Every day, a brief tweet with a time and a URL: it’s usually for 7:00 pm Berlin time, 1:00 pm in eastern North America. At almost precisely 7:00 pm, we click, and a 9:16 aspect ratio window opens. The view, about ten degrees left from perpendicular, shows the keyboard and the left half of a grand piano, a painting and a couple of lamps hanging in view. Igor Levit, dressed casually, wearing socks or slippers, walks onscreen and sits on his piano stool. He talks for about five to ten minutes, first in German, then in English. Then he plays: Beethoven, Liszt, Shostakovich, Billy Joel. Twitter/Periscope’s muffled, distorted sound and low-definition image offers anywhere from 15 to 150 minutes of the most intensely charged piano playing I’ve ever heard. The…