Ever heard of a vortex ring? According to Wikipedia, a vortex ring is a torus shaped vortex in a fluid; namely a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. Well, you probably still have no clue what a vortex ring is. That’s okay, since all you really need to know about it is that it’s really, really cool. The guys at BBC managed to actually build a vortex cannon and used it to blow a house of bricks over. Watching it in action is so much more fun than listening to the theory:
