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Petrov Day
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Meetup Month

by Raemon
17th Sep 2025
3 min read
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Community
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Meetup Month
7Screwtape
4Raemon
4Screwtape
2Screwtape
1Raphael Roche
1Leo.
2Raemon
3Duncan Sabien (Inactive)
1exmateriae
2Raemon
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[-]Screwtape10d70

ACX Meetup Czar here- I love a good meetup month, and we're presently five meetups away from having two hundred ACX Everywheres. If there's no meetup in your city yet and you want to add one in October, I'll take a late entry. Fill out a quick form and I'll get back to you!

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[-]Raemon9d40

Oh, I'd be happy to include a more explicit blurb about that in the post, I thought y'all were done acquiring new meetups there.

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[-]Screwtape8d40

Usually we would be. I do take late entries (a number of people only realize they over-procrastinated when the Times & Places announcement goes out) but usually shut it off after a few weeks. LessWrong's having a meetup month though! Seems a good excuse to try and get to two hundred :)

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[-]Screwtape8d20

If you want a blurb, how about

"ACX Everywhere is Scott Alexander's twice-a-year effort to shine light on local Astral Codex Ten meetups. If you'd like to talk to other readers of the blog, you can take a look at the list of meetups to see if there's one in your city! If there isn't one for your city yet, you can fill out a late-entry by filling out the form for an October ACX Everywhere. Running an ACX Everywhere can be pretty straightforward; pick a time (weekend afternoons are best) and a place (a local cafe will do just fine) and be ready to talk to interesting people!"

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[-]Raphael Roche2d10

I didn't know about Petrov. Wise man.

Sometimes I wonder if the anthropic principle can also apply to such historical cases.

In a world where Petrov reports a nuclear attack to his superiors, this starts a causal chain that has a very high probability of ending in WWIII and nuclear winter. In this world, I would not have been born one year later. The human population in 2025 would probably be only a fraction of what it is in our world.

So in a certain sense, we could consider abstractly that in the set of possible worlds, all other things being equal, there is statistically more chance for a posterior observer to exist in a world where Petrov acted as a hero than in a world where he obeyed orders. Same for the Cuban crisis and other critical moments.

It's as if history is always biased, relying on a posteriori probabilities, while the future appears unbiased because it relies on a priori probabilities. In the set of possible worlds, people born in 2100 would have a high chance of living in a world where alignment has been solved, simply because they exist to observe it. Like it was easy or likely ! This asymetry, this bias when we look at history, could be a drive toward excessive optimism.

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[-]Leo.8d10

Are there efforts underway to translate the book into other languages? I’d like to involve my parents and acquaintances who mostly speak Italian, and I imagine many others are in a similar situation. Translations could help make these discussions more international.

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[-]Raemon7d20

@yams @Duncan Sabien (Inactive) @Rob Bensinger ?

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[-]Duncan Sabien (Inactive)7d30

Yes, there are efforts; they are unfortunately controlled by the publisher and not the sort of thing we can outsource or influence.  Renegade translations seem morally good to me, if people are moved to create them, provided that they actually try to do a good job.

Languages that the book is being translated into include (85% probability on any member of this list; I'm a bit brain-dead this weekend): Mandarin, Italian, Spanish, Russian, Korean, Vietnamese, Dutch, and Bulgarian.  We're working on translating the online supplementals into at least those first four.

("Why such a strange list?" you might ask.  Well, the list isn't done; the publisher is still wrangling contracts in other nations/regions.  Contracts come in when they come in.  German, for instance, is highly likely to eventually get a translation—or at least, we'd be quite excited to see one, given Germany's prominence in the EU.  But again, out of our hands.  We put most of our prioritization energy into making sure there would be a Chinese-language translation, as that seemed super obviously the most important non-English-speaking audience.)

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[-]exmateriae11d10

Click here to create a Petrov Day event for the frontpage map.

no link?

