A self-replicating glider, anyone?

[Rhombic]

I had this idea, where one could create a spaceship gun spaceship, which, instead of emitting smaller or different spaceships, emits exactly the same spaceship. Basically, a self replicating spaceship.
Has anyone seen such a pattern before?
Is it possible for it to exist, even if it is very large in scale?

[dvgrn]

I had this idea, where one could create a spaceship gun spaceship, which, instead of emitting smaller or different spaceships, emits exactly the same spaceship. Basically, a self replicating spaceship.
Has anyone seen such a pattern before?
Is it possible for it to exist, even if it is very large in scale?

Perfectly possible, but not very easy to implement. The "easiest" way is probably universal-constructor based: imagine something rather like the Gemini spaceship, but more diamond-shaped, and instead of building just one copy of itself, it builds two, at 90 degrees to each other. This is tricky for a number of reasons, but not impossible. For it to count as a spaceship, it would have to include a self-destruct mechanism for the parent spaceship.

There's been speculation for many years about an actual moving loop carrying gliders -- something like a Cordership fleet. The loop would have to encode a slow salvo that builds seeds for another Cordership fleet just like it.

Unfortunately it's a lot less efficient to encode construction data as binary information -- the presence or absence of a glider every 96 ticks, or whatever -- as opposed to direct timing information, the way recipes are stored in the Gemini.

It's hard to figure out exactly how to read the gliders in the moving loop to create a slow salvo. Once the slow salvo is created, it might be sent backwards along the Cordership fleet's path to strike a target block that was left behind a long time ago, to construct and trigger the Cordership-fleet seed. It could also be a block that was placed by the previous construction, I suppose, maybe by a fast spaceship following a slow one.

[simsim314]

I've in mind design of a "smart loop". Smart loop is self replicating creature that uses universal construction to replicate, and has "brain" based on universal computation. The thinking part helps it to orient itself in its environment and decide whether this is a good time to replicate or not, and to what direction it's best to move.

Another speculative idea is to use neural network based on and/or gates to make decisions. This could be implemented using gliders as input, and/or gates are known in GOL, and then output a glider as input to the next layer. This design has the advantage of using parallel properties of GOL which other universal computers lack.

[wildmyron]

The closest thing I've seen which fits this description is some kind of puffer which emits copies of itself that interact to suppress further replication. There are examples in a number of different rules - mostly multi-state - such as members of the BSFKL rule space, the PlusMinus rulespace and possibly also Generations rules. Unfortunately I can only find one example at the moment: in a 5-state PlusMinus rule. The first pattern in that post is the core component of the puffer, shown here in a different phase:

Code: Select all

x = 9, y = 8, rule = PlusMinus2_004
2.3B$4.B.B$2.D3BACB$2B.B.4A$2B.B.4A$2.D3BACB$4.B.B$2.3B!

This engine moves at c and has period 32. At gen 57 you can see a copy of the puffer moving in the opposite direction. At gen 64 you can see the original puffer has now become a spaceship as a result of interaction between successive "offspring". The spaceship consists of the puffer engine and two "offspring" which interact to create a block and annihilate the block from the previous interaction:

Code: Select all

x = 79, y = 8, rule = PlusMinus2_004
72.3B$17.B.A6.2CD2C18.B2.2C20.B.B$15.2B3.CB2.CB2.B2.BC14.2B2.B20.D3BA
CB$2C13.2A3.2A2.9D14.2A2.A2.B15.2B.B.4A$2C13.2A3.2A2.9D14.2A2.A2.B15.
2B.B.4A$15.2B3.CB2.CB2.B2.BC14.2B2.B20.D3BACB$17.B.A6.2CD2C18.B2.2C
20.B.B$72.3B!

If you continue running for intervals of 57 gen you will see new puffer engines being formed which successively become spaceships traveling to the left and to the right.

The net effect is something like a statorless gun, but there is no part of the gun which is not part of the spaceships which are emitted. At any time you can take one of the spaceships, remove its trailing block, and you will have a replicating pattern again.

I don't know if this fits your definition, partly because it's a bit vague due to the contradiction with the traditional definition of spaceship.