Introduction
We all think we have a solid general knowledge. Yet some "truths" we have been repeating since childhood are completely false. These myths are so deeply embedded in our daily lives that they pass for established facts. Researchers at Harvard University have estimated that the average person believes at least 10 false common misconceptions without even realizing it. Word of mouth, movies, outdated textbooks, and now social media spread these errors from generation to generation.
Ready to find out if you have been caught out? Here are 15 general knowledge mistakes that almost everyone makes, along with the scientific and historical explanations that set the record straight.
History
1. "The Great Wall of China is visible from space"
The myth: You can see the Great Wall with the naked eye from space, or even from the Moon.
The reality is quite different. The Great Wall averages about 6 meters in width. From low Earth orbit (roughly 350 km), that is like trying to spot a human hair from 3 km away. Several astronauts, including Yang Liwei (the first Chinese person in space), have confirmed it is not visible to the naked eye. This myth dates back to 1932, long before the first space flights. In contrast, motorways and airports, which are much wider, are actually visible from orbit.
2. "Napoleon was short"
The myth: Napoleon Bonaparte was a very short man.
Napoleon was 1.68 m tall, which was perfectly average for the era (the average male height in early 19th-century France was around 1.65 m). The confusion stems from a difference between French and English inches. His height of "5 feet 2 inches" in French measurement actually corresponded to about 5 feet 7 inches in English measurement. Moreover, British propaganda of the time loved to caricature him as a tiny figure, an image that has survived for two centuries.
3. "Vikings wore horned helmets"
The myth: Viking warriors fought wearing helmets adorned with impressive horns.
No archaeological evidence supports this popular image. Real Viking helmets were simple iron designs, sometimes with a nose guard. The horned image comes from costumes created for a Wagner opera in 1876 and Romantic-era depictions from the 19th century. In battle, horns on a helmet would have been more of a liability than an asset, offering easy grips for the opponent.
4. "Christopher Columbus proved the Earth was round"
The myth: Before Columbus, people thought the Earth was flat, and he proved otherwise in 1492.
The ancient Greeks already knew the Earth was round. Eratosthenes had even calculated its circumference with remarkable accuracy around 240 BC, within less than 2% of modern measurements. During the Middle Ages, European scholars did not believe in a flat Earth. The real debate was about the size of the Earth and the distance to Asia sailing westward. Ironically, Columbus had underestimated this distance and would have perished without the accidental discovery of the Americas.
Science
5. "We only use 10% of our brain"
The myth: Humans only use 10% of their brain capacity, and we could unlock powers if we used the remaining 90%.
Modern brain imaging (functional MRI) clearly shows we use our entire brain, even though not all areas are active simultaneously. Each region has a specific function. Even a minor lesion in any brain area causes measurable consequences. This myth has been popularized by movies like Lucy but has no scientific basis. The brain accounts for only 2% of our body mass but consumes about 20% of our energy, which would be a colossal evolutionary waste if 90% were unused.
6. "Lightning never strikes the same place twice"
The myth: A place struck by lightning will never be struck again.
This is completely false. The Empire State Building in New York is struck by lightning about 25 times per year. Lightning preferentially strikes elevated points and metallic structures, so certain locations are far more likely to be struck than others, repeatedly. American ranger Roy Sullivan was even struck by lightning 7 times during his lifetime and survived each time.
7. "Sunflowers follow the sun all day"
The myth: Sunflowers turn their heads to follow the sun from morning to evening.
Only young, growing sunflowers track the sun (a phenomenon called heliotropism). Once mature and in full bloom, sunflowers remain permanently oriented toward the east. This morning orientation attracts more pollinators because the flower warms up faster with the rising sun, increasing bee visits by nearly 5 times compared to west-facing flowers.
8. "Glass is a liquid that flows slowly"
The myth: The windows of old cathedrals are thicker at the bottom because the glass has flowed over centuries.
Glass is indeed an amorphous solid, but it does not flow at room temperature. The uneven thickness of ancient stained glass is explained by medieval manufacturing techniques (crown glass blowing) that did not produce uniformly thick panes. Craftsmen often placed the thicker side at the bottom for stability. Physical calculations show that even over billions of years, glass would not flow perceptibly at room temperature.
