We Should Look for Star-Sized Supercomputers to Find Aliens, This Researcher Says

Today, our rovers are digging ever deeper for fossils in Martian rock, and our telescopes are spying ever more closely for organic breath in Venusian air. There’s the sense that we’re just now coming to terms with the idea that there really might be life beyond our little blue marble. But that perspective had actually once been widespread.

“For a long period of time the assumption was that all planets must be inhabited. ‘It would be crazy if they weren’t,’ people thought,” said Anders Sandberg, of the University of Oxford’s Future of Humanity Institute, in an interview.  “As people started doing better astronomical observations, they started going back and forth. People decided maybe we're alone in the universe.”

Over the last decade, scientific thinking on the topic has become increasingly optimistic. In 2014, results from the Kepler Space Telescope showed that Earth-sized planets around other stars are likely common. Intelligent life might therefore also be common. A number of researchers are currently searching for this life in what has come to be formally described in academic circles as the search for extraterrestrial intelligence, or SETI. 

Most SETI researchers are straightforward practitioners of physics and astronomy. Sandberg, however, has carved out a more unconventional niche. He earned his PhD in computational neuroscience, and his research spans a dizzying array of different topics, from bioethics, to cognitive enhancement, to computing. It is unified, however, by a few central themes. “Generally, what I try to do is do as rigorous thinking as possible about highly uncertain topics, and see, can we put useful bounds—based on known physics—on these possibilities?”

Sandberg’s work combines analytical rigor with the boundless thinking of a mad scientist. He’s arguably most widely known for his contributions to SETI, which have helped shape the field. In particular, he has contributed much to the theory of hypothetical alien megastructures called Dyson spheres, and is currently writing a book about them. He has been one of the leading thinkers behind looking for these epic celestial spheres—really, star-sized computers—to find life.

Of course, he was not the first serious scientist to propose searching for these objects. In 1960, physicist Freeman Dyson suggested that we might find alien civilizations by searching for the artifacts that they’d create. The particular artifact that he envisioned was an enormous power plant that would surround a civilization’s entire star. His thinking was simple: An advanced civilization would need energy, and lots of it. According to the laws of known physics, most of the energy in a solar system comes from its star. Intelligent aliens would therefore almost inevitably come to the point where they swallowed it. 

Dyson’s idea was radical for the time. SETI at that point consisted almost solely of listening for radio signals. 

“What Freeman Dyson did in his Dyson sphere paper is of course point out that, actually, we might want to look for industrial activities that are not intended to communicate,” Sandberg said. “It's just that [aliens] create structures that we would not normally see in nature and that would be very visible because they're so extreme. And that was a crazy idea back in the sixties and seventies. People were not really ready for it.”

In 1999, Sandberg wrote a remarkable paper proposing one specific conception of how such a structure might work. It was likely enough, Sandberg wrote, that Dyson spheres would be used to power star-sized computers. After all, if our own civilization is any guide, then computing becomes an ever more important objective with time, for any advanced civilization. That’s not to say that computing would be the only possible use of a Dyson sphere. 

“A key question is, what do you use your Dyson Sphere for? And I think you can find a bunch of very different uses,” said Sandberg. “Energy collection is just one. You can, of course, talk about it as living space, which is usually what science fiction tends to do, because it creates an amazing sense of awe when you get so much space.”

But the computational hypothesis seemed to him to be one of the most attractive. Even further, Sandberg envisioned a Dyson sphere supercomputer as powering a grand-scale artificial intelligence (AI). In his 1999 paper, he playfully referred to these star-sized supercomputing lifeforms as Jupiter brains. “The term Jupiter brain was somewhat of a joke from Keith Henson and others, when they were talking about literally converting Jupiter using nano machines into a giant computer,” Sandberg explained. “There are some practical problems with that, mostly cooling, but the name is kind of quite cool to play around with.”

The 1999 paper, thoroughly exploring the computational hypothesis, has become a landmark in the history of Dyson sphere theory. It has influenced modern searches, including the largest ever search for Dyson spheres, currently being undertaken and led by Matías Suazo and Erik Zackrisson of Uppsala University. 

These searches take advantage of the fact that a Dyson sphere would be warmed by its star, making it glow brightly with infrared light. Just as a star is visible to our eyes from vast distances, due to its abundance of light, so too would be a structure that enshrouded a star, due to its abundance of heat. “The interesting thing about looking for Dyson spheres is that it allows you to sample through a large volume, because they would be visible over long distances,” Sandberg said.

