I find it fascinating how many important discoveries were made more or less by accident -- either because a researcher was looking for something and stumbled upon something else, or because (s)he was just playing around in the lab and noticed something cool.
Here are a few of my favorite examples:
- Two researchers, George Beadle and Edward Tatum, were researching nutrition in a mold called Neurospora, and were particularly interested in why some strains of Neurospora starved to death even when given adequate amounts of food. Their research generated the concept of "one gene-one protein" -- the basis of our understanding of how genes control traits.
- Charles Richet was studying how the toxin of a rare species of jellyfish affects the body. His research led to the discovery of how anaphylactic shock works -- and the development of the epi pen, saving countless lives from death because of bee sting allergies, nut allergies, and so on.
- Wilhelm Röntgen was researching the newly-invented cathode-ray tube, which at that point had no practical applications whatsoever. That is, he was playing around. He noticed that when he activated the tube, even though it was completely covered, some fluorescent papers at the other end of the room began to glow in the dark. He had just discovered x-rays.
- In 1945 an engineer named Percy Spencer was working with a device called a magnetron that looked like it might have applications in ground-based radar systems. While messing about with it, he noticed that a chocolate bar in his pocket had melted. He patented a design that year that we now call the "microwave oven."
- Alexander Fleming was something of a ne'er-do-well in the scientific world. He did a lot of raising of bacteria on plates, and his favorite hobby was to take brightly-colored species of bacteria and paint them on agar media to make pictures. One day, a mold spore blew in and landed on one of his picture-cultures and spoiled it. His further investigation of how the mold spoiled the culture led to the discovery of the first antibiotic, penicillin.
- Roy Plunkett was working with gases that could be used to quickly cool vessels in scientific experiments, and after one failure he found that the vessel was left coated with a slick substance. He eventually named it "Teflon."