1D Conway's Life glider found, 3.7B cells long

Original Article ↗ Hacker News Discussion ↗

What the “1D” spaceship is

  • It’s an extremely large Conway’s Life spaceship on the standard 2D B3/S23 rule.
  • Initial state: a single row (1×3,707,300,605 bounding box) with relatively sparse live cells.
  • After 133,076,755,768 generations, the same 1D pattern reappears shifted by 2 cells along the line, leaving no debris, so it’s a pure spaceship (not a puffer or “smoking ship”).
  • “1D” just means at least one phase fits in a 1×N box; in between, the pattern is fully 2D and very complex.

High-level construction idea

  • The design is fully engineered, not found by random search.
  • Core technique: slow-salvo construction arms that emit carefully timed gliders to build and later dismantle complex machinery.
  • Four arms:
    • A blinker-based arm constrained to the initial line, using moving “fuses” on blinker chains to generate gliders with chosen phase and trajectory.
    • A binary arm, where bits are encoded by presence/absence of a second glider in a synchronized pair, modifying a target “anchor” and able to realize any needed period‑8 recipe.
    • Two ECCA (extreme compression construction arms) that implement a tiny “instruction set” (move steps, direction change, color/phase options) and interpret incoming bit streams to fire gliders with ~7–8 bits per glider.
  • A central “tape” is stored as blinkers/blocks along a spine; a fuse arm converts this into glider signals, which drive the binary arm and then ECCA1/ECCA2.
  • ECCA1 cleans and rebuilds the west side and creates ECCA2 and transition structures; ECCA2 cleans the east, stops all engines (switch engines, corderships, reflectors), destroys its own infrastructure, and converts the remaining machinery back into a shifted 1D line, starting the next cycle.

Visualization and simulation

  • Naive visualization at full resolution is infeasible; the effective 3D spacetime object would be astronomically large.
  • Golly with the HashLife algorithm can simulate a full period on a high‑RAM machine (tens of GB).
  • Observed large‑scale phases: a line → an arrow → arrow with nested kite‑like fronts → giant nested kites → collapse back to a line.

Terminology, rules, and open questions

  • Several commenters note the title should say “spaceship” rather than “glider,” though “glider” is used loosely in some CA contexts.
  • The rule is standard Life; there is no purely 1D Life rule here.
  • Discussion touches on Life’s Turing‑completeness, known self‑replicators, search techniques (soups + guided search + modular composition), and broader questions about random initial conditions, “superstable” configurations, and Life as a model of computation and physics.