Really, really real ... almost.

Leap into the mind-"goggling" world of virtual reality

Shana Collier, 17, is running fast; a hungry pterodactyl is on her trail. She ducks behind a giant pillar and waves her arms to ward off the predator ... but it's too late. One more teen becomes prehistoric pet food.

Sound like a bad dream? Actually, it's Dactyl Nightmare, a new arcade game that employs the technology of virtual reality (VR). Virtual reality uses computerized gear to create a believable, 3-D world--a place that looks, feels, and sounds real, but isn't.

To "enter" the game's playing field, all you have to do is strap on the computerized headgear--and you're "there." You can chase another human player across the checkerboard floor, while listening for the squawks of an approaching pterosaur. If feels like you're inside the game, Shana says. "Your whole body is moving, not just your thumbs."

When you grip a control stick, an image of your arm instantly appears before you on tiny screens inside your helmet. As you quickly lift your real arm, your "virtual" arm waves in the air.

Interactivity and the feeling of "being there" are the keys to virtual reality, says Thomas Furness, director of a VR lab at the University of Washington. Beyond video arcades, Furness and others hope to use VR to "explore" places and objects no human has experienced before. These virtual travels, many scientists say, can expand knowledge of our real universe and help us find new ways to solve old problems. For example:

* NASA scientists might don VR goggles and "fly" over the surface of Mars in search of new data without having to take long, expensive, and risky space flights.

* In towns struck by natural disaster, residents would be able to save money and time by "walking" through newly designed computerized neighborhoods, adding supermarkets, parks, or new homes--before rebuilding begins.

* Using a VR headset and a hand-held device that "feels" the attraction between atoms, biochemists, could reach out and manipulate giant, simulated cancer-cell molecules. They could use the technology to quickly test different drugs and see which ones bond test with the molecules to zap the cancer.

GET IN GEAR

Of course, you can't "do" anything or "go" anywhere in a virtual world without the proper gear. Scientists are rapidly improving on computerized headsets, gloves, body suits, and more--all wired to "trick" our senses, particularly those of sight, sound, and touch.

For example, the headset you wear to see your way around Dactyl Nightmare houses two tiny TV screens, one for each eye. The screens show slightly different views fot the computer-generated playing field, just as your eyes would if you were really there. (Cover one eye at a time to see each eye's different view.)

As you look at the two screens, your brain naturally puts the two pictures together to create a stereo-scopic scene. You experience it as three-dimensional.

Then, as you turn your head up to scan the "sky" for flying reptiles, the headset picks up signals and transmits them to a powerful computer. The computer instantly directs the frame to change in rapid-fire order--like a filmstrip--making you see a believable shift from virtual ground to virtual sky.

In addition, the computer is programmed to create perspective. If you gaze down a long hallway, you'll notice that closer objects look larger, faraway objects look smaller. Playing on that notion, the computer enlarges or shrinks the pterodactyl to help you experience it zooming in or flying away.

The computer can also make stereo sounds in the virtual world more realistic. Transmitting the sounds through the headset's earphones, the computer makes your flying opponent's shrieks grow louder or softer as it approaches or departs.

Perhaps the greatest challenge, though, is simulating the sense of touch. Think of all the things your hands experience in the real world: gripping a baseball, touching sandpaper or velvet, plunging a greasy dish into sudsy water.... Can scientists replicate all that?

They're working on it. To create the feeling of moving an object in a virtual environment, for example, you can wear a special glove wired to a computer. A digital hand appears on your screen and copies your hand motions. To "turn" a virtual doorknob, for example, you would make a grasping motion and turn your hand. The on-screen door would open.

FINE-TUNING

As exciting as VR may seem, scientists stress that the field is still in its infancy. The graphic displays are not yet up to par with movie images. The pictures are often blurry and cartoonlike, as in standard video games.

In addition, time delays between the viewer's movements and the shifting scene make some people dizzy. That's because the brain gets confused when it expects to see one scene (say, the sky), but instead sees another (the ground).

What's more, VR equipment is still very costly. An arcade company pays about $55,000 for one Dactyl Nightmare system, compared with $6,000 fore Super Street Fighter II. (That might explain the hefty $1.00 per minute you pay for a VR game.)

But think: Just over a decade ago, people couldn't imagine how affordable and useful personal computers could be. Virtual reality could be just the next step. Before you know it, you could be swimming through the deep sea, traveling to Earth's core, witnessing the signing of the U.S. Constitution--or maybe "signing" it yourself. What kind of virtual world would you want to visit?