There are many mysteries in the universe. Evolution or creationism? The chicken or the egg? What do women really want? Why do we get so annoyed at people using cell phones in public places? I can't shed any light on the first three, but I have a theory about the cell phones.

Time was, I was more than willing to join in any conversation bashing cell phone users for talking on them in restaurants, parks, and other public places. Then someone asked how using a cell phone was different than conversing with another person. If the place and volume are appropriate, what difference does it make if someone is talking to another human face-to-face or on the phone?

Intellectually this argument made sense. Loud conversation of any sort in a movie theater is rude and disruptive. Quiet conversation in a coffee shop or on the bus is not. I tried hard to embrace this new perspective, but something didn't fit. There was a difference, I just couldn't put my finger on it.

Not too long thereafter a mobile phone company aired series of ads in which a well-known actress walks into the middle of some activity, stops time, hands one of the participants a cell phone, then restarts the action. In one ad, a young man stuck in a long line uses his newly acquired phone to listen to a karate movie that his friend is watching at home. There was something there, my gut told me, but I still wasn't getting it.

A few weeks later, I was in a hospital coffee shop, sitting at a table that overlooked the main lobby one floor below. A woman at the next table was talking on her cell phone while her husband, seated across from her, drank his coffee. In the lobby below, a man on a bench was engrossed in his own cell phone conversation. Both people were talking quietly and not disturbing anyone around them. And finally I realized what bothers me about these conversations. It's not the volume or the setting, it's the fact that the caller is choosing not to share our present reality. He (or she) is saying, in effect, "There's nothing and no one right here, right now, that's worth my time and energy. And while you all may be stuck here, I'm not."

Whenever I go anywhere that might require me to sit and wait, I take a book. Reading is a way of leaving the immediate present and putting my attention elsewhere. And how many times have I let my mind leave the boring reality of a business meeting to daydream? Is talking on a cell phone all that different, or just more obvious? Right now, I don't have a good answer. I guess like many theories, this one still needs some work.