Nine everyday things that were invented by accident

Accidental discovery is more common than the tidy version of scientific history suggests. What separates a useful accident from a wasted one is almost always the same thing: somebody noticed.

1. Penicillin

Alexander Fleming returned from holiday in 1928 to a petri dish contaminated with mould. Bacteria near the mould had died. The contamination was the finding.

2. The microwave oven

Percy Spencer, working on radar equipment, noticed a chocolate bar in his pocket had melted. He tried popcorn next, then an egg.

3. Sticky notes

A 3M chemist produced an adhesive that was too weak to be useful. It sat unused for years until a colleague wanted bookmarks that would stay in a hymnal without damaging it.

4. Safety glass

A French chemist knocked a flask off a shelf. It cracked but held its shape — a plastic film left inside from an earlier experiment had kept the fragments together.

5. Vulcanised rubber

Charles Goodyear spilled a rubber and sulphur mixture onto a hot stove. Instead of melting, it hardened into something stable across temperature.

6. The Slinky

A naval engineer was developing springs to stabilise instruments at sea. One fell off a shelf and walked itself down a stack of books.

7. Saccharin

A chemist ate dinner without washing his hands after a day working with coal tar derivatives. The bread tasted sweet.

8. X-ray imaging

Wilhelm Röntgen noticed a screen across his lab glowing while he worked with a covered cathode ray tube. Something was passing through the cover.

9. Matches

An English chemist was scraping a mixture off a stirring stick. The friction ignited it.

The pattern

None of these were lucky in the sense of requiring no skill. In each case someone with relevant expertise encountered an anomaly and — instead of cleaning it up and starting over — asked why it had happened.

The accident supplies the anomaly. The training supplies the question.