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🏆 Fact of the Week
The Eiffel Tower grows about 15 centimeters taller in summer — heat makes the iron expand.
— filed under Science Facts
Home » Myths Debunked

🚫 Myths Debunked

Some "facts" are like houseguests: they showed up decades ago, nobody remembers inviting them, and they simply will not leave. Below, Frank rounds up twenty of the most famous false beliefs in circulation, explains where each one came from (when anyone knows), and files the truth in its place. Read the whole docket and you will be legally entitled* to correct people at dinner parties.

*Not legally. But morally, and that's better.

Myth #1: Goldfish have a three-second memory

FRANK SAYS: FALSE  Nobody knows exactly who started this one — it's an old comforting joke for people with small fishbowls — but the goldfish would like a word. In laboratory studies, goldfish have been trained to press levers for food, navigate mazes, and respond to feeding-time cues, retaining what they learned for months. Your goldfish remembers. Your goldfish is keeping notes.

Myth #2: Humans only use 10% of their brains

FRANK SAYS: FALSE  This chestnut likely grew out of garbled early-1900s remarks about untapped human potential — the psychologist William James wrote about unused "reserves," and somewhere along the way a self-help number got bolted on. Brain scans tell the real story: over the course of a day virtually every region of the brain is active, and damage to almost any part of it causes real problems. There is no dusty, unused 90% waiting to grant you superpowers. Sorry.

Myth #3: The Great Wall of China is visible from space

FRANK SAYS: FALSE  This claim is older than spaceflight itself — a Ripley's Believe It or Not! cartoon was pushing it back in 1932, decades before anyone could check. Then people checked. The wall is long, but it's only meters wide and roughly the color of the ground around it; astronauts — including China's own first astronaut, Yang Liwei — have reported they couldn't see it with the naked eye from orbit. Meanwhile city lights and airport runways show up fine, and nobody brags about those.

Myth #4: Napoleon was unusually short

FRANK SAYS: FALSE  Blame a unit-conversion mixup and enemy propaganda. Napoleon measured about 5 feet 2 inches in French units — but the French inch was longer than the English one, making him roughly 5'7" (about 1.69 m), average or better for a Frenchman of his era. British cartoonists like James Gillray gleefully drew him tiny anyway, and the caricature outlived the man. The "Napoleon complex" is named for a height problem Napoleon didn't have.

Myth #5: Bulls are enraged by the color red

FRANK SAYS: FALSE  Cattle are red-green colorblind — a bull can't even properly see red. What sets him off in the bullring is the movement of the cape; a fluttering cloth of any color gets the same review. The famous red muleta is tradition and theater for the human audience, not the bull.

Myth #6: You swallow eight spiders a year in your sleep

FRANK SAYS: FALSE  There is no documented case of this happening, let alone eight times a year on schedule. Spiders actively avoid large, warm, rumbling creatures — a snoring human is basically an earthquake with breath. The statistic is often said to have been invented for a 1990s article about how easily fake facts spread, and in a twist Frank savors, even that origin story is poorly documented. A myth about a myth. Sleep easy.

Myth #7: Einstein failed math

FRANK SAYS: FALSE  Einstein was excellent at math — by his own account he had mastered differential and integral calculus before age 15, and when shown this claim in print in 1935 he laughed it off. The kernel of truth: at 16 he failed the general entrance exam for the Zurich Polytechnic, but he flunked the language and botany-type sections, not the math, which he aced. If Einstein "failed math," Frank shudders to think what that makes the rest of us.

Myth #8: Bats are blind

FRANK SAYS: FALSE  "Blind as a bat" slanders roughly 1,400 species, every one of which can see. Many bats also echolocate — which isn't a replacement for eyesight, it's a bonus feature, like having headlights AND radar. Large fruit bats have sharp vision and mostly don't bother with echolocation at all.

Myth #9: Cracking your knuckles causes arthritis

FRANK SAYS: FALSE  The pop is just gas bubbles in the fluid that lubricates your joints. Studies have found no link to arthritis — most famously, a doctor named Donald Unger cracked the knuckles of one hand (and only one) for some sixty years as a self-experiment, found both hands equally fine, and won an Ig Nobel Prize in 2009 for his trouble. Your grandmother meant well; she was just tired of the noise.

Myth #10: Lightning never strikes the same place twice

FRANK SAYS: FALSE  Lightning is a repeat customer. The Empire State Building takes around 20 to 25 strikes in a typical year, and park ranger Roy Sullivan famously survived seven separate strikes in his lifetime, a record nobody is eager to challenge. Tall, pointy, and conductive gets struck early and often — that's the whole business model of the lightning rod.

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Myth #11: Sugar makes kids hyperactive

FRANK SAYS: FALSE  In double-blind trials — where neither the kids nor the observing parents knew who actually got sugar — sugar made no measurable difference in behavior; a 1995 review in the Journal of the American Medical Association pooled the studies and found the same. The kicker: parents who were merely told their child had eaten sugar rated the child as wilder anyway. The birthday party is the stimulant. The cake is innocent.

