The door to paranoia opens benignly-and early. just think of santa. he knows when you are sleeping. he knows when you're awake. he knows if you've been bad or good, for goodness' sake. And he knows these things all the time, even though you can't see him. Millions of kids all over the world happily and wholeheartedly believe in ubiquitous surveillance as a de facto piece of the annual Christmas present-getting machine. Parents just shake their heads in adoring wonder.

But those same parents might be shocked to learn how short the journey is from the pleasant surveillance fantasy of Santa to the freedom-squashing invasion of Big Brother. In the world detailed by George Orwell in the novel 1984, surveillance cameras follow every move a person makes, and the slightest misstep, or apparent misstep, summons the authorities. Now, similarly, police departments, government agencies, banks, merchants, amusement parks, sports arenas, nanny-watching homeowners, swimming-pool operators, and employers are deploying cameras, pattern recognition algorithms, databases of information, and biometric tools that when taken as a whole can be combined into automated surveillance networks able to track just about anyone, just about anywhere.

While none of us is under 24-hour surveillance yet, the writing is on the wall. As Scott McNealy, CEO of Sun Microsystems, starkly told reporters in 1999, "You already have zero privacy. Get over it." The techno-entrepreneurs who are developing and marketing these tools anticipate good things to come, such as reduced crime rates in urban environments, computer interfaces that will read eye movements and navigate the Web for you, and fingerprint or facial recognition systems and other biometric technologies that guarantee your identity and eliminate the need for passwords, PIN numbers and access cards-even identifying potential terrorists before they can strike.

But privacy advocates paint a far dimmer picture of this same future, accepting its reality while questioning whether it can be managed responsibly. "The technology is developing at the speed of light, but the privacy laws to protect us are back in the Stone Age," says Barry Steinhardt, associate director of the American Civil Liberties Union, which is among several groups that have tried, so far almost universally unsuccessfully, to introduce legislation aimed at protecting privacy. "We may not end up with an Orwellian society run by malevolent dictators, but it will be a surveillance society where none of the detail of our daily lives will escape notice and where much of that detail will be recorded."