A hot topic in technological circles these days is the concept of virtual reality. It has been the subject of numerous news stories and magazines articles, and has also inspired several movies and TV shows. Of course, a form of virtual reality has been around for a long time -- it's called "theater". First in stage plays, then in movies, the background and props are intended to represent a location that doesn't exist at that time or place. Use of computer editing has now allowed a greater degree of seamlessness in marrying actual movie footage and special effects, from the weather in Twister to the Presidential appearances in Forrest Gump. (By the way, I expect any day now to see ads for "personalized" videos, inserting the customer into his/her favorite film in a minor role. Impress your friends!)
However, what has some people excited is the possibility of an experience far beyond two-dimensional images. They envision a total bombardment of the senses with artificially-created impulses, interacting with that environment as if it were real. Applications might include a filing system where one would select a document by taking its book image from a shelf; virtual vacations, providing the sights and sounds of faraway (or even fictitious) places; and a conference occurring in several locations simultaneously, linked together via holographic images of the participants.
This situation reminds me of the state of artificial intelligence a few decades ago. Back then it was thought that computers could be programmed to "learn" complex tasks by trial and error; they could write poetry, carry on conversations, even develop personalities. But today it is acknowledged that AI is a dead-end field. Its only successes have come in areas where options are limited; true creative intelligence is beyond the capacity of even the most powerful computers.
I believe virtual reality will suffer the same fate. In some areas, such as flight training and amusement park rides, the quality of the illusion will be sufficient for its purpose. But in general, true reality will prove to be too complex to simulate. Paraphrasing Abraham Lincoln, "You can fool some of the senses some of the time, but you can't fool all of the senses all of the time." The GeoCities neighborhood that hosts this page is nice, but it will never look or sound (or smell!) like a place where real people live.