The question of finding intelligent life in the universe was most concretely addressed by two scientists years ago. One was Enrico Fermi and his paradox, which to paraphrase asks: If life is so common among the billions of stars in the trillions of galaxies, and if space travel is even relatively achievable, then where is everybody? The other was Frank Drake and his equation that attempts to quantify—or at least set the framework for quantifying—the likelihood of intelligent life appearing elsewhere in the universe.
Both of them miss a point that is, I think, obvious to anyone who thinks about it deeply enough: the universe is really big and really old.1 We ourselves have only been around for comparatively the last two seconds of all that time. So far, we’ve managed to explore the skin of just one local planet and populate only a fraction of it in any numbers. And we’ve placed a couple of dozen robot probes on the surface of, or in orbit around, the other planets in our own system. We have accomplished the latter in a remarkably short time, considering the age of our own species. In terms of the age of the universe, we’ve gone outside the Earth’s atmosphere in just the last microsecond.
Okay then, time scales. The universe, according to our best guesses and measurements, is about thirteen billion years old. Considering its vast size, that’s a bit younger than it should be if the whole works has been expanding at even roughly the speed of light for all that time since a putative Big Bang. To account for this, astronomers posit an “inflationary” period right after the dense monoparticle containing everything we can see, know about, or infer exploded, so that it all expanded faster than light speed just to catch up with modern observations. But I digress …
Our own solar system is approximately four billion years old. That is, the Sun and the planets started condensing out of a cloud of dust and gas some nine billion years after the whole shebang exploded or started expanding exponentially. And that dust and gas was the residue of earlier stars that had lived and died, vomiting up a rich mixture of hydrogen, helium, and every other type of atom on our periodic table. We live in a second- or third-generation—possibly a fourth-generation—star system and are richer for it. But I digress …
That curious reversal of entropy that we call “life” actually appeared on the surface of this third planet—one of only three in the habitable zone where water can appear as a liquid rather than a vapor or a solid—soon after the bombardment of planetoids and meteorites stopped and the planet’s surface had cooled enough to be solid and entertain pools of liquid. The first life was nothing remarkable and not really visible to the naked eye: single-celled bacteria and blue-green algae that processed the chemicals available in their environment and the sunlight streaming down by using a relatively sophisticated DNA-RNA-protein coding system—or perhaps just RNA-protein coding to begin with, because the DNA form may have developed a bit later. These simple creatures worked to—or I should say “evolved to”—exploit the existing chemistry of the planet and replace its original atmosphere of carbon dioxide, water vapor, ammonia, and methane with one that was mostly nitrogen and oxygen.
These bacteria and blue-green algae, which would only be really visible as mats of colored slime on the edges of the seashore, persisted for two or three billion years. Over that time, they developed environmental niches and separate species, but they still remained simple, mindless cells that processed chemicals and sunlight, grew and divided, and reworked the planet’s surface and atmosphere. It wasn’t until about five hundred million years ago, or three and a half billion years since the solar system formed, that the first multi-celled organisms appeared. This required variable expression of that DNA-RNA-protein coding system and the development of cell types that were different from each other but still originated with a single cell and worked together as a single system. This generative period was called the Cambrian Explosion because suddenly the Earth—or at least its seas—had plants and animals that a visitor from beyond the stars could recognize with the naked eye and avoid stepping on, if he-she-it were wading in a tide pool or shallow lake. The animals and plants didn’t move up onto the land masses until about a hundred and fifty million years later, during the Devonian period.
Here we’re still talking about relatively mindless beasts: fishlike vertebrates and scorpionlike arthropods who spent their entire lives grazing or hunting and reproducing in kind. Even when the land animals developed study legs and grew to the size of houses, such as the dinosaurs, they were still just predators and prey, fighting for survival, reproducing, and not much else. It wasn’t until sixty-five million years ago, when the Chicxulub asteroid wiped the slate of life nearly clean and allowed little mouselike nocturnal creatures, the earliest mammals, to survive and develop, that we got the sort of brains and intelligences that we recognize in primates, whales, dolphins, elephants, and ourselves. And even then, any visitor to this planet would not have found much in the way of interest, nothing to report home.
