On Wednesday, world-renowned physicist Stephen Hawking died at the age of 76 in his home in Cambridge, England, leaving behind a legacy of groundbreaking theories in astrophysics as well as providing an example of inspiring personal achievement after being diagnosed with motor neurone disease in his early 20s. In addition to his many contributions to his field, in the latter stages of his career, Hawking at times took on the mantle of a modern prophet, issuing ominous warnings to mankind about various trends and potential calamitous developments. Below is a list of five of his most famous apocalyptic pronouncements.
1. Humans will go extinct if we don't leave the planet soon.
In November 2016, Hawking predicted that man had only 1,000 years left on the planet. By the next year, he had greatly reduced our expiration date, to 100 to 200 years max.
"Although the chance of disaster to planet Earth in a given year may be quite low, it adds up over time, and becomes a near certainty in the next 1,000 or 10,000 years,” the physicist told the Oxford University Union in November 2016. "By that time, we should have spread out into space and to other stars, so a disaster on Earth would not mean the end of the human race."
In May 2017, Hawking predicted that man would have only around 100 years to figure out a way to get off the planet or see the extinction of our species because all the threats to Earth have grown "too big and too numerous" to be avoided.
"I strongly believe we should start seeking alternative planets for possible habitation," Hawking said in a speech at the Royal Society in London. "We are running out of space on Earth and we need to break through the technological limitations preventing us from living elsewhere in the universe."
2. Climate change is "close to the tipping point."
Among the reasons we've got such little time, Hawkings has stated a number of times in recent years, is climate change, which he said has reached a "tipping point."
"Our physical resources are being drained at an alarming rate," he told participants of the Starmus Festival in Norway in June 2017. "We have given our planet the disastrous gift of climate change. Rising temperatures, reduction of the polar ice caps, deforestation and decimation of animal species. We can be an ignorant, unthinking lot. We are running out of space and the only places to go to are other worlds. It is time to explore other solar systems. Spreading out may be the only thing that saves us from ourselves. I am convinced that humans need to leave Earth."
The next month, Hawking reiterated his claim to the BBC, saying, "We are close to the tipping point where global warming becomes irreversible."
3. An asteroid will inevitably collide with Earth.
Among the "too big and too numerous" potential calamities facing mankind is the inevitability that an asteroid will collide with Earth.
"This is not science fiction. It is guaranteed by the laws of physics and probability," he said. "To stay risks being annihilated. Spreading out into space will completely change the future of humanity. It may also determine whether we have any future at all."
4. Artificial intelligence could spell man's doom.
At the Web Summit technology conference in Lisbon, Portugal in November 2017, Hawking warned that the development of AI could end up "destroying" mankind.
"Success in creating effective AI, could be the biggest event in the history of our civilization. Or the worst," he said. "We just don't know. So we cannot know if we will be infinitely helped by AI, or ignored by it and side-lined, or conceivably destroyed by it. Unless we learn how to prepare for, and avoid, the potential risks, AI could be the worst event in the history of our civilization. It brings dangers, like powerful autonomous weapons, or new ways for the few to oppress the many. It could bring great disruption to our economy."
The comments echoed a statement he'd made previously in an interview with Wired. "I fear that AI may replace humans altogether," he said. "If people design computer viruses, someone will design AI that improves and replicates itself. This will be a new form of life that outperforms humans."
5. If we encounter aliens, it will likely be a "disaster" for human beings.
Hawking said in 2016 that he is "more convinced than ever" that aliens exist, but has also warned that we should probably avoid encountering them.
"As I grow older I am more convinced than ever that we are not alone. After a lifetime of wondering, I am helping to lead a new global effort to find out," Hawking said in the film Stephen Hawking's Favorite Places.
But he has also repeatedly said that meeting aliens would likely prove fatal for mankind. "I think it would be a disaster," he said in 2004. "The extraterrestrials would probably be far in advance of us. The history of advanced races meeting more primitive people on this planet is not very happy, and they were the same species. I think we should keep our heads low."