George's Secret Key to the Universe

George's Secret Key to the Universe is a children's book written by Stephen Hawking, his daughter Lucy Hawking and his research student Christophe Galfard. It was written to explain the universe and the laws of physics to children, in the form of an adventure story. It was published in 2007. There are another three books in the series, "George's Cosmic Treasure Hunt" (2009), "George and the Big Bang" (2010), and "George and the Unbreakable Code" (2014).