Yash Mittal•2026-03-17
Mythbusting Science Vol. 3: The 10% Brain Myth, Blood Color, and Falling Pennies
Do we only use 10% of our brains? Is deoxygenated blood blue inside your veins? Will a penny dropped from the Empire State Building kill someone? Three classic myths debunked.
Some myths refuse to die because they make for great movie premises or look intuitively plausible at a casual glance.
Let's apply empirical neuroscience, hematology, and terminal aerodynamics to three enduring urban legends.
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| DEBUNKING THREE CLASSIC URBAN MYTHS |
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| 1. 'WE ONLY USE 10% OF OUR BRAINS' |
| Fact: Evolution does not maintain a 3-pound, 20-Watt organ at 90% |
| idleness! fMRI scans show virtually 100% of the brain active! |
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| 2. 'DEOXYGENATED BLOOD IN YOUR VEINS IS BLUE' |
| Fact: Human blood is ALWAYS red! |
| Veins look blue because of optical subcutaneous light scattering. |
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| 3. 'A PENNY DROPPED FROM THE EMPIRE STATE BUILDING WILL CRACK A SKULL' |
| Fact: Aerodynamic tumble caps terminal velocity at ~40 km/h! |
| It stings like a pebble, but it cannot penetrate skin. |
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Myth 1: We Only Use 10% of Our Brains
Popularized by films like Lucy and motivational speakers, this myth is neurobiologically absurd:
- The human brain accounts for only 2% of total body mass, but consumes over 20% of resting metabolic energy and oxygen. If 90% of it were useless, natural selection would have eliminated that energetic liability millions of years ago.
- Modern functional Magnetic Resonance Imaging (fMRI) reveals that even while sleeping, almost all regions of the brain exhibit continuous neural signaling.
Myth 2: Deoxygenated Blood Is Blue
Many school textbooks depict deoxygenated veins in bright blue, leading people to believe blood turns red only upon contacting air:
- Blood is always red. Oxygenated hemoglobin is bright scarlet; deoxygenated hemoglobin is deep dark maroon.
- Veins appear blue through the skin because of subcutaneous optical scattering: red light has longer wavelengths and penetrates deep into subcutaneous tissue where it is absorbed by blood, while shorter blue wavelengths reflect off superficial skin layers back to your eyes!
Myth 3: The Lethal Empire State Penny
The trope says dropping a penny from a 102-story skyscraper turns it into a lethal bullet:
- In a vacuum, yes—gravity would accelerate it to lethal speeds.
- In Earth's atmosphere, a penny is flat and light (mass: 2.5 grams). As it falls, it tumbles and flutters like a leaf, experiencing intense aerodynamic drag.
- Its terminal velocity is barely 40 to 45 km/h. If struck on the head, it would sting like a falling acorn, but cannot crack bone.