The Sciences, November/December, 1995 Another realm of explosive population increase is in cyberspace, a phenomenon taken up in this issue with Sherry Turkle's "Ghosts in the Machine." Here the growth comes about not only in the traditional way but also in wildly non-traditional ways. People multiply themselves on the Internet, grafting various aspects of their personalities onto distinct characters. Even more unsettling, as Turkle wittily documents the matter, is that the Net is populated with "bots": robot sentence-parsing engines that can do fair impersonations of real people, often well enough to (provisionally) pass Alan M. Turing's test for machine consciousness. Do you really know who -- or what -- you're talking to? The future of all this is murky and mind-boggling: Information-seeking bots even now can tie up sites on the World-Wide Web. Bots impersonating people share chat groups with other bots, much the way telephone answering machines now "talk" to each other. Internet chatter gets so dense that bandwidth and other Net resources become strained: the site at the Los Alamos National Laboratory now (automatically) warns robots away with a chilling threat to "initiate automated 'seek and destroy' " action against the machine from which the robot seems to be launched. A conservative reaction may already be setting in, determined to have users identify, encrypt and authenticate every packet of information they send across the Net. Net fatigue becomes a recognized medical syndrome; Net detox centers spring up; Net warfare breaks out; Net starvation becomes a recognized social problem; Net demagogues undermine local democracies.... How many people can the Net support? -- Peter Brown, Editor ----- For "Ghost in the Machine" by Sherry Turkle, a professor of the sociology of science at the Massachusetts Institute of Technology. The article is adapted from her forthcoming book, *Life on the Screen: Identity in the Age of the Internet*, which is being published in November by Simon & Schuster: GHO_mac (16 kb) ... later this evening, that is.