Why Don't Birds Fall Over When They Take Off?

摘要

Aplump pigeon with fluffy grey feathers is perched comfortably on the window ledge of my apartment. Its head twitches jerkily from side to side as its fiery orange eyes scan the pavement below for a dropped crumb. But suddenly a car door slams shut, and the echoing thud panics the bird into action, lunging into the air with frantic clapping wings, a rapid ascent and then a swoop over the traffic below before a nimble and precise landing on the building opposite. This whole maneuver lasts less than two seconds but is so rich in physics that understanding it has kept scientists busy for decades.