Self-synthesizing oblique loopship

Self-synthesizing oblique loopship
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Pattern type	Spaceship
Number of cells	580460
Bounding box	3903968 × 3903985
Direction	Oblique
Slope	16461006/16460963
Period	75568091
Mod	75568091
Speed	(16461006,16460963)c/75568091 | Unknown
Heat	Unknown
Discovered by	Goldtiger997
Year of discovery	2021
Rules Outer-totalistic rules B3/S23 only # of rules 20 = 1
Glider synthesis Fewest gliders 144221† †Can be constructed with 15 gliders using the reverse caber tosser universal constructor.
Pattern files Macrocell ssol.mc

The self-synthesizing oblique loopship, or SSOL, is a self-constructing adjustable spaceship assembled by Goldtiger997 on August 2, 2021.

This pattern was voted Pattern of the Year for 2021 on the ConwayLife.com forums.

Overview

Like other loopships, the SSOL consists of a signal storage loop that moves by sending out two copies of a glider construction recipe. The first copy of the recipe is used to construct a new signal storage loop some distance from the original. The second copy is then directed into the new signal storage loop to allow the cycle to repeat. The previous loop circuitry self-destructs cleanly after it has emitted two copies of its contents.

The SSOL is the first loopship to use the new crabstretcher-based elbow push mechanism from the Speed Demonoid. It is also the first loopship that travels in an oblique direction. Perhaps most important, it is the first Conway's Life spaceship of any kind that is a non-trivial SMOS (spaceship made of spaceships): several of its phases consist of nothing but gliders, and yet the overall spaceship's velocity is different from the velocities of any of its component gliders. More generally, it is also the first self-synthesizing pattern constructed in Life, producing its own glider recipe in its evolution sequence.

Changes from previous loopship design

The previous orthogonal loopship was constructed before crabstretcher technology became available, so it used Cordership-based elbow pushes in a glide-reflecting design to allow for re-use of some of the corners of its signal storage loops.

This was necessary because Corderships travel slowly enough to make it more difficult to store a recipe for a simple diamond-shaped memory loop inside that same loop. Too much empty space is needed in the recipe, due to the need to wait until each Cordership gets far enough away before shooting it down to produce a target elbow; with a naive design, no matter how big the loop is made, the required wait times require such large gaps that there's no room left to store the actual construction recipe.

The new SSOL's crabstretcher elbow pushes move at c/4, and therefore requires much shorter gaps which leaves plenty of room for the rest of the recipe.

Infinite family of related spaceships

A script has been written to construct SSOL variants with signal storage loops of different sizes and shapes, and consequently different spaceship velocities. There are two primary degrees of freedom, corresponding to the NW/SE diameter and the NE/SW diameter of the signal storage loop. Many other timing adjustments can also be made, for example by adding or subtracting space between different components of the single-channel recipes, but it's not clear that this would result in any significantly new behavior.

Self-synthesizing glide-reflecting loopship

On March 8, 2022, Goldtiger997 completed a self-synthesizing spaceship with a design similar to the SSOL, except that it turns 90 degrees after every cycle and produces a mirror-image copy of itself. As a result it travels orthogonally in a zigzag pattern at a speed of 30985960c/144171206, which is approximately c/4.65. As with other loopships, the speed can be easily adjusted.