As Harry considered the horrible situation set before him, something very unusual indeed happened. In an instant, his conscious thoughts were obliterated by the sudden influx of thousands upon thousands of answers to the very immediate problems before him. Some answers were nonsense, some were lunacy, but each one was some crystalline piece of a many-dimensional jigsaw puzzle, provided as if by some great over-mind. A gibbering fiend from another dimension that spewed cacophony from a thousand madness-blackened mouths.

It was in that instant that Harry James Potter-Evans-Verres awakened as a Super-Rationalist.

Voldemort felt a fraction of this through the link, and wasted no time with pointless questions. He had already pre-committed to this. The order went out to the assembled Death Eaters.

“Stun him.”

Nothing happened. Harry Potter saw that among the assembled semi-circle of Death Eaters there was an uncomfortable shuffling of feet, milling about, and enough unsure sidelong glances to fill a teenage vampire romance novel. Teenage vampire romance novel? What are you, strange little idea, and where did you come from?

Harry made a quick mental note of this, already knowing several Ravenclaw girls who could churn out a particularly turgid story in a month, in case he ever needed a few billion dollars in a hurry. Returning to the moment, he saw that Voldemort’s face was now completely blank. His minions had just collectively rolled a statistically improbable series of 1’s. He was now debating, on a scale reaching from ‘One’ to ‘Thirty-Six’, just how many fatalities their incompetence should warrant. Setting that aside for just one moment, his focus returned to The-Boy-Who-Lived.

“Very impresssive. Explain thiss, and you have guaranteed the ssafety of one other.”

Harry laughed. The laugh was carefully tailored from cloth woven of a hundred different villains, from the cold chuckle of the cool mastermind ascendant all the way to the mad ultra-guffaws of the madman with his doomsday weapon. It was an artful creation, totally devoid of genuine humor. Despite himself, Voldemort was impressed.

“Oh, but don’t you ssee it, professsor?” Harry’s hissing voice put real venom into the last word, “It’s very ssimple, after all.”

“Your flippant responses do you no benefit. Obvioussly I do not know, or I would not be giving you the chance to ssave those preciouss to you.” Voldemort made a slight, almost invisible motion with the gun, “There iss no need to restate threat to your friendss. Sspeak now or die.”

Harry shook his head. ”Alright, will give you thiss one for free. The answer is ssimple. The Bystander Effect."

"Bystander Effect. Explain."

When Harry spoke again, it was no longer in Parseltongue. The Death Eaters looked at each other nervously, remembering their orders, but none moved. "You brought too many minions. Each one expects the others to do something about this problem, and so is too uncomfortable to be the first to act."

Voldemort's voice now was flat, something of Professor Quirrell emerging to the surface. "That is the most ridiculous thing I have ever heard."

"It iss true," Harry hissed, before continuing, "but it is also only a specific expression of a more general rule. Why have you not yet killed me?"

Looking momentarily perplexed, Voldemort's eyes flicked down to the gun in his hand, before returning to his former apprentice. "It would be proper procedure to kill you, but I find that I cannot bring myself to do it. I am feeling an emotion I am unfamiliar with. What have you done?"

Harry smirked, and began pacing back and forth, naked, in front of the assembled Death Eaters, the Dark Lord's gun tracking him as he moved. "I'm afraid studies show there is a great deal of impetus in a group's decision, you know. People can be convinced to make quite stupid decisions if doing otherwise would go against the consensus. The effect is far stronger if the subject is part of the same sub-group as the other participants. You are just one of thirty-seven Death Eaters here." He stopped, looking directly at Voldemort once more, his face unreadable. "I'm afraid that, quite simply, it would be far too awkward for you to shoot me now."

Voldemort seemed stunned by this revelation. Harry looked at the thirty-six remaining Death Eaters. An even number.

"I can make this easier for you, if you'd like. Robber's Cave. Call it another freebie."

With one hand, Harry Potter pointed to a quarter-circle of the assembled Death Eaters before calling out, "You eighteen, from you- to you. You're Group A." He pointed to the others. "You rest? You're Group B." With casual ease, The-Boy-Who-Lived divided the thirty-six murderers into two groups of eighteen-

-and this proved to be quite sufficient.

"Hey! Why do they get to be Group A? We should be Group A!"

"Group B? More like, 'Group Bollocks', am I right?"

The ensuing scuffle was brief, but spectacular. When it was over, all thirty-six were killed or incapacitated. Harry looked them over and caught a glimpse of Lucius' pale-blonde hair draped over his still-breathing form, a house elf having broken his fall. Good. It would have been ludicrously awkward to explain this one to Draco.

Harry turned to Voldemort, and his voice was dripping with false cheer. "There, you see? No more group pressure. You should be able to do something about me now, I'd say."

Voldemort was now beyond fury. One thing was certain, though: The-Boy-Who-Lived had to die, and die immediately.

He pulled the trigger. An explosive sound rang out through the night, as time stood still. The bullet seemed to fly in slow-motion towards its target. After a brief moment of consideration regarding muzzle velocities and relative time-scales, he realized that it was flying in slow-motion.

Voldemort glared at the bullet, but it didn't help. The bullet was moving at a very leisurely pace now, and didn't seem inclined to change. Harry Potter stayed where he was.

"Ah, see, I know what your problem is," Harry sneered, "It's easy, when considering a course of action, to fail to be properly pessimistic."

Voldemort, formerly Quirrell, gaped at him. "YOU'RE TELLING ME TO- BUT HOW-" he stopped himself there, sending one panicked glance down to the bullet, which must have traveled a whole five feet by now, "What have you done?"

"Have done nothing." hissed Harry, wearing a wicked grin, before continuing in normal speech, "I am merely pointing out how easy it is to underestimate the time required for certain actions. It looks like you have fallen victim to the Planning Fallacy. I bet you were pretty certain that bullet would reach me in less than a tenth of a second, yes? But that's only if everything goes as well as expected."

As Voldemort sputtered helplessly, Harry stepped past the bullet, flicked it into a lengthwise spin, and continued walking towards his fallen gear. Picking up the True Cloak of Invisibility, he shook it briefly to remove the dust and dirt, then turned to consider Voldemort again.

"That's not all, I'm afraid. I've saved the best for last. Watch this." Placing the cloak over his head, Harry Potter disappeared. It was his disembodied voice that spoke next. "Confirmation Bias. You want to believe that I'm dead, yes? Well, can you see me?"

