sing three fingers on their right hands and a lot of electronics, computer technicians in London and Cambridge reached across the ocean to virtually ''touch'' each other last Tuesday, marking the first time that computers have publicly demonstrated a sense of feel at such a distance.
''It's a first, and it's simple, but so were the first transatlantic telegraph, telephone, and video transmissions,'' said Mandayam Srinivasan, the director of the Touch Lab at the Massachusetts Institute of Technology.
The object they touched was nothing more than a cube that could be moved up, down, and around on a television monitor. The MIT engineers and their collaborators at the University College London hope that the technology, now in its infancy, will be particularily well-suited for medical applications. Using a remote-controlled robot, for example, a surgeon could operate on a patient hundreds of miles away by using the tactile feedback engineering system demonstrated yesterday.
''Who knows where this might go?'' Srinivasan said. ''Imagine trying to predict a century ago all the applications of the telephone.''
Creating a virtual world would not have been in the dreams of early computer designers, according to Mel Slater, a professor of virtual environments at the University College London. ''We have seen that the computer can think, see, and hear,'' he said. He acknowleded that there is some work going on in smell and taste, but ''touch is the next big frontier.''
''Imagine you are walking through a make-believe room, and you feel your knee hit a table. I think we are not more than 10 years away from such an experience,'' Slater said.
The demonstration in a cramped cubby of Building 36 at MIT used a monitor and a freely rotating robotic arm - a sophisticated mouse - that was about the size of a mini-desk lamp. Held gently between the thumb and first two fingers, a stylus at the end of the arm could be moved in any direction, its path echoed by a small colored square moving on the monitor.
Three thousand miles away in London, one Joel Jordan was sitting in a similar cubby with a similar set up and was moving different colored square. With tactile feedback communicated through each stylus, the players maneuvered a cube around the screen. They could also lift it, but only if the movement was perfectly coordinated, much like two people holding one chopstick each trying to pick up a slippery object together. I took a turn - and then cheated by telephoning Jordan in England for some verbal feedback as we played. The conversation went something like this:
Jordan: ''Let's take it to the ceiling.''
Arnold: ''I feel you. This is really weird.''
The cube, which had the feel of hard rubber, slipped and dropped toward what at the moment was Jordan's turf.
Jordan: ''You're pushing too hard. You're making my hand shake. More gentle now. Have another go at it.''
With equal pressure on either flank, the cube reached the top of the monitor seconds later. My enthusiastic response was unfit for print.
At the heart of the technology is software that allows seemingly instantaneous response through the stylus and through the Internet. While a one-way trip from brain to hand takes about 30 milliseconds, that same trip from MIT to London takes 150-200 milliseconds, depending on Internet traffic, Srinivasan explained. ''Our biggest hurdle is speed, getting the fastest feedback possible, because touch is not only the sensation of pushing something, but feeling the resistance of that object on your hand.''
He estimated that to take virtual touch to the next level, the tip of each finger will have to have access to approximately 100 tiny motors - or ''taxels'' as he calls them - so that the pressure distribution can be fully appreciated. Another challenge is to determine just how much the brain can be fooled into thinking a collision with a virtual table, for example, translates to sensation in the knee.
''The ultimate limitation,'' he added, ''is the speed of light, because at its best, the feedback of touch can only travel 186,000 miles per second.''
David Arnold can be reached at arnold@globe.com.
