How did I get so old? And what have I done with my life? Facebook triggers an existential crisis.I recently joined the Facebook bandwagon and posted a profile. In short order I reconnected with several good friends from college with whom I'd lost touch, which I suspect is Facebook's killer app for anyone over 30.

Renewing friendships is delightful, but each time the process was uncomfortably similar.

First there's an exchange of obligatory "Dude, what've you been up to?" messages. The highlights of your life since college -- in my case, 15 years -- are laid out like bullets in a PowerPoint slide: relocation, marriage, kids, and the sketch of a career arc.

Early on, messages are traded in a flurry of excitement, and you indulge in a bit of nostalgia: "Remember that time when the cops pulled us over?" If you live nearby, there are proposals to meet up. If you live far apart, there are vague promises to get together someday. Then your exchanges grow increasingly banal. And then there's a lull in communication.

You notice your friends have put on weight or are losing their hair. You wonder how you look to them. You are glad you didn't post that photo of you and the kids at the beach, with your pale white belly hanging over your bathing suit like a purse.

And you play a little game with yourself, tallying up their life accomplishments against your own. You rock at Wii bowling -- 10 points! Ed owns a house in San Francisco, and it's fully paid off -- 1 million points. You are secretly pleased to learn that Ed's novel/screenplay/demo record never went anywhere.

And as you think about old friends, uncomfortable questions arise. Fifteen years? What's happened in all that time? Are you in a place where you imagined you'd be? Have you become the person you meant to, or do you find your self on a side track, slightly bewildered as you race toward an unseen destination?

The daily crises that consume your life suddenly feel stupid. And what are they all for? Has anyone been saved? Have you had any impact on this world at all? Or are you measuring your life in coffee spoons?

Suddenly you realize what an insidious device Facebook is. It's not a goofy lark for hooking up with friends and letting the world know how cool your music catalog is. Facebook is a mirror you hold up to your life that compels you to ask "Who am I? What am I here for? How am I doing?"

I think it's time to cancel my account.