When something is thin enough to fit into an envelope, light enough to sit on your lap for a couple of hours without discomfort and so compact that it doesn't even bulge in an airline seat-back pocket, wouldn't it make sense that one could lose track of such a thing? Even if it is a computer?

Yes, it would make sense. Believe me. Please. Because I can't find my MacBook Air.

Can you really blame a guy for losing something that's called Air? True, Apple's new superslim laptop isn't transparent, and while its dimensions are anorexic (a profile ranging from 0.76 inches to 0.16 inches), we're not really talking about a dust mote here. It does weigh three pounds: impressive for a computer, but nowhere near the borders of nonexistence. In terms of utility, though, my MacBook Air (or, more accurately, the review unit that Apple lent me) might as well not exist. Because it's gone. Just another expensive miniature marvel of technology vanished into thin, um, air.

Let's walk back the cat (as the spies say) to try to solve this puzzle. It was a Wednesday morning. I thought I would take the Air to work with me. I was fairly confident of its location—an area of my apartment that includes a couch, a coffee table and a side table. This was also where I leave the white cube that is the computer's power supply, plugged into the extension cord right by the sofa. On that Wednesday, the power cord was indeed in place. But a quick scan did not reveal the presence of the laptop.

So I began a more thorough search. Looking for a MacBook Air, even in a New York City apartment, can be grueling. (Unlike the often-misplaced cell phone, it can't be called so you can locate it by ring.) You have to examine the bookshelves. You have to look under furniture. You have to scan through manila folders—because the Air is barely thicker than the papers inserted in those folders. Basically, you have to tear the whole place apart. Which I did. All I came up with was $6.80 in change and some credit-card bills for which I have already paid late fees. But no MacBook Air.

My next step was figuring out whether the laptop could have been lost—or stolen—at some other location. The last clear image I had of actually seeing it was the previous Friday afternoon, when (name-drop alert!) I was waiting to appear on "The Charlie Rose Show." I had shown the Air to another guest in the greenroom. Then I went to the studio, did the segment, grabbed my backpack and left. (Charlie Rose, who was in the studio the whole time, is not a suspect.) When I later asked the woman who runs the Rose show whether a MacBook Air had turned up, she said no.

I'm pretty sure, but not 100 percent, that after I got home that evening, I didn't take the computer out of the house again. Similar vagueness, I suspect, will lead to a lot of desperate searches for Airs over the next few years. (Most of these hunts, unlike mine, will turn up the computer.) The MacBook Air will not be the primary computer for many of its owners; lots of people need more storage than the maximum 80 gigabytes it provides. For those users, it will be a unit designated mainly for travel. This means that owners may well leave it in a perch that is later forgotten.