Accidental Discoveries That Changed the World

Luigi Galvani's twitching frog legs, Bologna, 1780s Galvani was dissecting frogs near an electrostatic generator when an assistant touched a scalpel to an exposed nerve and the leg kicked. The chance part was the timing; the years of follow-up were deliberate, and he waited until 1791 to publish, arguing for an electrical fluid inherent in the body. Alessandro Volta disagreed, insisting the charge came from outside the frog, and the experiments he ran to prove it produced the voltaic pile, an early battery. Galvani was right that muscles respond to electricity and wrong about where this charge came from, and the quarrel pushed both nerve physiology and electrochemistry forward.

Hans Christian Ørsted's compass needle, Copenhagen, 1820 During a lecture in 1820, Ørsted saw a compass needle near a current-carrying wire swing away from magnetic north. It moved so slightly that the audience did not notice. Accounts differ on whether the demonstration was set up to look for a link between electricity and magnetism, so this is the most arguable "accident" here, but the surprise is well recorded. Ørsted spent months testing it before announcing in July 1820 that an electric current generates a magnetic force. Ampère turned it into a law and Faraday later showed the reverse effect, and every electric motor and generator descends from that twitch of a needle.

Charles Goodyear's rubber on the stove, Woburn, Massachusetts, 1839 Goodyear had already spent years adding things to rubber, sulfur included, trying to make it less sticky and less sensitive to heat and cold. Then a sample mixed with sulfur landed on a hot stove and came out tough instead of soft. Versions of the moment vary, from a dropped lump to a flung sample, but the outcome does not: heat plus sulfur was the missing step. It still took him until 1844 to secure a patent for the process. Tires, hoses, seals and shoe soles all depend on it, yet Goodyear died in 1860 owing about $200,000, having spent his last years fighting infringers in court.

William Henry Perkin's failed quinine, London, 1856 Perkin was 18 and on Easter vacation from the Royal College of Chemistry when he tried to make quinine, the malaria drug, from chemicals derived from coal tar. He failed, but one product was a purple substance, and instead of discarding it he tested it as a dye. Mauveine became the first commercialized synthetic dye, and by 1857 he had opened a factory at Greenford Green outside London. The bigger consequence was what came next: synthetic dyes formed the basis of a new chemical industry and eventually the pharmaceutical industry too, which makes this teenage failure one of the most productive in history.

Constantin Fahlberg's sweet dinner roll, Johns Hopkins University, 1878 Fahlberg was working in Ira Remsen's Baltimore lab and had spilled an experimental compound over his hands. At dinner he picked up a roll and bit into a remarkably sweet crust, then ran back to the lab and tasted everything on his workbench to find the source. It is a lesson in bad lab hygiene as much as discovery. Remsen and Fahlberg published the synthesis jointly in February 1879, but in 1886 Fahlberg patented it claiming to be the sole discoverer, and Remsen protested. Saccharin, hundreds of times sweeter than sugar, became the first artificial sweetener and still sits in diet sodas and tabletop packets.

Wilhelm Röntgen's glowing screen, Würzburg, November 8, 1895 Röntgen was studying cathode rays and had wrapped his tube in heavy black cardboard, yet a fluorescent screen about nine feet away began to glow. Nothing he knew about could cross that gap, and he spent the following weeks testing the unknown rays, which he called X for that reason. One famous plate showed his wife Bertha's hand with her wedding ring clearly visible. He submitted his first communication on December 28, and within a year X-rays were an established part of diagnosis and therapy. The first Nobel Prize in physics, in 1901, went to him for it.

Henri Becquerel's cloudy week, Paris, March 1, 1896 Inspired by X-rays, Becquerel suspected that glowing uranium salts absorbed sunlight and gave it back out as X-rays. To test it he needed sun, and Paris stayed overcast for several days in late February, so the wrapped photographic plates and uranium sat in a drawer. On March 1 he developed them anyway, expecting a faint image, and found a remarkably clear one. Why he bothered is still debated, but he reported the next day that the salts emitted radiation with no sunlight at all. Marie and Pierre Curie took up the strange rays, and the three shared the 1903 Nobel Prize for work on radioactivity.

