A recent search for extraterrestrial signals in over 1,300 galaxies has refined expectations about the potential number of advanced civilizations beyond Earth. Using the Murchison Widefield Array (MWA) in Australia, researchers focused on low radio frequencies (80–300 MHz) that are relatively unexplored by SETI (Search for Extraterrestrial Intelligence), which typically monitors the 1,420 MHz hydrogen emission frequency.
Conducted by Chenoa Tremblay from the SETI Institute and Steven Tingay of Curtin University, the study targeted 1,317 galaxies with known distances in the constellation of Vela. While no alien signals were detected, the team concluded that their equipment could identify signals from a transmitter with a power of 7 x 10²² watts at 100 MHz.
“The MWA’s broad field of view and focus on low frequencies provide a unique advantage for such searches, guiding future SETI efforts.
SETI has traditionally searched within our Milky Way, but its scope has broadened in recent years. Other efforts, such as the Glimpsing Heat from Alien Technologies (G-HAT) project in 2015, surveyed 100,000 galaxies for Dyson swarms around stars but found no evidence of such advanced civilizations. A 2023 study suggested that there could be no more than one civilization within three billion light-years emitting a radio signal stronger than 7.7 x 10²⁶ watts toward the Milky Way.
The null results don’t rule out extraterrestrial life; they reflect the limitations of current searches. Advanced civilizations might use higher frequencies or be operating transmitters at lower powers than we can detect. SETI continues to refine its techniques and expand the range of frequencies it monitors to increase the chances of detecting an elusive signal.