This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 110.

There is a site dedicated to the story at, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on

Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically:

You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).

If there is evidence for X in MOR and/or canon then it’s fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that “Eliezer said X is true” unless you use rot13.

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After reading comments in /r/hpmor, I've realized that Professor Quirrell has a superior move in the previous chapter, which has hopefully updated or will update soon.

Be honest, Eliezer; you just got sick of all the naked Harry jokes.

How I laughed when I realised it! When I saw you had made a Good Voldemort to oppose the evil one - ah, how I laughed!

I guess now we know what Dumbledore was laughing about in chapter 17.

The Cloak of Invisibility was torn away from him, and the shimmering black Cloak flew away from him, through the air.

Professor Quirrell caught it, and swiftly drew it over himself; in less than a second he had pulled down the Cloak's hood over his head, and disappeared.

Quirrell can escape the trap because he is no longer reflected in the mirror, being hidden by the True Cloak of Invisibility. All he has to do is walk out of the reflection, which he did.

Into the hand of the Albus Dumbledore flew from his sleeve his long, dark-grey wand, and in his other hand, as though from nowhere, appeared a short rod of dark stone.

Albus Dumbledore threw these both violently aside, just as the building sense of power rose to an unbearable peak, and then disappeared.

The Mi

... (read more)

I guess now we know what Dumbledore was laughing about in chapter 17.

Oh yeah. 18 too, I guess:

"Of course you're in here blackmailing me to save your fellow students, not to save yourself! I can't imagine why I would have thought otherwise!" Dumbledore was now laughing even harder. He pounded his fist on the desk three times."

I think these are sufficient evidence that this is the real Dumbledore, not the mirror showing Quirrell what he wants.
Worth noting - it is immediately after that laughter that he gives over his father's rock. And given that this chapter comments on how Dumbledore has access to wacky divination, that rock starts to make a heck of a lot more sense. (I mean, we always knew it's be an Important Quest Item, but this does shed a bit of light on why)
Amusing that you should bring up that chapter, Harry's lesson learned there seems somewhat relevant now... . . DO NOT MESS WITH TIME

Not immediately relevant to anything, but on re-reading the last few chapters I've figured out what hex would be utterly devastating to Voldemort while also being something he might not think to calibrate his shields against: the Hurling Hex. Cast on a broomstick, it makes it go out of control and attempt to violently cast off its rider. Voldemort's bones count as broomsticks.

"Well," said Albus Dumbledore. "I do feel stupid."

"I should hope so," Professor Quirrell said easily; if he had been at all shocked himself at being caught, it did not show. A casual wave of his hand changed his robes back to a Professor's clothing.

Dumbledore's grimness had returned and redoubled. "There I am, searching so hard for Voldemort's shade, never noticing that the Defense Professor of Hogwarts is a sickly, half-dead victim possessed by a spirit far more powerful than himself. I would call it senility, if so many others had not missed it as well."

This is Dumbledore admitting he held the Idiot Ball. We've been promised nobody's holding the Idiot Ball. So something's up. I like the theory that mirror is operating as intended and showing Voldemort what he wants to see, that being Dumbledore making a mistake and losing. Alternately, it could be that Dumbledore was somehow able to make a version of him inside the mirror (maybe in his CEV he saw himself inside the mirror protecting the Stone, and that reflection-Dumbledore gained independent existence?). Or he could just have something else up his sleeve.

Honestly, it sounds like sarcasm. Dumble is even stranger than usual this chapter.

"Stranger than usual" could be an evidence for not being the real Dumbledore, but instead Voldemort's imaginary Dumber-dore. We were already shown in the chapter that Voldemort had a wrong model of him. (Maybe acting like insane was Dumbledore's long-term strategy to prevent his enemies from simulating him precisely. But that seems rather paranoid. On the other hand, he sometimes works with Moody.)

I'm not quite sure it's the idiot ball, for two reasons.


I would call it senility, if so many others had not missed it as well.

Even with the knowledge that Quirrel was possessed by Voldemort in canon, whether or not Quirrel was Voldemort was an active topic of debate among readers for quite some time.


Really, am I that hard to recognize without the glowing red eyes? ... Quirinus Quirrell seemed - what is the term I am looking for? Ah yes, that is the word. He seemed sane.

If Dumbledore is used to thinking of Voldemort as a cartoon villain, and expects his shade to also behave like a cartoon villain, I could see him missing Quirrell.

(There is, perhaps, also the third reason of motivated cognition brought on by McGonagall, but I always saw that as more plausible if it were magically brought on by Riddle than her really not caring who he was.)

There's also the possibility brought up earlier and echoed in a lot of the other threads: this may be a Dumbledore spawned by the mirror as part of reading Quirrell's mind and determining his CEV. That doesn't explain how real Dumbledore didn't see it, though.