We humanoids of the genus Homo didn’t come down from the trees and out onto the grasslands until about one or two million years ago. We didn’t develop the sapiens, or “wise” species, until about sixty-five thousand years ago. And even then we were in competition with the neanderthalensis species, named for a valley in Germany where their bones were first discovered. These other Homo species may or may not have been as developed intellectually as our direct ancestors. But any visitor from another star system would have found both the neanderthalensis species and our sapiens ancestors picking berries and killing slower-moving animals with sharp sticks and edged rocks, then sucking the marrow from their bones. These collective ancestors probably used a decipherable language, and some of them may have carved a whistle or rudimentary flute from a shinbone in an attempt at making music. But for the most part, you had to look and listen closely to distinguish them from a troop of chimpanzees or baboons. And still, the number of Homo sapiens—the species with such future promise—was pitifully thin on the ground.
It wasn’t until about ten thousand years ago that our ancestors began gathering in groups, usually along fertile river valleys, to practice farming, domesticate animals, and build shelters larger than a tent made of saplings and animal skins. It wasn’t until five thousand years ago that they begin to think about baking clay forms into useful pots, smelting metals for better tools and weapons, and writing down their grunts and squeaks as an encoded language that would last longer than this morning’s conversation.
It wasn’t until a hundred and eighteen years ago that Guglielmo Marconi sent the first long-distance radio transmission—across the Atlantic Ocean—and then that message was in coded a series of dots and dashes. Even in its heyday, radio was a broadcast system rather than beamcast, which meant that its signal strength dissipated exponentially under the inverse square law. The signal from a 50,000-watt radio station in Kansas, belting out Patsy Cline in the 1950s, would be something less than a whisper by the time the wave front passed Saturn, and hardly louder than a bug fart by the time it got out of the Oort Cloud on its way to the stars. That famous first television broadcast of Adolph Hitler opening the Berlin Olympic Games in 1936 would not have fared any better. And these signals would then have had to compete with the blasts of radio noise coming from our own Sun. And now that so much of our communications is carried by coax and fiber-optic cables, and beamed down from satellites in near-Earth orbit, our planet will have gone virtually dark within our local spiral arm of the Milky Way.
So, even if the universe is crawling with life at the stage of bacteria and blue-green algae, or shambling along with creatures that resemble the dinosaurs or our own Homo habilis, it’s not listening for us and not able to visit us. Even if an advanced species has developed radio sets and antenna with which to search the skies—and remember, we didn’t develop radio telescopes until the engineers at Bell Labs tried to establish the source of bothersome static on long-distance radio-telephone calls in the 1930s, about eighty years ago—they wouldn’t be likely to hear anything that sends them cruising toward Earth.
And did I mention that space is really, really big? The nearest star system is four light years away, which means that even if we could travel at light speed—and our mathematics says we can’t—it would take four years to make the one-way voyage, even if we had the proper technologies for propulsion and life support. Forget about science-fiction tropes like warp drives, wormholes, matter-antimatter energy sources, and other forms of magic. Going to the stars will still be a civilizational undertaking—for us and for any other species out there. Stellar empires might grow in the minds of speculative writers and nuclear physicists like Fermi, but establishing one and holding it together as an enterprise of cultural and economic exchange, under the conditions of generational time lag presented by the distances involved, would be a daunting and perhaps fruitless task.
Exploring the cosmos just to see if some other planetary system has developed something more than slime molds and dinosaurs, or even humanoids knocking over pigs and butchering them with sharp rocks, would be a remarkably altruistic or academic pursuit costing a huge percentage of a planet’s and a culture’s resources. Even beaming signals out in all directions in the hope of one day getting a response that made any kind of sense would be a significant undertaking.
pWhere are all the other intelligent species? I think they’re out there, but they’ve got better things to do than visit us.
1. I know, fellow writers, “really” is an adverb and we should eschew the use of adverbs. When you want to write “really” or “very,” just write “damn,” because it means the same thing. Still, I could use “really” about four times in succession to describe the universe’s magnitude and about twice to describe its age—but that would just sound silly. Hence, the rest of this essay.