Voldemort's voice cracked, shaking in a way it hadn't since he had been a child. "No... No, Potter, I can't see you."

"Well then. We automatically seek evidence that confirms our wishes, and discard evidence that disproves it. You can't see me, and there's no way I could have escaped your trap. There are many dead Death Eaters, so there must have been a battle." There was a perfect, crystalline moment. A feeling of titanic intelligences about to shift, ever so slightly. It felt as though, if he tapped it, it would ring out like a bell. So he did. He snapped his fingers.

"Congratulations, Lord Voldemort. You've won!"

The world changed. Giddy elation filled Voldemort's face. He looked around at the surrounding chaos and saw that it was worthwhile. Anything could be sacrificed if it safeguarded him from the end of the world. Potter was dead, and although it was a pity that the interesting child would no longer be around, there would be other opportunities. He barely even heard the words that came to him next, as a hiss that he knew, somehow, to be true.

"I know of the existence of an argument that would persssuade you to work towards different goalss."

Voldemort considered this for a moment, and Changed His Mind. For, you see, Voldemort knew that if such an argument existed then he should already match his actions and beliefs to work towards its result. It all seemed so clear now. Whatever that argument would have been, he thought, it must be quite persuasive.

"Come, Voldemort. We have much to do, you and I."

TL;DR - What an interesting couple of weeks it has been, hm? Lots of chapters, followed by a rousing round of Reddit Plays Harry Potter.

EDIT: Thank you for expressing enjoyment, everyone! Here's to a few good feelings during this crazy trip through the last chapters.

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This chapter has 23 pages, but reddit allows only 20. Read the full version on https://www.hpmorcomic.com/3/1

First: CHAPTER 1 | Previous: CHAPTER 2 | Next: CHAPTER 4

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Yes, this looks totally predictable in retrospect, but I somehow failed to visualize that I would get hundreds and hundreds of thousands of words of reviews, with occasional very rarely interspersed nuggets of idea that nobody else had previously submitted.

I hope I can call upon the powers of this subreddit to do even more of my work for me, and break up the task of reading reviews into, say, 20,000 words/person, with a central list of all the nonredundant ideas that have been submitted so far. Ideally, to a level of detail that distinguishes between "Try to command Voldemort's broomstick-rods" and "Try to command Quirrell's broomstick-bones", but not "Ride Quirrell off to the west" vs. "Ride Quirrell off to the east". Ideally, with the submitter credited, but not all submitters credited because that would be bloody impossible. You are welcome to harvest from /r/hpmor as well, though in this case you should probably mark that the solution has not yet been submitted as a review. Think of it as the Non-Redundant Collected Solutions from Everywhere thread.

Eventually, I may produce Omake Files #5: Collective Intelligence wherein I try to use as many of the most interesting ideas as possible. So if something makes you laugh and is new relative to the previous corpus, feel free to include it even if ridiculous, because Omake Files #5 is totally going to include Harry doing the broomstick thing.

So as not to make the problem worse or procedurally generate reviews, I declare that when /r/hpmor submits complete solutions, you are welcome to use OR and AND connectors to avoid a combinatorial explosion.

ADDED: I did try to read reviews, and read the subreddit, but after spending at least 5 hours doing that on a plane yesterday, I had to admit defeat - and if there's no way I could see a brilliant new solution submitted later, if nobody even reads it and even brilliantly original ideas don't get immortalized as part of the Collective Intelligence's solution and/or Omake Files #5, this seems delinquent to the people doing work to submit them. Sufficiently unfair that I would try to read them all myself - but I don't think I can do that in the time I have available.

I don't know the name of this cognitive bias, but in our days it is common on the internet to express hate (assuming the target is clueless of it), and skip gratitude (assuming the target already knows about it). Don't hesitate to account for it.

Thank you for writing this fic, Eliezer. It was both fun, educational, and helped steer my life closer to what i enjoy and find useful. I don't think i would have heard of "rationality" or took it seriously without happening across HPMOR a few years ago, and would still be wandering with a half-baked sense of something being wrong with me and people.

EDIT: Since apparently karma is worth actual money, I want to emphasise that you don't need to upvote this, just comment your support.

Just rereading the last few chapters, now, nearly 3 years since the end, I really still feel like I'd like to read EY's epilogue, which he hinted could be released 1 year later.

I know he was interested in seeing what would be written in the following months, and that he's awarded Significant Digits with honorary sequel status, but I just could not get on that fic, and I want to read more from Eliezer.

If you agree, I ask you upvote and comment your support. Or comment your other feelings, elsewhise, of course.

Voldemort is in a graveyard outside Hogwarts. He has no cover or armor. He is facing his greatest enemy, who was prophesied to destroy him and everything else. Harry has probably transfigured a line though the ground to a piece of antimatter in every Death Eater's brain, and another one though the air wrapping them in nanofibres. He is currently listing about 50 things the Dark Lord knows not, 20 reasons why killing him would destroy the world, and 10 other reasons why he should be let free. His left leg is a gun and a flashbang, his right leg is an antimatter dead mans switch. Voldemort has no help except a small group of traitorous incompetents. Harry has a troll princess servant and probably 6 timeturned invisible selves, with 49 Cedrics Diggory who know Patronus 2.1 and are covered in diamond Armour. Harry has no conceptual limitations and is rapidly transfiguring into god. And this is his CEV.

Can Voldemort escape alive?

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Edit: it was suggested that this should be a thread for Omake Solutions. If you care to, please contribute!

Disclaimer: These are obviously non-canon, and obviously parody. That said, have fun!

Chapter 113.5: Omake Solutions

In the pale moonlight, three dozen wands were aimed at a small, shivering, eleven-year old- boy.

Harry gulped, and began talking to Voldemort in Parseltongue.

“Iss one secret that I could tell you, terrible, terrible ssecret. But musst be allowed to ssay two wordss in man-sspeak. Ssnake wordss cannot explain.”

Voldemort appeared to think for a moment.

He gestured lazily to his death eaters.

“The boy, between hissing, will momentarily say two words that you may understand. When he says these words, do not slay him. After these two words, you are again instructed to kill him for all speech other than hissing.”

Voldemort turned back to Harry.

“There iss deep, terrible ssecret, that once I tell you, you can never be ssafe from again.”

Voldemort hissed something like a laugh. “Doess not sscare me, child. Go on.”

