In 1827, the English botanist Robert Brown noticed that pollen.
grains suspended in water jiggled about under the lens of the.
microscope, following a zigzag path such as the picture on page.
three. Brown had discovered what is now known as Browian motion.
or Browian movement. Even more remarkable was the fact that.
pollen grains that had been stored for a century moved in the same.
way. The motion appeared to be totally random and at first Brown.
thought that he had discovered the "primitive molecule". That is.
until he observed the same motion in dusty particles of inorganic.
matter. Many people tried to master the concept of Brownian.
movement and had to go through some testy times. In 1889, G.L.
Gouy found that the "Brownian" movement was more rapid for.
smaller particles. For example, we do not observe Brownian motion.
in cars, buildings, or people. In 1900, F.M. Exner undertook the.
first quantitative studies, measuring how the motion depended on.
temperature and particle size. And he found that the speed of.
movement increased with a rise in temperature, but then, it.
decreased if bigger particles were used in the observation. .
The first truly reasonable explanation of Brownian movement.
came in 1877 by a man with the name of Desaulx. In which he.
determined that the phenomenon was a result of thermal.
molecular motion in the liquid environment of the particles.
involved. Indeed, this is the case. A suspended particle is.
constantly and randomly bombarded from all sides by molecules of.
the liquid. If the particle is very small, the hits it takes from one.
side will be stronger than the bumps from other side, causing it to.
jump. These small random jumps are what make up Brownian.
motion.
The famous Albert Einstein persued the quantitative studies.
behind Brownian motion in the early 1900's. It is well known that.
Einstein published in 1905 five important papers, including two.
papers on the special relativity. Another is the paper on.
