INTRODUCTION

Whether you have heard it in school or read about it in some popular science magazine, most people know that atoms exist.

But how do we know that atoms exist?
AND
How do we know that all matter is composed of atoms?

THE ANSWER
1. Phenomenon of Brownian motion (depicted below)
2. Albert Einstein's 1905 paper on suspended bodies in liquids
3. Jean Perrin's experiments on Brownian motion.

BROWNIAN MOTION
As you can see from the above picture ⁶ , Brownian motion is simply the random motion of a suspended body when placed in a liquid.

However, before we can describe how these two facts lead to the existence of atoms, we first need to explore the history of those little things that make us all up!

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