he flight was typical: It was full, getting to my seat took forever, and, once I did, the overhead-bin space had run out. So I shoved my backpack under the seat in front of me, where my feet should have gone. I was in the middle—row 31, seat E, American Airlines flight 2070, Phoenix to San Francisco. My neighbors had claimed the armrests, so I had to wedge myself in place, elbows pinched against my ribs or folded toward my lap. I’d be uncomfortable for the duration of the one-hour-and-50-minute flight. As I said: typical. While I origamied my fairly average 5-foot-11, 172-pound frame into position, I realized I needed something from my bag. I leaned forward and hit my head on the seat in front of me. OK, going straight in wasn’t an option; I’d have to veer out of my allotted space. To my left sat a girthy man, his aisle-side arm resting upon his prodigious belly, the other spilling over the armrest and nearly into my lap. To my right, by the window, was a short but still quite stocky fellow; he wore large headphones, the bill of his ball cap tilted low. I began moving, very slightly, this way and that, in a manner not unlike someone parallel parking a semi. I tilted my torso down into the space near the shorter man’s legs and turned to face the aisle-side girthy man, my nose suddenly an inch from his arm. He recoiled. I apologized, and gestured toward my backpack. As I carefully dug around by my feet, a toddler wailed, and I thought, That is the sound we are all making on the inside. Our bodies want to move, and airplanes try to keep us still. We spill into each other’s spaces, banging elbows and heads as we do what we’re built to do.