Dumbledore may have seen it, and refused to let on. Quirrell is next to impossible to kill permanently. He says he can detach from a body if it is in danger, and if you kill the body, he detaches too. The argument would go that Dumbledore was luring Quirrell into the Mirror as a final solution, and therefore pretended not to recognize him. (Though wouldn't an easier play be a sneak attack by Dumbledore incapacitating Quirrel but not killing him? )
I'm not sure I agree. Everyone Is An Idiot Except Quirrel And Maybe Harry is a major theme of the whole series, not stronger than anti-deathism but certainly more consistent. Dumbledore bought the first level of Riddle's two-level bluff; in context that's pretty dumb, but not unusually so by MOR NPC standards.

Harry is the viewpoint character, and he thinks everyone is an idiot except him and Quirrell. He is in error. He has been consistently in error about this since ... forever. It's probably a character flaw that he shares with Voldemort, although Harry has a somewhat less murderous form of it.

For instance, Harry believes that the wizarding economy should be trivially exploitable via exchange with the Muggle precious-metals market. He believes this because even though he knows about half-bloods (i.e. witches and wizards who have a Muggle parent), he thinks that he is special and that nobody else ever would have thought of that.

Similarly, he believes that he is the first to come up with the idea of combining magic and Muggle science. He isn't that, either. He doesn't realize this even after he is given the (ostensible) diary of Roger Bacon.

And here's the thing ... he doesn't update about these errors. He's not particularly curious about them. "Hey, wait, there are Muggleborns; what's the chance any of them has ever had a relative in Muggle banking, finance, or economics?" "Oh, Roger Bacon was a wizard? I had better learn me some Latin so I can find out what the history of magic/science interaction has been."

I kinda agree, but...the Time Turners really didn't have protective shells. If you see what I mean.

Don't forget, his Occlumency teacher would mention after every session that he wished he would be allowed to remember the arbitrage trick. Eliezer has talked about how one of his main reasons for writing the story as a work of fanfiction is that it gets the audience to accept a world that is massively exploitable by the main characters, which they would have thought was a case of the author making things too easy on them if the author had actually created it. Eliezer wrote a story set in the world of Harry Potter because Rowling didn't think very hard about the implications of her worldbuilding and created a massively exploitable setting.
I don't think "didn't think very hard" get's to the point. She simply wanted to paint a strange world and didn't care.
In some cases, she cared later, and had to work her way around what she'd done. EDIT: The main example below is WRONG, but you can read on anyway if you want to know what I thought and why I thought it. A simple but revealing example: If you just read Philosopher's Stone, there is no indication that the Wizarding world is meant to be secret. When Petunia recalls the arrival of Lily's letter, there is no sign that anybody is surprised. The Evans parents are proud, and Petunia is disgusted, but they all think that they know what it means to be a Witch; they have opinions about it, not disbelief. The Dursleys do try to tell Harry that there is no such thing, but they know that they're in denial, and even Dudley isn't sceptical, just horrified (like his mother before him). It all fits in perfectly well with the style of Philosopher's Stone as a silly wish-fulfilling romp. The sequels are progressively more serious, and Rowling realized right away that it's much easier to build a coherent Wizarding world if it's secret. So she established the International Statute of Wizarding Secrecy early on in Chamber of Secrets, dealing with the Weasleys' flying car. Other things that Rowling didn't know in Philosopher's Stone: Harry's cloak is special, Ron's rat is special, Azkaban exists.
While the Statute of Secrecy was not mentioned explicitly in book 1, it was mentioned many times that the wizarding world is a secret. Just to name two instances: * Chapter 1: McGonagall clearly disapproves of the overblown celebrations of Voldemort’s disappearance (lots of owls, shooting stars), even stating that it would be a real mess if muggles found out about wizards. (No verbatim quote, since I don’t have the english book available right now.) * Chapter 5: Hagrid explains to Harry that the main task of the Ministy of Magic is to keep the existence of witches and wizards a secret. (Families of muggleborn witches and wizards will learn about the wizarding world, of course; but other muggles won’t.) With the rat, it’s less obvious: I would even argue that the relatively frequent mention of Ron’s rat in book 1 is weak evidence for it not being a normal rat. Plus, there’s a scene during the train ride to Hogwarts, where the rat is smashed into a window pane violently: Would a normal rat survive this without any apparent damage? Possible, but rather unlikely, so that’s additional evidence for the rat being somehow magical. (Wizards being more resistant to force than muggles is mentioned several times in the same book, as is the existence of animagi.) Regarding Azkaban: No mention in book 1, yes, but it is mentioned in book 2, before it started to play a major role in book 3. Regarding the last point (the cloak being special): Well, it belonged to Harry’s father but he gave it to Dumbledore for savekeeping. That alone is evidence that this is not just a normal cloak with a simple charm on it, which you could just buy again, if you lose it. Ron even says that such an invisibility cloak is extremely rare and valuable.
Thanks for keeping me honest, but I don't have the book available to me now either. If you can quote from a different language edition (especially German), that would help. Without the book to review, what I relied on in my comment[^1] was this: When I first read it, I came away with the impression that there was no secret. I remember reading about Petunia's letter and concluding that the Evanses knew all about Witches and Wizards. (The differing reactions to them are like the attitudes towards Mutants in Marvel comics.) [^1]: That, and checking the Wikia for first mentions. Perhaps, primed by this, I missed later references to secrecy. (But that doesn't help with any comments by McGonagall in the prologue.) I do remember being disappointed (but understanding) with the secrecy in book 2. Yes, certainly. In fact, I always thought that Hagrid's trip to Azkaban in book 2 was set up so that we'd know what the title of book 3 meant. (I knew that title before I read book 2.)
Here's the passage from chapter 1: My rough, not-a-native-German-speaker translation: I take from that that McGonagall doesn't expect the Muggles to know what it means that there are suddenly a bunch of owls everywhere, but that wizards everywhere nevertheless have a duty to make sure that Muggles don't see those sorts of things.
Thanks! (The translation is fine, btw.) A few lines later, McGonagall states it even more explicitly: (rough back-translation):
Here’s the quote from chapter 5, too: rough back-translation:
Thanks again, that is all very clear, in either language. I have edited my wrong comment.
I've always wondered about that. You're in the middle of a deadly war, and consider yourself to be in such danger that you use a rare and powerful charm to make your house not exist for the uninitiated. Why do you give away an invisibility cloak, normal or unique, and why do you give it to someone who explicitly states "I do not need a cloak to become invisible"?
Smashing a creature against a wall at a specific speed is dependent on the square/cube law, since the kinetic energy is proportional to the creature's mass, but that kinetic energy is being spread out over a proportionately greater cross-sectional area than a larger creature. That's why a cat can survive a fall from pretty much any height.
Which is also consistent with "Harry expects it to work and the teacher doesn't know much about finance".
Hell, I think we've even met one. Aren't Justin Finch-Fletchley's parents some kind of hot-shot financiers?
This is what I admire in Yudkowsky. He is not afraid of creating a rationalist character who makes grave mistakes, and even cases where rationality leads him to do bad decisions instead of saving the day.

