1929, a young bacteriologist, Sir Alexander Fleming, was tidying up his lab. After having been on vacation, he returned to work to find that a petri dish of Staphylococcus bacteria had been left uncovered.
1826, John Walker noticed a dried lump on the end of a stick while he was stirring a mix of chemicals. When he tried to scrape it off, voila, sparks and flame.
1940s, U.S. company Raytheon was working on wartime magnetron tubes used in radar defense. Percy Spencer, an engineer at the company, was working on a magnetron when he noticed that a candy bar in his pocket had started to melt due to the microwaves.
1853, Saratoga Springs restaurant cook George "Speck" Crum was annoyed with the complaints of a wealthy patron who repeatedly returned his thickly cut French style potatoes, so he sliced the potatoes as thinly as he could, fried the daylights out of them, and covered them in what he assumed to be a prohibitive amount of salt.
1895, German physicist Wilhelm Conrad Röntgen was tinkering with a tube of cathode rays, when he noticed that a piece of paper covered in barium platinocyanide began to glow across the room.
Researchers were testing sildenafil as a cure for hypertension and heart disease but the drug failed to show promising results for the heart.
2009, a small gaming studio in Finland was on the verge of bankruptcy, after making 51 failed games.