String Theory.(Ken Parker as a guitar maker)

Ken Parker's workshop lies an hour north of New York City, on a winding forest road that skirts the highlands of the Hudson River. It's a trapezoidal structure of concrete and glass, set into a steep slope like a piece of quartz, and serves Parker as a kind of Fortress of Solitude. "I'm in hiding," he told me. "I had a company for thirteen years that made thirty thousand guitars, and at least two thousand of their owners want to ask me a question." Par-ker's work tends to attract obsessives. He has spent his career not just building guitars but reinventing them from first principles, and his clients have included Pete Townshend, Paul Simon, Lou Reed, Eddie Van Halen, Joni Mitchell, and The Edge. On the Internet, his fans sometimes sound like Eric Clapton's of forty years ago: "Ken Parker is a god."

Parker is fifty-four. He stands more than six feet tall, with broad, ropy shoulders and thickly calloused hands--a body shaped by labor more than exercise. His forehead is a high domed outcropping; a scraggly gray beard juts from his chin. He walks with his spine stiff, his chest thrust out, a fat braid swinging behind him, like an old sailor with a tender back, and speaks in a boomy baritone that sometimes rises to a high, sweet giggle. His manner is more than genial, though it can't disguise his impatience with fools.

Guitars are often foolish devices, Parker says. Their bodies are ungainly, their necks easily warped, their intonation unreliable. The great majority are factory products, designed for assembly lines in Fullerton or Nazareth or Kalamazoo, staffed by "ladies with cat's-eye glasses and hairnets, listening to cowboy radio," as Parker puts it. In 1949, a former radio repairman named Leo Fender took a slab of ash, bolted on a neck, and screwed in some magnetic pickups to amplify the sound. Half a century later, Fender Telecasters are still made the same way. Acoustic guitars with steel strings have been around longer--they were developed in the early nineteen-hundreds and refined by the Martin company in the nineteen-thirties--and have changed even less. "Some pretty obvious things have not been tried," Parker says. "You pick up a violin and it weighs sixteen ounces. You pick up a guitar and it weighs seven pounds. Hasn't anyone wondered what a four-pound guitar sounds like?"

In the late eighties, Parker decided to take the electric guitar in hand. Together with the mechanical engineer Larry Fishman, he designed an ingenious instrument called "the Fly." Coated in fibreglass and carbon graphite, the Fly was lightweight, beautifully resonant, and nearly maintenance-free. It was awarded eleven patents, paraded on the covers of guitar magazines, and exhibited at the Smithsonian. Yet the Fly's sales fell far short of expectations. (Fender makes as many guitars in a week, Parker says, as he made in thirteen years.) Some loved its thin, twisted shape. "It looks like something you found on the beach," Joni Mitchell told Parker. The rest just thought it was strange. "Nice guitar," Keith Richards reportedly said. "But why does it have to look like a bleeding assault rifle?"

Parker sold his stake in the company in 2003, and promptly disappeared. He got a divorce, rented a cottage on Cape Ann, and thought about guitars. He fell in love with the owner of the cottage, moved into her house in the Hudson Valley, and began to build prototypes. A few months ago, some pictures of an odd new instrument showed up on his Web site. It had six strings and a slender neck, a hollow body and a high waist, but looked like no other guitar. The top was of unstained spruce, arched like the top of a violin. The neck seemed to float above the body, supported only by a golden post. The sound hole had been narrowed to a crescent and moved to the side, where it hung like a waning moon. Parker called his instrument "the Olive Branch," but as design statements go it looked more like a declaration of war. It looked like something that Picasso or Juan Gris might have painted: an old, familiar form made suddenly, startlingly modern.

The Olive Branch is an attempt to do for acoustic guitars what the Fly tried to do for electrics, but it's in every sense an even riskier venture. It's a virtuoso's instrument for a populist music; an acoustic device for an amplified age; a radical reinvention of a design all but abandoned decades ago. When I first saw it, I asked Parker what he was thinking as he built it. Did he imagine that someday everyone would make guitars like this, or that no one else in the world could make such an instrument? He was quiet for a moment, seemingly stumped. Then he shrugged. "Both," he said.

These ought to be excellent times for guitar designers. Theirs are the most popular instruments in the world, used by country crooners, gothic rockers, and African soukous players alike. Some three million guitars were sold in the United States last year--as many as all other instruments combined--and the best vintage guitars are extraordinarily valuable. Twenty years ago, a pristine 1959 Gibson Les Paul might have sold for ten thousand dollars; today, it can fetch four hundred thousand. And yet, along the way, guitars have become deeply conservative. Most electric guitars look like Les Pauls or Stratocasters, and three-quarters of all acoustic guitars are dreadnoughts--a fat-bottomed design from 1916. "This is rock and roll!" Parker says. "You would think that guitar players would be open and brave and experimental. And they are not. As a group, they are not. That guy with the purple Mohawk? He won't play anything made after 1960. Wait a minute, dude! You were made after 1960."