[SandmanDP]

> fixed-cost universal construction (it only takes fifteen gliders to build anything buildable)

Here’s the Hacker News discussion from when this was discovered: https://news.ycombinator.com/item?id=33797799

Dave, I’m still regularly blown away by this discovery. I don’t know what else there is to be said, but do you have any other comments regarding this?

[dvgrn]

Definitely I have lots more to say about 15-glider universal construction! It was a really exceptionally interesting collaboration, where several people working together were able to complete something that would have taken any one person a ridiculously long time to sort out.

Development of the RCT has slowed down a bit, though there's a hyper-optimized version in the works that will build a spacefiller instead of a Hensel decimal counter as its example pattern:

https://conwaylife.com/forums/viewtopic.php?p=180134#p180134

There's also another long-awaited project in the works, that will use quite a bit of the same technology along with some new ideas -- a unidimensional (one cell thick) spaceship:

https://conwaylife.com/forums/viewtopic.php?f=2&t=2040

It's improbably complex and awkward, of course, just like an RCT pattern, and it's huge though nowhere near as huge as an RCT pattern -- but there will be one phase of the spaceship that fits in a 1xN bounding box.