Not so long ago I arrived at Dulles airport, outside Washington, after a very protracted journey from Russia, including a layover in Germany. Like most transatlantic voyagers, I was weary, only approximately awake, and felt vaguely unwashed. Standing for a long time in a long line to present my passport to customs officials, I observed that an unusual number of my fellow travelers appeared to be elderly—that is to say, older than myself—and I could only surmise that the rigors of modern air travel were especially taxing for them.