I’ll be talking about SETI, the search for extraterrestrial intelligence; the Fermi paradox; and whatever else comes to mind — but first, the Copernican principle, which arguably sounds cooler than the mediocrity principle.
I think Earth is special, for the same reason I think Minnesota is special. I live here.
But I also think we’ve been finding the same elements, and same physical laws, throughout the universe. We’ve also been learning that the universe has been changing since it started, some 13,799,000,000 years back, give or take.
So there’s some truth in the Copernican principle. Which makes the lack of space alien visitors remarkable.
It’s a reasonable question.
That’s because many of this galaxy‘s 100,000,000,000-plus stars have planets somewhat like Earth.
Some fraction of those planets may support life, which might lead to intelligent life. Some of those planets are billions of years older than Earth.
If we had neighbors, and they’re anything like us, the assumption is that we’d have found at least the alien equivalent of 50-gallon oil drums and six-pack rings by now. We haven’t.
Folks have quite a few explanations for this lack of evidence, some more plausible then others:
- Extraterrestrial life is rare or non-existent
- We’re the only intelligent life
- Everybody else is low-tech
- Intelligent life
- Destroys itself
- Destroys other intelligent life
- Gets killed by natural events
- We’re the first
- It’s a big universe
- Intelligent civilizations are too far apart in space or time
- The Galaxy is too big for us to meet each other
- We haven’t been around long enough
- We’re not listening properly
- Civilizations broadcast detectable radio signals only for a brief period of time
- Civilizations tend to isolate themselves
- The aliens are too alien
- Everyone is listening, no one is transmitting
- They’re avoiding us
- We’re in a
- Wildlife preserve
- They’re afraid of us
- We’re in a
- They’re already here
- And hiding
- But the government/Big oil/Microsoft/The Illuminati won’t let us know
Like I keep saying, I don’t believe that life exists elsewhere in this universe, or that it does not. We don’t know, not yet.
If we do have neighbors, and we meet, I’m pretty sure that some folks will be upset, and that others will realize that the people from another world are — people.
That doesn’t mean that I think they’ll be particularly “human,” and that’s a topic for another post.
Depending on who’s talking, that’s a diagram of the scala naturae, ladder of nature/life, or chain of being.
It’s been around in one form or another for quite a while, and can be a handy way to categorize things.
Plato wrote about the father-son relationship; the nature of knowledge and opinion, perception and reality, nature and custom, and body and soul; and art.
Plato did write about metaphysics and his theory of forms. That’s the idea popularized by Plato’s Allegory of the Cave. Maybe “popularized” is putting it a bit strongly, but my guess is that you’ve heard of Plato’s cave.
Where was I? “Invaders from Mars,” the Fermi paradox, Plato’s theory of forms. Right.
We’ve learned a great deal since Aristotle’s day, so these days we divide living creatures into domains and kingdoms, two of which are plants and animals; but I think the “ladder” model is good enough for this post.
Humans are animals, living creatures with a material body. But we’re not just animals.
Each of us is an animal with free will who can think; a ‘someone,’ not a ‘something.’ We can decide what we do or do not do. It’s being rational creatures that makes us “in the image of God.” (Genesis 1:27; Catechism of the Catholic Church, 1700–1706, 1730, 1951)
Getting back to the “ladder,” we’re material creatures. In that way, we’re like rocks, plants, and animals. We’re also people: able to think and decide what we do.
If we meet folks who aren’t human, intelligent creatures made from the stuff of this universe, they’d be on the same ‘rung’ of the ladder as we are.
I think Brother Guy Consolmagno is right: they’d be so much like us, basically, that they’ll be more like cousins than “aliens.”2
- “ESA’s Gaia, HD 164695, and SETI”
(September 16, 2016)
- “Proxima Centauri b, Looking for Life”
(September 2, 2016)
- “Faith, the Universe, and Wisdom”
(August 28, 2016)
- “Humility isn’t Being Delusional”
(July 31, 2016)
- “Studying Thousands of New Worlds”
(July 29, 2016)
- 13,799,000,000 – universe starts
- 4,540,000,000 – Earth forms
- 4,100,000,000 – life starts on Earth
- 2,600,000 – Oldowan stone tools made
- 39 – Voyager 1 launched
Voyager 1 is currently about 20,200,000,000 kilometers from our sun, outward bound and still sending back data. That’s a tiny fraction of the distance to the nearest star. But if other folks were launching their first space probes while we were making our first stone chopping tools, today they could be using tech we’ll be developing 2,600,000 years from now. 2,600,000 years seems like a long time, but it’s less than one one-thousandth (26/45,400) Earth’s age.
“…Frankly, if you think about it, any creatures on other planets, subject to the same laws of chemistry and physics as us, made of the same kinds of atoms, with an awareness and a will recognizably like ours would be at the very least our cousins in the cosmos. They would be so similar to us in all the essentials that I don’t think you’d even have the right to call them aliens.”
(Brother Guy Consolmagno)