Optics Smackdown Explained

Yesterday, I posted a silly poll about optical physicists. Who are those people, and why should you care about them?

In inverse order of popularity:

Bringing up the rear in this race is John William Strutt, who, even more than Lord Kelvin in the thermodynamics poll, is hurt by the fact that people know him by his title, Lord Rayleigh. His notable achievements in optics include a formalization of the resolution limits for optical devices, and the phenomenon known as "Rayleigh Scattering," which is the short answer to the question "Why is the sky blue?" (The long answer requires a whole book.)

Next lowest in the voting is David Brewster, a Scottish mathematician and physicist. Brewster's main discoveries have to do with the polarization of light, and are honored in the name of "Brewster's Angle," which is the angle at which unpolarized light reflected off a surface is completely linearly polarized. You may not think this is a big deal, but it's why polarized sunglasses work to reduce glare, so fishermen and long-distance drivers everywhere should raise a toast in his honor.

Next up is Joseph von Fraunhofer, who is perhaps the most unjustly slighted of the people in this poll. Fraunhofer invented the diffraction grating spectroscope and discovered dark absorption lines in the spectrum of the Sun and lots of other sources. He turned spectroscopy into a science, and paved the way for quantum mechanics.

Thomas Young was a ridiculously brilliant English scientist, who made significant contributions to a whole host of fields in the early 1800's. His most important work in this context is Young's double slit, the experiment that definitively showed the wave nature of light.

The winner of this particular poll is Augustin Fresnel, a French physicist whose name is pronounced "freh-nell," not "frez-nell." It's an important one to remember, because it pops up all over the field of optics-- Fresnel lenses, the Fresnel rhomb, Fresnel diffraction, the Fresnel spot, the Fresnel zone plate, and many more. While Young's double slit experiment was the first unambiguous demonstration of the wave nature of light, Fresnel is the one who really locked down the theory, doing many careful studies of various types of diffraction, and working out the mathematical techniques used to calculate the patterns resulting from light diffracting off various sorts of obstacles.

Personally, my ranking would be Fresnel, Fraunhofer, Young, Strutt, Brewster. But that's why we do these polls-- to find out what other people think.

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Doesn't old Isaac himself deserve to be on the list as a pioneer?

The real pioneer would be the Arab scientist working in or near Baghdad whose book (translated from Arabic to Latin) found its way to Italy by way of the library in Toledo, Spain, while that city was under Moorish control.

That book triggered all sorts of practical work on optics.

BTW, thanks for these followups. I now know that Fresnel explained Fraunhofer diffraction, so I was giving the latter way too much credit in my comments in the original thread.

By CCPhysicist (not verified) on 30 Jul 2009 #permalink


I think you missed a big part of the explanation for this series of polls:

"The question of who is the greatest physicist of the physicists who are household names-- Newton, Einstein, Maxwell, etc.-- has been debated thousands of times, and will undoubtedly be debated thousands of times in the future. What isn't as often discussed is the ranking of physicists who aren't in that rare group of household names-- people whose surnames are attached to equations that GRE takers struggle to memorize, but whose given names and life stories are mostly forgotten."