Random note of confusion - Why is the mirror blank? Harry should be seeing his CEV right now, since he's unCloaked in front of the mirror.

Also, the Cloak is Harry's, yes? If Harry claims the Cloak right now, while Quirrell's wearing it, will that trigger resonance?

I had been thinking that Harry needed to get some mileage out of being the true owner of the Cloak too.

If Tom Riddle is the true owner of the cloak the behavior of the cloak under various circumstances is unknown. But no times like desperate times for nondeterministic saving throws.

.... Okay, I've got nothing. They are.. still in the mirror?

Dumbledore was acting very strange. The part of my mind that spits out theories is going "If Dumbledore can employ future-scrying-based planning techniques, please fuck off, I refuse to anticipate the plots of gods"

Edit: After bullying my imaginary voices. for a bit:

...I'm not at all sure Dumbledore was even there! Arrgh. "Illusion" is way up there in the plausible theories range. A whole ten percent or so.

The cloak is an obvious counter to a mirror trap.. But Dumbledore put the cloak into play. So... the cloak is trapped, somehow? .. dying while wearing it would shield him from his own hocruxes or something?

It was supposed to shield Harry in the event he ran the gauntlet?


General Theory; Dumbledore generally uses shot-gun plotting. Not just one plot, but many plots aimed at the same end. he has applied that principle to taking out Voldemort.

Still don't think "Flamel" is dead.

dying while wearing it would shield him from his own hocruxes or something?

holy crap, awesome you noticed this. Seems plausible.

