That's kind of amazing. I wish someone unpacked the units of abstraction/compilation that must surely exist here.
Surely they aren't developing this with 1 or 0 as the abstraction level!
It’s also a relatively sparse line, as the number of live cells is less than a hundredth of the line’s extent: https://conwaylife.com/wiki/Unidimensional_spaceship_1
Almost 10 years of development.
Given that it starts as a single line, it is symmetric in the axis implied by that line, and hence can’t possibly move diagonally or orthogonal to the line. Hence it moves in the direction of the line.
I was a bit confused by that wiki page because it says "Direction Orthogonal" but like you said that can't be.
> The third and fourth arms are extreme compression construction arms "ecca", where a programming language interpreter is created and individual incoming letters are interpreted as instructions specifying which phase (mod 2) and line of glider to emit.