beatrice's blog

searching for intelligent life in the Milky Way

I've always been interested in astronomy, planetary science, and just space in general. This year, I started reading more for fun about SETI efforts and human evolutionary history. I really enjoyed:

Here's my non-expert/pretty-much-knows-nothing-about-this opinion. Buckle up!

What Are The Chances?

We're currently only searching for alien life within our own galaxy, the Milky Way. There are tons more galaxies in the universe (potentially an infinite amount??), and each galaxy has tons of planetary systems like our Solar System. Taking a wide view of the universe, I do believe that somewhere out there, what happened to Earth--having just the right conditions to grow microbes--has probably happened on other planets.

But the thing about intelligent life is that it needs more than just microbes. In Harari's book Sapiens, he argues that intelligent life on Earth was a rare, accidental occurrence of evolution (he calls it the cognitive revolution). Of the total number of species on Earth (which is a lot), homo sapiens are the only ones to experience "advanced intelligence," aka the ability to build advanced technological civilizations, industrialization, medical devices, etc.

Of course, homo sapiens is just an animal on a planet full of animals. Other animal species can be highly intelligent--octopi and crows are scary smart. But SETI is searching for radio signals (also called technosignatures), which means they're searching for intelligent life that can build radio technology. These life forms must be able to learn math, physics, and engineering to build the types of civilizations that could produce signals that we can detect.

SETI is trying to answer the question: is there intelligent life out there? That's different from asking, is there life out there?

I think life is probably relatively common, even in our little corner of the cosmos, the Milky Way. The Kepler telescope estimates there are billions of habitable planets in our neck of the woods. I think there are probably microbes, plants, and animals littered throughout our galaxy. Hell, there could be microbes and marine life in our own solar system! (See my blog post on searching for life on Europa)

But the chances of any of those life forms in the Milky Way (just one galaxy in a universe full of galaxies) experiencing the same or similar cognitive revolution as homo sapiens is pretty low for me. It's just too many moving parts that all have to align perfectly:

  1. First, you need a habitable world with just the right conditions. This alone is a challenge
  2. Next, you need just the right chemical soup to begin forming the basics of life
  3. Then, you need a really long time for complex organisms like animals to evolve and grow to stable populations
  4. Finally, you need one of those species to accidentally stumble upon whatever evolutionary mutation that leads to hyperintelligence and start mastering math, science, and engineering

In our galaxy, I bet there are a few cases like that beyond homo sapiens. Will we ever find them and/or be able to communicate with them? Who knows. Probably not in our lifetime.

In the universe as a whole, I bet there are advanced civilizations all over the place, relatively speaking. The universe is simply too vast to eliminate the probability of any random accident occurring several times over. There could be entire galactic empires beyond our wildest imagination but if they're on the "other side" of the universe, there's just no way for us to find each other. The distances are too great.

So where does that leave me? While I don't think we're truly "alone" in the galaxy in terms of life or intelligent life, we're effectively alone because we haven't been able to find anything or anyone (yet). Same with the rest of the universe.

But it's cool to think that right now, in this moment in "time," somewhere else in the universe, there are other beings existing, moving, thinking, feeling, doing. There are probably other advanced civilizations out there also wondering if they're alone in the universe and trying to figure out if we exist. To them, we're the aliens they're searching for.