I once read a library book on meteors. The author used a program to simulate alternatives of the 20th Century.
In most simulations, someone was killed, but usually nobody knew it...one would start an avalanche that sweeps away a Swiss village, or one would sink an ocean liner, or hit a hunter in the wilderness, that kind of thing.
As he ran more simulations, bigger disasters happened (IIRC a Tunguska happened in London in 1901).
Anybody know that book? Anybody know if I can get the program?