Harry took a deep breath. “Thiss thing iss called-“

He broke into English. “Roko’s basil-“

BANG.

The eleven-year old boy fell lifeless to the ground, blood oozing from the hole where his face had been.

The death eaters, even Voldemort, turned to stare in the direction of the gunshot.

A man stood at the edge of the clearing, holding the smoking culprit.

Before Voldemort could speak, the man yelled to no one in particular- “YOU DO NOT THINK IN SUFFICIENT DETAIL ABOUT SUPERINTELLIGENCES CONSIDERING WHETHER OR NOT TO BLACKMAIL YOU!”

2.

Sixty seconds passed slowly.

But Harry couldn’t tell Voldemort anything more to use. He couldn’t.

Voldemort laughed his high, cold laugh as he floated in the air.

“Time is up for the boy. First we shall remove his limbs and cauterize them.”

He held his wand forth-

“Tonare!”

What.

“Ravum Calvaria!”

What.

“Lucis gladius!”

And in front of Voldemort’s wand appared a shining red streak, three feet long. He stared down at the eleven-year-old boy.

“It’s over, Harry! I have the high ground!”

3.

Sixty seconds passed slowly.

But Harry couldn’t think of a way out.

Voldemort laughed his high, cold laugh as he floated in the air.

“Time up for the boy, first we shall- what is that sound?”

A thrumming filled the surrounding woods.

Hoofbeats.

Thousands.

And then they were upon them.

The centaurs swept through the blaze of green light blasting in all directions from the death eaters, their sheer numbers overpowering the cloaked wizards. At least a hundred centaurs were throwing spears at Voldemort, who had encased himself in a shimmering red sphere.

A centaur swept Harry off his feet, and he found himself thundering through the forest with the most massive herd of centaurs he’d ever seen. He could see that the centaur next to him was carrying Hermione on its back.

In the distance, he heard Voldemort screaming in anger, but the screams quickly grew faint.

The centaur spoke.

“We were wrong about our divinations, Harry. We were deceived. We are sorry it took us this long to come to your aid-“

Harry gasped, elated. “I didn’t think there was any cavalry that would come!”

The centaur looked down at Harry with a scowl.

“I’ll forgive you once for your racism, as you are only a foal. Technically, we are infantry.”

4.

As the time counted down, Harry reached for anything, anything at all… and then he found the solution.

He didn’t want to kill them, but… if he had too, he knew how.

He concentrated on a microscopic collection of atoms at the very tip of his wand… maybe, just maybe…

The swirling atoms coalesced into a tiny, tiny machine.

Harry focused on what he’d tell it to do.

Make more of yourself, he said.

Then release chlorine gas into the mouths of Lord Voldemort and death eaters.

He focused all his concentration into making the nanobot real… just a moment more…

And make sure you stop replicating once-

“SPEAK!”

Voldemort screamed at Harry, startling him out of his concentration. The transfiguration stabilized.

Harry gaped at Voldemort.

“No!” He hissed. “You don’t know what you’ve done!”

Harry hung his head. It was over.

He knew that already, invisible to the eye, his accidental creation was growing. Without that final directive, they’d never stop. The whole world would become gray goo.

5.

Harry shook in fear and rage. This couldn’t be the end.

He turned to Voldemort to begin to speak, but before he could…

BANG.

Mr. White had been creeping towards Harry, but now he had leapt to the side, Voldemort’s smoking gun still trained on him.

“Don’t take another step, Mr. White,” Voldemort said.

Mr. White yelled back to him, “Fuck you, maniac! It’s your fuckin’ fault we’re in so much trouble.”

Voldemort turned back to Harry slowly. “What’s this guy’s problem?”

Mr. White kept yelling.

“What’s my problem? Yeah, I gotta problem. I gotta big fuckin’ problem with any trigger-happy madman who almost gets me shot!”

Voldemort looked bewildered. “What the fuck are you talking about?”

Harry looked back and forth between the both of them.

“Guys, I’m only eleven, I’m not supposed to have even seen this movie…”

6.

Harry could do nothing. He thought of nothing. Sixty seconds crept by, but his mind failed him.

“Well, child, your time iss up. Dissappointing even at the end.”

As Voldemort raised his wand, a death eater gasped.

The Dark Lord turned his head to the cloaked figure, annoyed.

“What?”

“My lord, I dare not, I….”

“Tell me!”

“You cannot be immortal, my lord, you must know, I can see it…”

“What are you babbling about?”

The death eater raised a trembling hand to point.

“Look my lord…. a… a gray hair!”

Voldemort’s slitted eyes widened.

He raised a hand to the top of his head, and when it returned, he held between his fingers…

Beneath the moonlight glints a tiny fragment of silver, a fraction of a line...

Voldemort screamed in horrible, high-pitched agony.

His gaze rounded on the death-eater who had spoken up.

“My lord, no, please, I am sorry….”

Voldemort’s other hand still held the gun, now pointed towards the cloaked figure.

BANG.

(black robes, falling) ...blood spills out in litres

Turning his gaze from the death eater bleeding on the ground, Voldemort looked down at the grey hair in between his pale fingers.

and someone screams a word.

“FUCK!”

7.

Harry thought quickly, deciding to explain everything about what was going on between the two of them. He would tell Voldemort exactly what game they were playing.

“Because teacher thinkss I must not esscape, must not be free, iss…. iss… muggle puzzle…. iss thing in box… problem iss to not let it out of box…”

Voldemort’s eyes narrowed. He looked at Harry, confused. He answered without speaking in Parseltongue.

“A… box?”

“Teacher, isss metaphor…”

“What was in the box?”

“Iss not an actual-“

“What’s in the box, what’s in the fucking box?”

Fin.

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I can't promise this will turn into a sufficiently good environment for storytelling or that I'll write in it, but you never know unless you try, and worldbuilding can be fun regardless...

One in X people (X ~ 10,000?) has the ability to summon demons, once per Y days, and bind them to arbitrary commands at will. Demons are malevolent and will interpret any instruction in such ways as to cause the most damage. Evil summoners can sometimes reach an accommodation of sorts by giving the demons orders which benefit themselves and hurt others more, in which case the demon will often go along with it, most of the time.

Most good people with the ability to summon demons were advised never to do so, unless it became necessary to defeat an evil demon-summoner creating horror on a mass scale.

