Hypothesis: Harry lives in a close to post-singularity universe. The source of magic is a boxed AI, created by the Atlanteans and Harry himself.

Currently, the boxed AI can be manipulated by means of spells, potions and rituals and is acting as a limited outcome pump. Harry, in his quest to end death, will release the AI from the box, thus bringing about a true singularity end state and the foretold end of the universe as we know it.

The method through which Harry will achieve this (releasing the boxed AI while simultaneously being partly responsible for its creation by the Atlanteans in the past) will be a trick using multiple time turners and something like the algorithm Harry invented in chapter 17 for solving an NP complete problem coupled with Timeless Decision Theory.

If you build a device capable of factorising in less than polynomial time, you have a major building block of a supercomputer. If you can do it in negative time (solution before input) you've built an AI. Harry attempted this in chapter 17 but was stopped by a future Harry with the admonishment "DO NOT MESS WITH TIME" which Harry resolves to obey until age 15. That intervention could have been from an even further future Harry.

The theft of Hermione's body could also have been conducted by an even further future Harry which allows him to pass the questioning of the headmaster.

If Harry can figure out how to bypass the limitations of the time turner, that is all he needs to do to bring about the scenario I outlined, and build an outcome pump that will restore Hermione, be established as the source of magic in the past and the bringer of the singularity in the future.

I assign 60% confidence to this hypothesis.

I still don't see why repeat castings with hatred would require higher amounts of effort each time,

This is weird: In many cases hatred would peter out into indifference, rather than positive value, which ought to make AK easier. In fact, the idea that killing gets easier with time because of building indifference is a recognised trope. It's even weirder that the next few paragraphs are an author tract on how baseline humans let people die out of apathy all the time, so it's not like Yudkowski is unfamiliar with the ease with which people kill.

Something I haven't heard discussed elsewhere:

Merlin created the Interdict because he believed, based on prophecy, that this would prevent the otherwise inevitable end of the world and its magic.

If resolved!Harry is "the end of the world", as per Trelawney's prophecy, then whatever he is going to do must therefore involve bypassing the Interdict of Merlin.

The only way we presently know to do that is Salazar's basilisk-transmitted lore, which is now probably only available via Quirrell (assuming he is Tom Riddle and Tom Riddle was the Heir of Slytherin who opened the Chamber of Secrets).

Hypothesis: Quirrell will teach Harry Salazar's ancient lore, which Harry will then use to "tear apart the very stars themselves" and, in some sense, end the world and its magic.

If Eliezer actually picked that route then it is likely to be something like a UFAI consuming the universe to build magic paperclips. I don't see it as likely, though.

Apparently word of god is that there is going to be no AI. I think it likely that there will be a happy ending, but that 'destroying the stars' will resolve itself into a concrete threat. Somehow 'Epilogue: than over the next few billion years superintelligent Harry turned stars into computronium' seems a little unsatisfactory.

That said, I expect Eliezer to have come up with something more mind-blowing than vacuum-blowing.

I dunno, vacuum-blowing seems reasonably mind-blowing to me. Do you have any alternative theories?

Not related to CH102, but I just realized that "Slytherin System" messages are a physical implementation of Tor. Entry node who knows only the sender and the middle node, middle node who knows only the entry and exit nodes, exit node who knows only the middle node and the receiver.

Hypothesis:

• The prophesied 'end of the world' will involve meddling with Time.

Some semi-random observations/conjectures supporting the hypothesis:

• The 6-hour information transfer limit is tied to the Interdict of Merlin. A 6-hour timeframe seems rather arbitrary in terms of describing a purely natural constraint of the underlying physical reality. It makes perfect sense, on the other hand, as a human-designed complementary measure of enforcing the Interdict as otherwise wizards would be traveling back in time to learn from old masters before their deaths, thereby negating the Interdict.

• The whole plot generally revolves around paradoxes and uses of Time. Atlantis is supposedly 'erased from Time' (not destroyed). Hogwarts castle's random changes have time patterns (certain years and days in the week). References to students getting lost and coming back as old men or going higher than the castle's highest level (implying shifting passageways transporting people into Hogwarts castles in some alternative times/realities?).

• Repeated allusions to Harry destroying stars is unlikely to be referring to a literal physical annihilation of all visible stars. I would place a much higher probability on the possibility that the current time/reality in which Hermione is irrevocably dead will be destroyed as a result of Harry deciding to change the fact.

• What spells are most likely to be declared so dangerous to warrant the Interdict? No magic (aside from Time travel), no matter how destructive, comes even close in my mind to justify Merlin sacrificing himself to impose this rather oppressive restriction that limits indirect information exchange of ALL wizards in ALL of time, present AND future!

