Harvard physicist Avi Loeb is not shy about his idea that Earth's 2017 interstellar visitor being an extraterrestrial craft and is set to release a book to defending his claim with more detail. The book, titled 'Extraterrestrial: The First Sign of Intelligent Life Beyond Earth,' argues the consensus that Oumuamu is not a comet or asteroid, but a light sail – a method of spacecraft propulsion. In a recent interview ...