Space probes, like NASA's recent Pathfinder mission to Mars, have radio transmitters of only a few watts, but have to transmit pictures and scientific data across hundreds of millions of miles without the information being completely swamped by noise. Read about how coding theory helps.
Have you ever been in an aeroplane on a smooth flight when suddenly the plane bumps up and down for a short time as it goes through turbulent air? The study of turbulence is used to understand a range of phenomena from the simple squirting of a jet of water to the activity of the sun.
Daniel Bernoulli (1700-1782) discovered the relationship between the density of a fluid in a pipe, the speed it is travelling in the pipe and the pressure exerted by the fluid against the walls of the pipe. This is the story of what happened.