For most of us, the idea of finding an extraterrestrial life form is a grand notion, the inspirations of which are driven more often by science fiction than by science. So, rarely do we write a fascinating story about finding an alien microbe on a distant planet or of a cute alien bug paying us a visit. We want our first encounter with an otherworldly life form to be an extraordinary story, hopefully, one including a savvy spaceship and a very mysterious but friendly creature inside. We want them to have skills that we do not possess, we want them to be intelligent and above all we want them to really really like us.
When you work in a similar field this is a question you are asked very often and it almost always throws me off- mostly because my understanding of it is still based on anecdotal references and little on facts. So this article is also a way of me trying to get a sense of how to hold a realistic discussion about life outside earth. It is funny, as soon as you start to see what science has to say on this, a lot of the mystery starts wearing off as you start running into studies and theories that are contradicting each other, statistical charts that do not give you an intuitive understanding of the issue and uncertainties on the authenticity of sources.
Starting with the question of odds, Fermi paradox in simple terms describes the contradiction that seems to exist between the high probability that an intelligent life form can exist somewhere in the universe and the extreme lack of evidence of the same. There is a story of Enrico Fermi yelling out in frustration during lunch hour “Where are they?” which could be understood as a layman’s version of that paradox. So what is that high probability Fermi was talking about? Based on the Kepler space mission data there are about 11 billion Earth-like planets orbiting a sun-like star in its habitable zone in the milky way galaxy alone- the nearest of which is located about 12 light years away [source: NASA JPL]. Even simply assuming only earth like planets can hold life that is already a staggering number.
Now, how do we or what do we look for to detect life? The space missions focusing on extraterrestrial lives, look directly for biosignatures that might prove that life has existed outside of earth in some form. We currently have rovers on the surface of Mars that are capable of looking for/recording them. Another direct way of inquiring for life would be looking for the presence of life-sustaining features (as we understand it) such as the presence of water/methane/atmosphere. Jupiter’s moon Europa and Saturn’s moon Titan have been very interesting candidates in this regard for several years now owing to the strong possibility of a liquid water ocean beneath its icy surface and the presence of a significant atmosphere respectively.
Now on to the big question of why has no-one contacted us yet? To answer that I am linking an equation here which you will come to see is only intimidating in its length.
This is the Drake equation which is more a mathematical formulation of probabilities than a definitive tool, gives the number (N) of Milky Way galaxy civilizations already capable of communicating across interplanetary space. The only thing we need to understand here is the term L which is the length of time over which such civilizations broadcast detectable signals into space. So intuitively this would mean if an alien civilization is not capable of developing a technique to reach out in a detectable way, we might never get to know them. Although the validity of this equation has been widely contested it still gives us a vague answer of why no one might not have contacted us yet.
The Voyager probe carries a Golden record on board that contains a cornucopia of information on us humans. Even there, our understanding of an intelligent species is of one similar to life on earth, ones who are capable of having technologies that could decode recorded pieces of sound.
The Golden Records were carefully designed to reach extraterrestrials, and now they’re within reach of the public.
Arrival is one of my favorite movies on this subject. It at least began to question our cliched understandings on this subject.
This post really fails to accomplish what I set out to do but at least I hope it has given you some starting points to go out and explore discussions on alien life that are shy of UFO sightings and crop circles.
See you soon with another snippet of this fascinating universe that we live in.