- SETI is the search for extraterrestrial intelligenceIt looks for signals of intelligent life on other worlds or for signs of their structures.
- A new search for 2,800 distant galaxies by astronomers in Australia is the first of its kind. Until now, astronomers have mainly searched among stars in our own galaxy.
- Extraterrestrial civilizations that are more advanced than ussay these researchers, could transmit signals or use enough energy to be detectable across galactic distances.
In search of extraterrestrial intelligence
The search for extraterrestrial intelligence (SETI) is about looking for artificial radio signals from alien worlds. Or it is about looking for other types of technosignatures, other signs of past or present technologies. And so far, the search has focused mainly on stars in our home galaxy, the Milky Way. But now a new initiative has expanded the search for intelligent aliens to other galaxies. It is the first search of its kind for extraterrestrial intelligence, with 2,800 galaxies being searched.
On August 26, 2024, the SETI Institute, the Berkeley SETI Research Center, and the International Centre for Radio Astronomy Research announced their new extragalactic SETI search. They said they used the Murchison Widefield Array (MWA) in Western Australia to scan the galaxies.
The researchers published a preprint version of their new paper on arXiv on August 19, 2024.
SETI observes 2,800 galaxies simultaneously
These researchers were able to conduct their search using the Murchison Widefield Array’s wide field of view (the circle of sky visible through the eyepiece). The wide field of view allowed them to observe 2,800 galaxies simultaneously. They focused primarily on the 1,300 or so galaxies whose distances are known. In addition, the search also focused on low radio frequencies (100 MHz), for which the Murchison Widefield Array is well suited. The scientists’ paper states:
In studies aimed at finding artificial signals produced by distant civilizations, researchers often focus on galactic sources. Recently, researchers have begun to focus on searching for all other sources within the observed field, including the vast population of background galaxies.
In a background galaxy population toward the supernova remnant Vela, we search for technosignatures and spectral and temporal features consistent with our understanding of technology.
Of these galaxies, we focus on the 1,317 sources with known redshifts, as these can be used to estimate distances and thus the power requirements of the transmitters.
Chenoa Tremblay of the SETI Institute is one of the two lead researchers. She said:
This work represents a significant advance in our efforts to detect signals from advanced extraterrestrial civilizations. The MWA’s wide field of view and low frequency range make it an ideal tool for this type of research, and the limits we set will guide future studies.
Supercivilizations
The signals the study was looking for are a specific type of technosignature. Basically, a technosignature is any sign of advanced alien technology. It could be radio signals, laser/light signals, or Dyson spheres and other artificial structures. It could even be artificial pollution in a planet’s atmosphere. Notably, any alien civilizations this type of search could discover in other galaxies would be more advanced than us. Essentially supercivilizations. Because the galaxies are so incredibly far away, any signal would have to be strong. In fact, it would require technology powerful enough to harness the energy of their sun or even other stars in their galaxy. The paper described this in more detail:
It is widely accepted that supercivilizations harness the energy of natural objects and transmit signals over long distances. Haliki (2019) and Chennamangalam et al. (2015) have developed a model in which pulsars, rapidly rotating neutron stars, could be used as modulated beacons to contact other civilizations. Their recommendation was that Type III civilizations could not only harness the beacons of light and change the modulation to communicate, but could potentially build an entire communications network. Since modern radio telescopes can detect pulsars in galaxies outside our own, this provides another potential mechanism for generating emissions, although these are broadband in nature (frequency width over MHz); we could potentially detect the resulting energy of the technology.
No signals found yet
In this case, no signals or other technosignatures were found during the search. But it is only the first search of its kind. The newspaper states:
Although no signals were detected, we limited the transmit power over the 1,317 galaxies to about 1022 W. Kardashev (1985) assumes that a large-scale technology would have a lot of mass, a large energy potential and a high volume of information. With the sensitivity of modern radio telescopes, it might be possible to detect the radiation emanating from such a supercivilization even over galactic distances.
In fact, the study represents a novel avenue for future searches. As co-lead author Steven Tingay of Curtin University noted:
The MWA continues to open up new possibilities for exploring the Universe for intelligent civilizations and technosignatures, using the same data to study the astrophysics of stars and galaxies. This work is novel and original, but also paves the way for future observations with even more powerful telescopes.
Conclusion: A new SETI search for extraterrestrial intelligence by astronomers in Australia is the first of its kind. The search was for technosignatures in distant galaxies.
Source: An extragalactic wide-field search for technosignatures with the Murchison Widefield Array
About the SETI Institute
Read more: SETI searches for extraterrestrial signals in the heart of the Milky Way
Read more: Will SETI 2.0 lead to the discovery of intelligent aliens?