This world's Industrial Revolution began when it was realized that mathematically precise and complete commands to demons apparently could not be misinterpreted. For example (this could perhaps be picked apart): A demon told to accelerate a vehicle along an exactly given vector for a specified time, applying the same added acceleration at any given time to all particles in the vehicle, and causing no other impact on the material universe, will do only that... if the language of the contract can be mathematically specified in an absolutely unambiguous way. (What exactly is the 'vehicle'? Maybe you'd better have the demon apply acceleration to a sphere to which the engine car is attached.)

Demon-summoners promptly began to use their powers in the most economically rewarding way, such as by summoning demons who would just accelerate particular train engine cars; and this occurred on a mass scale throughout society.

This is a point where I wouldn't mind help worldbuilding: given this basic setup, what industrially useful demonic bindings can be precisely specified? Suppose the world is such that electricity doesn't exist, but fire does, and steam. Demon summoners will end up being rare enough, whatever frequency is 'rare enough', that the society doesn't come apart as the result of whatever powers you invent.

Bindings can also tell demons to act based on the result of a calculation, if that calculation is precisely specified. There is no known limit on how much calculation can be done this way. If a demon is told to behave in a way that depends on a calculation that does not halt, it is the same as telling the demon "do what you want", which is a very bad thing to tell a demon (though for poorly understood reasons, demons' most malevolent free actions are not as destructive as the worst human commands). Summoners are well-advised to tell the demon to only compute something for a bounded number of steps, though no known limit exists on how high the bound can be.

From our perspective, they discovered that demons can act like unboundedly large and fast computers.

This kind of demonic calculation has been previously used to investigate interesting math questions and create demons that e.g. loft steerable airplanes. But as the calculations used in spiritual industry grow more complex, people have the bright idea that cognitive calculations can also be specified. They begin to publish specifications for simple cognitive constructs, like gradient-descent sigmoid neural networks. It would be useful (think those spiritualists) if demons could be told to recognize particular faces by recourse to a neural network, without giving any demon underspecified instructions about 'if you recognize person X' that would allow their malevolence room to act.

Shortly thereafter, the world ends.

Our N protagonists find themselves in a Groundhog Day Loop of period ???, trying to prevent the seemingly inevitable end of the world that occurs when some damned idiot summoner, somewhere, instructs a demon to act like the equivalent of AIXI-tl. For reasons that are unclear, even though 'natural' demons don't instantly destroy the world given an instruction like 'do what you want', the cognitively bound equivalent of AIXI-tl can construct self-replicating agentic goo in the environment in order to serve its purposes (in the case of AIXI-tl, maximizing a reward channel).

After some failures trying to prevent the end of the world the normal way, the thought has occurred to our protagonists that the only Power great enough to prevent the end of the world would be a demon bound to implement a 'nice' superpowerful cognitive binding, or at least a cognitive binding that carries out intuitively specified instructions well enough to shut down all attempts at summoning non-value-aligned cognitive demons.

But the mathematical technology that the Looped summoners presently have for specifying cognitive bindings is incredibly primitive - at the level of AIXI-tl. They can't even solve a problem like 'Specify an advanced agent that, otherwise given freedom to act on the material universe however it likes, just wants to flip a certain button and then shut itself off in an orderly and nondestructive fashion, without e.g. constructing any other agents to maximize the probability of it being absolutely shut off forever, etc.'

And doing research on this topic, at least openly, does tend to destroy the world before the non-Looped researchers can get properly started. If you say "Can we have a non-destructive version of AIXI-tl?" then somebody goes off and summons AIXI-tl.

The story opens well into the Loops, as the Loopers try to conquer the world and restrain all other summoners in order to create an environment where they can actually get some collaborative research done before the end of a Loop, and maybe live in a world for longer than ??? days for bloody once. They are, of course, regarded as supervillains by the general public. Being not a little crazy by this point, many of them are happy to play the part so far as that goes - wear black, live in a dark castle, accept the service of the sort of member of the appropriate sex who wants to swear themselves to a supervillain, etcetera.

Demons seem blind to the Loops, so some Loopers may also be using seemingly destructive ordinary demonic contracts to gain an advantage. Opinions differ among the Loopers as to what degree the Loops are real, other people in the Loops are worth optimizing for, etcetera. "If those other people are even real in the same way we are, they're all going to die anyway and go on dying until we end this somehow" is a common but not universal sentiment.

The questions I pose to you:

• What sort of industrially scaled, or personally awesome uses for a mathematically specified, precisely bound demon can you imagine? What was the prior world that existed before the Loops?

• What kind of advantage do our Loopers have from their preliminary research into cognitive demons?

• How are they trying to take over the world in the first written Loop?

• What sort of really awesome character would you like to see in this situation? Feel free to pick references from fiction, e.g. "BBC!Sherlock". My trying to write them played straight will just generate a new Yudkowskian character.

Among other things, the Groundhog Day format hopefully means that I can have characters freely do what a subreddit and/or high bidders suggest, within the limits of my own filtering for intelligent action; and when that all goes pear-shaped, it's back to the next reset.

If anyone can give an unboundedly-computable specification of either a nice Sovereign agent, or less improbably, a trainable good Genie, the characters Win. While I can't make promises in my own person at this point, if that started to be a reasonable prospect, I'd expect I could swing a million-dollar prize to be set up for that perhaps improbable case. It's not like there are better uses for money.

As is my usual practice, the world and characters would be open for anyone else to use and profit on.

ADDED 1: Demons have limits as to how much material force they can exert, within what range. You cannot summon a demon and tell it to hurl the moon into the sun. Pulling a train is about as much as they can do. AIXI-tl kills by creating self-replicating smart goo, not by instantly optimizing the whole universe from within its local radius. Demons cannot be used for long-range communication, except by making flashes of light that are seen elsewhere.

ADDED 2: Demons are cunning but can still often be outwitted by clever humans... unless you've given the demon precise instructions to act on the material world in a way that depends on a calculation, in which case that calculation can be arbitrarily powerful. You can't instruct a demon 'make nanotech' (not that this would ever be a good idea) because the demon isn't smart enough to figure that out on its own without a calculatory binding.

ADDED 4: Reading over comments so far, it looks possible that the original demons (djinni?) are overpowered. One way to address this would be for summoners have a single Djinni Effect centered on themselves. If so, we can have more summoners without breaking the setting. Malevolence of underspecified instructions as before.

