A large number of discoveries in science have been accidental, so much so that there is an actual term for this phenomenon. It’s called the ‘Principle of Limited Sloppiness.’ Here are some discoveries that were accidents and proved to be very useful to humankind.
Smallpox vaccination.
Edward Jenner, a British surgeon, noticed that the dairy maids who contracted cowpox never contracted the dreaded smallpox. It struck him that this could lead to the development of a vaccination for smallpox. He took the pus from the cowpox sores of a dairy maid and injected an eight year old boy with it. The boy developed a fever, but had no other adverse reactions to the vaccination. Later, Jenner injected the boy with the smallpox virus. The boy, having developed resistance, did not contract the disease.
This was not just the discovery of the smallpox vaccine, it was the discovery of the very idea of vaccination, which has proved extremely valuable for us.
Penicillin
Dr Alexander Fleming was conducting research on flu in 1928. He saw that some mold had contaminated one of his petri dishes containing a flu culture. He decided to examine the dish more closely, and saw that the area surrounding the mold was clear of bacteria. This led to the development of penicillin, which remains a very important antibiotic to this day.
X-rays
German physicist Wilhelm Conrad Rntgen was studying cathode rays in 1895 when he happened to discover X-rays. He was trying to see if cathode rays could penetrate a glass tube completely covered with black cardboard. He noticed a glow appearing in his laboratory, many feet away from his glass tube covered in cardboard. With some more investigation, he found that the rays which were escaping the tube were very different from cathode rays and could penetrate a variety of substances.
X-rays have since found vital applications in medical science, where they are used to diagnose fractured bones in the human body.
Radioactivity
Henry Becquerel was working with phosphorescent materials in 1896 when he stumbled upon radioactivity. He wrapped a photographic plate in black paper and placed phosphorescent uranium salts on it. These salts blackened the photographic plate. Becquerel saw that the blackening of the plate had nothing to do with phosphorescence, because the same effect was also achieved when he used metallic uranium or one of its non phosphorescent salts.
These rays seemed to be similar to X-rays at first, but further studies by Becquerel, Marie and Pierre Curie and Ernest Rutherford led to a better understanding of these rays.
Radioactive decay finds significant applications in paleontology and archaeology, in the form of radiocarbon dating. It has helped our understanding of evolution considerably.