Louis Pasteur & Germ Theory
Before 1677, people had no clue that microscopic life existed all around them. Once the microscope was invented, scientists could finally see bacteria for the first time, opening up a whole new world of discovery.
For centuries, people believed in spontaneous generation - the bizarre idea that germs and bacteria just magically appeared from thin air when things started rotting. This theory seemed logical at the time, but it was completely wrong.
Louis Pasteur, a brilliant French chemist, wasn't buying this spontaneous generation nonsense. In 1860, he designed his famous swan-neck flask experiment to get to the bottom of why beer and wine kept going sour (a pretty important problem for the French!).
His experiment was genius in its simplicity. Pasteur took sterilised water and put it in two different containers - one with a curved swan-neck that prevented airborne particles from entering, and another completely open to the air. The sealed flask stayed clean whilst the open one bred germs, proving that microbes travel through the air and don't just appear magically.
Key Insight: Pasteur discovered that heating drinks to the right temperature kills harmful microbes - a process we still call pasteurisation today!
This breakthrough led Pasteur to develop germ theory in 1861 - the revolutionary idea that bacteria actually cause infection and disease through biological processes, not chemical ones. Suddenly, the invisible world of germs made perfect sense.