Mark Weiser (1952–1999) The Founder of Ubiquitous Computing Mark Weiser was the chief technology officer at Xerox’s Palo Alto Research Cen- ter (Parc). He is often referred to as the father of ubiquitous computing. He coined the term in 1988 to describe a future in which invisible computers, embedded in everyday objects, replace PCs. Other research interests included garbage collection, operating sys- tems, and user interface design. He received his MA and PhD in computer and com- munication science at the University of Michigan, Ann Arbor. After completing his PhD, he joined the computer science department at the University of Maryland, College Park, where he taught for 12 years. He wrote or cowrote over 75 technical publications on such subjects as the psychology of programming, program slicing, operating systems, pro- gramming environments, garbage collection, and technological ethics. He was a mem- ber of the ACM, IEEE Computer Society, and American Association for the Advance- ment of Science. Weiser passed away in 1999. Visit www.parc.xerox.com/csl/ members/weiser or contact [email protected] for more information about him. 18 PERVASIVEcomputing REACHING FOR WEISER’ S VISION Images not reprinted. Some were omitted and others reproduced. The Computer for the 21st Century Specialized elements of hardware and software, connected by wires, radio waves and infrared, will be so ubiquitous that no one will notice their presence. he most profound technologies are colleagues and I at the Xerox Palo Alto Research those that disappear. They weave Center think that the idea of a “personal” computer themselves into the fabric of everyday itself is misplaced and that the vision of laptop life until they are indistinguishable machines, dynabooks and “knowledge navigators” from it. is only a transitional step toward achieving the real TConsider writing, perhaps the first information potential of information technology. Such machines technology. The ability to represent spoken language cannot truly make computing an integral, invisible symbolically for long-term storage freed informa- part of people’s lives. We are therefore trying to con- tion from the limits of individual memory. Today ceive a new way of thinking about computers, one this technology is ubiquitous in industrialized coun- that takes into account the human world and allows tries. Not only do books, magazines and newspa- the computers themselves to vanish into the back- pers convey written information, but so do street ground. signs, billboards, shop signs and even graffiti. Candy wrappers are covered in writing. Such a disappearance is a fundamental conse- The constant background pres- quence not of technology but of human psychology. By Mark Weiser ence of these products of “liter- Whenever people learn something sufficiently well, acy technology” does not require they cease to be aware of it. When you look at a active attention, but the infor- street sign, for example, you absorb its information mation to be transmitted is ready for use at a glance. without consciously performing the act of reading. It is difficult to imagine modern life otherwise. Computer scientist, economist and Nobelist Her- Silicon-based information technology, in contrast, bert A. Simon calls this phenomenon “compiling”; is far from having become part of the environment. philosopher Michael Polanyi calls it the “tacit More than 50 million personal computers have been dimension”; psychologist J.J. Gibson calls it “visual sold, and the computer nonetheless remains largely invariants”; philosophers Hans Georg Gadamer and in a world of its own. It is approachable only Martin Heidegger call it the “horizon” and the through complex jargon that has nothing to do with “ready-to-hand”; John Seely Brown of PARC calls the tasks for which people use computers. The state it the “periphery.” All say, in essence, that only when of the art is perhaps analogous to the period when things disappear in this way are we freed to use them scribes had to know as much about making ink or without thinking and so to focus beyond them on baking clay as they did about writing. new goals. The arcane aura that surrounds personal com- The idea of integrating computers seamlessly into puters is not just a “user interface” problem. My the world at large runs counter to a number of pre- Reprinted with permission. Copyright 1991 by Scientific American, Inc. All rights reserved. PERVASIVEcomputing 19 REACHING FOR WEISER’ S VISION WIRED AND WIRELESS NETWORKS link Pad computers and allow their users to share programs and data. The computers pictured here include conventional terminals and file servers, pocket-size Radio machines known as tabs and page-size frequency ones known as pads. Future networks must be capable of supporting hundreds Infrared of devices in a single room and must also Radio Infrared cope with devices—ranging from tabs to frequency Tab laser printers or large-screen displays— that move from one place to another. electric motors made it possible first to give each tool