Historical Facts

10 Things You Didn’t Know Were Invented by Accident

History is full of brilliant minds and meticulous experimentation, but some of the world’s most transformative inventions didn’t follow a plan. Instead, they were stumbled upon by accident: the by-product of unrelated experiments, unintended chemical reactions, or simple human error.

Below, we uncover ten world-changing inventions that remind us how often history turns not on intent, but on unexpected discovery.

Penicillin

Discovered by: Alexander Fleming, 1928

Accident: A mold grew on a petri dish he had left unattended.

Impact: Ushered in the era of antibiotics.

While researching bacteria at St. Mary’s Hospital in London, Fleming noticed something peculiar — a mold (later identified as Penicillium notatum) was killing surrounding bacteria in his dish. This accidental observation led to the development of penicillin, the world’s first true antibiotic. It would ultimately save millions of lives, especially during World War II.

Microwave Oven

Discovered by: Percy Spencer, 1945

Accident: A candy bar melted in his pocket during radar experiments.

Impact: Revolutionized cooking technology and kitchen convenience.

Spencer, an engineer with Raytheon, was working with magnetrons — components of radar systems — when he noticed a chocolate bar in his pocket had melted unexpectedly. Curious, he placed popcorn kernels near the magnetron, which promptly popped. His innovation led to the development of the first microwave oven, initially used in restaurants and later adopted in homes worldwide.

X-Rays

Discovered by: Wilhelm Conrad Roentgen, 1895

Accident: Observed a glow from a fluorescent screen while experimenting with cathode rays.

Impact: Transformed medical diagnostics.

Roentgen was testing vacuum tubes when he noticed that a nearby screen began glowing, even though the tube was shielded from it. The mysterious rays were able to pass through solid objects. Within months, X-rays were being used in hospitals to examine broken bones and locate bullets. Roentgen received the first Nobel Prize in Physics in 1901.

Post-it Notes

Invented by: Spencer Silver and Art Fry, 1974

Accident: Created a weak adhesive instead of a strong one.

Impact: Became a global office staple.

Silver, a scientist at 3M, developed a low-tack adhesive with no clear application. Years later, colleague Art Fry used it to anchor bookmarks in his hymnbook — and the Post-it Note was born. What was once deemed a failed experiment became one of the most ubiquitous tools in workplaces and schools.

Safety Glass

Discovered by: Édouard Bénédictus, 1903

Accident: Dropped a glass flask coated with plastic cellulose nitrate — it cracked but didn’t shatter.

Impact: Paved the way for shatterproof glass in vehicles and buildings.

The French chemist’s lab accident revealed a surprising property: the glass remained largely intact due to the presence of the plastic film. Today, laminated safety glass is standard in car windshields, lab equipment, and architectural glazing.

Vulcanized Rubber

Invented by: Charles Goodyear, 1839

Accident: Spilled rubber and sulfur on a hot stove.

Impact: Enabled durable rubber products for industry and transportation.

Goodyear had been desperately trying to make rubber more stable. One day, he accidentally dropped a rubber-sulfur mix on a hot surface. Instead of melting, it hardened into an elastic yet resilient material — the birth of vulcanized rubber, used in tires, hoses, and shoes.

Saccharin (Artificial Sweetener)

Discovered by: Constantin Fahlberg, 1879

Accident: Failed to wash his hands before dinner and noticed a sweet taste.

Impact: Introduced the first zero-calorie sweetener.

While researching coal tar derivatives at Johns Hopkins University, Fahlberg unintentionally tasted his experiment. The result was saccharin, the world’s first artificial sweetener. Though its safety was once debated, it paved the way for sugar substitutes and diabetic-friendly products.

Teflon (PTFE)

Discovered by: Roy Plunkett, 1938

Accident: Gas in a cylinder polymerized into a slippery solid.

Impact: Found wide use in cookware, machinery, and aerospace.

Working for DuPont, Plunkett was experimenting with refrigerant gases when one canister failed to release its contents. Upon opening it, he discovered a waxy white substance that was incredibly slick and non-reactive — Teflon, used in everything from non-stick pans to NASA gear.

Corn Flakes

Invented by: John and Will Kellogg, 1894

Accident: Left boiled wheat sitting out too long.

Impact: Helped launch the breakfast cereal industry.

The Kellogg brothers, operating a sanitarium in Michigan, were preparing a simple diet for patients. One day, they accidentally let boiled wheat sit out. It turned stale, but when rolled flat and baked, it formed crispy flakes. They later repeated the process with corn, creating corn flakes, the cornerstone of modern breakfast cereal.

Anesthesia (Ether Use)

Discovered by: Crawford Long, William Morton, and others (1840s)

Accident: Observed people injuring themselves while intoxicated on ether and feeling no pain.

Impact: Enabled painless surgery.

Ether was commonly inhaled recreationally in the 19th century. Physicians noticed that people didn’t feel pain while under its influence. Crawford Long and William Morton later introduced it into surgical practice. This accident ushered in modern anesthesia, transforming the entire field of medicine.

Accidents That Reshaped the World

These stories remind us that historical progress often follows paths no one could have predicted. While we often think of invention as the result of calculation and perseverance, many of our most essential breakthroughs were the results of chance, curiosity, and observation in moments of failure or distraction.

In each case, what mattered most was not the accident itself, but the person who recognized its potential for harm.