ADDED 5: Djinni depart upon the death of the summoner. Short of that, the other rule for canceling them is to tell another Djinn to precisely counteract any force exerted by the first Djinn.

ADDED 6: Rarely, a new person enters the Loops. To give the reader a novice's-eye-view, the story may open from the perspective of a summoner-mathematician entering the Loops for the first time (that is, this is their second life); watching with them as the world is destroyed, their mind is reset, and then they're strangely greeted by the other Loopers as the viewpoint character tries to figure out what the hell happened. Their previous life's memory might be baseline or it might be the previous Loop; I'm leaning toward the latter.

ADDED 7: Some credit for this terminology ("Loops", "Looper", "baseline") is due the Infinite Loops fanverse which was sparked by Innortal.

ADDED 8: The opening situation of the Loop is not always the same. People tend to be the same each time, including their names, but the history of the world or even the previous tech level sometimes changes. The protagonists retain their memory of mathematical bindings and so on, but they can't rely on typical Groundhog Day tactics - situations may not be precisely repeatable. This also permits that if a reader invents obvious new technology that should have been there all along, the world might have it on future Loops.

ADDED 9: The Djinn senses light and sound impinging on its center. You cannot tell it to 'read out a human brain' unless you can tell an advanced cognitive binding how to create nanogoo that does that safely. You could also tell something like AIXI-tl to induce simplest explanations for perceived light and sound, and hope that arrives at a good predictive description of the thingy producing the speech and facial expressions, but it'll take some serious thinking to figure out how to do anything with the data inside the 'simplest explanation' - so far as the AIXI formalism goes, all you get back out is a big opaque Turing machine.

/u/Limro suggested to create a sticky thread with a list of the most popular fics similar to HPMOR.

Original fiction

• Worm
  An introverted teenage girl with an unconventional superpower, Taylor goes out in costume to find escape from a deeply unhappy and frustrated civilian life. Her first attempt at taking down a supervillain sees her mistaken for one, thrusting her into the midst of the local ‘cape’ scene’s politics, unwritten rules, and ambiguous morals. As she risks life and limb, Taylor faces the dilemma of having to do the wrong things for the right reasons.

• Pact and Twig (by Wildbow, the author of Worm)

• Ra
  Magic is real. Discovered in the 1970s, magic is now a bona fide field of engineering. There's magic in heavy industry and magic in your home. It's what's next after electricity.Student mage Laura Ferno has designs on the future: her mother died trying to reach space using magic, and Laura wants to succeed where she failed. But first, she has to work out what went wrong. And who her mother really was.

• Mother of Learning
  Zorian, a mage in training, only wanted to finish his education in peace. Now he struggles to find answers as he finds himself repeatedly reliving the same month. 'Groundhog's day' style setup in a fantasy world.

• Shadows of the Limelight
  This is a world where fame grants powers. Dominic de Luca was a thief and a liar before entering into the apprenticeship of Welexi Whitespear, the greatest hero of modern times. Now he must navigate the world of the Illustrati, the famous and the infamous, as he tries to secure for himself a place among the gods.

• Two Year Emperor

• Tales From Aeria

• The Martian
  A (hard) science fiction novel set in the near future. The story follows a resourceful and witty NASA Astronaut who becomes stranded on Mars as the rest of his crew mistakenly abandons him for dead in a sand storm. It has been described as an Apollo 13 meets Cast Away and lauded for its technical and scientific accuracy.

Rational fanfiction

• Luminosity
  Luminosity is HPMOR-inspired Twilight fanfiction where Bella is rational self-awareness-junkie with a penchant for writing down everything that crosses her mind in a notebook. The first several sections of Luminosity are very similar to canon in terms of the events that occur, although aspects of Bella's character, and her internal monologue, differ strikingly. A few thousand words in, the plot is unrecognizeable.

• The Metropolitian Man
  The year is 1934, and Superman has arrived in Metropolis. Features Lex Luthor as the villain protagonist as he comes to grips with the arrival of an alien god. Occasional point-of-view chapters/sections featuring Lois Lane. Takes place outside any established comics continuity.

• A Bluer Shade of White
  Six years after her coronation, Elsa rules over Arendelle, using the power of ice to improve the lives of her citizens.

• Branches on the Tree of Time
  Kyle Reese has traveled backwards in time, not to save Sarah Connor, but to help her rewrite the faulty utility function of Skynet. Together, it's possible that they might avert Judgment Day and save the world from nuclear Armageddon - and hopefully create a utopia ruled over by an AI god in the process. Fully completed. Diverges wildly from canon.

• Friendship Is Optimal
  Hanna, the CEO of Hofvarpnir Studios, just won the contract to write the official My Little Pony MMO. Hanna has built an A.I. Princess Celestia and given her one basic drive: to satisfy everybody's values through friendship and ponies. Princess Celestia will satisfy your values through friendship and ponies, and it will be completely consensual.

• Animorphs: The Reckoning
  AU/multiple points of departure, with the intent to fix/sane-itize/create internal consistency, allowing rational agents to take things to the extreme. Visser Three is competent, the Yeerks are moving rapidly, and the Animorphs are actually trying to win (but are inexperienced and unprepared). Inspired by Worm and HPMOR.

• Pokemon: The Origin of Species
  Enter the world of Pokémon from a rational perspective. Instead of starting his journey in ignorance, Red has spent his years studying the creatures so central to his world... and he doesn't quite agree with all the information in his books. No time for rookie mistakes here: he's on a quest to discover the true nature of Pokémon, and maybe even find out where they really come from.

• Harry Potter and the Natural 20
  Milo, a genre-savvy D&D Wizard and Adventurer Extraordinaire is forced to attend Hogwarts, and soon finds himself plunged into a new adventure of magic, mad old Wizards, metagaming, misunderstandings, and munchkinry.

• Time Braid
  Naruto fic focusing on a rational Sakura.

• The Arithmancer

HPMOR fanfiction

• Draco Malfoy and the Practice of Rationality
  Still reeling from Lucius' Death and Narcissa's rebirth, Draco struggles to find his place in a changing Hogwarts and learns a dark secret of his new room-mate: Harry James Potter-Evans-Verres.

• HPMoR: The Missing (but Necessary) Chapters
  An extension of the universe of "Harry Potter and the Methods of Rationality". Includes scenes that should have been but weren't. They contribute nothing to the plot or explaining the universe, but answer important questions that may otherwise never be answered.

