Let's face it: The planet is heating up, Earth's population is expanding at an exponential rate, and the the natural resources vital to our survival are running out faster than we can replace them with sustainable alternatives. Even if the human race manages not to push itself to the brink of nuclear extinction, it is still a foregone conclusion that our aging sun will expand and swallow the Earth in roughly 7.6 billion years.
So, according to famed theoretical physicist Stephen Hawking, it's time to free ourselves from Mother Earth. "I believe that the long-term future of the human race must be in space," Hawking tells Big Think. "It will be difficult enough to avoid disaster on planet Earth in the next hundred years, let alone the next thousand, or million. The human race shouldn't have all its eggs in one basket, or on one planet. Let's hope we can avoid dropping the basket until we have spread the load."
Hawking says he is an optimist, but his outlook for the future of man's existence is fairly bleak. In the recent past, humankind's survival has been nothing short of "a question of touch and go" he says, citing the Cuban Missile Crisis in 1963 as just one example of how man has narrowly escaped extinction. According to the Federation of American Scientists there are still about 22,600 stockpiled nuclear weapons scattered around the planet, 7,770 of which are still operational. In light of the inability of nuclear states to commit to a global nuclear non-proliferation treaty, the threat of a nuclear holocaust has not subsided.
In fact, "the frequency of such occasions is likely to increase in the future," says Hawking, "We shall need great care and judgment to negotiate them all successfully."
Even if humans manage to avoid a nuclear stand-off over the next thousand years, our fate on this planet is still pretty much certain. University of Sussex astrophysicist Dr. Robert Smith says eventually the aging Sun will accelerate global warming to a point where all of Earth's water will simply evaporate.
"Life on Earth will have disappeared long before 7.6 billion years," says Smith, "Scientists have shown that the Sun's slow expansion will cause the temperature at the surface of the Earth to rise. Oceans will evaporate, and the atmosphere will become laden with water vapor, which (like carbon dioxide) is a very effective greenhouse gas. Eventually, the oceans will boil dry and the water vapor will escape into space. In a billion years from now the Earth will be a very hot, dry and uninhabitable ball."
Finally, between the next thousand years or so that Hawking says it will take man to make the planet uninhabitable and the billion years it will take for the sun to turn our planet into an arid wasteland, there is always the chance that a nearby supernova, an asteroid, or a quick and painless black hole could do us in.
Why We Should Reject This Idea
Despite what Hawking describes as humankind's "selfish and aggressive instinct," there may be some biological impediments to finding another planet to inhabit.
"The nearest star [to Earth] is Proxima Centauri which is 4.2 light years away," says University of Michigan astrophysicist Katherine Freese, "That means that, if you were traveling at the speed of light the whole time, it would take 4.2 years to get there."
Unfortunately, at the moment we can only travel at about ten thousandth of light speed, which means if man were to use chemical fuel rockets similar to the those used during the Apollo mission to the moon, the journey would take about 50,000 years. Without the use of a science-fiction-like warp drive or cryogenic freezing technology, no human would live long enough to survive the journey. In addition, "the radiation you would encounter alone would kill you, even if you could get a rocket to go anywhere near that fast," says Freese.
On the upside, if man ever develops the technology to travel at the speed of light while remaining shielded from cosmic radiation, he could effectively travel into the future. "A five year trip at light speed could push an astronaut forward by 1000 earth years," says Freese, "If he wanted to see if any humans were still around by then."