relativity

On Saturday, I had an exceptional bicycle ride, for once fighting the wind on my way out. Then on the way back, it was amazing. Sometimes when you ride with the wind, it is like one of those Einstein relativity thought puzzles. Imagine a woman traveling to Kenya on a train; she drops a book of poetry out the window. To her, the book appears to fall straight down. But to a boy herding goats by the tracks, the book (which he is about to own) seems to fall at an angle, carried forward by the motion of the train. And when abandoned rails are pulled out to make a bike path, and when a person is riding on it in the same direction as the wind and at about the same speed, to him there is no wind. To an old woman standing at a wooden bridge dangling a fishing line into a small river, there is a strong wind blowing, so she ties her hair up in a scarf as the cyclist speeds past her, exchanging hellos with her as he passes. But to the rider, there isn’t even the usual resistance of pushing against still air. He cannot feel wind in his face or on his back. It feels more like a vacuum is drawing him, pulling him forward. So exhilarating, Einstein would whoop!