In his book "Brief Answers To The Big Questions", Hawking wrote that it was "almost inevitable that either a nuclear confrontation or environmental catastrophe will cripple the Earth at some point in the next 1,000 years". "Try to make sense of what you see, and wonder about what makes the universe exist", he said.
"Travel back in time can't be ruled out according to our present understanding", he wrote.
"I want to share my excitement about these big questions and my enthusiasm about this quest", says Hawking in an excerpt of his final book.
In "Short answers to big questions" the physicist suggested that wealthy people will soon be able to use gene editing to become a superhuman memory, invulnerability to disease, extraordinary intelligence and durability.
Recognized for his work on black holes, Hawking published his first book "A Brief History of Time" that sold over 10 million copies and was translated into dozens of languages. The book was meant to collect Hawking's answers to the questions he received most frequently from answer seekers.More news: LeBron James loses in LA Lakers debut despite sensational start
More news: Barnier: Brexit deal at 90%, Ireland a 'sticking point'
More news: Banksy's Secret Video Reveals How 'Girl With Balloon' Shredding Should Have Worked
"How do we shape the future?", he wrote. The panel included Hawking's children, his academic colleagues, and others who knew him.
Scientist Stephen Hawking of "Into The Universe With Stephen Hawking" speaks via satellite during the Science Channel portion of the 2010 Television Critics Association Press Tour at the Langham Hotel on January 14, 2010 in Pasadena, California.
"With Brexit and Trump now exerting new forces in relation to immigration and the development of education, we are witnessing a global revolt against experts, and that includes scientists", he said.
Hawking's daughter Lucy, who attended the book launch, said hearing her father's unmistakable voice had been 'very emotional.' 'I turned away, because I had tears forming in my eyes, ' she said.
In his last Reddit post before his death, which took place as a Q&A on the forum, Hawking said he feared Earth would have a "catastrophic ending" in the near future and that it he thought it could be due to smart robots that might take over the planet.
What other questions do you wish Stephen Hawking answered in his last book?