Shades of the past: a clearer view of cosmic inflation, through the polarized light of the big bang.(OUT THERE)

Publication: Natural History

Publication Date: 01-JUN-06

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COPYRIGHT 2006 Natural History Magazine, Inc.

It's late afternoon on a cloudless day at the beach, and the Sun is hanging just above the horizon. You want to watch the sunset, but you can't bear to look: not only is the Sun itself too bright to view, but the reflected glare from the waves hurts your eyes. No problem: you slip on a pair of polarized shades, and voile! You still can't look directly at the Sun, but the glare off the ocean is gone.

Polarization is one of those scientific terms that show up in regular speech all the time. Unfortunately, the political sense of the word is almost the reverse of its optical sense. A polarized citizenry, of course, is one whose opinions are so divided that the camps might as well be coming from opposite poles of the world. Polarized light, by contrast, marches in lock-step; it's uniform and coherent.

Polarized light comes at us through polarizing sunglasses and camera filters, as well as from such technogadgets as cell-phone screens, computer monitors, and flat-screen TVs. It also emanates from almost any reflective surface--the ocean, for instance.

You can add the universe itself to your list of polarized-light sources. In fact, polarized light has long been a vital tool for us astronomers. Much of what we know about dust-enshrouded, super-massive black holes...

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