The Berlin Philharmonic under Sir Simon Rattle is still frequently referred to as the world’s greatest orchestra, and few other ensembles could even think of challenging the assertion. But what is often underplayed is not how good the Berlin is, but how young its musicians have become. “Nearly half the 122 members are under 40, including 13 20-somethings. Seventy-seven were born after Jan. 1, 1960, and the average age is 45. That is about five years younger than during the Karajan period.”