“A hyper-advanced civilization might raid other galaxies for stars to keep the Milky Way glowing for trillions of years. Over a period of billions of years our progeny could secure many trillions of stars that would have otherwise fallen victim to the expansion of space, beyond our reach forever. These stars could ultimately become gravitationally bound to the future version of the Milky Way, leading over time to the formation of an enormous supergalaxy.”
It might not seem like it, but the inhabitants of Earth are on the threshold of leaving the solar system continues Dan Hooper, author of Dark Cosmos in today’s Scientific American. On cosmic timescales—measured in millions or even billions of years—it will be no time at all before our descendants begin to spread outward and across the Milky Way Galaxy. Unless technological progress is brought to a halt by some kind of major catastrophe, the era of our Earthly confinement is about to come to a close.
Imagine that over the course of the next hundred million years or so a hyperadvanced civilization emerges from Earth—much as our early ancestors once migrated out of Africa—and expands across the entirety of the Milky Way. Futurists have long argued such beings will build structures called Dyson spheres around stars, capturing and putting to use as much of the energy released in starlight as possible. It seems entirely conceivable that 100 million years from now every star in the Milky Way will be surrounded by a Dyson sphere, providing roughly a trillion trillion, or 1024 times more power than human beings currently produce and consume.
I don’t claim to have any great insights into what this kind of civilization will chose to use their vast quantities of energy to accomplish. Maybe they’ll use it to tackle unsolved math problems or to create and maintain vast simulations of virtual worlds. Perhaps they will direct it to the expansion of their civilization or to the creation of art or other such pursuits. Regardless of their goals, however, one thing is clear. Every act, including thinking, requires energy. This means no matter what an advanced civilization may want to accomplish, harnessing the power of as many stars as possible will help them to do it.
To such a civilization, the greatest long-term threat will be the expansion of space. The stars, planets and other forms of matter that make up our galaxy are bound together by the force of gravity, and thus we don’t easily notice the effects of this expansion. But across much larger distances the expansion of space is steadily pulling galaxies apart from one another, riding on the very fabric of spacetime. Exacerbating this further is the fact our universe is not only expanding but is doing so at an accelerating rate, being driven by what cosmologists call “dark energy.”