When we meet the unnamed narrator of Ben Lerner’s latest novel, he is holding an unread book and toying with his phone. The setting is a train to Providence, Rhode Island, where he is going to interview an eminent German polymath named Thomas, his old mentor from his college days there. It’s 2024; Thomas has just turned ninety. It’s possible that this will be their last meeting, not to mention Thomas’s last published interview. The narrator needs to think up a good opening question, but he can’t focus on the great man’s latest book because he has a seat “facing opposite the direction of travel….…