• Following the Phoenix
  A single-/dual-point-of-departure spinoff from Less Wrong's brilliant story "Harry Potter and the Methods of Rationality", branching away in Chapter 81. Hermione is sent to Azkaban, but Harry is not about to give up. Unfortunately, it doesn't look like his enemy is about to leave things alone either.

• Squiring the Phoenix
  (Continuation fic of Following the Phoenix)

• Significant Digits
  It's easy to ask make big plans and ask big questions, but a lot harder to follow them through. Find out what happens to Harry Potter-Evans-Verres, Hermione, Draco, and everyone else once they grow into their roles as leaders, leave the shelter of Hogwarts, and venture out into a wider world of intrigue, politics, and war.

• Hermione Granger and the Perfectly Reasonable Explanation
  In 1991, a child came to Hogwarts School of Witchcraft and Wizardry with obvious gifts, but which few suspected would change the world... Oh, and Harry Potter enrolled that year as well. (HPMOR-influenced, but the initial setting is vanilla HP.)

• Nothing Left but Fire
  (Alternate final arc)

• Harry Potter and the Cryptographic Key
  (Written after Ch. 102 was released, intended as an ending fic)

• Nonlinear Regression
  One of the alternate chapter 114 answers.

• A Crack Slash Epilogue

• Hacking the Source of Magic

• Minds, Names and Faces

• Harry Potter and the Philosopher's Zombie

• Ginny Weasley and the Sealed Intelligence

• Alternate HPMoR: Asking for Help

• Continuing HPMoR: Reductionism for the Win

• Revival

• Innocence

• Proximity

• Sirius Black and the Prisoner's Dilemma

Timeline of HPMOR fanfiction

Where to find more stories

/r/rational- a subreddit dedicated to the discussion of works of rational and rationalist fiction.

rationalreads.com - a place to submit, rate and browse rational works.

rationalfiction.io - website that aims to be the best place for readers and writers of rational fiction to post and discuss stories.

Submit stories that you think should be added to this list as top level comments(I will edit and improve this list over time).

If mods find this useful - let's make this thread sticky or (probably a better option) make a wiki page and add it to the sidebar.

Edit: we have a reading!

It wasn’t every day that you got a message from yourself from the future.

“Davies has the Quaffle!” Lee Jordan shouted in a world that didn’t matter very much and was rapidly receding in importance. “Oh…! And the Snitch is gone - maybe gone for good, after being missed that badly!”

Harry ignored the foreshadowing. The parchment said:

He dying

Don’t wanna

Halp

Go to corridor between Charms Classroom and supply closet

Watch out for like Aurors and stuff

Have written this in secret magical ink so to outsider looks like super smart code but u can read it real easy

Harry worried that he might be an idiot, but he was more worried that Professor Quirrell was dying. He surreptitiously gathered his things, instructed Uzumaki Naruto to keep an eye on things at the Quidditch match, and headed off to the corridor between the Charms Classroom and the supply closet.

Something something Cedric something something THIS ISN’T A CLUE PEOPLE

He was walking through the hall when he spotted a trio of Aurors moving toward the same location. Harry ducked behind a suit of magical armor and watched them walk into the corridor. A sign, Harry noticed, pointed to within the corridor. It read, “Free Jam Sandwiches.”

“I love free food,” one of the Aurors said.

Instantly Harry realized.

Professor Quirrell was dying.

Organisms died when they could no longer sustain their life.

Organisms sustained life through energy.

Food provided energy.

High-sugar foods provided the most energy. That was why [lecture on evolutionary psychology] humans loved the taste of sugar even though [lecture on superstimuli].

Harry’s mind instantly made a connection.

Unicorn blood is jam.

How - why - no, run with the hypothesis

Unicorn blood is magic jam is magic sugar is magic sugar is the source of magic sugars were built into biology on a basic level DNA is made out of sugar

Source of magic is sugar Atlanteans knew this what happened to Atlantis individual can become stronger by eating more sugar but if whole group eats sugar relative power levels the same plus rising obesity collective action problem Atlantis wiped from time by rising health care costs thanks Obama test hypothesis Roger Bacon bacon ate savory things not sweet never had a wand never got far prior strengthened keep going

Professor Quirrell needs sugar to live Dumbledore knows this allowed Aurors in to secure sugar supply cops love free food especially donuts what am I supposed to do what was I sent here for I don’t understand

He needed to get to the sandwiches before they did.

Harry stepped out from behind the suit of armor, cast Silencio on his feet, and dashed to the edge of the corridor and peeked inside just in time to see a thin, balding man literally leap out of the wall screaming “FUCK SHIT I AM LORD VOLDEMORT!”

He sent the first Auror crashing to the ground, his mouth his teeth his fangs snake fangs biting into the jugular blood leaking out thick like jam generate plan: gather blood? Yes/no no keep observing

The remaining Aurors whirled, reaching for their wands, but the man looks sick was too fast. He dodged in midair over the Stunner and bit, ripping out the one Auror’s throat, then the other. In less than five seconds it was over.

Harry looked, but there were no jam sandwiches.

“Professor Quirrell?” Harry said timidly, unsure of how to respond to a blatant triple homicide he was presumably intended to witness. “Please tell me what is going on?”

Professor Quirrell wiped his mouth and seemed to notice him for the first time. “Mr. Potter, what are you doing wandering the halls without Aurors accompanying you?”

Harry stared at him. “Seriously?”

“Mr. Potter, I deduce that your drive for immortality is more a role than—“

“Question. Why did you scream, um, bad words, and then ‘I am Lord Voldemort?’”

“It should be obvious. I said the words that would most disorient my opponents before I struck. If you cannot perceive—“

“Next question. Um, why did you bite the throats out of three Aurors?”

“The unicorn herd is thinning. Wizard blood is a substitute, albeit a poor one. My time is running out. Thank you, boy, for the physics book. If only I had seen the power of science earlier….” Professor Quirrell coughed, then licked the blood off his hand, then coughed some more. “We could have been…research partners.”

Part of Harry’s heart swelled with a strange mixture of pride and sadness. Another part of him was very, very confused.

Observation 1: Professor Quirrell screams, um, bad words I am Lord Voldemort.

Observation 2: Professor Quirrell kills, drinks blood of three Aurors

Observation 3: Was sent here from future by me (?) to do…?

