Question: Lucy Hawking co-wrote the book "George and the Unbreakable Code" with which famous theoretical physicist?
Context: The Theory of Everything is a 2014 British biographical romantic drama film directed by James Marsh and adapted by Anthony McCarten from the memoir "Travelling to Infinity: My Life with Stephen" by Jane Wilde Hawking, which deals with her relationship with her ex-husband, theoretical physicist Stephen Hawking, his diagnosis of amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig's disease or motor neurone disease), and his success in physics. George's Cosmic Treasure Hunt is a 2009 children's book written by Stephen and Lucy Hawking.  George and Annie, the middle-school cosmologists, return in this sequel to the 2007 story, "George's Secret Key to the Universe".  The book was followed by "George and the Big Bang" in 2011,"George and the unbreakable code" in 2014 and "George and the Blue Moon" in 2016. Stephen William Hawking, {'1': ", '2': ", '3': ", '4': "} ( born 8 January 1942) is an English theoretical physicist, cosmologist, author and Director of Research at the Centre for Theoretical Cosmology within the University of Cambridge.  His scientific works include a collaboration with Roger Penrose on gravitational singularity theorems in the framework of general relativity and the theoretical prediction that black holes emit radiation, often called Hawking radiation.  Hawking was the first to set out a theory of cosmology explained by a union of the general theory of relativity and quantum mechanics.  He is a vigorous supporter of the many-worlds interpretation of quantum mechanics. Lucy Hawking (born 2 November 1970) is an English journalist, novelist, educator, and philanthropist.  She is the daughter of theoretical physicist Stephen Hawking and writer Jane Wilde Hawking.  She lives in London, and is widely known as a children's novelist and science educator, though her career has spanned a variety of areas. George's and the Blue Moon is a 2016 children's book written by Lucy and Stephen Hawking with Christophe Galfard.  The book was preceded by "George's Secret Key to the Universe" in 2007, "George's Cosmic Treasure Hunt" in 2009, "George and the Big Bang" in 2011 and "George and the Unbreakable Code" in 2014 George's Secret Key to the Universe is a 2007 children's book written by Lucy and Stephen Hawking with Christophe Galfard.  The book was followed by four sequels, "George's Cosmic Treasure Hunt" in 2009, "George and the Big Bang" in 2011, "George and the Unbreakable Code" in 2014 and "George and the Blue Moon" in 2016.  It is intended for readers aged 9 and up. George and the Big Bang is a 2011 children's book written by Stephen and Lucy Hawking.  The book is the third book in the George series, following "George's Secret Key to the Universe" and "George's Cosmic Treasure Hunt".  "George and the Big Bang" is available in paperback, hardback and audio versions. Professor Hu Ning (Traditional Chinese: 胡寧; Simplified Chinese: 胡宁) (1916–1997) was a famous theoretical physicist and educator in China. George and the Unbreakable Code is a 2014 children's book written by Stephen and Lucy Hawking.  The book is the fourth book in the George series, following "George's Secret Key to the Universe", "George's Cosmic Treasure Hunt", "George and the Big Bang" and "George and the Blue Moon". Stephen Hawking: Master of the Universe is a documentary television series produced by the television broadcaster Channel 4.  The subject of the series is British theoretical physicist Stephen Hawking, known for his work on black holes, who is also the presenter of the series.  The series includes interviews with astrophysicist Kim Weaver, Bernard Carr, a student of Hawking's, and three theoretical physicists: Michio Kaku, Edward Witten, known for his work on superstring theory, and Lisa Randall.  The first episode premiered in 2008, twenty years after the publication of Hawking's bestselling popular science book "A Brief History of Time".  The title is derived from a "Newsweek" cover, which labeled Hawking "Master of the Universe".
Answer: Stephen Hawking