In June 2006, Steven Spielberg announced he would direct a scientifically accurate film about "a group of explorers who travel through a worm hole and into another dimension", from a treatment by Kip Thorne and producer Lynda Obst. In January 2007, screenwriter Jonathan Nolan met with them to discuss adapting Obst and Thorne's treatment into a narrative screenplay. The screenwriter suggested the addition of a "time element" to the treatment's basic idea, which was welcomed by Obst and Thorne. In March of that year, Paramount hired Nolan, as well as scientists from Caltech, forming a workshop to adapt the treatment under the title Interstellar. The following July, Kip Thorne said there was a push by people for him to portray himself in the film. Spielberg later abandoned Interstellar, which was eventually directed by Christopher Nolan.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): In what year did Christopher Nolan become a director?
unanswerable