its own source of motive force, then to put many motors into a single machine. A glance through the shop manual of a Workstation File server Laser printer typical automobile, for example, reveals 22 motors and 25 solenoids. They start the engine, clean the windshield, lock and unlock the doors, and so on. By paying sent-day trends. “Ubiquitous computing” otherwise inaccessible—the insides of cells, careful attention, the driver might be able to in this context does not mean just com- the surfaces of distant planets, the infor- discern whenever he or she activated a puters that can be carried to the beach, jun- mation web of data bases—virtual reality motor, but there would be no point to it. gle or airport. Even the most powerful is only a map, not a territory. It excludes Most computers that participate in notebook computer, with access to a desks, offices, other people not wearing embodied virtuality will be invisible in fact worldwide information network, still goggles and bodysuits, weather, trees, as well as in metaphor. Already computers focuses attention on a single box. By anal- walks, chance encounters and, in general, in light switches, thermostats, stereos and ogy with writing, carrying a superlaptop is the infinite richness of the universe. Virtual ovens help to activate the world. These like owning just one very important book. reality focuses an enormous apparatus on machines and more will be interconnected Customizing this book, even writing mil- simulating the world rather than on invis- in a ubiquitous network. As computer sci- lions of other books, does not begin to cap- ibly enhancing the world that already exists. entists, however, my colleagues and I have ture the real power of literacy. Indeed, the opposition between the focused on devices that transmit and dis- Furthermore, although ubiquitous com- notion of virtual reality and ubiquitous, play information more directly. We have puters may use sound and video in addition invisible computing is so strong that some found two issues of crucial importance: to text and graphics, that does not make of us use the term “embodied virtuality” to location and scale. Little is more basic to them “multimedia computers.” Today’s refer to the process of drawing computers human perception than physical juxtapo- multimedia machine makes the computer out of their electronic shells. The “virtual- sition, and so ubiquitous computers must screen into a demanding focus of attention ity” of computer-readable data—all the dif- know where they are. (Today’s computers, rather than allowing it to fade into the ferent ways in which they can be altered, in contrast, have no idea of their location background. processed and analyzed—is brought into and surroundings.) If a computer knows Perhaps most diametrically opposed to the physical world. merely what room it is in, it can adapt its our vision is the notion of virtual reality, behavior in significant ways without requir- which attempts to make a world inside the How do technologies disappear into the ing even a hint of artificial intelligence. computer. Users don special goggles that background? The vanishing of electric Ubiquitous computers will also come in project an artificial scene onto their eyes; motors may serve as an instructive exam- different sizes, each suited to a particular they wear gloves or even bodysuits that ple. At the turn of the century, a typical task. My colleagues and I have built what sense their motions and gestures so that workshop or factory contained a single we call tabs, pads and boards: inch-scale they can move about and manipulate vir- engine that drove dozens or hundreds of machines that approximate active Post-it tual objects. Although it may have its pur- different machines through a system of notes, foot-scale ones that behave some- pose in allowing people to explore realms shafts and pulleys. Cheap, small, efficient thing like a sheet of paper (or a book or a 20 PERVASIVEcomputing http://computer.org/pervasive Chris K Batteries Xer ent ox P Microprocessor ARC Control button Infrared light-emitting diodes The Active Badge. This harbinger of inch-scale computers contains a small microprocessor and an infrared transmitter. The badge broadcasts the identity of its wearer and so can trigger automatic doors, automatic telephone forwarding and computer displays customized to each person reading them. The active badge and other networked tiny computers are called tabs. magazine) and yard-scale displays that are size of an employee I.D. card, first devel- will leave the screen free for information and the equivalent of a blackboard or bulletin oped by the Olivetti Cambridge research also let people arrange their computer-based board. laboratory. These badges can identify projects in the area around their terminals, How many tabs, pads and board-size themselves to receivers placed throughout much as they now arrange paper-based pro- writing and display surfaces are there in a a building, thus making it possible to keep jects in piles on desks and tables.