Guttenberg's printing press needed paper to make a revolution. The clunky e-book needs e-paper. And it's on the way.

With PowerPoint presentations, Palm Pilot-beaming executives and cell phones trilling in the audience, last November's e-Book World seemed typical of the hundreds of business-tech gatherings held every year. But it wasn't. In fact, it was the first conference devoted solely to the forthcoming transformation of the book world by digital technology. Hundreds of people from around the world paid as much as $995 to hear some of the most influential editors and publishers in the United States forecast radical changes in the writing, distribution and reading of printed material.

During the two-day conference, the agents, authors, technologists and publishers in attendance repeatedly heard that the day of ordinary books, magazines and newspapers was almost over. The key cause of this demise, attendees were told, will be the newly developed e-book. So powerful will be the onrushing wave of e-books, confidently predicted Dick Brass, Microsoft vice president of technology development, that "the last paper edition of The New York Times will appear in 2018."

The new e-books were on display in the exhibit space. They were, for the most part, keyboardless computers, each about the size of a paperback. Visitors gingerly tapped the screen or thumbed a button to "turn" the pages on these gray boxes; with some models, readers could "bookmark" favorite passages. Don't be fooled by their unprepossessing appearance, conference organizer and author Michael Wolff warned in his keynote speech. "The e-book," he proclaimed, "is the most significant development in the book business since the advent of the paperback." Maybe. Digital technology and books, magazines and newspapers are certainly going to collide, just as Wolff said. And, as he also said, the results will have an enormous social and cultural impact. But the key invention will not be the electronic book-at least not the gray boxes on exhibit at e-Book World. Instead, it will be a development that not a single speaker at the conference addressed-a product that not one of the companies in the exhibit displayed.

Although the collective imagination of the publishing industry has been captured by the current generation of electronic books, the technology that is most likely to transform reading and writing will be electronic paper. A handful of leading technology companies are vying to create the first practical electronic paper-a digital display thin and flexible enough to roll into a tube or fold up like a map, yet cheap enough to be sold in reams or wired with a few hundred other screens into the spine of a notebook. Recent progress has been so rapid some researchers believe that in just a few years this novel kind of display could replace paper in many situations, leading to the creation of books, magazines and newspapers made from sheets of wired plastic.

"We're talking about something that would be the first real change to the technology of the book in 500 years," says Paul Drzaic, technology director at E Ink, a startup in Cambridge, MA that unveiled an initial prototype of e-paper late last year. "You have to be aware of the implications. We're not comparing ourselves to Gutenberg in any way, but it's incredible to think that we could be in a time that would be mentioned in the same breath."

Historians have long argued that the technology needed to create a printing press with movable type had been in Europe for more than a century before the 1440s, when Johann Gutenberg and several other craftsmen in the German city of Mainz set up the first composing rooms. "But the important thing was missing," historians Lucien Febvre and Henri-Jean Martin wrote in The Coming of the Book, a classic account from 1958. "It would have been impossible to invent printing had it not been for the impetus given by paper, which [only] came into general use by the late 14th century."

Before paper-a Chinese invention, sent to Europe by the Arabs-Europeans wrote manuscripts on vellum and parchment, which were made from, respectively, lambskin and sheepskin. (The terms are inexact; sometimes goats or calves provided the raw material.) Although animal hides could be shaved into sheets of amazing thinness, they were expensive, did not take ink well and were generally too brittle to pass through a press. Even if skins could be printed on, large editions would necessitate mass slaughter: the historian Aloys Ruppel once calculated that stamping out a hundred copies of the Gutenberg Bible on vellum would have consumed 15,000 lambs. Only when paper became widespread on the Continent did printed books become technically and economically feasible.

The history of electronic paper is shorter and less colorful, but as a historian might say, it is not devoid of incident. Perhaps the first researcher to consider electronic paper seriously was Nick Sheridon, a physicist at Xerox's Palo Alto Research Center (PARC), birthplace of the mouse-and-windows computer interface. In 1975, when Sheridon joined PARC, he noticed a paradox. His colleagues at PARC were excitedly imagining a future world in which printed books and magazines would be supplanted by computer displays. But the monitors actually used at PARC-bulky devices with green-and-white displays-had such poor contrast that researchers often had to draw their blinds to see what they were doing. "A Newsweek or Time that was replaced by a flat version of one of those computer monitors would have been almost unreadable," Sheridon says. "I thought, I guess, that instead of replacing paper with the monitor, it might be smarter to replace the monitor with paper."

