There are some things we see so often that we stop noticing them. Airplane windows are one of them. We lean against them to catch a glimpse of mountains, cities, or clouds, but rarely think about why they look the way they do.Take a closer look the next time you fly. Unlike the doors, overhead bins, or tray tables, the windows don't have sharp edges. Instead, every commercial aircraft has windows with smooth, rounded corners.It's easy to assume …