In this issue: THE FINANCIAL PAGE "How Low Can Oil Go?", by James Surowiecki: Cheap oil is probably too good to last. THE TALK OF THE TOWN "A Couple of Ambassadors", by Rebecca Mead: The visiting Cambridges with Downton Abbey's advisor on protocol. PROFILES "In the Land of the Possible", by Evan Osnos: Ambassador Samantha Power's evolution from an activist who was often critical of the foreign-policy establishment to a diplomat and senior adviser to President Obama. INNER WORLDS "Bus Stop", by Tatyana Tolstaya: The author recalls how her writing life began. "The Word Shed", by Colum McCann: The author remembers his father's writing shed. THE THEATRE "Sideshow", by Hilton Als: A review of The Elephant Man POP MUSIC "Test Patterns", by Sasha Frere-Jones: A review of reviews TV on the Radio's latest album.