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MousetrapAn old grade school demonstration of nuclear fission. Lay a bunch of mousetraps on the floor in a regular grid, and load each mousetrap with two ping pong balls. Drop one ping pong ball in the middle and watch the fun begin! (Unfortunately, Swarm does not yet support sound.) We implemented this in Swarm as an example of a simple discrete event simulation. Time stepping each mousetrap would be incredibly inefficient, since most mousetraps are doing nothing most of the time. Instead, we simulate each ping-pong ball as an event on the schedule. This method is much more efficient: you only compute when there is something to be done. One power of Swarm is that it supports both discrete event and time stepped models.
These are snapshots of the world over time (from early on through the end of the reaction). Mousetraps change from blue to red when the trap fires. Each time a mousetrap is triggered, it schedules two trigger events for two random nearby mousetraps sometime in the near future. The balls only fly a limited distance; that induces a spreading aspect to the reaction.
These two graphs show detail about the reaction rate. The top graph, the number of traps triggered over time, shows the classic result: the reaction initially spreads rapidly, but slows down and stops when it runs out of fuel (loaded mousetraps). The bottom graph is simply the number of events pending on the schedule, this corresponds to the number of ping pong balls currently in the air. |
Mousetrap
