"Born Originals," the 18th-century English divine and poet Edward Young, the author of Night Thoughts, once asked, "how comes it to Pass that we die Copies?"

I twitter--often, several times a day. Most of my 140-character posts to the microblogging service are gnomic little mutterings, many are telegraphic self-advertisements (the quotidian, new-media equivalents of "THE NILE IS SETTLED STOP SPEKE"), and some are bluntly promotional of stories on TechnologyReview.com. You'd think no one would read such stuff, but you'd be wrong. About 900 people follow me.

I Pownce, too--sharing images, music, or videos on the file-sharing service. I also have a Facebook profile, where more than 700 "friends," most of whom I have never met, note my status updates, nod over the books I read, and peek at my photos. I Digg. Occasionally, I blog. And all my social-media activities are rolled up on FriendFeed. If you subscribed to my feed, you'd see how often I use social technologies: 24 times on Thursday, July 31.

I am not sure why I do all this. Anything I write for Tech­nology Review or other publications reaches a far larger audience. I began because I felt I shouldn't write or edit stories about social technologies without having used them. Then, too, everyone young seemed to use social media all the time, and I didn't want to be generation-gapped by the little freaks. But I persisted because social technologies allowed me to talk with readers and sources in new, interesting ways. Also, it was fun! By now, using social media has become habitual, like keeping a diary.

But I will never use social technologies quite as the young use them, because I do not thrill to continuous attention and I value my privacy. Thus, the Jason Pontin who occupies the social space is a constructed persona, designed to be unchallengingly personable, humorous, and thoughtful. I am none of those things very often. The preoccupations of that Jason Pontin are professional: he thinks about emerging technologies all the time. And I never broadcast the substance of my inner life, because I know it would become insubstantial the moment I did.

Social-media Jason Pontin, in short, is a function of my business life. I know that this identity is inauthentic, because there is so much about which I do not post or blog. Do other habitual users of social media, whose social identities are as carefully constructed to attract attention, but who blog and post about everything (and thus feel no alienation), not know that those identities are inauthentic? Bemused by the difference between themselves and their social-media selves, are they mere Copies, cast from a few popular molds, endlessly reproduced among false friends?