Although the range of Stephen Hawking’s cosmological investigations is almost boundless, he’s long been drawn to a handful of really big ideas that are also powerful engines of curiosity and imagination across the world. Professor Hawking continues his quest to make his science accessible to all and never more than right here with the “three big things” — Leaving Earth, Aliens and Time Travel.


Cosmologists ponder not only the nature of the universe but also humanity’s role in its grand design. Looking outward, there is much about the cosmos we may never know. Yet when we look within, it’s easy to see that humanity values one need above all others: survival.

The odds, however, are stacked against the long-term survival of the human race. The existence of life is due to a very precise alignment of ideal conditions. We’re on just the right planet, bound to just the right star in a universe with physical properties conducive to the evolution of life. The eons ahead present numerous obstacles — and a countdown to potential annihilation.

Surviving Our Own Worst Enemies

First, humanity must survive itself. Two centuries of rapid scientific advancement have made our penchant for warfare and self-destruction all the more dangerous. If we survive nuclear obliteration and environmental disaster, we still have to worry about the rise of artificial intelligence. If computer viruses are, in fact, the first primitive forms of computerized life, then what chaos might the future hold?

A number of natural changes and disasters also threaten the planet. Within 75 million years, all the world’s continents will cluster around the South Pole. By this time, a Manhattan-sized asteroid may have collided with the planet, too, and wiped out all life.

In order to safeguard our survival, we can adapt to geological change and deflect advancing asteroids. We can colonize both the moon and Mars, yet even a human empire such as this will remain susceptible to catastrophe. Gamma rays from a nearby supernova may destroy our small cluster of habituated worlds. We detected similar blasts as recently as 1967, and the nearby star WR-104 is a ticking time bomb of colossal proportions.

In short, every species on the planet is earmarked for extinction. If we remain on Earth, we can only hope to evolve into a more adaptable species, to augment ourselves with technology and perhaps sustain a habitable environment. Nevertheless, such a course would still see humanity written into the fossil record as just another extinct species — and even this testament will ultimately burn in the fires of planetary upheaval.

Fleeing a Doomed World

Humanity cannot survive in this solar system indefinitely. In 5 billion years, our dying sun will scorch even the surface of Mars. As it bloats into a red giant, it will swallow all the inner planets. Humanity must therefore flee to such distant, Earth-like worlds as Gliese 581d. To do so, we will need to master high-speed stellar propulsion and the means to prolong or preserve human life across decades or even centuries of travel. Exodus would entail tremendous technological advancement and substantial resolve.

Leaving the planet will not only prolong our legacy beyond the life span of the Earth, but also introduce new environments and worlds, each a powerful engine of evolutionary change. A space-faring species would truly be unlike any before, transforming as it expands.

In such a great scattering of humanity and its descendants, we would colonize other worlds and perhaps even flee the Milky Way itself before it merges with Andromeda. Yet even a galactic empire of genetically-engineered, technologically superior post-humans would continue to face long-term perils. Billions of years from now, according to the latest estimations, the expansion of the universe will have proceeded so far that space will overwhelm everything. Any single vantage point will reveal only a vast emptiness — what some physicists call the “end of cosmology.” Will humanity find a way to escape this final oblivion? Are there other universes to which we can flee?

If any humanoid cosmologists make it to the far-flung future they will likely ponder these very questions.



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