Free Astronomy Magazine November-December 2020

41 NOVEMBER-DECEMBER 2020 ASTROBIOLOGY listen to our favorite radio station, we are tuned to a frequency in the FM band, and probably to one used by Tremblay and Tin- gay to search for alien broadcasts. The two researchers simulta- neously listened to over 3,000 channels with a resolution of 10 kHz, sufficient to distinguish any pow- erful alien transmis- sion sent from the planets closest to us among those in orbit around the approxi- mately 10 million stars framed by the MWA. Each single observation (listening) of the en- tire probed area lasted only 5 minutes, for a total integration time of 17 hours. How- ever small this period may seem, the survey conducted by Tremblay and Tingay is to date the deepest and most extensive carried out in low frequency. As Trembley herself pointed out: “The MWA is a unique tele- scope, with an extraordinarily wide field-of- view that allows us to observe millions of stars simultaneously. We observed the sky around the constellation of Vela for 17 hours, looking more than 100 times broader and deeper than ever before.” Despite this, all the channels listened to were silent. Here is what Tingay said about this, not at all surprised by the negative re- sult: “With this dataset, we found no tech- nosignatures — no sign of intelligent life. As Douglas Adams noted in The Hitchhiker’s Guide to the Galaxy , ‘space is big, really big’. And even though this was a really big study, the amount of space we looked at was the equivalent of trying to find something in the Earth’s oceans but only searching a vol- ume of water equivalent to a large back- yard swimming pool. Since we can’t really assume how possible alien civilizations might utilize technology, we need to search in many different ways. Although there is a long way to go in the search for extraterres- trial intelligence, telescopes such as the MWA will continue to push the limits — we have to keep looking.” Tingay is not new to these performances. Previously, he had probed similar frequency ranges by pointing the MWA towards the Galactic Center and the Galactic Anticenter regions, both with the same results: ab- solute silence (excluding interference of ter- restrial origin). In fact, although the MWA has been installed in a remote place (Boolardy, Western Australia) and is pro- tected from radio signals emitted by inhab- T he authors of the survey discussed in this article: Steven Tingay and Chenoa Tremblay. [Curtin Univer- sity, ICRAR]