Myth #12: Vikings wore horned helmets

FRANK SAYS: FALSE  No horned helmet has ever been found in a Viking-age warrior context — the genuine articles were sensible, hornless domes, because horns on a combat helmet are just handles for your enemy. The look we all picture came from 19th-century romantic painters and, above all, the costumes Carl Emil Doepler designed for Wagner's opera cycle in 1876. The Vikings got their signature look from the theater department, a century-plus after retiring.

Myth #13: A penny dropped from a skyscraper can kill a pedestrian

FRANK SAYS: FALSE  A penny is light, flat, and tumbles as it falls, so air resistance caps it at a terminal velocity of very roughly 25 to 50 miles per hour — enough to sting like a flicked ear, not enough to do serious damage. Physicists and television myth-testers alike have run the experiment. (Frank's lawyer adds: do not throw things off buildings anyway. Frank concurs.)

Myth #14: Swallowed gum stays in your stomach for seven years

FRANK SAYS: FALSE  It's true your body can't digest gum base — but "can't digest" and "keeps forever" are different filing cabinets. Your digestive system simply escorts the gum through with everything else, and it exits within a few days, like corn kernels or seed husks. The seven-year figure appears to be pure playground invention, presumably because it sounded scarier than "Tuesday."

Myth #15: The tongue has separate taste zones (sweet at the tip, bitter at the back...)

FRANK SAYS: FALSE  That diagram in your old science book descends from a 1901 German study that found only slight differences in sensitivity around the tongue — differences a later American textbook writer inflated into a hard map of exclusive zones. In reality, taste buds all over the tongue detect all the basic tastes: sweet, salty, sour, bitter, and umami. You can confirm this at home with a grain of salt on any part of your tongue, which is also the right way to take the diagram.

Myth #16: Shaved hair grows back thicker and darker

FRANK SAYS: FALSE  Clinical tests going back to 1928 have found that shaving changes neither the thickness nor the growth rate of hair. The illusion is geometry: a razor slices the hair at its widest point, so the regrowing stubble has a blunt, bristly tip instead of a natural taper, and short dark stubble is simply easier to see. The hair is the same. The haircut is doing the acting.

Myth #17: Medieval people believed the Earth was flat

FRANK SAYS: FALSE  Educated people had known the Earth was round since the ancient Greeks — Eratosthenes even measured its circumference around 240 BC, using shadows and a well. Medieval scholars carried that knowledge right along; the real debate around Columbus was about the Earth's size (and Columbus, for the record, had lowballed it). The flat-Earth-medieval story was largely popularized by Washington Irving's romanticized 1828 biography of Columbus, which was a better yarn than a history.

Myth #18: You lose most of your body heat through your head

FRANK SAYS: FALSE  This one traces to mid-1900s military cold-weather experiments in which volunteers were bundled into Arctic survival suits — everything covered except their heads. Naturally, the heat left through the only exit available. In truth you lose heat roughly in proportion to whatever skin is exposed, and the head accounts for something like 7 to 10 percent of your body's surface. Wear the hat; just also wear the coat.

Myth #19: Daddy longlegs are the world's most venomous spiders — their fangs just can't pierce skin

FRANK SAYS: FALSE  This myth is wrong twice, which Frank almost admires. The classic "daddy longlegs" (the harvestman) isn't a spider at all and has no venom glands whatsoever. The spindly cellar spider, which also gets the nickname, does have venom — but there's no evidence it's remarkably potent, and when television myth-testers coaxed one into biting a human, the result was a brief, mild burn. Most venomous creature in your basement? Not even close.

Myth #20: Dogs see only in black and white

FRANK SAYS: FALSE  A mid-20th-century assumption that stuck around long after the science moved on. Dogs have two types of color receptors to our three, so they see the world roughly the way a red-green colorblind person does: blues and yellows come through fine, while reds and greens go muddy. That flaming-red toy you bought? To your dog it's a brownish lump in the grass. Buy blue.


✅ And One That Sounds Fake But Isn't

Jars of golden honey, which will outlast us all

Honey never spoils

FRANK SAYS: ACTUALLY TRUE  After twenty demolitions, Frank offers one reprieve: this famous claim holds up. Archaeologists have found pots of honey in ancient Egyptian tombs, thousands of years old and still perfectly edible. Honey is so low in moisture and so acidic that microbes can't set up shop, and the bees even add an enzyme that produces trace hydrogen peroxide as a preservative. Kept sealed and dry, honey is effectively immortal. It may crystallize — that's not spoilage, that's retirement.

"The truth is more interesting than anything anybody could make up — and it has the advantage of staying true when somebody checks." Frank says: one myth gets the treatment every Friday in Frank's Five. Bring your skepticism.

Feeling sharper already? Prove it in The Trivia Quiz, or see what's verifiably enormous over in the Hall of Records. And if you've heard a "fact" that smells funny, send it to Frank — he enjoys the paperwork.

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