Been thinking this through all day now. Situation at the start of the school year: The stone is in the mirror, and it is anticipated Voldemort will be attempting to retrive it. Dumbledore is in possession of the true cloak of invisibility, and has "Flamel" on speed dial. Harry is known to be a harrycrux, which means Voldemort will either be taking over his body, or at least checking up on him. There is no way Dumbledore gives Harry the cloak without anticipating Voldemort using it against the mirror. He wasn't obligated to hand that thing over to a first year, as opposed to hiding it under the proverbial rock in Greenland. Probability this was a misstep so low I can't be bothered to calculate it. It isn't just that he would have to miss the potential interaction here, every other person involved in building the trap would have to also miss it. For an entire year. So it's a plot. This is the point where my certainties become less certain - I think what is going on is that the trap is set up to give Voldemort the false impression of victory at every step of the way while at the same time trying to take him off the board in various ways. This is being done to avoid him fleeing via blowing up Quirell's skull. This means either Dumbledore was a fake of some kind or if actually there, that he lied through his teeth agreeing with every point of fact Quirrel brought up in order to convey zero actual information. Beyond that I thought of so many possibilities for what the actual trap could be that my head is currently spinning. Option one : The True Cloak of invisibility is no such thing. They made a ringer. Option two: They flat out just cursed the darn thing. Option tree: The cloak has funny interactions with spirits, and the entire point is to kill voldemort while he is wearing it. Option 4.. you get the point. I also think that there are likely plots in motion not related to the mirror at all - it would fit dumbledore's style to attack this problem at every possibl
Supposing (though it might be wrong) that mirror-Dumbledore is speaking truth, it's not clear that he realises what Harry is until that point in ch17 where he starts laughing. Which is after Harry has received the cloak. (And, I think, after D. has promised not to take it away from him -- though he hasn't promised not to require him to store it somewhere secure away from Hogwarts.)
That is when Dumbledore realizes Harry is a "good" Tom Riddle. We don't know when he realizes Harry is a horcrux. EDIT: In fact, it's almost certain that Dumbledore realizes that Harry is a horcrux before that scene, or at least suspects it. It doesn't look like anything in that conversation in particular would make him realize that, and he clearly knows it by that point.
The thing is, my reasoning doesn't actually depend on the horcrux realization, tough I give it better than even odds they knew that long before he even got the Hogwarts letter. Like, some time around the bitten math teacher or the science fair incident. The cloak is the obvious counter to the mirror. Using it isn't some super-obscure piece of lore. The mirror has power over things reflected, the cloak removes you from that category. Put yourself in Dumbledores shoes as you are packaging up that thing after spending oceans of time and effort setting up the mirror. Just No. This is not a plausible mistake. I'm shocked and a bit dubious Voldemort is buying it, but he does think everyone is a complete idiot, so... If Dumbledore didn't want the cloak to be used against the mirror it would be stashed someplace very obscure. Or if he was feeling smartass, in the mirror itself. Handing it over to Harry was a deliberate move to put it into play.
I do assume that Dumbles operates on extensive access to prophecy as well as his own plotting, so it's possible that he gave Harry the cloak because he know this is required even if he doesn't know why. One possibility I've been kicking around is that Harry will destroy this world with Quirrell in it (and the stars themselves) to take out all of his horcruxes, but will transport himself and much of the rest of the world into a mirror realm first. The mirror and it's contents will survive, and Quirrell will be left out of the mirror world escape because the cloak is covering him. I can't really make the details work in my head, but it's a scenario where the cloak becomes a liability to Quirrell.

And further, since I do not want you throwing shoes -" Professor Quirrell made another gesture, and just within a globe intersecting the Greater Circle of Concealment, a slight shimmer appeared in the air. "Thiss barrier will explode if touched, by you or other material thing. The resonance might lash at me afterward, but you would also be dead.

So I guess Q disabled the Greater Circle of Concealment and the Globe before taking the Cloak.

I suppose it's all moving very fast, but shouldn't Harry have triggered the barrier to explode once he hear... (read more)

Tom Riddle can't kill himself.
Harry can't kill himself?
And two weeks later, Quirrellmort is back at the same power level thanks to his next-gen Horcruxes and can make a new attempt to get the cloak, while Harry (who is most likely the most notable rival Quirrellmort had) stays dead. Doesn’t sound too strong to me. (Unless you value “Quirrellmort doesn’t get the cloak” about as high as “Quirrellmort doesn’t reach world domination”, which I don’t.)
No, Harry would have died from the explosion (or would he? What happens if you suffer a fatal injury while wearing the cloak that hides you from Death?). Quirrell would then struggle with the magic resonance, either fighting it again or throwing his wand away and turning into his animagus form. Either way he probably would have been around long enough for the trap to finish springing. I wonder what would have happened if Quirrell had just abandoned his Quirrell body?
My assumption was that Harry dies in the explosion, as promised by Quirrell, and that Quirrell is momentarily staggered by the resonance. I assume that Quirrell can't get out of the trap by abandoning his body, because otherwise he could just kill his current host to get out, and D would have anticipated at least that, if not Quirrell's ability to detach voluntarily. But I liked the point about abandoning his body. No body => no reflection, and hence can escape. I'm not sure the words Dumbledore used precisely details the actual constraints, but would expect him to anticipate Quirrell's self termination as a ploy he had to contend with.
It’s impossible to be certain, since we don’t know the detailed mechanisms of two pieces of magic that are involved (each of which is highly non-trivial on its own). My guess was that Voldemort would still be able to leave his body as long as the Process of the Timeless has not quite snapped into place (which did not happened until a few moments after Harry lost the cloak.) Leaving his current body voluntarily might take some time, if the descriptions of the Sphere-of-Stars-spell is any indication, so he might not be able to finish that process in time. (Killing his body, on the other hand, would presumably expel his spirit instantly, so he could escape in that manner.) (… all of which is, of course, just a fancy way of shrugging my shoulders and saying “I dunno” ;) )
Actually, this might be one of the only plays Harry could have made which wouldn't have that result, because it seems the purpose of the trap is to lock away Voldemort's shade where it can't access other victims even by leaving his body. If Voldemort died while talking to Dumbledore, his shade would probably still be stuck inside the mirror world. Although speculatively, this might not work because his shade has no reflection, but if that were the case then Voldemort would have an out even given the powers Dumbledore already knew him to have.

