Interlude Drake & Fermi
Interlude
Drake & Fermi
Transcribed excerpt from The Debunker podcast archives:
Calvin: Extraterrestrials. Interplanetary visitors. Intergalactic travelers. Aliens. We have a lot of well-known terms for the idea of life originating from a different corner of our universe.
It might surprise some of my listeners to hear that I wholeheartedly believe in aliens. The scope of the universe is mind-bogglingly large. There’s no conceivable way we’re the only ones out here. Statistically speaking, if we exist, we can’t be the only example of life in the universe.
Now, the question of life from far-flung places in the galaxy making the long journey all the way to our little corner of the cosmos is a different story. I’m more skeptical when it comes to that. Ironically, for the very same reason I’m sure other life exists, the universe is unfathomably large.
Then you throw in all the other complications: It takes a long time and a lot of precise conditions for life to develop.
And even longer for life to evolve long enough to traverse space.
Rogue planet-destroying asteroids, violent and self-destructive species—there’s so much room for things to go wrong before we make contact with an alien species.
Do I think life exists elsewhere in the universe?
Absolutely. Do I think people are being abducted and probed?
Absolutely not. Aside from the deliberate hoaxers out there, I think some of them sincerely believe they are telling the truth, but that’s an entirely different topic for a different type of expert.
Are we alone? Humans have been shouting this question, asking the universe for an answer for as long as we have had the ability.
What are the chances there’s other intelligent life in our galaxy that could shout back to us?
To try and answer that, let’s take a look at a famous equation you may or may not have heard of, depending on how much of a nerd you are: the Drake equation, formulated in 1961 by Frank Drake.
N = R* · ?p · ne · ?l · ?i · ?c · L
On the left side of the equation, we have the answer we seek, N, which stands for the number of civilizations in our Milky Way galaxy with whom it might be possible to communicate.
So this is going to be an advanced life-form, not microbes or creatures who aren’t able to communicate across the galaxy.
Probably an older life-form that’s had a while to develop.
This number of potential alien species we might communicate with is based on a bunch of probabilities multiplied together over on the right side of the equation.
The math is pretty easy when you get down to it.
You start with R*, the rate of star formation in our galaxy. Then you multiply it by the fraction of those stars that have planets, fp. This gets us a starting point, a count of all the planets in our galaxy.
Then you multiply by the fraction of those planets that have the potential to support life, ne. Basically, you’re narrowing the list of planets by excluding those unable to support life: gas giants, planets too far from their sun, etc.
Multiply that result by the fraction of those potentially life-supporting planets that actually develop life at some point, fl. Meaning, cut out the planets that could develop life but, for one reason or another, remain lifeless.
Cut the number even further with factor fi, the fraction of those planets harboring life that evolve advanced life. In other words, only count planets with intelligent life-forms, not just microbial life.
Then go even further and look at only planets with civilizations that develop enough technology to release observable signals of their existence into space, fc.
We aren’t concerned with planets populated by the extraterrestrial equivalent of dinosaurs.
It might surprise you to realize that our own Earth wouldn’t meet this cutoff until the turn of the twentieth century when the first radio waves were broadcast.
We still aren’t done. Finally, you factor in L, the length of time those civilizations release detectable signals into space for us to find. This removes planets whose civilizations fell before reaching the cosmos, civilizations that died out before we ever got the chance to communicate.
And that will get you to your final number, N, a count of the extraterrestrial civilizations in our galaxy whom we might be able to contact.
Now all this to say, there’s a great deal of uncertainty when you plug values into this equation.
Different assumptions give widely different answers.
A generous estimate gives us over fifteen million possible civilizations in the galaxy with whom we might be able to communicate.
But the most conservative estimate suggests we may be alone in our galaxy.
It’s easy to forget scale here, so let me just remind you that we’re talking about our galaxy, not our universe.
Our universe contains billions, maybe trillions of galaxies.
Metaphorically, we’re talking about our neighborhood, and leaving off the existence of entire countries.
I tend to think we’re somewhere in the middle. Which brings me to the next big question. If there’s a high likelihood that we aren’t alone in our galaxy, where is everyone? This question, known as the Fermi Paradox, has a great many possible explanations.
Basically, we’re missing a factor in the Drake equation. The great filter, some last threshold or challenge that knocks down our final number of potential advanced alien civilizations enough to explain their absence.
As humans, we like to think of ourselves as intelligent, higher beings, at the top of the food chain. But what if we aren’t? It wasn’t so long ago we were earthbound. Small groups of us banding together, trying to survive the long, dark nights full of predators.
What if we’re still the prey in a dark forest full of predators? What if we’re making a mistake shouting into the cosmos for anyone to hear? Maybe we haven’t spotted the lion watching from the bushes as we trample loudly along our merry way through the woods.
Maybe someday soon we’ll finally get an answer to the calls we’re always sending out across the radio waves. Maybe someday soon we’ll hear back from the aliens. A desperate warning from someone a little more advanced than us.
“Be quiet, or they’ll hear you.”