A small action can be amplified to become a large one, even if you are unaware of it

A domino can knock over another domino about 1.5x larger than itself. A chain of dominos of increasing size makes a kind of mechanical chain reaction that starts with a tiny push and knocks down an impressively large domino.

Original idea by Lorne Whitehead, American Journal of Physics, Vol. 51, page 182 (1983).

See

http://arxiv.org/abs/physics/0401018 and

http://arxiv.org/abs/1301.0615

for sophisticated discussions of the physics.

As seen on QI in the "kinetic" episode. I was contacted by those Elves.

http://youtu.be/9jzlUEpXK48?t=39m30s