The Internet has exploded. From a few hundred thousand computers in 1993, the global network now totals 140 million computers and rising. No wonder: By letting computers talk with one another, the Internet makes each machine smarter.

You haven't seen anything yet. Never mind PCs and mainframes. Think photocopiers, refineries, heart monitors, cameras--and just about anything else that can hold a computer chip. Plug a constellation of devices into the Internet and the myriad gadgets of everyday life will get smarter and more useful. When people hook up their PCs to the Web, they transform glorified typewriters into windows on a world of information. The Internet can do the same for countless other things.

Developers see air conditioners that can turn themselves on in response to an e-mail message zapped before you leave your office. Everything from a car to a dishwasher could monitor itself, sending out electronic pleas for help when something malfunctions and preventing the repairman from showing up with the wrong parts. Connected to the Internet's digital umbilical cord, marketers could beam out new instructions that would update the features of toys and VCRs.

Companies already are thinking of the day when they will have vending machines that call out over the Internet for a refill of ginger ale and security systems that enable someone to let visitors into a workplace from 1,000 miles away.

To Nicholas Negroponte, chief guru at the famed Media Lab at the Massachusetts Institute of Technology, the rise of gadgets on the Internet signals a whole new era of computing. There were mainframe computers in the 1960s and minicomputers in the '70s, he notes, followed by personal computers in the '80s and the Internet in the '90s. Now, says Mr. Negroponte, the new thing is "things," as any sort of device with a microprocessor is wired to the Net. "Things that think want to link."

Once all manner of things are conjoined, they will also start talking to one another. emWare Inc., a Salt Lake City start-up, has created a prototype of this idea, with a lawn-sprinkler system that hooks up to the Internet. A homeowner at work can tell it to turn on, via the Web, and the sprinkler itself could automatically query the Web site of the National Weather Service to make sure the forecast doesn't call for rain.

"It's still just a sprinkler, a simple device," says emWare technical chief Chris Sontag. "But now it's more intelligent."

Dave Smith stares at a computer screen as a satellite map of North America telescopes down to a grid of a major city and, finally, to a single neighborhood with green space and railroad tracks.

He clicks a mouse. A dial tone sounds, followed by the screech of a modem. Suddenly a little panda icon with a red bow tie appears at the intersection of Linwood Drive and Warren Road. A few seconds later, amid more tones and screeches, the panda lurches to another spot on the map.

"He's out on the highway now," says Smith, a former Defense Department computer programmer. "We're within 100 yards of that right now--well within visual range."

Smith, now a private computer consultant, has just accessed a global positioning satellite unit, or GPS, in Canada. But he's not tracking a stolen car. He's hunting down a kidnapped child--or, rather, a software engineer in Toronto posing as one for this test.

All from a tiny office in South Carolina peach country. All because a pair of businessmen-grandfathers decided that if you can track a stolen car, you should be able to track a stolen child. The pair have spent about $250,000 of their own money to develop a system that can be hidden in the bottom of a backpack or in an unobtrusive fanny pack.

There are more than 600,000 abduction attempts on children each year, according to the National Center for Missing and Exploited Children. Each day, 2,300 children are reported missing and entered into the FBI's computer system.

The GPS unit weighs around 1½ pounds. Technicians expect the unit to cost about $200, with a monthly activation fee of as little as $5. They envision the day when a GPS unit can be sewn into a child's jacket or tucked into a shoe.

The processor inside your PC might do a passable job at lots of tasks, but there is precious little that it absolutely excels at. It was designed that way, because people like to do many different things with their PCs. Far better to have one machine that is OK for playing games, paying invoices and word processing than it is to buy a different computer for each job.

The downside of this is that your PC is a jack of all trades and a master of none. But what if the processor could adapt to the software you were running like a living organism adapts to its habitat? Then it could turn into a specialist chip dedicated to turning out graphics for games or to number-crunching for spreadsheets.

Researchers around the world are pursuing just this goal. They are creating "evolvable hardware"--computer chips that can adapt, reproduce and heal themselves. Instead of being programmed, they learn as needed.

Curiously, even this early work of designing such chips is revealing that evolution is much more creative than people. A pioneer of evolutionary hardware is Adrian Thompson of the University of Sussex. Thompson has been trying to evolve a simple circuit that can distinguish between two sounds such as "stop" and "go." When Thompson had a look at the circuit, he was amazed by what he found. A small island of logic blocks were completely unconnected to the main ones, yet the chip stopped working if they were removed.

Thompson says evolution has proved very "innovative"--which is really shorthand for doing something he can't explain. "[It] is exploiting properties of the chip I can't even measure," he says, "I really have no idea how it works."

Gianluca Tempesti and colleagues at the Swiss Federal Institute of Technology in Lausanne want to create an entire organism using customizable chips. So far the team have created something called a biodule--the digital equivalent of a cell.

With some clever programming, the Swiss researchers have worked out how to make the cells reproduce and heal themselves. They can even work out what job they are supposed to do, given their location--just like real cells which take on the job of the organ they find themselves in. Once a "mother" cell is given the configuration program and starts to reproduce, the cells swiftly self-organize into a coordinated unit. If a biodule is damaged, the organism isolates it and all the cells around it work out what their new task should be. This is in stark contrast to existing chips, which stop working if they suffer the slightest damage.

Customers of a Texas bank can do away with plastic cards and secret codes. They'll only have to look their automatic teller machine straight in the eye to get cash.

Here's how it works: A customer has a close-up photo of his eye taken at the bank, and the picture is stored in a computer. When the customer goes up to the ATM to take out money, a press of a button starts an eye scan. The ATM then matches the picture of the iris with the one stored in the bank's database to confirm the customer's identity.

The concept works because the intricate pattern of each person's iris is more distinctive than even a fingerprint. An iris contains 266 measurable characteristics while a fingerprint contains about 35.

To demonstrate, Richard Swartz, a 25-year-old Rice University graduate student, had his iris photographed by a bank employee. Minutes later, Swartz was able to withdraw $40 from his account without inserting a card or punching in a secret code.

Then, Swartz's identical twin Michael walked up to the machine. But his iris didn't match his brother's, and the ATM refused him access.

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A device that reads brain waves through the skull has enabled paralyzed people to write sentences on a computer screen, scientists said. Several teams around the world are developing systems to allow "locked in" patients to communicate, New Scientist magazine reported.

Two patients have managed to write messages on a computer screen via electrodes planted in the brain by researchers at Emory University, Atlanta, Georgia.       

Because brain surgery involves the risk of infection or hemorrhage, other groups are trying to develop systems that do not require implants.

Now researchers in Germany and the United States have placed small electrodes on top of patients’ heads to record signals from the brain. Once patients learn to control the computer cursor in this way, they can begin to write messages.

The cursor is used to select characters, and researchers found patients could write a short sentence in about half an hour. "We’ve got patients writing messages who couldn’t communicate at all," said Edward Taub of the University of Alabama at Birmingham.

Computer scientist Robby Gardner of Flinders University of South Australia won an award for his latest creation, a talking computer program called Albert. The prize was for "the world's best chat-bot-a computer that can hold a conversation." Its witty one liners, quirky questions and only occasional non sequiturs managed to convince almost 11% of people that it was human.