EACH DAY’S HEADLINES jolt us with the same unnerving reality: There has never, in the history of the Republic, been a stranger time to be old. We live in a kind of gerontocracy that feels both accidental and deeply entrenched. Our best hope for unseating the about-to-turn-74-year-old in the White House, whose reign is propped up by a terrifyingly powerful cable network that serves as the plaything of an ultrarich 89-year-old, is a former vice-president who, at 77, won the Democratic nomination over a 78-year-old senator whom young people preferred during the primaries. If elected, he will, one hopes, work effectively with the 80-year-old Speaker of the House or may, one worries, be thwarted by the truculent 78-year-old Senate majority leader. Until then, several crucial rights, including access to health…