Life in life
Why Hacker News recommends it
The canonical visual for nested simulation, Turing completeness and self-reference; HN readers call it mind-blowing and reach for it constantly.
What it is
A two-minute video of Conway's Game of Life running inside Conway's Game of Life, built from OTCA metapixels and Golly. It zooms smoothly between scales.
Recommended by 6 HN commenters across 6 different months, 2013 to 2025.
What Hacker News said
Strong rec lqet · 2020-10 · on “Building a computer in Conway's game of life”
I remember seeing that video 3 years ago and being blown away. In case someone doesn't already know it, here is Conway's Game of Life simulated in Conway's Game of Life: [this video]
Strong rec pierreyoda · 2023-01 · on “Tetris Is Capable of Universal Computation”
This is an excellent link, well known in the "community" around this. To add to it, here's a famous and really clear sub-2 minutes representation of the scales involved if it helps make things clearer, for those who've never seen the scales involved: [this video] (and that's "just" the Game of Life in the Game of Life). I think I would enjoy helping push the state of the art in this field, but it's far beyond my abilities for the moment. If it wasn't, I would love to work on a new library specifically built for the kind of things like your idea, with the API aimed at working with metapixels-based "hardware", but with the lowest-level constructs (maybe by far) being thinks like RAM or CPU caches a
Recommends avian · 2017-09 · on “Building a working game of Tetris in Conway's Game of Life”
Here's a nice video showing OTCA metapixels in action, implementing Game of Life in Game of Life. [this video] It would be amazing to see this Tetris computer rendered into a video like this.
Recommends Groxx · 2020-04 · on “Build a Working Game of Tetris in Conway's Game of Life (2014)”
2017 post has a much-needed youtube video of the metapixels as the top comment: [this video] I haven't been able to find one for tetris tho
Recommends fishtoaster · 2022-12 · on “Recursive Game of Life”
This is amazing! I've seen "life in life" as a video from ages ago[0], but this is just suck a slick implementation of it! [0] [this video]
Recommends zamalek · 2025-02 · on “Ask HN: What's the best implementation of Conway's Game of Life?”
It might be argued that one of the dynamic programming (caching) ones would be the best by a reasonable standard. These can be used to simulate absolutely monstrous grids, and is where we see simulated CPUs and whatnot. Here's the game of life running in the game of life: [this video] - that one uses Golly.
Cites lelf · 2013-09 · on “Game of Life News: Prime numbers (2010)”
Not only that, but it can find lowest common denominator, solve a system of linear equations, and even run the complete RSA algorithm (albeit with a pseudorandom RNG that's deterministic). Or run a game of live's simulation [this video]
Cites posterboy · 2017-06 · on “Oh My Gosh, It’s Covered in Rule 30s”
I'd guess that GoL and Cellular Automaton Theory preceded and inspired rule 30 etc. So, maybe the architects implied metarecursion, that GoL metaphorically generated rule 30. GoL is Turing complete. I guess that means there is a starting condition that converges to a rule30 cellular automaton. edit: video of GoL emulated inside a turing machine in GoL [this video] (link replaced)