I'm finding it quite hard to keep track of who is in the mirror and who is not. Can someone break it down for me?

My understanding:

Start: Quirrellmort is trapped in the reflected portion of Hogwarts; Harry is under the cloak and thus not reflected, but still trapped in Quirrelmort's ring; Dumbledore is on the other side of the mirror, unrestrained AFAIK.

Dumbledore starts the time-freeze on the Hogwarts side; Quirrellmort reveals Harry, takes the cloak and puts it on himself so he then doesn't have a reflection, and steps out of the reflected portion of Hogwarts.

Dumbledore reverses the time-freeze to act on his side to protect Harry. Dumbledore then disappears from the mirror.

End: Quirrellmort is free to roam about the physical world and has the cloak; Harry is still presumably trapped in the reflected portion of Hogwarts, but he is safe from the time-freeze; Dumbledore is frozen somewhere, but the Elder Wand and the Line of Merlin Unbroken have been left unfrozen as he cast them aside right before he disappeared; they are possibly now in the physical world with Harry and Quirrellmort.

[edited iteratively]

Are we sure that that is a binary answer?

like a dumb animal that cannot understand it is being sent away

Is it just me or is that kind of a weird comparison for a good guy to make... when I think of an animal that is being sent away and, not understanding, keeps wanting to return, I see Albus feeling compassion for the animal, rather than seeing it as something to which to liken an enemy/someone whose intelligence he wants to insult.

Made me wonder if it's a real Dumbledore in there or just a conjured one that Quirrel wanted to see.

A satisfying victory against an opponent just one move behind... Sure seems like Q's desire. Only thing is this doesn't explain why Harry can see it. I'd say it has to do with the Riddles being the same person, but that would mean a mere confundus broke that link? Is it possible Voldemort was able to get the true Quirrell to confund himself? This seems improbable. More likely what we saw was special programming of some sort, keyed to a trait common to the Riddles, and not just a normal desire show--though not necessarily what it appeared to be.
Well, keep in mind that Harry did just see Voldemort's reflection with Dumbledore's family before the Confoundment wore off. I don't recall the mirror doing that in the original canon, but it might just have been changed to make the scenes flow better rather than due to a specific mechanical change in how the mirror is supposed to work.
I thought Harry couldn't see that.
Dumbledore is human (or, at least, wizard). He hates Voldemort, who has killed thousands. He has motive to talk to him to keep him there long enough for the Fixed Instant to trap him. The temptation to spend a little of that time insulting Voldemort is too much for even his self control to resist. Voldemort, by contrast, is just playing with him, letting him waste time till he won't be able to cancel the Fixed Instant, such that when Voldemort grabs the True Cloak of Invisibility Dumbledore will have no choice but to choose who dies forever, the "good Voldemort" or himself. Its very similar to how he toys with Rita Skeeter before murdering her.
I know all that. My point is not that it's out of character for Dumbledore to insult Voldemort. It's the choice of the insult.
Its really hard to make "you return when you are killed", which is really quite the complement, into an insult. The dog metaphor was the best he could do.

Dumbledore, who feared not death, shall never die. Guh.

Meh. The big Dath Bey Yewoonen prophecy may not apply to this one, but Harry will certainly consider this to be "death" for his purposes - and Harry does not intend to leave anyone dead. And what magic can do, an immortal rational wizard can undo...

It seems like Mirror-Dumbledore acted in accordance with exactly what Voldemort wanted to see. In fact, Mirror-Dumbledore didn't even reveal any information that Voldemort didn't already know or suspect.

Odds of Dumbledore actually being dead?

He's not dead; he's just out of time. It seems likely that Harry can restore him, if he manages to make it out of this alive and with his values intact.
The Mirror in canon isn't limited to the viewer's knowledge (cf. the appearances of Harry's extended family); it's unlikely that the HPMOR version has been given that limitation, so fulfilling that limitation is not a strong indicator. Moreover, Quirrellmort's CEV probably is not to defeat Dumbledore, so the Mirror should not show it. I think odds are high that this was the real Dumbledore, and that he has been, not killed, but cast out of the time stream. Removed from game, if you will.
No? Should we assume he has never seen pictures of his family, after being raised by his mother's sister? Maybe. That your entire CEV could be shown in a mirror seemed rather unlikely, but since he is already immortal, defeating Dumbledore has got to be pretty close to the top of the list for Quirrell. I was actually really interested in seeing just what EY would show as Q's CEV.
I recall him not having seen the people before, and inferring that they were his family. However, whether or not they're actually what his family looked like, or just what he expected them to look like, is not certain (but the former is more likely).
Additionally, recall that this is the canon Harry we're taking about. His stepmother hated and feared Lily and everything about her, and wanted her life not to be tainted by association with her, so it's unlikely that she'd keep a photo album with Lily in it just lying around. Also, given Harry's relationship with his wicked step-parents, they'd hardly dig out the photo album for him if it existed.
Which is exactly how the mirror was always advertised to work?

