When the planes hit on September 11, 2001, I was in the F train. The conductor made a bland announcement regretting delays following “an incident.” “What incident?” I asked my neighbor. He shrugged. I arrived at my office at BusinessWeek, then at 6th Avenue and 48th Street, and watched the towers collapse on TV. My baby son was home with the sitter, my daughter at kindergarten. My husband was safe. No one I knew was hurt, miraculously. For months, I cried. I was terrified of a subway bombing. I tried to plan how we would evacuate in the event of a nuclear attack.