Last updated Sept 16, 2019

September 26 is Petrov Day.
In 1983, the story of humanity nearly ended. We’re gathered here to remember that moment, and others like it.
But to experience the magnitude of those events, we need to visit them in their proper context. Let us begin the story of human history...
Jim Babcock's Petrov Day ceremony

Petrov Day on Easy Mode: Hang out. Share a meme.

Petrov Day on Normal Mode: Have a quiet, dignified ceremony.

Petrov Day on Hardcore Mode A: During said ceremony, unveil a large red button. If anybody presses the button, the ceremony is over. Go home. Do not speak.

Petrov Day on Hardestcore Mode: If anyone presses the button, you may never celebrate Petrov Day again.

Petrov Day on Multiplayer Hard[est]core Mode: As Hard[est]core Mode, except instead of an inert button, you use a website connected to another house where people are also celebrating Petrov Day. If anyone in one house presses the button, the other house receives a launch alarm. They have 60 seconds to respond. At the end of 60 seconds, their party is over, and they must go home silently. The website has some chance of giving you a false alarm.

Habryka made a website last year that allows houses to choose each other as nuclear targets, and then potentially launch missiles at each other. You can log in, create a "house" account, and then communicate with another house about the rules and conditions of your Petrov Day celebration.

(Note that the website is a bit janky, and that anyone who can guess the name of your house could potentially target it with nuclear missiles)

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I built a small app that allows you participate in the button game:

  • You can sign up for an account by providing a house name
  • You can lock-on to another user by entering in their name
  • If you do that a large button appears and the other player can see that you are locked-on to them
  • If you press the button, an alarm will play on their screen and will give them 60 seconds to retaliate
  • If they retaliate, you are both dead
  • If they do not, they die, but you are still alive
  • If you are dead, you can no longer target other locations and launch rockets

You are welcome to use this for your own Petrov day celebration. There is no way to get other people's house names without them telling it to you, so if you choose something non-obvious there should be no way for other users to ruin your event.

so if you choose something non-obvious there should be no way for other users to ruin your event.

No way for them to ruin your event?

Something something security mindset. :P

Does this app provide some probability of a false alarm?


I have completed the updates for the 2018 version of my fork of the ceremony. I'm fairly happy with it's google doc form and expect to maintain in the future. Version notes include:

Version Notes


  • Introductory segment to ensure everyone is ready
  • Added death of Petrov
  • Added Litany of Gendlin (from Daniel Speyer 2017)


  • Removed Fermi Paradox
  • Added Sadako Sasaki quote (h/t Ozy)
  • Added Milgram Experiment
  • Added explicit notes for The Button
  • Reduced strength WWII and Arkhipov claims
  • Added explicit notes for the slightly-dangerous-candle
  • New readings for final candles (inspired by Ozy 2018)
  • Updated Arkhipov version to be less certain / Orlov quote
  • Moved Industry Candle in-between science and WWII— Added moments of silence of escalating length

Worth noting that Ozy has also got a version of the Petrov Day Ceremony that is less focused on AI risk and more focused on the general case of global coordination.

Made a blog post summarizing the events and takeaways of the 22nd.

it's down

One fun fact about the Petrov Day ceremony is that it pairs surprisingly well with the Tron Legacy soundtrack. It's sort of like the Wizard of Oz / Dark Side of the Moon thing – the pacing of the soundtrack just happens to perfectly sync up with each section of the booklet as you read it aloud (when human history gets sad, the soundtrack gets sad, etc)

You do have to remove the tracks "The Grid" (which has spoken words), and the last two songs (End Credits and Finale, which ironically is not the actual Finale). The playlist I use is here:

the link is now broken, but I found it on YouTube (without said tracks removed):

Stickying this post for the next week to help people who'd like to coordinate on Petrov Day celebrations. See habryka's comment for details on the web app for mutually assured destruction.

anyone who can guess the name of your house could potentially target it with nuclear missiles

this seems like a major downside ;)

It sure is. :p

We developed the app in about 2 days. If you’d like to co tribute more dev time to it or make an improved one, you are welcome to. :)

Sorry, I think I sounded negative, and wasn't trying to. Edited to include a ";)".

