Hacker News Reader

Comment by chaosmachine | Hacker News Reader

When I read the headline, I thought they had created a pattern that would generate an endlessly increasing population of clones, but as far as I can tell from that video, it's just a big ship disassembling and reassembling at another point on the grid.

Is it really replication, or just an obfuscated form of movement? Perhaps it should be called a transporter?

View on HN

There's already a term - "spaceship" - for patterns which, after a certain number of generations, are translated images of themselves. Indeed, the forum post by the pattern's author describes it as such. However, it seems that the mechanism by which this pattern is translating itself is self-replication followed by self-destruction (if I'm reading the original post correctly - I'm not an expert on the Game of Life), which is unique.

You have to see it in action to appreciate how cool this is. Get yourself a copy of Golly, load the pattern, and let it run for 34 million generations (which will take about half an hour on a modern machine). What you will see is a long diagonal line. If you zoom in to the upper left corner you will see the replicator itself. The rest of the pattern is an instruction tape that extends down and to the right. When it runs you will see the tape "running through" the replicator, which builds up a copy of itself piece by piece very, very slowly.

The cool bit is not that it replicates and destroys itself, but that it does so under the control of the instruction tape (which gets replicated along with the replicator itself). This allows you to fine-tune the behavior of the replicator. For example, you can change the rate at which it replicates by adding no-op instructions to the tape. This kind of fine-grain control over the behavior of a Life replicator has never been achieved before.

Good summary. It is unique and novel - indeed, as one 'Lifer' said, it is in a category of its own. But I was a little disappointed insofar as it is not quite self-contained or self-replicating yet. By the latter I mean spinning off an independent copy of itself which in turn reproduces, etc.

Incidentally, does anyone happen to know of any '3d life' platforms, rather than the basic Cartesian variety?

For 3d "Life", see Carter Bays http://www.cse.sc.edu/~bays/d4d4d4/

Many thanks!

My understanding (I have not tried to run gemini for more than a few thousand steps) is that the tape is not replicated, but is bounced over to the replicated copy of the ship. Best explanation I've seen:

"The program of Gemini is like DNA, and the replicators are proteins. The original Gemini program is only capable of replicating one protein: the replicator itself."

You can also program your own quick copy in C# http://www.primaryobjects.com/CMS/Article106.aspx

At this size, you may need a hash-life to see it run at any speed. That's not as quick to write as a naive algorithm--but of course still doable.

You will DEFINITELY need hashlife. In fact, one of the indications of the complexity of this pattern is how slowly it runs even in hashlife. It's instructive to compare the speed at which gemini runs with the speed at which the demo patterns that come with Golly run. At maximum speed, Golly routinely cranks out so many generations that it requires exponential notation to display the number. Gemini by comparison runs very slowly even at maximum speed. This fact alone makes it interesting. It is not easy to design a pattern that Golly can't optimize the bejesus out of (try it).

Reply on news.ycombinator.com