h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

This is now the third time I've heard the Brownian motion referred to in a comical way and I feel sorry that the joke goes over my head every time.

I didn't study enough physics: What *is* the Brownian motion?

Imagine a pool table where the balls don't decelerate. Take a break and the balls fly off in all directions contantly banging into each other and the cushions of the table.

Now place a larger ball, say a soccer ball, in the middle of all this - and it will be bumped into and moved by the pool balls appearing to move around randomly.

The faster the pool balls move the faster and more eratic the motion of the football. Now if the pool balls are molecules and the soccer ball is a microscopic particle you observe Brownian motion in the microscopic particle.

Named after Robert Brown, biologist, who discovered it in pollen suspended in water, if my memory serves me correctly.

Thankyou for that!