THE INTERNET IS changing the way people learn, work, and buy things. The Net's greatest impact, however, may be on how people relate to one another. Shortly after users began to post messages on the early computer networks, they began to have what one might call "out-of body-experiences." For example, in the early 1970s, according to Katie Hafner and Matthew Lyon,

two people had logged in to the University of Utah [computer system]. One saw that somebody else he knew but had never met was logged in. They were in talk mode, so he typed, "Where are you"" The other replied, "Well, I'm in Washington." "Where in Washington"" "At the Hilton." "Well, I'm at the Hilton, too." The two turned out to be only a few feet from each other, attending the same conference.

When people are on-line, their actual physical location does not...