The Future of the Universe Is Dark, But Aliens Could Harness Stars to Light the Way
The universe has been around for about 13.7 billion years, but looking farther down the road, things start to get pretty bleak. In 100 billion years, dark energy will have caused the universe to expand so much that we may not be able to see other galaxies.
At the same time, stars beyond the Local Group (a group of 54 galaxies that includes the Milky Way and Andromeda Galaxy) will have become so far away that we won't be able to observe or reach them.
This inexorable increase in distance on a cosmic scale has prompted the Senior Scientist and Head of the Theoretical Astrophysics Group at Fermilab, Dan Hooper, to propose that advanced civilizations (human or otherwise) would be forced to start collecting stars and pulling them closer to their Galactic Center in order to survive.
The reasoning goes that advanced (potentially interstellar) civilizations would need huge amounts of energy to keep themselves afloat.
Even a resource-rich planet probably would conceivably have trouble sustaining its population's energy needs for over a million years, not to mention the fact that ruthlessly exploiting a planet's resources might result in extinction in the end game.
With this in mind, the creation of Dyson spheres or something similar would probably be the ultimate solution to fulfilling a massive civilization's needs: by enclosing stars in megastructures that can absorb 100 percent of the energy radiated by a star and funneling it somewhere else, a civilization would have huge amounts of power at its disposal.
We're talking about an unfathomable amount of energy here—the likes of which humanity has never seen. As Hopper points out in the paper, the amount of power an advanced alien civilization could harvest with enough sophisticated technology at its disposal is truly mind-boggling.
He says aliens able to command this star-harvesting technology would be capable of storing "the total amount of energy... available to a future civilization by a factor of several thousand."
So if an advanced civilization was really planning for the future, they'd realize that they need to collect as many stars as possible before they become inaccessible.
Hooper's study outlines which stars would be most valuable for this purpose and even gives some potential signs astronomers can look for that would signal that an alien civilization is already doing this, but it doesn't seem to offer a mechanism for moving the stars around.