He conducted a series of elegant experiments in the 1860s using swan-necked flasks. These experiments showed that:
* Sterile broth remained sterile even when exposed to air, as long as the swan neck prevented dust particles from entering the broth.
* When the neck was broken, allowing dust to enter, the broth quickly became contaminated with microorganisms.
This demonstrated that microorganisms did not spontaneously arise from the broth itself but were instead introduced from the environment, specifically via dust particles.
Pasteur's work revolutionized our understanding of the origins of life and laid the foundation for the germ theory of disease.
