(AP) — Physicist Stephen Hawking says God wasn’t necessary for the creation of the universe.

In his new book, “The Grand Design,” the British scientist says unraveling a complex series of theories will explain the universe. The book, written with American physicist and author Leonard Mlodinow, will be published Sept. 9.

In an extract published Thursday in The Times, Hawking wrote that it was “not necessary to invoke God.”

“The Universe can and will create itself from nothing,” Hawking wrote. “Spontaneous creation is the reason there is something rather than nothing, why the Universe exists, why we exist.”

In “A Brief History of Time,” Hawking had appeared to accept the possibility of a creator, saying the discovery of a complete theory would allow humans to “know the mind of God.”