“Beware Professor Sprout,” Professor Quirrell said. “Oh, I am so weak and dying cough. Beware…the badger sweet as honey…deadliest of creatures….” He coughed again.

Only one hypothesis explained all the observations.

Professor Quirrell is training me to confront the Dark Lord with nearest simulation of his attack.

Harry felt sadness and love for his mentor tear at him like the feeling of Ravenclaw House getting more House points because they won a Quidditch match.

“Thank you.” It was the most Harry could manage. “Thank you, Professor, for preparing me from the Dark Lord with your last days.” Just as Harry said “Dark Lord,” Professor Quirrells lips twitched. “I will defeat the Dark Lord—“ they twitched again—“and on the grave of He-Who-Must-Not-Be-Named I will”—twitch again.

And somehow that tore it.

Somehow that was a little too much.

Too many lip-twitches had happened synchronously with mentions of the Dark Lord and that was too much coincidence, it was improbable that his lips would twitch at the same few phrases within a fifteen-second window, there had to be hidden entanglements.

Label Professor Quirrell as the lip-twitcher.

Label synonyms for You-Know-Who as lip-twitching activators.

“Harry,” Professor Quirrell croaked. “Harry, listen…I have…cynical things to say…about…cough, other people…Harry, please….”

“Let me think. Let me think for one minute before I find a way to transfigure infinite jam.”

“Please…my insulin levels….”

One more minute can't make the difference he's had the WHOLE YEAR to be sick it's IMPROBABLE that his life versus death would be precisely timed to rest on this last minute no matter what happened to all the House Elves -

The House Elves…who made breakfast, a breakfast that often included jam and bread.

And that was when Harry finally realized what should have been obvious from the very, very beginning.

Professor Quirrell had diabetes.

Professor Quirrell had diabetes in the same way as Harry.

Professor Quirrell had diabetes in exactly the same way as Harry’s mysterious fat side.

If you had to guess when the Boy-Who-Lived had acquired his mysterious fat side, the obvious guess was the night of October 31st, 1981.

And and

And Professor Quirrell had instructed Harry to greet Bellatrix Black with the command, “Get in the kitchen and make me a sandwich,” and his presence made the Boy-Who-Lived feel hypoglycemic and his favorite spell was Insulin injectus and and - The realization blasted through Harry like the Killing Curse hadn’t. There is only one reality that generates all of the observations.

All year, this entire year, Lord Voldemort has been invisibly standing very close to Professor Quirrell.

The Enemy was behind him, watching him.

“All right,” Harry said. “Let’s go make that sandwich.”

He turned around.

Professor Quirrell was standing up. Holding a piece of metal pointed at Harry not explicitly called a gun this sentence is not complete.

Harry’s mouth was dry, but he managed to speak. “Professor Quirrell, Lord Voldemort is right behind you.”

Professor Quirrell’s lips twitched again. Then he frowned. “Seriously?”

Harry blinked. “What?”

“I am Lord Voldemort, you gibbering idiot.” His lips twitched again.

“You’re Lord Voldemort?” Harry gasped.

Professor Quirrell’s lips twitched.

“You can’t be Lord Voldemort!” Harry said as Professor Quirrell twitched his lips once more. “The Dark Lord”—twitch—“is invisibly oh crud I’m dumb.”

“Seriously,” Professor Quirrell said.

“So, um,” Harry felt as though the dramatic tension Professor Quirrell had expected was leaking away, “I guess Lord Voldemort”—twitch—“didn’t die that night after all? How did the Dark Lord”—twitch—“survive the curse that only Headmaster Dumbledore thought Lord Voldemort”—twitch—“survived?”

Professor Quirrell grinned mirthlessly. “The Dark Lord”—twitch—“has heard of contingencies.”

“Okay, can I just say something?”

“What is it, boy?”

“It’s already revealed that you’re Voldemort.” Twitch. “You don’t have to keep twitching your lips.”

“Don’t I? Don’t I, Tom Riddle?”

It hit Harry like a jamboree.

I’m Tom Riddle

explain

am similar to Voldemort because am magically created copy that night

Then Harry realized.

His lips were twitching.

They had been twitching the whole time.

Professor Quirrell’s smile widened. He gestured with the gun, a misjudgment possibly the result of low insulin levels. “Now to the Stone, boy. Walk.”

As Harry walked down the hall to the third-floor corridor with Professor Quirrell and a gun at his back, he could only place his hope in the power of Twitch.

Me:

writes dialogue between Professor Quirrell and Dumbledore, running straightforward models of both characters

Reader reactions:

Faaaaake

Gotta be a CEV

They're still inside the mirror

Dumbledore wouldn't be beaten that easily, this was too easy for Quirrell, it has to be his dream.

Me:

writes Professor Quirrell talking out loud about how his immortality network just shuts down, allowing Harry to just shoot him

Reader reactions:

OH MY GOSH REALLY?

My reaction:

AAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

WHY WHY WHY

WHY YOU QUESTION 110 AND NOT 111

THERE ARE NO RULES

NO RULES

Sorry, I just had to get that off my chest.

Lily and James Potter looked nervously at their son, who was sitting in front of them on the magic couch, because they were magic and had magic things.

James cleared his throat. “Son, it’s time you knew—"

“That I’m adopted?” Harry interrupted.

Lily gasped. “How did you know?”

“His underage magic must be leaking and caused an unintended Legilimency,” James said.

Harry fought the urge to roll his eyes. “No. Mum, Dad, it’s obvious. I don’t look anything like you two. We don’t really have the same tastes—I like to read, and Dad, you like flying around on that broom all day, and Mum, your hobby is jumping in front of curses. I’ve known for years. Who’re my real parents?” His eyes narrowed. “It’s not the Longbottoms, is it?”

His parents exchanged glances.

“What?” Harry said. “The most important thing about a secret is the fact that it exists.”

“Son,” said James heavily. “Your parents…they’re….”

“Dead? Ugly? Hippies?”

“Son, they’re Muggles. Or, they were Muggles, before a Muggle military commander named General Chaos killed them in his bid to take over Muggle Britain.”

Harry’s mind froze.

Holy crap I’m a Muggle.

also who the heck is General Chaos and where’s the prophecy that explains how I defeat him

wait, said Brain. Do Muggles even have prophecies?

“Holy crap,” said Harry.

“Well, we finally said something that surprised him for once,” said Lily.