While the science of searching for Dyson spheres has by now become concrete, it took a long time to get there. Until the last decade, Dyson sphere papers rarely appeared in the astronomy literature. Now, there are often multiple papers coming out every year, as illustrated by a recent review paper by Jason Wright, an astronomer at Pennsylvania State University. Why is that?

“What happened is that I think Dyson spheres might have become more thinkable. And some of that might just be that we have done better science and understand that yeah, they can be built,” Sandberg said. “Some of the groundwork on thinking about them has been laid, and that leads to the next step.“

Yet even as the idea of the Dyson sphere has become more conceivable, it retains a speculative air. There is no way of knowing with certainty what any future civilization will do. What if new physics is discovered, upending our understanding of technology? Sandberg believes the search is justified, anyways, under a risk-to-reward calculation. “If the impact is big enough, you should actually take it seriously,” he said.

Not only that, but there would be enormous implications to finding a Dyson sphere, as opposed to discovering rather pedestrian radio signals. “It would be awesome if we discovered a civilization like ours a few thousand light years away,” Sandberg says. “But if you find a Dyson sphere, you know that super civilizations are possible. That's kind of an important fact. That tells us that, okay, at least some civilizations get their act together and do pretty impressive things.”

As of yet, of course, no SETI project has detected any serious candidates for intelligent life. But that null-finding, if it continues to hold, might in and of itself say something extremely important. “The empty sky could be a message, that ‘Uh oh,’ intelligent life tends to be doomed. And that would mean that we need to put a lot of effort into existential risk reduction. Or it could just be that the empty sky tells us, ‘Hmm, life is quite rare.’ And the universe is big. Understanding where the answer lies in that question tells us quite a lot about our moral responsibility for ourselves and the universe.”

Since his original work on the subject, Sandberg’s thinking has evolved in some major ways. “Back in the nineties, I was thinking, yeah, you want to get the maximum amount of computations per second out of these things. So, you probably want to make things that are super dense, that do a lot of very intense computation.” But in 2017, Sandberg and coauthors released a paper proposing that Dyson spheres might be built—only to hibernate. 

To understand why Dyson spheres might “aestivate”, as Sandberg calls it, imagine building a Dyson sphere around our own sun. We know that our sun will burn out in approximately five billion years. “That's still quite a lot of time, especially when you start thinking about realistic clock rates for even fairly normal computers. That's a lot of clock cycles,” he said. Yet we also know that the current era of the universe, the stelliferous era, will continue for up to thousands of times longer than that. And as the universe ages, it cools. And just like running an air conditioner is more efficient in cold weather than hot weather, doing computation is more efficient in a cool universe than in a hot universe. By aestivating for a long period, a Dyson sphere could wait until it gets to work, and at that point, get much more done. 

“Time might be cheap,” said Sandberg. “And if you only want to maximize computation, then you might want to do it slowly.”

In other words, as if the idea of a Dyson sphere weren’t radical enough on its own, Sandberg feels it should quite possibly be conceived of as existing on cosmic time scales. But once you wait until the end of the universe, physics is expected to get weird, and many things become hard to evaluate, he admits.

A central hypothesis that Sandberg still stands by is that Dyson spheres will most likely be used as computers. On the other hand, he’s come to believe that there’s a wide variety of scenarios that could happen, different technology paths that a civilization might choose to tread down. “It’s very hard to predict what civilizations will do,” Sandberg told me. “There is a lot of symmetry breaking going on where a civilization or culture might decide on certain ideas or certain goals for reasons that are almost arbitrary,” he said.

In the end, then, just as Sandberg continues to refine the theory of the Dyson sphere as a supercomputer, he retains an open mind to the possibilities. Humanity takes all kinds of paths, after all. So might intelligent aliens. “It's a bit like the problem of sending people to the stars. I'm totally convinced that the reasonable way of doing it is to send a few grams of nanomachines and diamond memory and then build stuff at the destination. Sending actual flesh and blood humans is ridiculous. That takes an enormous amount of resources.”

“But I can totally imagine a Dyson sphere civilization where some Elon Musk character or some renaissance reenactment people say, 'Let's send a ramjet to the stars,' and the response is, 'No, we could just send some nano machines,’ and they say, 'Yeah … but let's make a ramjet because it's cool.' And if you have enough resources, cool stuff occasionally gets done.”