AI Summary
5 min readFor a man who just spent days obsessively arranging 152 Crayola crayons by color theory, Michael Stevens has a surprisingly unsettling question: why do artists use a color wheel when the physics of light is a straight line? The answer, he explains, is that purple does not exist.
The electromagnetic spectrum is a line. Crank up the energy of a radio wave and it becomes a microwave, then infrared, then visible red light. Keep going and you get orange, yellow, green, blue, violet, and then ultraviolet, X-rays, gamma rays. It is a one-dimensional progression from low energy to high energy. There is no point where adding more energy loops you back to red. Yet every artist’s color wheel bends violet around to meet red, completing a circle. The reason is a quirk of human biology. Our eyes have three types of cone cells that detect short, medium, and long wavelengths—roughly blue, green, and red. When your eye receives only short and long wavelengths (blue and red) with little medium (green), your brain has no direct spectral color to assign. It invents one: purple or magenta. This is a purely psychological phenomenon, not a physical property of light. The color wheel is a map of human perception, not of physics. It closes the loop because our brains create a bridge between the two ends of the visible spectrum that nature left open.
Continue reading the full summary in the app — free to try.
Read Full Summary →Free • No credit card required
Never miss an episode of The Rest Is Science
Get every new episode summarized in your inbox — free, ~5 minutes to read.
No spam. Unsubscribe anytime.
What you'll learn
- 1 (00:00) **Welcome & The Crayon Obsession** - Michael Stevens reveals his latest obsession: sorting a box of 152 Crayola crayons, which has forced him to learn color theory.
- 2 (05:41) **The Central Mystery: Color Wheel vs. Color Line** - Michael poses the core question: why do artists use a color wheel when the electromagnetic spectrum of light is a straight line?
- 3 (08:17) **The Non-Existent Color: Purple/Magenta** - Michael explains that purple is a psychological construct, not a spectral color, created by the brain to fill a gap in the visual system.
- 4 (10:48) **The Camera's Blind Spot: Fluorescent Colors** - Michael demonstrates how phone cameras fail to capture certain colors, specifically fluorescent crayons like "Outrageous Orange."
- 5 (15:06) **Michael's Favorite Crayons: Maroon & Shadow** - Michael reveals his two favorite crayons, which are surprisingly muted earth tones, and explains their unique physical properties.
- 6 (17:31) **Seeing the Invisible: Infrared on Camera** - Michael demonstrates how phone cameras can detect and render infrared light, revealing a hidden world invisible to the naked eye.
- 7 (19:32) **The Impossibility of Neon Brown** - Michael explores the definition of "neon" and "brown" to explain why a neon brown crayon cannot exist.
+ Full timestamped outline available in the app
Guests on this episode
Show Notes
Colour wheel or colour line? Light itself runs in a straight line from red to violet, yet every colour theory chart bends that spectrum into a circle and the reason has nothing to do with physics.
Professor Hannah Fry and Michael Stevens (VSauce) dig into why human vision refuses to see colour the way light actually behaves, tracing the visible light spectrum from one end to the other and asking where all the "missing" colours, like magenta and purple, actually come from if they don't exist on that spectrum at all.
It turns out the colour wheel is less a description of light and more a diagram of a workaround your brain performs constantly.
Send your questions to [email protected] or find us at r/TheRestIsScience on Reddit.
Find the wetter water Michael discusses at - https://winsol.com/products/wetter-water
-------------------
For more information about Cancer Research UK, their research, breakthroughs and how you can support them, visit https://cancerresearchuk.org/restisscience
Cancer Research UK is a registered charity in England and Wales (1089464), Scotland (SC041666), the Isle of Man (1103) and Jersey (247). A company limited by guarantee. Registered company in England and Wales (4325234) and the Isle of Man (5713F). Registered address: 2 Redman Place, London, E20 1JQ.
-------------------
Find The Rest Is Science all over the internet by clicking here.
-------------------
Video Producer: Adam Thornton + Oli Oakley + Jack Meek
Animator: Sam Benson
Video & Social: Bex Tyrrell
Assistant Producer: Lucy Lipscombe
Producer: Simona Rata
Senior Producer: Lauren Armstrong-Carter
Chief Digital Officer: Samuel Oakley
Exec Producer: Neil Fearn
Learn more about your ad choices. Visit podcastchoices.com/adchoices
More from this podcast
The Rest Is Science →