For more than 2,000 years, we humans have been arguing about life and, in particular, intelligent life in the universe. But arguing was pretty much where it always ended.
For all that time, we never had any evidence or any data that could raise the discussion above two people with different opinions yelling at each other.
But this era may well be nearing its end.
The “exoplanet” revolution of the last 20 years has shown us that the universe is awash in alien worlds. More exciting, we now have methods where the atmospheres of those worlds may provide indirect evidence — called “bio-signatures” — for the existence of life.
Over the next few decades we may finally have data relevant to the question of other life in the universe.
But what if we want to ask about intelligence? What about alien civilizations — or, as I like to call them, “exo-civilizations”? This is something I have been thinking about a lot over the last few years (it’s the subject of my new book). In carrying out my own studies, I have often been drawn to the work of Harvard astrophysicist Avi Loeb.
Loeb works on a variety of subjects, including black holes and early cosmic history. But together with collaborator Manasvi Lingam, Loeb has carried out work that is simultaneously deep and expansive on the topic of astrobiology and exo-civilizations.
When we think of aliens and science, we usual usually think of the Search of Extraterrestrial Intelligence (SETI). This has often meant radio telescopes being used to search for messages purposely beamed at us from an exo-civilization. But unlike these kinds of purposeful signals, a “techno-signature” is an unintentional marker of the civilization’s existence. With the discovery of so many exo-planets, astronomers will now be spending a lot time staring at these other worlds in many different wavelengths of light (not just radio). This is how they hope to find bio-signatures.