Under Rayleigh scattering, violet light scatters more tha... | funfact.wiki | funfact.wiki
Under Rayleigh scattering, violetlight scatters more than blue because shorter wavelengths scatter more. Yet the sky looks blue, not violet: the sun emits little violet light, and our blue cones are much more sensitive than violet ones.
Purple does not exist in the light spectrum. When red and blue light simultaneously stimulate the eye, the brain creates this color to resolve the contradictory signals.
Hot water can freeze faster than cold — a phenomenon called the Mpemba effect. Known since Aristotle but still unexplained, it was named after Tanzanian student Erasto Mpemba, whose question physicist Denis Osborne took seriously enough to research together.
The "photic sneeze reflex," nicknamed ACHOO syndrome, causes people to sneeze when suddenly exposed to bright light. It's surprisingly common—affecting 18–35% of Americans and about 25% of the Japanese population.
In 1818, Siméon Denis Poisson argued that if light were a wave, a bright spot should appear at the center of a circular object's shadow — which he thought was absurd. But when Arago actually ran the experiment, the bright spot appeared, proving light's wave nature.
A train's left and right wheels share one axle, always spinning together. Yet turns are possible because the wheels are conical. On a curve, centrifugal force shifts the train, changing each wheel's contact diameter and allowing a smooth turn.