• The first time we hear Quirrelmort's inner monologue is when we learn that he is honestly afraid of what Harry will do. I cannot think realistically what Harry can do to threaten his 'modified' interstellar probe at present time unless he can prevent it being modified (horcruxed?) to start with, i.e. go back in time.

• Time paradoxes are ruled out. Why? Because reality is somehow ensuring consistency? But then, how could Atlantis 'erase' itself from Time? I assign much higher probability that this restriction is designed as part of the Interdict again rather than a naturally occurring phenomenon.

Thoughts?

Until we hear otherwise, he has access to all the knowledge of Salazar, who knew enough to build Hogwarts.

This may be an exaggeration. First, it seems improbable that Salazar entrusted all his magical knowledge to the basilisk, if only because that would have been a ridiculous amount of magical knowledge. Salazar wouldn't have known which pieces of knowledge from his time were going to become lost, only that some would based on existing trends, so if he was going to tell the basilisk everything he thought valuable, it would have taken forever. Also, there's no reason to believe that basilisks have perfect memories - unless I'm misremembering, the basilisk as a species was chosen for its snakeness, deadliness and longevity rather than its intellect.

Which also means the source code to the wards and the means to change them.

Salazar was only responsible for part of Hogwarts. We don't know that he was at all responsible for the wards, only that he had admin access to them (in order to make them ignore the basilisk), which is no surprise since he was one of the four founders. We also don't know that Godric didn't revoke said admin access after Salazar betrayed him and left, in which case that portion of Salazar's knowledge would be useless. In fact, it would be downright weird if Godric hadn't done so.

Can you even transfigure something that transfigures itself back? Of course Quirrell can do it if it's possible, but is it possible?

Since I feel the wrathful shade of Professor McGonagall watching over my shoulder, I'm going to say "I don't know". But if I had to guess, a transfigured object takes on all the properties of its new form, including the property of "not having troll regenerative powers". So if you could initially transfigure the troll faster than its regeneration kicked in, you'd have no trouble maintaining it thereafter.

On the other hand,

"Because all alchemical circles have to be drawn 'to the fineness of a child's hair', it isn't any finer for some alchemies than others.

strongly implies that different alchemical procedures require different circles. What are the odds that Dumbledore just happens to have the right circle for philosopher's stone creation ready, given that he has no desire for immortality, no special need for gold, and access to an existing philosopher's stone anyway?

/u/solipsist, in another comment on this thread:

Do not try to obtain Sstone yoursself. I forbid.

This was said by Quirrell in Parseltongue. If you can only tell the truth in Parseltongue, then Quirrell was really forbidding Harry from obtaining the stone himself.

If Quirrell can't lie in Parseltongue (and not just Harry, since Harry's speaking as a standard Parselmouth but Quirrell is speaking as a sentient snake), and if that prohibition enforces the sincerity of imperative commands and not just declarative statements, then clearly what Quirrell is saying is that Harry should try to make his own Philosopher's Stone.

"It's not a secret." Hermione flipped the page, showing Harry the diagrams. "The instructions are right on the next page. It's just so difficult that only Nicholas Flamel's done it."

"Well, it can't work," Hermione said. She'd flown across the library to look up the only book on alchemy that wasn't in the Restricted Section. And then - she remembered the crushing letdown, all the sudden hope dissipating like mist. "Because all alchemical circles have to be drawn 'to the fineness of a child's hair', it isn't any finer for some alchemies than others. And wizards have Omnioculars, and I haven't heard of any spells where you use Omnioculars to magnify things and do them exactly.

So the first thing Hermione mentions as a limitation of doing alchemy is the insane precision of the circle you have to draw. But what if there were already an acceptable, permanent alchemy setup just lying around somewhere where Harry could get to it?

The three of them stood within the Headmaster's private Transfiguration workroom, where the shining phoenix of Dumbledore's Patronus had told her to bring Harry, moments after her own Patronus had reached him. Light shone down through the skylights and illuminated the great seven-pointed alchemical diagram drawn in the center of the circular room, showing it to be a little dusty, which saddened Minerva. Transfiguration research was one of Dumbledore's great enjoyments, and she'd known how pressed for time he'd been lately, but not that he was this pressed.

Just to check: Chapter 100 is the scene foreshadowed in the opening quote, right?

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

(Unicorn blood)

(black robes, falling)

(The aurors and McGonagall falling from their brooms)

...blood spills out in litres, and someone screams a word.

...this doesn't quite fit, unless I'm picturing the scene wrong.

Edit: Uncertainty. Based on replies, I'm now leaning against this being the foreshadowed scene.