Clouds 1

From Softology's collection · B13-14,17-19/S13-26

A dense random fill clumps into smooth clouds within a few generations, then holds still.

Clouds 1 in the 3D Game of Life: cells as cubes in a 15×15×15 box, 40 generations in.
Open Clouds 1 in the simulation →
After 40 generations from a random fill with 60% of cells alive, in a 15×15×15 box that wraps at its edges: 3,031 live cells.

The rule

In Softology's notation 13-26/13-14,17-19/2/M: a live cell survives with 13 or more live neighbours, half of its 26 or more, and a dead cell is born with 13, 14, 17, 18 or 19. Two states, so a cell is simply alive or dead. A cell needs a crowd around it either way, so lone cells and thin strands vanish and noise smooths into rounded masses.

What it does

It starts from a random fill with 60% of the cells alive. In 20 seeded runs in a 30×30×30 box, every one had stopped changing between generations 7 and 12, with about 89% of the box alive: from outside, a block. The cutaway (C) and the slice view (S) show the shapes inside it.

Clouds 2 has fewer births (13 or 14) and survives from 12: in the same test its clouds were thinner, about 70% of the box.

Run Clouds 1 from its start →

How the rule works

Picking it in the app restarts the world from a random fill with 60% of cells alive. Its seed is fixed, so it is the same world every time, one still alive 40 generations later in the default 15×15×15 box; N tries another seed.

Notation

Birth/survivalB13-14,17-19/S13-26
Softology, MCell (S/B/C/N)13-26/13-14,17-19/2/M
NeighbourhoodMoore (26 cells)

B lists the neighbour counts at which an empty cell is born, S those at which a live cell survives, and C the number of states. How to read a rule

More of Softology's rules

All 30 rules · From 2D to 3D: why Conway's rule needs changing in 3D