Looking for life in the Milky Way is so 20th century - today's alien-hunters are going intergalactic to look for signs of alien intelligence.

Radio astronomer Chenoa Tremblay of the Search for Extraterrestrial Intelligence (SETI) Institute and astrophysicist Steven Tingay of the International Centre for Radio Astronomy Research did just that and published their findings this week. Their work, the pair wrote, is the "first low-frequency [between 98 and 128 MHz, in this case] extragalactic technosignature search."

Spoiler alert: they didn't spot any signs of hyper-advanced alien civilization lurking in one of the 1,317 far, far, away galaxies they surveyed.

The pair didn’t search for ET with radio waves, because at intergalactic distances radio signals would be so faint as to be indistinguishable from background noise.

"We are not so much looking for communication in this case, like we are for things within our Galaxy, but for signs that advanced civilizations are manipulating their environments on a very large scale," Tremblay told The Register in an emailed statement. "This is more focused on mega structures or large energy use devices which would require a connection of multiple stars or harnessing the energy of a single star."

Civilizations capable of such feats are ranked on The Kardashev Scale, which measures energy capture capabilities. Type 1 civilizations can access all the energy of their planet, while Type 2 civilizations can harness the energy of their star. Type 3 civilizations would be able to harness the energy of an entire galaxy.

Earth is not even a Type 1.

The pair theorize that interplanetary or galaxy-spanning civilizations in Kardashev categories 2 or 3 would emit emitting intense electromagnetic radiation detectable as radio waves, even at galactic distances.

The vast distance between Earth and other galaxies means any signs of alien life would be ancient. Tremblay said that could mean aliens we learn of today may no longer exist in any recognizable form.

"Whether the radio emission was created in the past or present doesn't matter - we are looking for the possibility of their existence," Tremblay said. "There are so many unknowns when it comes to searching for technosignatures, so, we look anywhere, anytime, and as much as possible."

In this case, the search was a largely opportunistic, Tremblay told us, because the MWA had a set of data from a previous galactic survey available for these purposes, and conveniently none in a set of radio frequencies typically monitored by the SETI community.

"We … have not put a lot of effort [into] searching the low radio frequencies for signs of life," Tremblay said. "However, as we have not yet detected signs of technosignatures, prematurely narrowing down where we search in wavelength space can be a detriment."

Adding to the novelty of this search, the MWA data comes from a region of the sky not typically targeted by SETI.

"Exploring a new set of data for a new frequency range for a new group of sources … is what makes this work unique," Tremblay told us.

Despite no success yet in finding advanced life viewable from an intergalactic scale, Tremblay and Tingay aren't giving up. Experiments at Europe's Low Frequency Array (LOFAR) are scheduled to start up soon and will be specifically designed to look for signs of advanced alien life, instead of just trying to tease out the details from a galactic survey.

Whether we'll get any evidence for distant and super-advanced alien life with this next round of research remains to be seen, but so far Earth remains isolated - for now.

"If we don't search, we definitely won't find anything," Tremblay noted. And we're always finding new ways to search. ®

https://www.theregister.com//2024/08/29/seti_intergalactic_search_alien/