I have noticed many descriptors of the time, sky and moon in the story recently. I think they might be a clue.

At the Quidditch match:

• "June in Scotland meant plenty of daylight; sunset wasn't until ten."

• "As the sun set and Harry started using Lumos to read his books"

• "And as the stars began to come out"

• "Harry glanced at his watch - eleven-oh-four at night. Harry was now reading a sixth-year Transfiguration textbook; or rather he'd weighted the book open, illuminated by a Muggle glowstick,"

At the graveyard:

• "The moon above was over three-quarters full, already seeming bright with night not fully fallen."

• "gleaming darkly beneath the fading twilight sky"

• "A tall form rested upon the altar, and even in the dimming twilight it looked too pale."

• "Red eyes gleamed beneath the fading twilight,"

• "on a twilight-lit stone altar."

• "The twilight sky had dimmed further"

• "but the moonlight was too faint for certainty"

• "Harry saw by the moonlight that they all now lay in another heap by the altar"

• "The gibbous moon riding higher in the cloudless sky, the stars and wash of the Milky Way visible in all their majesty within the darkness"

If it is fully dark, it must be well past 10pm, as the text says the sun sets at 10pm. Harry left the quidditch match shortly after 11.04pm to prepare for his quest, so he could be missed or quidditch-disrupting-events could happen any time after that. Despite this, we are assured the cavalry is not coming. If it were past 11pm, what else would have to be true to know that the cavalry isn't coming?

So I did some research.

Moonlight chart

Definitions of 'shades' of twilight as shown in chart

To my surprise, my research indicates that the night never gets to 'astronomical twilight' in Scotland on the night of June 13-14. The sun sets for several hours, but doesn't go more than 12 degrees below the horizon. The sun needs to go more than 18 degrees below the horizon for the silhouette of the horizon to disappear and to be able to see the fainter stars with the naked eye.

Given all the focus on images of the stars in this story, I expect Harry, Voldemort and Eliezer to notice the difference between "the stars and wash of the Milky Way visible in all their majesty within the darkness" and the dimmer stars being missing because it is not dark enough. What does this indicate?

Are they not in Scotland? Are they not in June? Is that the real sky? Are they playing out some astronomy fan's wish fulfillment in the mirror? (Harry is already very confused that Hermione was resurrected.)

Harry's interest in astronomy enables him to notice that it shouldn't be this dark - it won't have been for some days or weeks now. Can he test any of the above without getting in too much more trouble?

This may also be a genuine mistake, my reading too much into things, a spell Voldemort cast for the ambience, or something else, but I thought it worth considering. Any thoughts?

Observation: If the purpose of this exercise is to run an AI box experiment, with EY as gatekeeper and the internet hivemind as the AI, then the ability to speak in parseltongue is problematic: It appears to make the game easier for the AI, thereby preventing the results from being generalized to a standard AI box experiment.

So why did Eliezer include the parseltongue constraint?

Maybe parseltongue is meant to introduce the concept of provability in a way that everyone can understand. To speak in parseltongue in real life, you just speak in logic statements and supply a proof with any statement you make. It seems reasonable (modulo computational complexity and provability concerns) for an AI to be able and/or required to supply proofs in an AI box experiment and parseltongue enables that in version of the game in the story.

I don't understand the constraint to speak only in parseltongue. Is that there to force us to focus on a solution set that is somehow of interest for friendly AI research?

Here's a flawed solution, but maybe someone can fix it.

Harry performs partial transfiguration on his brain, to transform it into a state where he thinks that he's booby-trapped the universe (for example, by transfiguring some strangelets along with a confinement field that will expire before the strangelets do). Then he just explains honestly to Voldemort why the universe will end if he dies.

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 not. (Is this right? Is there a hardness proof?)

Here are some possibilities to preserve efficient simulation:

• The mirror is a trick and doesn't do what it says it does
• Perhaps the NPCs are programmed to have known CEVs
• Causality goes in the other direction. Computing the CEV from the source is hard, but constraining an actor to act in a way consistent with their CEV might not be. Perhaps everyone's CEV is set when they first look in the mirror, and then they are constrained to act in accordance with this. (This is somewhat akin to the way of avoiding paradoxes in a quantum universe with time travel, whereby if you go back in time and shoot your grandmother, the bullet diffracts around her.)
• Maybe the previous item is only true of the NPCs. Is the mirror blank at the end of 110 because Harry is a PC (alternatively: simulating him is the purpose of simulation) and computing his CEV is too hard?

This will be the last meetup at my apartment.

I sadly can't make this one.

We plan to discuss metaethics. It might be useful to narrow this down.

Ben, is this Friday meetup at the standard location, or is Richard hosting it?

Bonus incentive: I give a free upvote to every comment that includes an expectation of attending!