Take a look around you. A deep breath of the cold night air. Lush green, in the few remaining corners of the world. Stretch your legs, and pause to ask yourself: "Is this really happening? Or is existence merely an illusion?" Philosophical issues are for those terminally tired of living. For the wired, like you and me, this is a question about an over- hyped phenomenon of the past few years, virtual reality (VR). While it is impossible to introduce, far from discuss, this topic without resorting to hype, I shall try to be somewhat objective. Firstly, the name itself. Virtual reality. Like many recent newsmakers born out of information technology (such as artificial intelligence), the term is an oxymoron. Virtual reality is a catchall coined by the musician turned computer enthusiast Jaron Lanier, for a set of technologies aiming to make a computer generated experience appear as real as the one described above. Unless you are totally digital, you'll want to know how, and why.

For some time it has been technically possible to generate 3- dimensional, fairly realistic scenery through powerful computers, simulating, for instance, an aerial excursion over the surface of Mars. With the cascading costs of new technology, and the de- militarisation of simulation technology used in trainers for expensive aircraft, this processing power may soon be in your hand. For realistic visual perception, VR uses stereoscopic displays - a bit like giant goggles, with a little screen on each eyepiece. The dataglove, with a swarm of sensors, detects the position and posture of your hand to generate the "virtual" hand seen through the goggles. Extrapolate this to a datasuit, and the computer knows your posture, resulting in a generated image of a Mohawk when you play Cowboys and Indians against virtual gunslingers.

Entertainment is always quickest to take advantage of new technology, after the military. However, there are many more reasons why hundreds of serious scientists are working hard at developing VR tools. In the information age, interaction with and action in response to changing data is crucial. Just as visualization of airflow about an airplane nose greatly helps designers, VR helps molecular engineers build new materials by "holding" atoms and "moving" them in place, providing tactile feedback through a joystick far more immediate than numbers on a sheet.

Of course, no VR Space Invaders arcades are likely in India in the near future, but you can buy the Commodore Amiga CD32, which comes with extremely realistic games. The distributor, Silicon Holdings, plans to market datagloves soon.

Potential uses of VR are enormous and varied. Experienced surgeons performing through remote control. Tourism ("Would you like to get a feel of Honolulu, Ma'am?"). The exploitation of instinctive tactile skills as in the experiment with currency markets, where when a currency "rises," you reach out and grab it. Or even, as alluded to in Aerosmith's music video "Amazing", virtual sex!