<| Forest Fire Simulation [11.2008]
This program simulates a fire spreading through a 2-D grid of trees.
Trees which are "on-fire" will set off trees on adjacent nodes during successive time-steps,
and the fire will spread throughout the grid.
The trees occupy grid cells at random, with a selectable probability density.
The results are highly-nonlinear and non-intuitive.
For low tree-densities, the fire quickly burns out, but at intermediate densities the fire burns
patches of trees exhibiting characteristic "fractal" patterns (as shown, right).
Then, above some critical tree-density, the fire quickly spreads to burn essentially
all trees in the grid.
Of note, the range of tree-densities from few-burned to all-burned is extremely narrow, and the
curve relating %trees-burned to tree-density is highly-nonlinear ("S"-shaped curve in diagrams).
This simulation has some relationship to other situations involving random distributions of
active-nodes which can "infect" neighboring nodes, including "real" forest fires,
the spread of epidemics, spread of "memes", etc.
See next page for more details about the
Forest Fire Simulation.