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[-]Raemon11d20

Whoops, fixed now

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It’s meetup month! If you’ve been vaguely thinking of getting involved with a some kind of rationalsphere in-person community stuff, now is a great time to do that, because lots of other people are doing that!

It’s the usual time of the year for Astral Codex Everywhere – if you’re the sorta folk who likes to read Scott Alexander, and likes other people who like Scott Alexander, but only really can summon the wherewithal to go out to a meetup once a year, this is the Official Coordinated Schelling Time to do that. There are meetups scheduled in 180 cities. Probably one of those is near you!

This year, we have two other specific types of meetups it seemed good to coordinate around: Celebrating Petrov Day, and reading groups for the recently released If Anyone Builds It, Everyone Dies.

Petrov Day

September 26th is Petrov Day – a day when humanity came close to the brink of nuclear war. Stanislav Petrov worked in the Soviet military, and received an alert indicating a nuclear attack. But the information was suspicious – the alert reported only five warheads incoming. His orders were forward the report of a nuclear attack to his superiors, who may likely have retaliated and initiated a large scale nuclear war.

Instead, he reported it as a false alarm.

(It was, indeed, a false alarm, possibly triggered by a flock of birds)

On LessWrong, Petrov Day has come to be celebrated as a holiday about existential risk more generally. There have been many ways of celebrating Petrov Day. But the version I’ve found pretty meaningful as a holiday ritual is Jim Babcock’s hourlong ceremony, designed for 6-12 people. (If you have more people than that, he recommends splitting up into multiple subgroups who each fit around a table).

It involves printing out some booklets and some candles, and taking turns reading through the story of Petrov Day (along with context from throughout human history). 

In previous years, Jim and/or I have one a mad last-minute scramble to remind people and try to buy candles. (Note: there’s a bunch of ways you can screw up ritual candles). 

This year, we thought “let’s try to help people think about this more than 2 days in advance.”

If you want to host a Petrov Day ceremony, you’ll want some supplies. There ceremony involves 8 candles. Two of them don’t actually get lit, and represent futures where humanity flourishes or extinguishes itself. 

For a mix of aesthetics/practicality, I recommend getting these candles, with these candle holders. (I personally like having two fancier candles representing the flourishing and extinction futures, such as this one for flourishing and this one for extinction)

You’ll also need to print out a 8-12 copies of this booklet for readings[1]. (I recommend finding a local Fedex or similar, to print out several copies, to simplify the process.)

Click here to create a Petrov Day event for the frontpage map.

If Anyone Builds It reading groups

MIRI’s new book launches this week. It’s particularly valuable if people buy copies of it by Sep 20th (to make it more likely to appear on bestseller lists, which in turn make it more likely to get press and get into the mainstream consciousness).

The book is a (relatively) succinct articulation of the core arguments for AI being likely to destroy humanity. It’s a pretty big topic to think through, and it seemed valuable to encourage public (or semi-public) reading groups where people can read and discuss it together.

Some considerations:

  • The book is short enough it might make sense to have a single meetup for discussing it, but, you might also consider holding multiple meetups that discuss a given chapter, or, group of chapters.
  • If you’re discussing one chapter per session, you might consider explicitly scheduling an optional opening hour for reading the chapter, for people who’d have trouble making time but would enjoy reading it quietly with friends.

Click here to create a lesswrong event for an If Anyone Builds It reading group for our frontpage meetup map.

You can buy copies for your group here.

Note, if you would like some support getting your reading group running (i.e. suggested discussion questions, and potentially financial help buying the books) you can fill out this form.


Meetups will show up on our home page map, for people viewing the site on desktop:

And, of course, if you aren’t particularly interested in any of those things but just want to (re)connect with your local LessWrong meetup for whatever events they’re currently hosting, you can view our usual community map filter for the “LW” events.

Happy meeting up, happy book launch, and happy Petrov Day. :)

  1. ^

    Note: This version of it is optimized for reading, or printing single-sided, rather than printing a doublesided booklet, if you want to look it over.

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17Celebrate Petrov day as if the button had been pressed