Space Aliens and Life’s Ladder

I’d be surprised if many folks took movies like “Earth vs. the Flying Saucers,” “Invaders from Mars,” and “Plan 9 from Outer Space,” seriously: as something other than entertainment, anyway.

All of which has about as much to do with space exploration, astronomy, and SETI, as “Keeping Up with the Kardashians” does with family counseling.

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.

That’s the idea that Earth isn’t the center of the universe, and that conditions here aren’t unique. One of these days I’ll probably talk about Anaximander and the Ptolmaic system, but not today.

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.

Where is Everyone?

The Fermi paradox — both Enrico Fermi and Michael H. Hart raised the question, I don’t know why it’s named after Fermi — is a nifty name for the ‘where is everybody’ question.

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.

Folks who are anything like us could have sent interstellar probes here from the other side of the galaxy in about a million years. That’s a very short time, on a cosmic scale.1

A few of our spacecraft are already headed out of the Solar System, sending back data about conditions beyond the heliosphere.

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:

  1. Extraterrestrial life is rare or non-existent
  2. We’re the only intelligent life
  3. Everybody else is low-tech
  4. Intelligent life
    • Destroys itself
    • Destroys other intelligent life
    • Gets killed by natural events
  5. We’re the first
  6. 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
  7. We haven’t been around long enough
  8. We’re not listening properly
  9. Civilizations broadcast detectable radio signals only for a brief period of time
  10. Civilizations tend to isolate themselves
  11. The aliens are too alien
  12. Everyone is listening, no one is transmitting
  13. They’re avoiding us
    • We’re in a
      • Zoo
      • Wildlife preserve
      • Terrarium
    • They’re afraid of us
  14. 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.

Scala Naturae: The Ladder of Nature

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.

He didn’t discuss cosmology much, although Pythagoras had called the order of the universe κόσμος, cosmos decades before Plato was born.

Alexander von Humboldt dusted the Pythagorean word off and used it as the title of his “Kosmos” about two dozen centuries later — and that’s another topic.

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.

Skipping lightly over Aristotle, Plotinus, and Neoplatonism, which hasn’t been new since Saint Augustine of Hippo wrote “De libero arbitrio,” and that’s yet another topic.

Where was I? “Invaders from Mars,” the Fermi paradox, Plato’s theory of forms. Right.

Anyway, Neoplatonism includes a celestial hierarchy which arguably goes back to Aristotle’s idea of the The Great Chain of Being/Scala Naturae/Ladder of Life.

Sharing a Rung with Cousins

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, 17001706, 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

More-or-less-related posts:


1 Lets see how many years ago a few key events happened:

  • 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.

2 From “Brother Astronomer;” Chapter Three, Would You Baptize an Extraterrestrial? — Brother Guy Consolmagno (2000)

“…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)

About Brian H. Gill

I'm a sixty-something married guy with six kids, four surviving, in a small central Minnesota town. I mostly write and make digital art. I'm only interested in three things: that which exists within the universe; that which exists beyond; and that which might exist.
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