In the popular imagination, scientific breakthroughs are the direct result of methodical hypothesis testing inside spotless laboratories where every variable is tightly controlled. Yet a surprising number of the inventions and medical miracles that define modern civilization were born from clumsy laboratory accidents, forgotten petri dishes, and experiments that went completely wrong. Coined in 1754 by the English writer Horace Walpole after an ancient Persian fairy tale called The Three Princes of Serendip, the word serendipity describes the art of finding valuable things not sought for. As the French microbiologist Louis Pasteur famously observed, however, in the fields of observation, chance favors only the prepared mind.
Alexander Fleming and the Mold That Created Penicillin
Prior to the late 1920s, a minor paper cut, a dental infection, or a scraped knee in a rose garden could easily result in fatal septicemia because physicians possessed no reliable way to kill bacteria inside the human bloodstream without poisoning the patient. In August 1928, the Scottish bacteriologist Alexander Fleming left his cluttered basement laboratory at St. Mary’s Hospital in London to take a summer vacation with his family in Suffolk. Before locking the door, Fleming stacked several glass petri dishes containing colonies of Staphylococcus aureus bacteria on a corner bench out of reach of his antiseptic lysol tray.
Returning to his laboratory on September third, 1928, Fleming began sorting through the discarded dishes to wash them when one plate caught his eye. A microscopic spore of a blue green mold—later identified as Penicillium notatum—had drifted into the dish, likely from a mycology lab located one floor below. Instead of merely grumbling that his bacterial culture was ruined and tossing it into the disinfectant wash, Fleming paused and muttered his famous understated remark: that’s funny. All around the fuzzy ring of mold, the deadly Staphylococcus colonies had dissolved completely into transparent droplets. Isolating the “mold juice” he named penicillin—which was later purified for mass clinical manufacturing in the early 1940s by Howard Florey, Ernst Chain, and Norman Heatley—Fleming’s messy workbench saved an estimated two hundred million human lives.
Wilhelm Röntgen and the Mysterious Glowing Screen of X-Rays
On the dark autumn evening of November eighth, 1895, fifty year old German physics professor Wilhelm Conrad Rontgen was working alone in his laboratory at the University of Wurzburg, investigating how electrical currents pass through rarefied gases inside a glass Crookes cathode ray tube. To block out the visible purple glow of the tube itself, Rontgen wrapped the glass cylinder tightly in a jacket of thick black cardboard and darkened the room completely to check for light leaks.
The instant he switched on the high voltage induction coil, a faint, ghostly green shimmer caught the corner of his eye several feet away from the table. Lighting a match, he discovered that the glow was coming from a small cardboard screen painted with barium platinocyanide that happened to be sitting on a nearby bench for a future phase of the experiment. Because ordinary cathode rays could only travel a few centimeters through air and were completely blocked by black cardboard, Rontgen realized that an unknown, invisible form of radiation—which he named X rays after the algebraic symbol for an unknown quantity—was passing straight through solid matter. Calling his wife, Anna Bertha, into the lab weeks later and placing her hand over a photographic plate for fifteen minutes, Rontgen captured the world’s first medical radiograph: the haunting skeletal outline of her finger bones and her wedding ring, launching the field of diagnostic radiology and earning the very first Nobel Prize in Physics in 1901.
Percy Spencer and the Melted Candy Bar Behind the Microwave Oven
During the Second World War, the self taught electrical engineer Percy Spencer worked for the American defense contractor Raytheon in Massachusetts, designing high powered vacuum tubes called cavity magnetrons that generated short wavelength radio signals for Allied military radar systems. One afternoon in 1945, while Spencer was standing directly in front of an active magnetron tube on a test bench, he reached into his trouser pocket looking for a snack and noticed something bizarre: a peanut cluster candy bar he had been carrying had melted into a warm, sticky puddle inside its wrapper, even though he had felt no heat against his leg.
Realizing that the high frequency electromagnetic waves leaking from the radar tube were vibrating water and fat molecules inside the food, Spencer immediately summoned a colleague and sent out for a bag of unpopped corn kernels. Placing the kernels on the table in front of the waveguide horn, the engineers watched in delight as white popcorn began popping and flying across the laboratory floor. The next morning, Spencer cut a hole in the side of an empty metal kettle, placed a raw whole egg inside, and aimed the magnetron into the hole; when a curious engineer leaned over the kettle to peek inside, the superheated egg exploded straight into his face. Filing a patent in October 1945 for the “Radarange,” Spencer turned wartime radar weaponry into the ubiquitous countertop microwave oven.
Roy Plunkett and the Frozen Gas Cylinder That Became Teflon
On the morning of April sixth, 1938, at the DuPont Jackson Laboratory in Deepwater, New Jersey, a twenty seven year old chemist named Roy J. Plunkett and his assistant, Jack Rebok, were attempting to synthesize a new, non toxic chlorofluorocarbon refrigerant gas to replace dangerous sulfur dioxide and ammonia in household refrigerators. The night before, Plunkett had pumped one hundred pounds of tetrafluoroethylene gas into heavy steel cylinders stored on dry ice. Yet when Rebok opened the brass valve on one of the cylinders to let the gas flow into the reaction chamber, nothing came out.
Assuming the gas had leaked out overnight, a lesser chemist might have tossed the cylinder onto the scrap heap. However, when Plunkett lifted the “empty” cylinder and placed it on a scale, it still weighed the exact same amount as when it was full. Taking a hacksaw into the workshop, Plunkett and Rebok sawed the steel cylinder straight in half from top to bottom. Coated across the interior walls of the tank was a mysterious, waxy white powder: the gas molecules had spontaneously polymerized under high pressure using the iron container walls as a catalyst, forming polytetrafluoroethylene (PTFE). Testing the powder, Plunkett discovered it was the slickest solid substance on Earth, impervious to boiling acids, extreme heat, and solvents. Used initially in secret during the Manhattan Project to line valves holding corrosive uranium hexafluoride gas at Oak Ridge before being trademarked as Teflon in 1945, the accidental white powder revolutionized everything from aerospace heat shields to nonstick frying pans.
Constantin Fahlberg’s Unwashed Hands and the Birth of Saccharin
In June 1878, Constantin Fahlberg, a young Russian chemist working in the Baltimore laboratory of Professor Ira Remsen at Johns Hopkins University, spent a long day oxidizing coal tar derivatives—specifically orthotoluenesulfonamide—in a routine study of hydrocarbon reactions. Running late for dinner after sunset, Fahlberg hurried home to his boardinghouse without stopping to wash his hands thoroughly at the laboratory sink.
Sitting down at the dining table, Fahlberg picked up a piece of crusty bread roll and took a bite. To his surprise, the bread crust tasted intensely, shockingly sweet—far sweeter than glazed cake. When he wiped his mouth with his napkin, the cloth tasted sweet too, and when he rinsed his mouth with water, the glass itself seemed coated in sugar. Licking the tip of his thumb, Fahlberg realized the sweetness was coming directly from a chemical residue on his own skin. Running all the way back to the Johns Hopkins laboratory in the dark, he recklessly tasted the contents of every beaker, evaporating dish, and flask on his workbench until he located an overboiled beaker of benzoic sulfinide. Three hundred times sweeter than cane sugar yet passing through the human digestive tract without adding a single calorie, Fahlberg’s unwashed hands had discovered saccharin, the world’s first artificial sweetener.
