Smart Facts – Brownian motion
Ten fascinating facts about Brownian motion to share with your KS3 science students.
- Brownian motion is named after Robert Brown who, in 1828, observed small particles from pollen grains moving about on the surface of water. He couldn’t explain why but he did publicly describe his observations.
- Robert Brown did not study the movement of pollen – this is too large to be moved by water particles. He actually studied tiny starch grains which are found inside pollen.
- Albert Einstein published a paper in 1905 which explained Brownian motion: water molecules were bumping into the pollen grain particles, causing them to move.
- Einstein’s paper about Brownian motion showed that it was possible to work out how many molecules were hitting a single pollen grain particle and how fast they were moving.
- The French physicist Jean Perrin used Einstein’s predictions about Brownian motion to work out the sizes of atoms. He won a Nobel Prize for his work.
- The idea about everything being made up of atoms has been around since the time of the ancient Greeks – but it took until 1905 for Einstein to prove it.
- Robert Brown was not the first person to record the jittery motion of small particles, but we credit him with the discovery, calling it Brownian motion.
- The first recorded observation of what we now call Brownian motion was made in 1785 by Jan Ingenhousz. He used charcoal dust on alcohol.
- A Roman, Lucretius, in around 60 BC, described Brownian motion of dust particles in a poem. He even said that this might be due to atoms!
- Scientists studying tiny nanoparticles suspended in liquids find Brownian motion a real annoyance, as the particles keep moving around!
Exploring Brownian motion with your students this term? Why not check out the following free resources?
Scientist Biography: Robert Brown
Free video: Random force and Brownian motion
Homework Activity: Swirling colours and water molecules