September 9, 2011


Fantastic light, from science fiction to fact

Next time you switch on a light, consider the enormity of this everyday phenomenon. Light allows us to travel back in time to explore the origins of the universe. Even after thousands of years of study, we still don't fully understand light, yet we are harnessing its powers in ways that transform our daily lives and turn science-fiction fantasies into real possibilities.

"The technology of light keeps getting more and more amazing," says Emory physicist Sidney Perkowitz.

Perkowitz' new book is called "Slow Light: Invisibility, Teleportation and other Mysteries of Light."

"Only three percent of your brain is needed to figure out what you're hearing, while 30 percent is needed to figure out the meaning of what you're seeing. So if you want one number to explain how important and complex light is, that's it," Perkowitz says.

He describes Isaac Newton's use of a prism, to demonstrate that white light contains a spectrum of colors, as the single most important experiment in the history of light. By the end of the 19th century, it was clear that light is an electromagnetic wave defined by its wavelength.

Physics started getting more complicated when Albert Einstein showed that light comes in discrete packets or particles of energy, which were later named photons. That discovery helped give birth to quantum mechanics.

"Like Dr. Frankenstein's creature, Einstein's creation was remarkable but troublesome to its creator and others," Perkowitz says. The photon was at odds with the wave theory of light, and Einstein himself was baffled by it.

Light can travel the way "Star Trek's" Captain Kirk did when he'd say, "Beam me up, Scotty."

"You can take a particle of light and mysteriously transport it from point A to point B, apparently without it traveling through the space in between," Perkowitz says. "I find that the weirdest single thing that we know about light."

Even though we don't fully understand the quantum nature of light, we're able to use it for remarkable technology, like lasers and optical fiber networks that channel photons around the world. When you communicate by Internet or phone, your message is carried by light, Perkowitz says. "If you stop and think about it, that's truly amazing."

Harry Potter's invisibility cloak seemed like a child's fantasy when the fictional character debuted in 1997. An actual cloak began taking shape about a decade later, however, when engineers at Duke University deflected microwave beams so they flowed around a small object, making it appear as if nothing was there. Since then, the race to perfect invisibility technology has heated up.

Light lies at the heart of one of the biggest mysteries of science. If we could merge the theory of relativity and quantum mechanics into a so-called "theory of everything," all kinds of things could break loose, Perkowitz says. "For instance, the fact that the speed of light is the ultimate speed limit might turn out to no longer be true. And if that were the case, then the universe opens up because you might be able to go to the furthest reaches in a reasonable time."

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