While humanity has so far found no conclusive evidence of alien civilizations existing somewhere out there, scientists continue to tirelessly look for signs of extraterrestrial life in the vastness of space.
Rather than trying to spot biological signs of life on other planets, some researchers look for hints of alien technology that may indicate the existence of advanced alien civilizations, though this approach may be more difficult that it might seem, say Macy Huston and Jason Wright, astronomers from Penn State.
For example, while the search for intentional radio and laser signals remains one of the most popular strategies of the search for extraterrestrial intelligence (SETI), this approach is based on the assumption that aliens actually want to communicate with other lifeforms, the researchers explain in an article published in The Conversation.
Nevertheless, even if a reclusive civilization does not want to advertise its presence to its potential interstellar neighbors, it does not mean that such a civilization cannot be detected – provided that it actually exists in the first place.
As Huston and Wright point out, mankind does not send many intentional signals into space, but many of our existing technologies emit radio transmissions that get leaked into the cosmos, and some of these signals may actually be detectable if they were coming from a nearby star.
“Research is ongoing as to whether current emissions from cell towers in the radio frequency on Earth would be detectable using today’s telescopes, but the upcoming Square Kilometer Array radio telescope will be able to detect even fainter radio signals with 50 times the sensitivity of current radio telescope arrays,” the researchers write.
And then there is also the probability of alien civilizations building megastructures that would be difficult to hide, such as the hypothesized Dyson sphere – a gargantuan structure that would encompass a star in order to harvest its energy.
Also, chemical pollutants produced by industry, along with artificial light and heat emitted by cities and industrial facilities, may also serve as telltale signs of alien presence.
The researchers point out, however, that “no astronomer has ever found a confirmed technosignature,” not to mention that no one really knows what alien technology may actually look like.
“The bottom line is that there are many avenues for detecting distant life,” Huston and Write state. “Since no one knows what approach is likely to succeed first, there is still a lot of exciting work left to do.”