London (CNN) There is no God -- that's the conclusion of the celebrated physicist Stephen Hawking, whose final book is published Tuesday.

The book, which was completed by his family after his death, presents answers to the questions that Hawking said he received most during his time on Earth.

Other bombshells the British scientist left his readers with include the belief that alien life is out there, artificial intelligence could outsmart humans and time travel can't be ruled out.

Hawking, considered one of the most brilliant scientists of his generation, died in March at the age of 76.

"There is no God. No one directs the universe," he writes in "Brief Answers to the Big Questions."

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