Robert Wood helped perfect one invention. That invention made a lot of creepy science photos, gave a distinctive character to raves, and, oh yeah, helped the Allies win World War I. How? By hiding signals in plain sight.

One of the incredible things about science is the domino effect of one tiny discovery. Figure one thing out and its effects cause ripples. It may not just advance one field of science, but change the way other scientists do their research, give people a different way of seeing the world, and perhaps alter the course of a war. This is, possibly, what Robert Williams Wood did when he created Wood's Glass.


Born in 1868, Wood had spent most of his impressive scientific career researching optics. And he wanted to discover a way to see the world differently — in a literal sense. Ultraviolet light and infrared light were well-known, but it was very hard for people to see them. Since both types of light were accompanied by copious amounts of visible light, the visible spectrum generally overwhelmed the ultraviolet and infrared light, in much the way city lights overwhelm starlight.

After much experimentation, he came up with a barium-sodium-silicate glass with a bit of oxidized nickel thrown in. It was nothing more than a filter, taking out visible light and allowing infrared and ultraviolet light to pass through. Suddenly, the world became a very different place. Wood himself used the glass to produce very creepy pictures, such as a landscape in infrared or himself in ultraviolet. Other people slapped it over certain light bulbs so that only UV light came through. And that is how black lights (and raves) were invented.


Sometime after World War I, Wood let on how the army had used it. Wood's glass allowed invisible signals to be sent and received between allies via a kind of optical telegraph. Unless both sides knew exactly the wavelength of light being sent, and had the appropriate glass, the signals couldn't be intercepted.

Today most people use a cheaper and more crack-resistant descendant of Wood's glass, but one insight branched out into a thousand uses. Wood's invention changed everything from the way scientists could observe the world, to party scenes, to the very fate of a world at war.

[Via MIT, United States Naval Institute Proceedings, American Journal of Science.]