Collisions with atoms or molecules in a fluid causes random movement of nanobubbles and other particles. The phenomenon, also called pedesis, takes its name from Robert Brown, a 19th-century Scottish botanist.
However, is Brown really deserving of having the movement of random particles in fluid named after him? Yes, he described pedesis but he wasn’t able to explain it. Furthermore, he wasn’t even the first to observe it. As it turns out, we owe our understanding of what we refer to as Brownian motion to a handful of scientists across numerous centuries. Brown is only one of them.
Atoms are the smallest constituent unit of matter, invisible to the naked eye. It was impossible to prove their existence before the invention of the powerful microscopes in use by researchers today. However, ancient scientists and philosophers theorized about their existence. One of these was a poet in ancient Rome named Lucretius.
Lucretius identified what we now know as Brownian motion in 60 B.C. by describing the motion of dust particles in the air which, though not a liquid, is nevertheless a fluid. Lucretius regarded this motion of minuscule particles as evidence of the existence of atoms.
The existence of atoms was still a theory at the beginning of the 20th century. Einstein published a paper in 1905 that theorized that the motion of pollen in the water that Brown observed was caused by the movement of water molecules. This suggested the existence of molecules, as well as the atoms that come together to form them, but the evidence was still indirect.
Perrin was a French physicist and contemporary of Albert Einstein. Building on Einstein’s theories, he won the Nobel Prize in Physics in 1926 for confirming his hypothesis through experimentation.
Each of these men contributed something significant to our current understanding of Brownian motion.