Quickly he came up with a possible means, which he called Gyricon, from the Greek for "rotating image." In its present incarnation, Gyricon is a transparent silicone-rubber sheet in which are embedded thousands of tiny plastic spheres, each smaller in diameter than a human hair. Each sphere has a black half, which carries a very small static electricity charge, and a white half, which is electrically neutral. If an electric field comes near the spheres, it attracts or repels their black halves, causing the spheres to rotate. If the white halves end up tilting toward the upper side of the rubber sheet, the viewer sees white dots; if the black halves face the viewer, the dots are black. Placing a Gyricon sheet between the same types of circuit that control the pixels on a laptop screen will arrange the spheres in much the same way, creating a black-and-white image.

Soon Sheridon had a crude working model. Resembling a country cousin of the Etch A Sketch, it could produce an X for Xerox. He thought it would be ready for the market around 1985, if he could just lick a few practical problems. Foremost among them was a manufacturing question: while Sheridon had devised a means of fabricating the little balls, it did not yield uniform spheres; he found himself poking through the tiny globes, looking for good ones.

Another, more daunting, problem lay ahead. The rubber sheet had to be controlled, or addressed, by the electrodes on a circuit board, and all known flat-circuit display boards were stiff and inflexible-totally unlike paper. Worse, they were expensive. Indeed, such circuitry was (and is) the reason laptops cost more than regular computers. As a result, the Gyricon prototype was more like a rigid, expensive electronic clipboard than a bendable, cheap sheet of paper. Unable to see much value in research that seemed to be producing a pricey black-and-white-only substitute for laptop screens, Xerox pulled Sheridon away from e-paper in 1977.

Years later, in the mid-1990s, a young physicist named Joseph Jacobson joined the Media Lab at MIT (see "Print Your Next PC," TR November/December 2000). He, too, had been thinking about electronic paper. With two students, he set about duplicating Sheridon's work. But the MIT group, too, couldn't make the black-and-white balls come out right. Instead, they came up with a variant of the idea. Like Sheridon, the MIT group uses a thin sheet of rubbery plastic crammed full of tiny spheres. But these spheres are not solid; they are hollow capsules filled with colored oil and small, electrically charged chips of titanium dioxide paint. When a current passes near the sheet, it pushes or pulls the chips up or down, coloring the top of the capsules, which thus act like pixels on a monitor. In 1997 Jacobson and his two students co-founded E Ink, which has attracted more than $50 million in venture capital.

Meanwhile, Xerox had interested itself again in its own technology; Sheridon was put back on the e-paper trail in the mid-1990s. He refined the manufacturing process, and Xerox signed a deal with 3M to manufacture Gyricon sheets in large quantities. By 1999 IBM was also in the fray, and Philips was rumored to be sniffing around the e-paper market. However, despite being founded more than 20 years after Sheridon began work at Xerox, E Ink won the first leg of the race to market. Its initial product, introduced in May 1999, was an in-store display sign for J. C. Penney that could change messages to shoppers. But this "e-placard" lacked a vital characteristic of paper: it couldn't bend, because the capsules needed to be addressed by a rigid circuit board. Its inflexibility, however, was being addressed from an entirely different direction.

In some sense, Sheridon was too early. Around the time he developed the Gyricon balls-the "ink," so to speak, for electronic paper-other researchers were discovering the principles that eventually would make possible the electronics critical to making the paper itself. But their work came to fruition well after Xerox initially abandoned the Gyricon. And it came as a by-product of an explosion of new research into a seemingly unrelated subject: electrically conducting plastic.

Long known as an insulator, plastic has only recently become known as an electrical conductor. Indeed, the three men most responsible for the discovery of plastic's conducting properties won the Nobel Prize for chemistry last December. The field they created is generically known as "organic" electronics because the plastics that conduct electricity are based on the kind of carbon-containing molecules that characterize life, even if these particular substances are not found in living beings. Plastic will probably always conduct electricity more slowly and inefficiently than inorganic materials like silicon and copper, researchers say. But plastic is fast enough for many electronics applications-and lighter, cheaper and more flexible than silicon and copper will ever be.

Around the world, chemists and physicists in academia and industry are learning how to create organic circuits in continuous processes, printing or spraying or stamping circuits onto rolls of plastic in a process analogous to printing a newspaper. Despite that analogy, however, the "terrific" idea of e-paper "never occurred" to the discoverers of organic electronics, says Alan Heeger of the University of California, Santa Barbara, one of last year's Nobelists. But the connection was obvious to researchers involved with electronic inks, like Sheridon and Drzaic at E Ink.

In 1999, E Ink and Lucent Technologies agreed to spend a year trying to learn whether they could actually create the first workable model of true electronic paper. Lucent used its expertise in organic semiconductors to rubber-stamp the addressing circuitry onto a sheet of transparent Mylar. In this innovative process, a thin film of gold is sprayed onto the Mylar; the stamp, which has thin ridges that are coated in a special liquid resist (a chemically protective material) imprints dark lines across the gold; a solvent then washes away the gold, except for the lines shielded by the resist. When E Ink placed a layer of electronic ink on top, the sheet, following its electronic instructions, switched back and forth between a checkerboard pattern and the corporate symbols for E Ink and Lucent. "A world first for that kind of display," said Pierre Wiltzius, head of condensed-matter research at Bell Labs, the research arm of Lucent, when he announced the result last November.

