What makes up the universe? How does gravity work? What is time? Scientist Brian Cox answers these questions and more in the BBC’s Wonders of the Universe series, now on DVD, and in his book, Wonders of the Universe. Recently, Cox visited the TIME For Kids offices, in New York City, to chat with us about his work and about the show. Watch the video interview, above. (Reporting by Vickie An / Videography by Kelli Plasket / Editing by Stephanie Kraus)