Édouard Bénédictus's dropped beaker, France, 1903 The French chemist knocked a glass beaker to the floor and watched it crack without falling apart. A cellulose nitrate solution had dried inside it into a thin film that held the shards in place. Plenty of people have dropped a dirty beaker; the step that mattered was seeing a use for it, and he patented the first laminated glass in 1909. A sheet of plastic sandwiched between panes is still how car windshields keep from spraying passengers with glass, and the same idea now protects shop fronts, skylights and bulletproof windows.

Eric Fawcett and Reginald Gibson's waxy solid, ICI Winnington, England, March 1933 The two ICI chemists were pushing ethylene and benzaldehyde together at very high pressure, looking for new reactions rather than a plastic. On March 27 they found a waxy solid in the vessel: polymerized ethylene. Nobody could repeat it reliably until the missing ingredient turned out to be a trace of oxygen in the ethylene, a narrow margin, since too much made the mixture explode. Full-scale production began on September 1, 1939, the day Germany invaded Poland, and polyethylene transformed the design and installation of airborne radar during the war. Today it is the most common thermoplastic in the world, in everything from shopping bags to pipes.

Roy Plunkett's empty cylinder, DuPont's Jackson Laboratory, April 6, 1938 Plunkett was making tetrafluoroethylene gas for refrigerant research when a cylinder refused to release any, even though it weighed the same as before. Instead of writing it off as faulty, he and his assistant Jack Rebok opened it and tipped out a white powder. The gas had polymerized inside into PTFE, which proved extremely heat-tolerant and stick-resistant. Its first job was in the gaseous diffusion process of the Manhattan Project. Teflon pans came years later, and the same material now coats everything from satellite components to cookware. The photo is a later reenactment of the discovery by Plunkett, Rebok and Robert McHarness.

Harry Coover's too-sticky plastic, 1942 and 1951 This is an accident that had to happen twice. In 1942 Coover's team was looking for a clear plastic for precision gunsights, found that cyanoacrylates stuck to everything, and rejected them. In 1951, at Eastman Kodak's plant in Kingsport, Tennessee, the same compounds came up again in other research and proved just as sticky, and this time Coover recognized what a fast, strong glue was worth. Kodak sold it as Eastman 910 from 1958, the product the world now calls super glue, and during the Vietnam War field surgeons used it on open wounds to stop bleeding until soldiers reached medical care.

Percy Spencer's melted candy bar, Raytheon, mid-1940s Spencer was an engineer working on magnetrons, the tubes that power radar, when he noticed the candy bar in his pocket had heated up while he stood near one. Sources disagree on the year and even the kind of candy, but the follow-up is well documented: he put popcorn kernels near the magnetron and watched them pop across the lab, and Raytheon filed for a patent on a microwave cooking oven. The first Radarange, sold from 1947, stood almost 6 feet tall, weighed about 750 pounds and cost around $5,000. Twenty years later, in 1967, an Amana countertop model brought it into ordinary kitchens for $495.

Arno Penzias and Robert Wilson's unwanted noise, Bell Labs, Holmdel, New Jersey, 1964 to 1965 The two radio astronomers were using a horn antenna built for satellite communications as a radio telescope, and could not get rid of a faint background hiss that seemed to come from every direction. They suspected the pigeons roosting in the horn, removed the birds and cleaned out their droppings, and the signal stayed. The explanation came from Robert Dicke's group at Princeton, who were looking for exactly this: leftover radiation from the early universe. The two teams published side by side, and the hiss became strong evidence for the Big Bang. Penzias and Wilson shared the 1978 Nobel Prize in physics.

Jocelyn Bell Burnell's "bit of scruff," Cambridge, 1967 Bell Burnell was a graduate student checking the output of a new radio telescope that produced about 100 feet of chart paper a day. Among it she spotted a small, unusual signal and kept going back to it until it resolved into pulses about 1.3 seconds apart. The surprise was real, but this is the clearest case here of a prepared mind: a less careful reader would have skimmed past lines scrunched into a quarter of an inch on a 400-foot roll of chart. The paper in Nature in early 1968 announced the first pulsar, a spinning neutron star. Antony Hewish received the 1974 Nobel Prize; she did not, though she later won the 2018 Breakthrough Prize.