Imagine that you spent your whole life at a single house.Each day at the same hour you entered an artificially-lit room,undressed and took up the same position in front of a motion picture camera.It photographed one frame of you per day,every day of your life. On your seventy-second birthday,the reel of film was shown.You saw yourself growing and aging over seventy-two years in less than half an hour（27.4minites at sixteen frames per second）。 Images of this sort ,though terrifying, are helpful in suggesting unfamiliar but useful perspectives of time. They may ,for example ,symbolize the telescoped ,almost momentary charater of the past as seen through the eyes of an anxious or disa-ffected individual. Or they may suggest the remarkable brevity of our lifes in the cosmic scale of time. If the estimated age of the cosmos were shorted to seventy-two years, a human life would take about ten seconds.
But look at time the other way. Each day is a minor eternity of over 86000 seconds. During each second, the number of distinct molecular functions going on with the human body is comparable to the mumber of seconds in the estimated age of the cosmos, A few seconds are long enough for a revolutionary idea, a startling communication, a baby’s conception, a wounding insult, a sudden death. Depending on how we think of them, our lives can be infinitely long or infinitely short.