Harry couldn't see Confundus!Quirrell's CEV in the mirror (the conversation with Dumbledore's family.)

What the man might be seeing there, Harry could not tell; to Harry it seemed that the flat, perfect surface still reflected the room behind it, like a portal to another place.

So I take from that the Dumbledore in the mirror was real, and not a victory fantasy of Quirrell's, since Harry could also see it.

Also, Dumbledore mentioned how he laughed when he found out that Harry was a good version of Riddle, which many readers have taken to refer to this scene in Chapter 17:

Dumbledore started laughing. Laughing a lot harder than Harry would expect, almost howling. It seemed positively undignified. An ancient and powerful wizard ought to chuckle in deep booming tones, not laugh so hard he was gasping for breath. Harry had once literally fallen out of his chair while watching the Marx Brothers movie Duck Soup, and that was how hard Dumbledore was laughing now.

"It's not that funny," Harry said after a while. He was starting to worry about Dumbledore's sanity again.

Dumbledore got himself under control again with a visible effort. "Ah, Harry, one symptom of the disease called wisdom is that you begin laughing at things that no one else thinks is funny, because when you're wise, Harry, you start getting the jokes!" The old wizard wiped tears away from his eyes. "Ah, me. Ah, me. Oft evil will shall evil mar indeed, in very deed."

This was a scene that Quirrell was most definitely not present for, and thus the fact that Mirror!Dumbledore knows about it further suggests that Mirror!Dumbledore was not simply some CEV-illusion of Quirrell's.

"But let us pointlessly delay to talk of other matters first. How did you come to be waiting inside the Mirror? I thought you would be elsewhere."

"I was there," Albus Dumbledore said, "and also inside this mirror, unfortunately for you."

So Dumbledore most likely either made a mirror-copy of himself or used a time-turner.

In the former case his sacrifice would make more sense, as there would still be another Dumbledore out there.

In the latter case he must have valued Harry instrumentally more than himself, as he said befo... (read more)

Remember that Dumbledore is truly willing to sacrifice himself, and he has access to a number of prophecies. He likely knows that this is the right call, both by his altruistic morality and whether or not it will lead to Voldemort's defeat. (He also probably correctly thinks it is more likely that Harry can rescue him from being frozen than he could rescue Harry.)

Remember that Dumbledore is truly willing to sacrifice himself, and he has access to a number of prophecies.

In particular he knows that either Harry or Voldie must win - Dumbledore cannot destroy BOTH. He KNOWS that it can't go down that way.

As long as Quirrellmort doesn't kill Harry as soon as he gets the stone, which seems like a rather salient possibility. Assuming Dumbledore was acting rationally, we can take this as evidence that Dumbledore knew there was a reason why Quirrellmort would want to keep Harry alive, though it's also likely that Dumbledore was just being impulsively selfless in sacrificing himself.

... Huh.

... Is it just me, or is Harry Potter now in the same room as the Elder Wand and the Philosopher's Stone?

... Well, there's a great big Dark Lord in the way, but.

0Michael Wiebe9y
Does Quirrell have the Resurrection Stone? If so, that's 3/3 Deathly Hallows (invisibility cloak and elder wand).
He had it when he learnt what it was, and he would hardly have let himself lose it afterwards.
My reading was that he threw the objects aside, not through the mirror, so they got sealed together with Dumbledore's pocket mirrorverse (a mirrorverse... he must have been hiding a goatee under that fake beard!)

My reading was that he threw the objects aside

Outside of the mirror's reflection, and into the real world. It probably be devastating to the government / long-standing enchantments on Britain if the Line of Merlin Unbroken were broken, and Harry will miss out on set bonuses if he doesn't get the Elder Wand.

I've reconsidered. This remains the interpretation I consider most likely, but the secondary interpretation is that Dumbledore is storing them in the mirror so that Harry can retrieve them.
I assumed that by throwing them away, they were not taken into the Mirror with Dumbledore when he sent himself into the frozen instant, instead of Harry.
Also Dumbledore's scepter-thing (Line of Merlin Unbroken?), if that has any power.

Dumbledore behaves very strangely in this chapter.

He likens Riddle's spirit to a dumb animal, which does not know that it was sent away. That's a sad, sympathetic image.

