Imagine falling into a jackpot in the search for intelligent extraterrestrial life. That is precisely what scientists expect to find when swept by the net for Dyson spheres utterly colossal structures that advanced alien civilizations might build around their stars in an effort to capture energy. In this premise, the scientists have now pinned down seven stars in our Milky Way galaxy that are showing unusual activity, possibly indicating the alien megastructures.
A Dyson sphere, which a physicist, Freeman Dyson, first postulated a structure for in 1960, is not a single solid shell enveloping the star, but a collection of satellites with wide surfaces dedicated to collecting solar power. The logic in this structure would be an unlimited energy source, and hence the alien society that would spread and thrive without any problem; but such a megastructure would leak radiation out into space through its gaps.
It is this radiation escaping, or infrared excess emissions, that scientists would be on the lookout for. “These are satellites with very broad surfaces floating around the star,” co-author of the study Suman Majumdar, associate professor in the department of astronomy, astrophysics, and space engineering, Indian Institute of Technology, explained. That means the reradiated light might be picked up as pulses of infrared radiation that, in theory, would allow scientists to detect a Dyson sphere from afar. Theoretically and ideally, of course, from very far away: from the Earth.
For example, in their paper, Majumdar and his co-authors streamed through the infrared signals for more than 5 million stars within our galaxy in search of IEEs. The origin of such excess light can be anything but a Dyson sphere. “There’s a lot of reasons that stars might have extra infrared emission,” suggests Jason Wright, an astronomy and astrophysics professor at Penn State University. Thus, for instance, young stars that wear protoplanetary disks also radiate infrared light. Their short list of candidates was whittled down by an agonizing winnowing process to seven that were very hard to explain by natural mechanisms.
All this has been made possible only with the help of the Gaia satellite, a mission by the European Space Agency that maps the three-dimensional positions of more than a billion stars of the Milky Way. “It took more than a year to go through this,” Majumdar said. Without Gaia, winnowing down the candidates would have been close to impossible. “I’m so excited for this big data era,” said Tabetha Boyajian, an associate professor of astrophysics at Louisiana State University, who wasn’t involved in the study. “All the big surveys that are coming out—all the things we can learn from this data by looking at it in different ways.”
The researchers’ further frontier in days ahead will be to do a more sophisticated spectroscopic analysis on all these seven stars. This shall provide them more on the radiation of these stars and might finally debunk all the natural explanations for IEEs of the stars, he went on to say. To say confidently that this is not something that nature is doing, it’s something that an advanced civilization is doing that will take a lot of rigor, said Boyajian.
Meanwhile, the search for Dyson spheres goes on. Gaia is mapping its database with new stars, and Majumdar and Wright, among others, will be looking for other candidates. “The same analysis can be actually done on the newer candidates that are populating the catalog,” Majumdar noted. So while we might be standing on the threshold of a discovery monumental in scope and importance, the journey has only just begun.
Now, with more plausible, with more advanced alien life in civilization, you could look at this one factor: A Dyson sphere could become a harbinger of our not being alone in the universe. Although the end result is not conclusive, the search for these megastructures has continued to challenge premises, fueling our curiosity about the cosmos.
Keep looking up at the stars, for who knows what other wonders we shall come across?