Lol, I was also trying to include smiley’s so my reply didn’t sound so passive aggressive. :p

Typo in pg. 31 of the ceremony guide: "sir ead" -> "is read".

Some disconnected thoughts:

In Boston we're planning Normal Mode. (We rejected Hardcore Mode in previous years, in part because it was a serious problem for people who underwent significant inconvenience to be able to attend.)

I'm good at DevOps and might be able to help the Seattle folks make their app more available if they need it.

I happened to give a eulogy of sorts for Stanislav Petrov last year.

I'm currently going through the latest version of the ritual book and looking for things to nitpick, since I know that a few points (notably the details of the Arkhipov story) have fallen into dispute since last year.

I'd be curious to know what considerations are affecting your decisions to possibly change Petrov Day.

The Seattle and UK groups apparently celebrated today, but with a somewhat different scenario (instead of going home quietly, they each had cakes, and if they got nuked they had to burn their cake instead of eating it. At least this is my present understanding).

There was a web thing with a Big Red Button, running in Seattle, Oxford (and I think Boston also).

Each group had a cake and if they got nuked, they wouldn't get to eat the cake.

At the time when the Seattle counter said that the game was over for 1 second, someone there puched the button for the lulz, but the Oxford counter was not at zero yet and so they got nuked, then they decided to burn the cake instead of just not eating it.

I hope we all learned a valuable lesson here today.


This is both hilarious and horrifying.

"We have a positive singularity, let's launch nukes for fun"

No, we didn't participate in this in Boston. Our Petrov Day is this Wednesday, the actual anniversary of the Petrov incident.


I still don't understand, in the context of the ceremony, what would cause anyone to push the button. Whether or not it would incinerate a cake, which would pretty much make you history's greatest monster.

Ben Pace summarized this as "You know how, sometimes, you just find yourself having invented a terrible technology with the potential to easily destroy everything for no reason and you sort of wish you hadn't but, well, here you are though?"

Actually, the emphasis is a little off.

The point isn't that anyone sane would push the button. It's that we as a civilisation are just going around building buttons (cf. nukes, AGI, etc) and so it's good practice to put ourselves in the situation where any unilateralist can destroy something we all truly value. When I said the above, I was justifying why it was useful to have a ritual around Petrov Day, not why you would press the button. I can't think of any good reason to press the button, and would be angry at anyone who did - they're just decreasing trust and increasing fear of unilateralists. We still should have a ceremony where we all practice the art of sitting together and not pressing the button.

Hm. I'd been thinking the whole thing would work better if each party could perform some small negative-sum defection against the other. Along the likes of, each party commits to destroy $10, and has the ability to restore $1 to themselves while increasing the other party's obligation by $2 up to a max of $30. (And after either party gets nuked, the money values remain fixed.)

I think that would be a good thing for us to practice, but I agree the "just don't press the button that you have no reason to press anyway" variant is also good to practice.

Adding money to the mix for some reason just makes it more salient to me that pushing the button straight up makes you a jerk. (Although your setup here is... somewhat better than the variant someone else proposed, where you more directly give each other money. By virtue of being a weird setup that I have to think about before having opinions about)

The idea I came up with yesterday which I actually like is something like "if you push the button, there's a cool ceremonial bottle rocket to launch or sparkler or effigy you burn or something", that's cool enough to look exciting and tempting, but whose value is entirely symbolic and fun.

Because of the nature of the holiday, a prize that involves harming the other group actually feels worse-than-nothing (making me definitely not want to press anything), whereas a prize that involves a cool symbolic thing for ourselves is more tempting.

You know, upon reflection it is a bit alarming that I didn’t even notice I had substituted an entirely different question for the one Zvi asked.

(Although in my defense I think in the original context I think you also gave the answer in response to someone asking ‘why would I press the button?’, although I’m not sure)

Lol, seems fine ;)