He laughs at the skewed symmetry between Good Riddle and Evil Riddle, saying that this is what Riddle could have been if he'd been raised by parents who loved him. If you feel any sympathy for Riddle at all then that's not funny, it's tragic: Riddle's crimes and suffering, his whole live, arose from sheer bad luck on his part. To think it a joke, or to expect Riddle to share it, is somet... (read more)

We've seen that Dumbledore has worked very hard all his life to be wise and compassionate and generally fit the archetype of the true hero. I can't help wondering if Voldemort is the one person he allows himself to truly hate, which is why that hatred is unusually intense and fully brings out Dumbledore's otherwise unseen dark side (or as fully as Dumbledore has one, which is still less intense than most people's when faced with someone who's hurt them that much).
I was wondering how EY would play this. For my part, the "pity me, I couldn't help being me" argument is not very compelling. He is what he is. I had assumed that he was busy faking divinations strategically.

Grab the Elder Wand, Harry!


Is Dumbledore also passing the Line of Merlin to Harry? We don't know what's required to pass the Line between holders.


I note that my outside view observation here was right about the 'probability of success' story, in that it would look like Dumbledore is about to save the day and then make things worse, and wrong about the mechanism.

Assuming what happened to Dubledore was real, he made two very stupid mistakes:

  • he didn't count with the possibility of Voldemort having Harry and the Invisibility Cloak with him

  • he gloated like a cartoon villain about how he'll trap Voldemort. Why? He needed time for the time stopping spell to charge, but why did he reveal what kind of spell it was? Also, Voldemort couldn't have simply run away, he tried but failed. Voldemort did have extended knowledge but there was a chance he was not familiar with the spell Dumbledore was casting. So why take the unnecessary risk to warn him?

I love the image of Dumbledore gloating like a cartoon villain. You're right, of course.

The mirror and efficient simulation

Until the mirror appeared, the HPMOR universe could be simulated efficiently, at least as far as we knew. Time travel is limited to a six-hour cache; you can't transfigure arbitrary things, and Harry's attempts to use time travel to solve computational problems failed. This is likely to be deliberate.

So, how does the mirror exist? According to the inscription on the back, the mirror shows the actor's coherent extrapolated volition (CEV). Is this possible to compute efficiently from an actor's source code? I would guess no... (read more)

Self-consitant time travel seems far harder to simulate than CEV.

Scientists of LessWrong, I have Important Questions for you:

What would happen if Harry donned his invisibility cloak and stepped through the mirror?


  • Assuming CPT symmetry, Would the mirror universe be composed entirely of antimatter? Would the anti-nitrogen molecule annihilate with dust particles on Harry's cloak, emitting vast quantities of gamma rays?
  • If so, would the cloak shield Harry from the gamma rays, or would they be "duplicated" the way visible light photons are? If the gamma rays are duplicated, the temperature of Harry wo
... (read more)

would he be able to metabolize proteins? Carbohydrates? Fats? Nucleic acids? Are there any essential amino acids Harry will be missing?

Only metabolizing fats, glycerol, and the simplest amino acid, glycine. Everything else is chiral, including a hell of a lot of vitamins. Mirror sugars still taste sweet though. I have no idea if mirroring a protease changes its ability to digest protein (for all the good liberating mirror amino acids would do) but know nucleases and starch-degrading enzymes would be useless.

Though for energy alone he could also consume alcohol, acetic acid (think vinegar), and some ketones and aldehydes that are pretty nasty in large quantities but you can get some cellular energy from like acetone. Unable to get any of the essential amino acids histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, valine, or lysine.

Regular bacterial cell walls contain a few mirror amino acids produced enzymatically during wall production - mirrored glutamate, glutamine, and alanine. Not gonna be much. You could probably make about half the nonessential amino acids internally by drinking VERY VERY dilute ammonia (or thicker glycine) and eating f... (read more)

Levulose (mirror dextrose, as the names indicate) is a good non-caloric sweetener for this reason; it behaves for the chemical purposes of cooking exactly like dextrose. You can't get it commercially, because it costs too much to manufacture (or so Wikipedia tells me), but it would be perfect if only it were cheap.
If the mirror universe was antimatter, Harry would be annihilated instantly because his feet are touching the floor, even if the Cloak could shield everything else.
Couldn't he crawl?
He has to breathe.


That happened.

I'm rather hoping (too tired to put numbers on it, sorry) that Harry can summon a phoenix straight from the mirror-he never tested the claim that a phoenix only shows up once, after all...and now he's got the source of phoenixes right next to him. That's a gun that's just itching to fire.

"All your hallows combine" is fairly obvious, though the location of the stone is not entirely clear.

