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Myths Debunked

Popular beliefs examined with primary sources — and found to be completely false.

Some of the most confidently repeated "facts" are myths. The brain myth, the goldfish memory myth, the lightning myth — each has been circulating for decades despite being directly contradicted by peer-reviewed research. Every page here includes the primary source, the actual science, and the exact origin of the wrong belief.

10 Myths Debunked
100% Primary Sources
30 Citations
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✗ MYTH

You Only Use 10% of Your Brain

False. You use virtually all of your brain, continuously. Brain imaging studies using fMRI and PET scans show …

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✗ MYTH

Goldfish Have 3-Second Memories

False. Goldfish can retain memories for months, not seconds. Controlled studies have trained goldfish to opera…

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✗ MYTH

The Great Wall of China Is Visible from Space

False. The Great Wall of China cannot be seen by the naked eye from low Earth orbit. At its widest, the wall i…

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✗ MYTH

Cracking Your Knuckles Causes Arthritis

False. No scientific study has found a causal link between knuckle cracking and arthritis. The most famous sel…

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Lightning Never Strikes the Same Place Twice

False. Lightning routinely strikes the same location many times. The Empire State Building is struck by lightn…

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✗ MYTH

Reading in Dim Light Ruins Your Eyesight

False. Reading in dim light causes temporary eye strain and fatigue, but no clinical evidence shows it causes …

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✗ MYTH

Napoleon Bonaparte Was Unusually Short

False. Napoleon was approximately 5 feet 7 inches tall (170 cm), which was average for a French man of his era…

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✗ MYTH

Humans Swallow 8 Spiders Per Year in Their Sleep

False. There is no scientific evidence that humans routinely swallow spiders in their sleep, and multiple biol…

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✗ MYTH

Bulls Are Enraged by the Color Red

False. Cattle are red-green colorblind (dichromats) and cannot distinguish red from green. Bulls in bullfighti…

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✗ MYTH

Humans Have Only Five Senses

False. Humans have far more than five senses. Depending on how strictly you define a "sense," modern neuroscie…

Common Questions

What is a common myth about the human brain?

The claim that humans only use 10% of their brain. Brain imaging studies confirm all brain regions are active during normal daily life.

Is it true that goldfish have 3-second memories?

No. Research at Plymouth University showed goldfish can retain memories for months, not seconds.

Can you really see the Great Wall of China from space?

No. The wall is at most 9 meters wide — far too narrow to be resolved by the naked eye from orbital altitude.