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In context: Radio waves from distant galaxies are too faint to provide meaningful data for potential space observations. However, a sufficiently advanced alien civilization could harness energy in such a way that an entire galaxy could be affected. SETI is looking into it.
Researchers used a powerful ground array for low-frequency radio observations to look for potential signs of life outside the Milky Way. Radio astronomer Chenoa Tremblay of the Search for Extraterrestrial Intelligence Institute (SETI) and astrophysicist Steven Tingay of the International Centre for Radio Astronomy Research recently published a study about their efforts to discover "technosignatures" coming from distant parts of the cosmos.
SETI and other scientific projects searching for intelligent extraterrestrial life usually focus on targets located in the Milky Way. Radio waves coming from external galaxies would be indistinguishable from background noise when looking for signs of radio-based communication.
"We search for technosignatures, spectral and temporal features consistent with our understanding of technology," the researchers explained.
Chenoa and Tingay's study targeted over 1300 "foreign" galaxies by directing the Murchison Widefield Array toward the Vela supernova remnant. Tremblay told The Register that advanced civilizations could manipulate their galactic neighborhood on a large scale, and we could undoubtedly detect electromagnetic radiations from these efforts.
The researchers looked for "mega structures" or other signs of artificial devices capable of harnessing a single star's energy or even connecting multiple stars. They quoted the notorious Kardashev Scale proposed by Nikolai Kardashev in 1964, a method to rank alien civilizations depending on their abilities to manipulate and exploit energy sources.
A Type I civilization should be able to access all the energy available on its home planet, the Kardashev Scale states. In contrast, a Type II civilization would directly consume the energy stored in a whole star. Finally, a Type III civilization should be able to capture energy emitted by an entire galaxy, including stars, black holes, and other energy-rich space phenomena. A Type IV civilization, which Kardashev did not include in his original theory, could use an amount of energy comparable to the power of the entire universe.
The researchers focused on Type II and Type III civilizations, as they would likely emit electromagnetic radiations intense enough to reach Earth telescopes. The study is the first low-frequency extragalactic technosignature search ever performed. Perhaps unsurprisingly, it hasn't yet turned up anything.
"There are so many unknowns when it comes to searching for technosignatures. So, we look anywhere, anytime, and as much as possible," Tremblay said.
Radio waves from other galaxies would have traveled millions of years before reaching our Solar System. The theoretical alien civilizations in question would likely be ancient history by the time we detected anything. Still, the researchers aren't interested in this specific matter. They are just looking for the possibility of their existence. Until that happens, Dyson spheres (masthead) and ancient aliens will remain in the realm of science fiction.
Image credit: Rebekah Smith