In December, financially troubled Xerox spun off Gyricon as an independent subsidiary. "E-paper is still something we're considering," a spokesperson says. "But right now we want to look at networked in-store signage. Did you know that's a $14 billion market?"

Nonetheless, Wiltzius says, "electronic paper is what captures the imagination." In three to five years, he thinks, the E Ink/Lucent team might have e-paper with a resolution equivalent to about 100 dots per inch. "That's a little better than a [Palm] Pilot," he says. "We already have the viewing angle down-you can read across a much wider range of angles. And then there's the issue of color, which I think can be done." He ticks off challenges: durability, reliability, printing registration. "There's some good work to do before this paper is ready to change the world," he says.

The book of the future, e-paper researchers like to say, will look just like a regular book. It will have a hard cover and a spine and several hundred thin, white, flexible pages. But the spine will be filled with electronic circuitry and a wireless data port and maybe a stylus; the pages will be electronic displays. Readers will open the cover and-here the vision gets a little fanciful-be confronted with a list of the works contained in the book, arranged by title, author or subject matter. Because this is 10 or more years from now, data-storage devices will have shrunk even further, and thus embedded in the spine of this single volume may be a hundred novels, even a thousand, all downloaded through the data port. The reader may tap the name "Charles Darwin" and be offered a list of works ranging from the The Voyage of the Beagle to The Origin of Species.

After the reader selects the Origin with the stylus, the text swims noiselessly onto the empty pages of the volume. Tap a footnote with the stylus, and the appropriate text appears in a window on the bottom of the page. Does that book contain a reference to another work by Darwin? Scribble a request on the inside cover and jump onto the Net to grab a copy. Scientific texts could be continually altered to keep pace with research.

Some of this will be possible with conventional e-books, of course. But electronic paper, which is reflective, is inherently more readable than backlighted computer displays: even the crude prototypes made so far are legible at a greater angle and in brighter sunlight than most computer monitors. Not only that, conventional e-books sacrifice many of the best design features of books-the possibility of flipping back and forth between pages, the capacity to negotiate a text by remembering the physical placement of favored passages, and the chance to underline passages and mark pages. In addition, electronic paper could be so inexpensive that a few hundred sheets of it in a book could cost less than most laptop screens. Like the printing press before Gutenberg, the e-book will need paper to become important in most people's lives.

Newspapers, too, may be little changed in appearance but greatly altered in function by the advent of electronic paper. Robert Steinbugler, an IBM designer, won a 1999 Industrial Design Excellence Award from the Industrial Designers Society of America for a mock-up of the newspaper of tomorrow. It looked like a thin version of The New York Times, except that the loose pages were bound to an aluminum spine mounted on a hard pad, slightly larger than the e-pages, which contained command buttons. In Steinbugler's design, the spine and pad held a battery, a data port and enough memory to store hundreds of newspapers. Future readers could flip through the sheets, which had the serendipitously jumbled-together articles of real newspapers, but switch between sections by clicking buttons; with a jab from the thumb, the news would vanish from the page and be replaced by the sports. The effort wasn't merely conceptual; IBM is gearing up its own e-paper drive, using another variant of organic circuitry. "E-paper is the key," Steinbugler says. "I always say that the last person to enjoy reading on a stiff tablet was Moses."

Moses may be an appropriate reference, Steinbugler suggests, because the cultural consequences of e-paper could "be biblical in proportion." If every blank book is a potential library, will there continue to be a need for libraries? What will it mean to our experience of a novel if every other novel we have ever read can be called up from within its pages? If texts are instantly available on the Net, will authors and publishers continue to be able to make a living? The questions are "just endless," Sheridon acknowledges. "But I think this in the end will bring down the cost of books so much that it will make it possible for more people to have their own personal libraries." Without the costs of printing and distributing, book prices could fall without loss of income to writers and editors. Because an entire book reduces to a scatter of iron oxide particles on a computer hard drive, no text need ever go out of print-it can always sit there, whirling on the hard drive, until needed by the reader.

In response to a question, Sheridon talks about the Library of Alexandria, that ancient symbol of humankind's quest for total knowledge. Wanting all the books in the world, Ptolemy III searched every boat that entered the harbor for scrolls, copied any that he found, and returned the copies to the owners. For the last few years, floppy sheets of Gyricon have sat on Sheridon's desk. They can be erased and filled again with text more than a million times, he says. A book of such sheets could suffice for all the reading anyone does over a lifetime. In a way, every time Sheridon picks up a Gyricon sheet he is holding the prototype for the next Library of Alexandria.