Renowned theoretical physicist Stephen Hawking said in a speech at Oxford University Union that humanity only has about 1,000 years left of viable existence if it doesn't leave the planet and colonize the stars.

The professor argued that humanity is unlikely to survive all of the different crises we will face over the next millennium. But humans can avoid extinction, he said, if we have colonized other planets by that time, giving humanity a fighting chance away from our "fragile" Earth.

Dr. Hawking's prediction may seem gloomy, but much of his speech took an optimistic tone. After all, a thousand years is a long time to figure out how to colonize space, and plans are already underway for humans to visit Mars with an ultimate goal of colonizing the red planet. Scientists continue to discover potentially habitable exoplanets elsewhere in the galaxy that could potentially be new homes for humans – if we can make it there.

During his speech, Hawking noted that the biggest and most immediate challenge for humanity will come in the next century, with threats such as potential nuclear terrorism, climate change, and the rise of artificial intelligence potentially outcompeting humans foremost in his mind, according to The Washington Post.

"Although the chance of a 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," Hawking said in the speech. "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."

NASA has already discovered thousands of exoplanets using telescopes like Kepler, which can detect planets based on fluctuations in light created by planets passing between their stars and the telescope. While only a few are potentially habitable, and almost all are out of the reach of current technology, a rapid increase in our ability to detect Earth-like planets and the development of new propulsion methods could one day lead us to multiple new worlds for future generations to inhabit.

While large-scale colonization of space still feels like a goal rooted more in science fiction than science fact, Elon Musk, the founder and chief executive officer of Tesla and SpaceX, unveiled a plan last September to begin colonizing Mars by 2024, beating NASA's timetable for such a task by 10 years, as the Christian Science Monitor's Lonnie Shekhtman reported:

Mars' first colonists will contend with unprecedented obstacles. First there's the hefty price tag. Under current conditions, Musk estimates that a trip to Mars would cost about $10 billion per person. (By comparison, NASA pays $70 million per seat to fly on a Russian spacecraft to the International Space Station). By some projections, it would cost NASA around $100 billion over 30 years to send astronauts there and bring them back. Other predictions have attached a $500 billion price tag to the trip. As of today, there isn’t a rocket in operation that can transport humans even to the moon, which is 200 times closer to Earth than Mars. To make colonization sustainable, Musk says, would require reducing the cost to about $200,000 per person, or approximately the median cost of a house in the United States. Achieving that would involve making rockets reusable and increasing capacity and efficiency of the Mars journey. Musk estimates that SpaceX initially would need to build a fleet of about 1,000 ships, carrying 100 people, departing from Earth every 26 months to make the venture economically viable. "The key is making this affordable to anyone who wants to go," Musk said.

While exploration farther into space stalled after the end of the cold war, the growing role of private space companies in recent years has created a new kind of space race between corporations such as Boeing, Blue Origin, and SpaceX. The commercial nature of corporate space programs ensures a cash flow that traditional government agencies can't always count on. Private companies often collaborate with NASA to facilitate many of the government agency's more ambitious projects, including the co-development of NASA and Boeing's Space Launch System, a heavy-lift rocket for deep space exploration, as the Monitor previously reported.

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This kind of collaboration might allow humanity to spread out into space before we hit Hawking's expiration date in 1,000 years.

"Remember to look up at the stars and not down at your feet," Hawking said, according to The Independent. "Try to make sense of what you see, wonder about what makes the universe exist. Be curious. However difficult life may seem, there is always something you can do and succeed at. It matters that you don’t just give up."