Geography
9. "The Sahara is the world's largest desert"
The myth: The Sahara Desert is the largest desert on the planet.
The world's largest desert is Antarctica. A desert is defined by its precipitation (less than 250 mm per year), not by heat. Antarctica, with about 50 mm of annual precipitation, is technically a cold desert spanning 14 million km², compared to 9.2 million km² for the Sahara. The Arctic is also a polar desert and the world's second largest.
10. "Everest is the world's tallest mountain"
The myth: Mount Everest is indisputably the highest point on the planet.
It depends on how you measure. Everest has the highest summit above sea level (8,849 m). But Mauna Kea in Hawaii, measured from its underwater base, reaches 10,203 m in total height. And Chimborazo in Ecuador, thanks to the equatorial bulge of the Earth, has its summit farther from the center of the Earth than Everest, by about 2,168 meters.
The Human Body
11. "You must wait 24 hours before reporting a missing person"
The myth: The police refuse to take a missing person report before 24 hours.
This is a dangerous myth spread by movies and TV shows. In reality, you can and should report a disappearance immediately. The first hours are crucial in an investigation. No law imposes a waiting period. The sooner authorities are notified, the greater the chances of finding the person. Police forces everywhere are required to accept reports without delay.
12. "You swallow 8 spiders a year in your sleep"
The myth: On average, a person swallows 8 spiders per year during sleep.
This "fact" has no scientific basis. Spiders are sensitive to vibrations and a sleeper's breath, which naturally drives them away. They have no reason to venture into a human mouth. This myth reportedly originated from a 1993 article by journalist Lisa Holst, who invented it to show how misinformation spreads -- an experiment that ironically proved her point.
13. "Nails and hair keep growing after death"
The myth: The nails and hair of the deceased continue to grow for several days.
This is an optical illusion. After death, the skin dehydrates and retracts, giving the impression that nails and hair are longer. In reality, cell growth stops very quickly due to lack of glucose and oxygen. This myth is so widespread that it even appears in Erich Maria Remarque's novel "All Quiet on the Western Front."
Animals
14. "Chameleons change color for camouflage"
The myth: Chameleons change their color to blend into their environment.
Chameleons change color primarily to communicate emotions (stress, courtship, dominance) and to regulate body temperature. Camouflage is only a secondary benefit. Their color changes are controlled by crystals in their skin cells (chromatophores and iridophores) that react to nervous and hormonal signals. A stressed chameleon often becomes darker, while a courting male displays bright, vivid colors.
15. "Goldfish have a 3-second memory"
The myth: Goldfish forget everything after 3 seconds.
Scientific studies have proven that goldfish can retain information for months. Researchers at the University of Plymouth demonstrated they can learn to pull a lever for food and remember how to do it long afterward. Some can even recognize their owner. Other studies have shown they are capable of navigating mazes and remembering the route for several weeks.
FAQ: Common Questions About Misconceptions
Why do we so easily believe common misconceptions?
Our brains are wired to accept information that is frequently repeated (the illusory truth effect) and that comes from sources we perceive as reliable (parents, teachers). Moreover, myths often have an apparent logic that makes them plausible, and we naturally tend to seek confirmation rather than refutation.
Are there other common myths not mentioned here?
Of course! There are hundreds of popular misconceptions. For example, blood is never blue in your veins (it is always red), bats are not blind, and dogs do not see in black and white. We could easily write a follow-up with 15 additional myths!
Make it a habit to cross-reference sources. Consult reliable scientific sources, check recognized fact-checking websites, and be wary of claims that start with "everyone knows that..." Critical thinking is a muscle that needs daily exercise.
Conclusion
How many of these myths had fooled you? If you believed more than 10, do not worry: these misconceptions are so widespread that even the most educated people fall for them. The important thing is to maintain a critical mind and to question the "facts" that have been repeated to us since forever.
Test yourself: True or False?
Want to test your knowledge now that you have debunked these 15 myths? Launch a True or False quiz on QuizFury and challenge your friends to do better than you!
