Dr. Roy Lowry wanted to demonstrate a few basic principles of science, notably the behavior of liquid nitrogen under pressure. But how to get that across in a way that even the least scientifically curious student would think of as awesome.

Easy: Just add ping-pong balls!

Lowry and his assistants put together the "experiment" quite simply. He just pours a small measure of liquid nitrogen into a soda bottle, caps it off, and sticks in the bottom of a trash can. Then he and an assistant dump 1,500 ping-pong balls on top of it.

The thing about liquid nitrogen is that it becomes a gas very quickly... but the gas has nowhere to go. The resulting explosion pushes the trash can six feet in the air and launches the ping-pong balls all over the room where Lowry is showing off.

It looks neat but we've got to ask... who picked up all the ping pong balls?