Regarding Chekov's Elder Wand:

We have been repeatedly told about Dumbledore's "long dark wand" (Ch. 56,57,77,81,94,110), a "wand of dread power" (Ch. 77), which we know from Canon is the "terrible device" Grindelwald possessed (Ch. 77). In Azkaban (Ch. 57), Dumbledore confirmed this:

"Nonsense, my dear," the old wizard said cheerfully as he strode off yet again, waving as though in admonition his fifteen-inch wand of unidentifiable dark-grey wood, "I'm invincible."

Query: A key point in canon is the mast... (read more)

So what was the source of the resonance between Harry and Q?

Did I miss it?

I always assumed it was ritual magic, as arranged by Dumbledore and Lily, and performed by Lily.


“James and Lily would have gone willingly to the death, if they had known.”

Which seems to imply that they hadn't known.

But it seems just way too convenient for Lily to just happen to fulfill the terms of a ritual, and it's unclear that V would have violated the terms by imposing his horcrux on Harry anyway.

At one time, I wondered if Harry was a time turned version of V, and that... (read more)

The source of the Harry-Voldemort resonance is that Harry was made into a Horcrux of Voldemort. Chapter 108:
I saw that, but didn't see an answer in it. "When I had shaped the baby's spirit to be like my own..." ...? And? Quirrell describes the series of events, but provides no causal model that I see. So you think that if Quirrell had tried to make a Quirrell imprint horcrux of any other person the same thing would have happened? The resonance relation is created as a side effect of casting that spell?
Presumably that they're equal but opposite.
They're not numbers, they're people. They're neither "equal" nor "opposite". What they are is very similar, with some differences. I guess if Magic Land recognizes them as two versions of the "same" person, as in labeling them both as Tom Riddle, you can play that game. I've seen some comments here or on reddit to that effect, but they seemed snide comments about confusing the Atlantean operating system. The snideness would be appropriate, IMO.

Blue-sky speculation: Harry's father's rock is the real Philosopher's Stone, and Dumbledore only pretended to believe that Voldemort could locate the Philosopher's Stone wherever it was. Confidence: far too low to assign a number, given that we've already seen what looks to be the real Stone, in the Mirror where it was always thought to be.

I think we finally have a good explanation for Harry's Father's rock: Dumbledore's mysterious divination power. He somehow knows the rock will be important, but perhaps not exactly how or why.
The rock was important to kill the troll. That's the sum of its importance.
But how did Dumbledore know that it would be a good idea to carry a rock? It's not a good weapon against humans; it's not a good weapon against things you can stun; it's not a standard precaution. (Also, Harry's still carrying it)
I've assumed this for a long while. "Dumbledore does things for no real reason but accidentally gets important long-range decisions right all the time" never made any sense. There were some other possible but unlikely explanations for the rock, but you add in his meddling in Lily's life and other times when he seems to be walking down a known, pre-determined path and it's just too much. Dumbles is wading knee-deep through prophecies, always has been.
There's also the alarm clock he gave Professor Trelawney--as I understand it, readers have assumed that it's spelled for surveillance. So there is at least one known mechanism by which Dumbledore would have extraordinary access to prophecy.
Could be prophecies, could be "patterns" > You start to see the pattern, hear the rhythm of the world. You begin to harbour suspicions before the moment of revelation. > And being mysterious at people, knowing things I have no way of knowing, making cryptic statements which can only be understood in hindsight, and all the other small ways in which powerful wizards amuse themselves after they have left the part of the pattern that allows them to be heroes. Could be anthropic bias, could be that universes with magic have more measure if they make good stories, could be lots of stuff.
I don't discount the patterns, but that isn't specific enough to be the whole story. How could Dumbledore know that it would be important for Petunia to be pretty? It could just as easily have been that prettiness would land her a life of trophy wife with an abusive rich guy. Dumble would have to already know that she would take care of a significant person, and that the fork of her life where she's pretty produces better results from that child. Patterns aren't enough for that, you know? ETA: It doesn't have to be prophecy, exactly, but the guy has future knowledge from much more than 6 hours ahead, and prophecy is all we know about that can do that. Edited again to change "give birth to" into "take care of".
It seems like the centaur proclaimed that giving Petunia the beauty portion will end the world.
Agreed, but how does that alone make Dumbledore decide it's a good idea? Plus, Dumbledore doesn't want to take Harry to the hall to hear his own prophecy, and this is most likely because he knows there are other prophecies that Harry would hear. And he never actually confirms that he got his information from James and Lily, Harry comes up with this and Dumbledore let's him believe it. I think Dumbledore had other access.
Random wild guess: Dumbledore has the Lost Diadem of Rowena Ravenclaw. According to canon, it enhances the wearer's wisdom, and is concealed in Hogwarts (specifically in the Room of Requirement, which either does not exist in this AU or perhaps was kept very secret by Dumledore after he found it). We already know that Gryffindor's Sword exists in HPMOR and has special powers, and Slytherin's Locket has been alluded to, so it's plausible that Ravenclaw's Diadem is around as well.