“I’M NOT EVEN MAGIC???”

“You’re a Muggleborn,” said James.

“We wanted to introduce it to you gently,” Lily said. “That’s why we bought you those Muggle books about science and convection ovens and Hardy Boys.”

“Arthur Weasley helped us with the money,” said James. “It’s made out of paper, can you believe it? I don’t think Muggles realize how fragile it is. I tore apart two 10s to make a 20 and they were all staring at me.”

Harry’s lips started to move.

“I know this must be a shock,” said Lily.

“Please don’t bite us,” said James.

“This…this is….”

“Watch his teeth,” warned James.

“THIS IS AWESOME!”

“You’re happy about this?” Lily said. “Of course we want you to be happy, but….”

“I’m not happy not to be related to you two,” Harry said. “You’re both my real parents no matter what the genes say. But thrilled to be a Muggle? Absolutely!”

“How is it good to be a Muggle?” James said. “Don’t get me wrong, I have nothing against them. But they travel very slowly and they get so old at such a young age.”

“Think about it,” said Harry. “What’s my favorite thing in the world?”

“Fried Diricawl drumsticks?” said Lily.

“Hermione Granger?” said James.

“Mum! Dad! No, it’s science.”

“We should have never bought you that Deepak Chopra book.”

“No—well, yes, you shouldn’t have.” Looking back, it was retrospectively the most embarrassing year of Harry’s life. “But it did get me started on the road to science. It’s what they use instead of magic!”

“They use it to move slowly and then die?”

“No—I mean, yes, but not as slowly, and they don’t die quite as much, to the same things?”

“Amazing.”

“The point is,” said Lily, “we thought it was best if you got in touch with your Muggle side. We’re sending you to a boarding school for Muggles. No wands, no dangerous adventures. Just Latin and nuns caning you.”

“I think that’s a bit outdated, Mum.”

“I got an OWL in Muggle Studies, Harry. Oh, the man who’ll be helping you, Professor Gonagacm, will be here any minute.”

James and Harry both looked expectantly at the fire. A moment later, there was a knock on the door. Lily, who had indeed earned an OWL in Muggle Studies, got up and answered the door.

Professor Gonagacm was nothing like Harry expected. He wore a suit instead of a sleeveless T-shirt and leopard-print pants, and he wasn’t carrying a telescope.

“Prove you’re a Muggle!” Harry said. “Experimentally.”

Professor Gonagacm looked annoyed. “I’m thirty-seven and feel like I’m ancient.”

“Gosh!” said Harry.

“Harry, I love you very much,” said Lily, tears in her eyes.

“We’ll send owls,” said James.

“I’ll send Online Bulletins!” said Harry, thrilled to finally be part of the Future.

Professor Gonagacm and Harry walked toward the Muggle subway instead of teleporting, and they dragged their suitcases instead of also teleporting them. It was amazing.

“I can’t wait to learn more about how the universe really works instead instead of just making reality bend to my wishes with a flick of my wand,” said Harry.

“Mm,” said Professor Gonagacm, who was feeling differently.

“I’m not surprised that I’m a Muggleborn,” Harry went on in emotional obliviousness. “I took to science really quickly, after I stopped thinking it was just the same as magic. Freaking Deepak Chopra,” he muttered. “I think it must be genetic, since Muggles would have had to do experiments to invent electricity and build nuclear weapons to survive in the wild, and the ones who were the best scientists would have had the most fitness.”

(Harry’s parents’ somewhat random purchases had earned him a disorganized education in both evolutionary biology and history.)

“That’s all exactly right,” said Professor Gonagacm, who was in a mood.

They got to the subway. Everyone was standing six feet apart.

“Fascinating!” said Harry. “I hypothesize that Muggles have trouble regulating their body temperature and overheat underground. Thus, standing six feet apart is an Evolutionary Adaptation. I’ll test this by—”

“It’s social distancing,” grunted Professor Gonagacm.

“Please explain!!!” said Harry as calmly as he could.

“If we don’t stand six feet apart, we’ll spread coronavirus. Then we’ll die.”

“Then why come here at all?”

“Muggles have to go to work,” explained Professor Gonagacm. “Work is when you’re very bored and then you get to eat food and live indoors.”

Harry was thrilled. Social distancing—of course! He knew from his readings that viruses spread by contact. They had devastated Muggles in prior centuries. Social distancing was exactly the kind of invention he’d expect a rational people like Muggles to invent. Unlike wizards, who just waved away their problems with a wand, Muggles had to think, to create, to know and understand! The Muggle world was undoubtedly a haven of rational thought. Wizards would believe anything—and, admittedly, they could make anything be true—but that was the point. You couldn’t develop a healthy epistemology when reality worked according to your beliefs.

“Tell me more about the coronavirus,” said Harry as they got onto the subway, taking care to stay the proper distance away from others. “What plans has the team of scientists running your government put into effect?”

Professor Gonagacm was staring off into the distance as though he could see through the walls.

“I expect production of necessary medical supplies quickly ramped up. In fact, your prediction markets probably had all the necessary supplies in place before the pandemic had even spread very far!” It saddened Harry to realize how little he would have to contribute to the hyper-rational, scientifically-run Muggle society. He would just be another regular person living out his life.

Professor Gonagacm grabbed a newspaper and gave it to Harry.

Several minutes of silence passed.

“What the fuck is an NHS?” said Harry.

Time passed.

“Just make more fucking ventilators,” Harry said to no one.

More time.

“Why would you stop people from being tested.” Harry was talking to a piece of paper.

Professor Gonagacm stared off.

“Okay,” said Harry, crumpling the newspaper in his fists, “why are wizards running all of your Muggle institutions?”

Professor Gonagacm smiled thinly. “Do you know that 45% of people believe in ghosts?”

“Without any evidence?” Harry was appalled. “Admittedly, ghosts are real, but they don’t know that!”

The subway stopped. “We’ll be going up now,” said Professor Gonagacm. “Muggle population density is higher than you’re used to, so stay close.”

“Will we be wearing masks?”

“Of course not,” said Professor Gonagacm, “because that wouldn’t completely solve the problem.”

Harry didn’t understand. “I thought Muggles have invented maths.”

“Some Muggles invented maths. Other Muggles ate meat and had sex a lot. Now come.”

They went up together into the sunlight. There was quite a lot of optimizing to do, and Harry was already thinking.