god-like powers and cognitive abilities to take Hermione's body apart atom by atom and reconstruct her back as a living Hermione, helps her ascend as well, so that the two of them can defeat death, optimize the world, and go on doing all those awesome things Harry once said he wanted to do with immortality ...and then Harry looks down and sees that he has a nano-factory in his pocket that can help him start this transition.

I mean, while EY told us that Harry would not build an FAI, he did not say "Harry will not become an immensely-powerful FAI"

This whole trail of thought also reminded me of what a certain Milo Amastacia-Liadon from a certain other HP fanfic saw in the mirror. We all know that Rational Harry doesn't aim low, does he?

Continuing on Izienwinter's reasoning:

Harry and Voldemort sprung the trap, they are now inside the mirror, Dumbledoor is outside.

It is now an AI box experiment, with Dumbledoor as Gatekeeper and Harry as the AI wanting out!

Can the mirror be used to hack the Time Turner restriction? GAH!

Also, reading the letter backwards:

Is how not your face but your coherent extrapolated volition .

Observe that the writing on the back of the Mirror is in runes, not any particular alphabet. The fact that Harry can read anything out of them at all suggests that there is an effect meant to make them 'readable' regardless of what languages / alphabets the reader knows. This effect was presumably placed by someone who knew what the Mirror does and wanted to make sure that knowledge was preserved even if languages changed and the history of the Mirror was lost.

But then why would someone want to obscure the answer by making those runes the Words of False Comprehension? The end result of having both effects in place is that readers get a simple puzzle in a language they know, hidden behind a magical effect that makes them believe they understand the runes without any further effort. What goal would motivate a great effort to make the puzzle solvable, but only if you realize it’s there to be solved?

My answer is that it’s not a test of "can you read backwards and fix some spacing in a language you know," it’s a test of basic rationality skills. The word reversal and changed spacing is just to prevent bypassing the rationality test.

What would someone reading the back of the Mirror need to do, to solve the puzzle? Ask the fundamental question of rationality: "What do I think I know, and why do I think I know it?" Realize that their initial beliefs about the meaning of the runes are free-floating beliefs, ones that don’t connect to the rest of their beliefs and don’t constrain anticipations. Realize that the free-floating beliefs are useless, discard them, and look past the false feeling of comprehension. Find the real puzzle, possibly aided by hearing that the runes are Words of False Comprehension.

And then once they’ve found it and converted it to words they recognize, put in the effort to understand what the words actually mean and connect those words to the rest of their beliefs rather than guessing the teacher’s password. We know that "coherent extrapolated volition" has a specific technical meaning, but Harry doesn’t and is going to have to work it out from his knowledge of English and stories about the Mirror.

Also: "It is claimed by several authorities that the Mirror alone of all magics possesses a true moral orientation".

So here are my predictions:

At the end of Chapter 109, Quirrell and Harry are trapped in an alternate plane generated by the Mirror. 65%

Harry and Quirrell are going to wind up on different sides of the Mirror. 60%

Confunded!Quirrell received a fake Stone. 50%

Quirrell’s conception of Dumbledore, as Quirrell used to Confund himself, lacks full human wish complexity. 80%

There is a magical 'translation' effect (not the False Comprehension effect, although both may be part of the same spell) on the runes on the Mirror which enables people to 'read' the runes. 95%

The Mirror is involved in a test meant to distinguish some subset of rationalists (not necessarily a proper subset) from other people. 80%

The Mirror is involved in a test meant to distinguish Light Rationalists from other people, under some conception of Light / Good. 75%

Conditional on the Mirror being involved in a test meant to distinguish some subset of rationalists (not necessarily a proper subset) from other people, passing the test grants some type of additional power (including from knowing more about the Mirror and therefore being better able to use it). 90%

It is said, in certain legends that may or may not be fabrications, that this Mirror reflects itself perfectly and therefore its existence is absolutely stable.

I take it "reflect" here means some kind of self-modeling aside from just optical reflection?

I see. "Heart's desire" indeed.

So... Atlantis managed a neutral AI? But see convergence of methods - I'd expect a hypothetical NAI to be considerably harder to build than an FAI.

(Also, nice Duane shout-out.) In what sense is Altantean Magic more like Wizardry than post-Antlantean magic, though? Just the bits about making the Holy Grail as opposed to merely operating it?

(Heh. True Magic.)

Even Riddle would wish to be happy, I think. Or rather, if he knew more, was more capable, and was more the sort of person he wants to be... he would wish to be happy and immortal. Why not, after all?

I wonder how Dumbledore turned that into a trap, though?

For that matter, if Harry is right and Aberforth has the stone... there is another way of getting it, if this one is copy. There's more than one way to see someone who's dead, after all.

The thought of making a better horcrux, of not being content with the spell I had already learned... this thought did not come to me until I had grasped the stupidity of ordinary people, and realised which follies of theirs I had imitated.

This apparently happened significantly later in his life. However

"Nine years and four months after that night, a wandering adventurer named Quirinus Quirrell won past the protections guarding one of my earliest horcruxes.

Doesn't this suggest that Quirrell stumbled upon a horcrux v1, given that it was one of the earliest horcruxes, and that it was 'hidden' by the less wise Riddle?

I suspect Eliezer just didn't notice this, or that the explanation is that after inventing v2, Riddle went back and upgraded all his old horcruxes or something. The alternative explanation is that all v1 horcruxes upgraded automatically when he went for the v2, however we know that Harry is also a v1 horcrux, so that wouldnt make sense.

Chapter 89 (spoken as prophecy, heard by Quirrell):

“He is here. The one who will tear apart the very stars in heaven. He is here. He is the end of the world."

Chapter 109:

Merlin left written instructions that the Mirror did not need to be sealed away, despite it having certain powers that might normally cause one to worry. His exact wording was that, given how painstakingly the Mirror had been crafted to not destroy the world, it would be easier to destroy the world using a lump of cheese.

I would say this implies that Quirrell ought to have triggered a safeguard on the Mirror, without Dumbledore needing to have installed it.

It looks like AI will make an appearance in hpmor! I had thought that Eliezer was simply going to go with an anti-death plot for the climax and not include AI, but here we are with the mirror. Looking forward to seeing how it plays out.

I don't really have much to say after reading that. My thought process is pretty much summed up like this: "But Dumbledore can't beat Voldemort!" "Maybe he can. In canon he can (kinda), and even in the last few chapters QQ has given him some grudging respect," "Seriously? Voldemort was winning the Wizarding War, whilst holding back!" "Dumbledore might have been as well. Anyway, we've only got Voldemort's word on this. Also, check to see what parts of ch 108 were in Parseltongue. Maybe there's a better reason for why Voldemort didn't win in three days."

So, I guess I'm going to go check this now. Otherwise, bye-bye Albus. EDIT: there is no Parseltongue used in that particular dialogue. Quirrell claims that he didn't want to go back to Solitaire, but it is possible that he just ran up against Dumbledore in earnest.

Wait a minute, aren't all human CEVs supposed to converge to roughly the same thing? (tell me if I've catastrophically misunderstood or misremembered the concept, it's been a while since I read the sequences)

Does anyone remember an event from the whole book when Harry thought about Turning Time while already being in past.

OK, that answers a bunch of questions. Magic is an unfriendly tool AI, Atlantis was destroyed by misusing it, and the mirror is an incomplete but stable (reflectively consistent, haha) friendly AI. That makes perfect sense and many people have suggested similar theories, but didn't Eliezer promise not to do that?