One rule. Four is too many. Pour sand and watch order assemble itself.

The rule

On the table

  • 0 · empty0
  • 1 grain0
  • 2 grains0
  • 3 grains0
  • 4+ toppling0

Avalanches log–log

size in topplings how often waiting for rain
0 measured

Small slides are common, vast ones rare, and nothing in the rule says where one becomes the other.

fig. 1 · the tableopen edge · what falls off is gone