It’s often said that the search for aliens is too parochial — that our continuing efforts to locate cosmic radio broadcasts or laser beams are really just quests for analogs of ourselves.

Why so? Well, these efforts presume that extraterrestrials have enough curiosity to reach out to others in the galaxy, or at least send messages skyward for their own purposes (perhaps as a galaxy-wide newscast). These are motives we can understand because our descendants might do something similar.

But what about truly advanced beings? What would a higher-than-high-tech society do that others in the galaxy might notice? This is worth thinking about because broadcasting might not be their thing.

One possibility is that they would build or rearrange big stuff — in other words, engage in civil engineering on the scale of planets or larger. That would produce the kind of artifacts that astronomers might hope to see with their telescopes. Such undertakings would be a burden on Klingon taxpayers, so whatever they did would have to be worth the money.

Can we imagine a super-sized infrastructure project that would be a justifiable expense for the galaxy’s truly superior societies? Dan Hooper, a physicist at Fermi National Accelerator Lab near Chicago, believes he’s thought of one.

He notes that if you’re a long-lived culture, planning to hang around for semi-eternity, then the expansion of the universe is the ultimate bummer. The star-filled galaxies are now known to be moving away from one another (although the stars within a galaxy won’t do this). Worse, the speed of their sprawl is increasing. Even a Hubble-like space telescope will someday be a bad investment for our distant descendants, as very few galaxies will be close enough for it to observe.

That would frustrate future astronomers, of course. But an alien populace might see the thinning of the cosmos as an existential threat. Stars are useful energy sources, and each galaxy contains a few hundred billion of them. But every day, these fuel reserves retreat to greater and greater distances.

Hooper suggests that aliens would have the foresight to grab these stars while the grabbing’s good. They would snag them from surrounding galaxies and park them in their backyards for future use — a kind of nuclear nest egg that would provide sustenance during a dark and lonely future.

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