It’s true that, in life, sometimes the best things can happen to us when we least expect. Although many of the biggest breakthroughs and innovations in our world have been derived from years or even decades of meticulous research and development, several others have been happy accidents.

Whether it’s a failed experiment, a fortuitous mistake, or simply being in the right place at the right time, there are many accidental discoveries in our history that have changed industries for the better.

Below, we’ll explore in more detail about four of the most famous inventions that weren’t supposed to happen and ended up being game-changers in various sectors.

From perpetual motion fail to iconic gaming tool

French mathematician Blaise Pascal was on a journey to try and invent the world’s first perpetual motion device. This is a machine capable of generating its own energy to keep moving forever. Spoiler alert – we now know that perpetual motion isn’t possible, but Pascal wasn’t to know.

Although Pascal didn’t manage to crack the energy problem, he did manage to conceive the basis of the world’s first roulette wheel. Roulette became a popular game in Pascal’s native country of France, with his little physics experiment gone wrong creating the mechanism needed to power one of the most famous casino games of all time.

Roulette is now just as popular online as it is offline in land-based casinos. Today, random number generators (RNGs) are used to replicate the randomness of roulette games online. There are variations of the game involving wheels with a green single zero pocket, wheels with double zero pockets, known as American roulette wheels, and even modern twists known as Lightning roulette that pay out multipliers on random numbers.

The moldy petri dish which saved lives

Did you know that Alexander Fleming wasn’t someone who had a vision of changing the world of medicine forever? Far from it, in fact. Fleming was a humble scientist who was merely working in an untidy laboratory.

Before heading on holiday, Fleming accidentally left an open petri dish of bacteria out in the open air. Upon his return, he found a strange mold growing within the dish. It wasn’t a mold he’d seen before, since it was latching onto and killing the bacteria left in the dish. Fleming was intrigued. He looked more closely and, to his amazement, discovered he’d developed the world’s first antibiotic that we all know today as penicillin.

How a melted chocolate bar inspired the microwave

Picture the scene: you’re a busy engineer using radar technology. You’ve eaten half a chocolate bar and put the rest in your pocket to eat after work is finished. That’s what Percy Spencer did way back in 1945, when he discovered his chocolate bar had melted after working at close quarters with magnetrons.

Spencer deduced that the microwaves emitted by the magnetrons were heating up the chocolate, causing it to melt. Spencer tested his theory further still, using magnetrons to cook popcorn and even eggs, the latter of which exploded in his face during testing!

His discoveries led to the creation of the microwave oven, which has since become a kitchen staple in all four corners of the globe.

One man’s weak glue was another’s Post-it Note

In the 1960s, a scientist named Spencer Silver was working at American conglomerate 3M, trying to create a super-strong adhesive. Instead, he ended up with a weird, low-tack glue that could stick to surfaces but could also be easily removed without leaving any residue. It seemed like a total failure—after all, who needs a weak glue?

For years, no one knew what to do with it. Then, one of Silver’s colleagues, Art Fry, had an idea: what if they used it to create reusable sticky notes? That’s how the Post-it Note was born. Today, these little yellow squares are found in offices, schools, and homes everywhere. So, what started as a “failed” glue ended up revolutionizing the way we jot down reminders.

What’s the key takeaway here for business owners and fledgling entrepreneurs? Mistakes can often be breakthroughs in disguise. The next time something doesn’t go as you expect it, try and learn from it. You may just have discovered the next big breakthrough in your field, whether that’s opening a new restaurant or designing the next digital product.