["Open Mike" is the often off-topic Editorial page of TOP, some of which go where none have gone before.]
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I believe aliens exist, but only as a matter of logic. There are between one hundred and two hundred billion galaxies just in the observable Universe (many more in total), and each one of them contains, on average, 100 million [CORRECTION: 100 billion] stars. Even if rare, there still must be tens or hundreds of millions of hot-core planets in the Universe that orbit their stars at the perfect distance to be temperate, and that feature the chemical stew that leads inexorably to life. It's purely a matter of numbers. We think we're special, but that's because we're hominids and that's how hominids think—heck, we even think our tribal groups are special compared to other tribal groups. (And the aliens know this, probably. They've seen it a million times, in a million solar neighborhoods.) But we can't be. It doesn't stand to reason. It's like the old joke, "You're unique, just like everyone else."
Is there really any plausible reason why aliens would visit Earth? We like the place, and have a high opinion about how interesting it is, but then, we evolved to fit it; but aliens wouldn't have done, and would most likely find it unsuitable. So what's to bring them here? What's the attraction? We're a little planet mostly covered by water, with only one moon, circling a medium-sized, middle-aged star halfway between the center and the edge of the galaxy. It's similar to the principle that burglars don't tend to pick the poorest-looking house on any given block to break into: there must be more tempting places for space-traveling aliens to target, wouldn't you think? Or, failing that, more convenient places for them to reach, assuming they hail from a more happenin' neighborhood. We like us, so naturally we think everything is here and that any alien would want to be here too. But I doubt it.
Human beings have been recognizably human for somewhere between 90,000 and 300,000 years, depending on how you look at it. That sounds like a long time, but it isn't. The dinosaurs became extinct 65 million years ago; before they did, though, they dominated life on Earth for 165 million years. If you pick 120,000 years as a sensible compromise for the length of our tenure, that means we've been here (occupying their abandoned house, as it were) for 1/2000th of the amount of time they were. That's the briefest little flash in the pan, in terms of geologic time.
If aliens did come here—on a survey mission, perhaps—then it stands to reason that they probably think Earth is a lush planet mostly occupied by giant lizards. Just based on the chance of timing, odds are that that's all they've ever observed.
(Illustration by Joe Wos)
According to us, however, they just started visiting Earth in maybe the 1930s (the "War of the Worlds" radio broadcast occurred in 1938), with a big uptick in the '50s and ever since. We think we know a few things about them. Not just that they're green and get around in flying saucers and have tiny versions of 1950s rabbit-ear TV antennae growing out of their heads. We assume they are clever and advanced—because they must be, if they are able to travel here: the furthest we've been able to get, ourselves, so far, is a short reach past the outer edges of our own solar system, and that's with an unmanned spacecraft, Voyager 1. Impressive, but nothing close to interstellar travel by living beings. Aliens, if they are indeed lurking, must also be as adept at staying out of sight as city coyotes—clever enough that all the folks who believe they've been here haven't been able to prove it.
Let's say that extraterrestrial galactic surveyors might have passed by Earth, taking notes, some number of times since the dinosaurs arrived. Picking a number out of a hat, let's say they've been here on their rounds a dozen times. (Because, y'know, mapping the galaxy would be low-priority for the consortium of alien civilizations that engage in it, and receive only a scanty budget—scientific research never gets enough funding, as any scientist here on Earth will be happy to tell you.) In that case, just given the timeline, you would think it logical that they might know about the dinosaurs' disappearance by now. They probably checked in a few times in the 65 million years since the dinosaurs departed. Maybe they were surprised by that at first, maybe even curious as to what happened—where did all the giant lizards go?!—although it's also possible that they've seen it all before, on other temperate planets in the galaxy; they're interstellar surveyors, remember. But if they visited on a regular interval, a dozen visits in 230 million years is only about one visit every 20 million years! And we haven't even existed as a species for a half-million years yet, not by a long stretch. It would take a stroke of luck, a true coincidence, for them to have happened to come by during the short time humans have existed.
And of course, even if they did, they would have had to come by just in the past five or six thousand years to see much of anything. That far tinier window is the time since human civilizations around the world suddenly flourished. But otherwise, how would they know we had become a distinctively dominant sort of animal? For most of our own history our numbers have been small and our accomplishments minimal. If they came a hundred thousand years ago, let's say, would they have distinguished us from all the other creepy-crawly mammals all over everywhere, on the veldts and under the canopy? We certainly wouldn't have been the most impressive creatures on Earth, not compared to woolly mammoths and the biggest whales. What would distinguish us? Cave paintings? Too modern—the oldest are only 40,000 years old—and anyway you can't see those on a fly-by. Stone tools? Crows and various other animals use tools. You might say it's because we covered our bodies; even bonobos don't do that. But how about this—we don't even know that cavemen wore clothes! We think we do; all our "caveman" representations show early humans dressed in skins (and a tie, in the case of Fred Flintstone). But the oldest intact corpse ever found, Ötzi, is only 5,200 years old. He was wearing clothes, but that doesn't mean human ancestors were wearing clothes 94,800 years earlier than that.
It certainly doesn't seem logical or rational that aliens have visited Earth many times just since we started fantasizing about it in earnest not even a century ago. If they had taken the trouble to travel here, you'd think they would have announced themselves somehow, or simply done something more definitely noticeable. Why would they merely lurk about in the skies keeping mostly out of sight? And why would they come dozens or hundreds of times a year—only to do nothing much when they got here? Look at it from their perspective. What's the attraction or the purpose in it, for them?
Actually, the best reason that "intelligent" life may be so hard to detect on any planet is probably that it effloresces for such a short time and then winks out. Not like the dinosaurs, who knew how to live here sustainably. And even they had their day, and then were gone.
Mike
P.S. Science fiction, I read somewhere, is a dialogue between fiction and science. I'm not a reader of the genre, but I try to get to the hits. By way of a manly if hopeful attempt to get you to use my links, here are six classic "sci-fi" stories of various sorts which might be called must-reads, having stood the test of time. (I've read three of them.) All are cheap for Kindle:
The Time Machine by H.G. Wells
The Foundation Trilogy by Isaac Asimov
Brave New World by Aldous Huxley
Frankenstein (1818 edition) by Mary Shelley (which everyone really should read at one time or another!)
Journey to the Center of the Earth by Jules Verne
Flowers for Algernon by Daniel Keyes
I wish I could name a handful of great recent speculative fiction titles, but alas, I can't.
Original contents copyright 2023 by Michael C. Johnston and/or the bylined author. All Rights Reserved. Links in this post may be to our affiliates; sales through affiliate links may benefit this site. As an Amazon Associate I earn from qualifying purchases. (To see all the comments, click on the "Comments" link below or on the title of this post.)
Featured Comments from:
Tom Burke: "Interesting post, and on a topic that interests me greatly. I am in no way an astrophysicist or cosmologist, but I have read up on the topic, and my conclusion is that we may well be alone, at least in our neighbourhood of our galaxy:
"First, it seems that solar systems like ours, with a rocky planet in the habitable zone (the region where water can exist in its liquid state) are very rare.
"We now know a lot about other solar systems, and there do indeed seem to be planets everywhere, but there are very, very few in the habitable zone. One of the most common planetary configurations is one with a Hot Jupiter, a planetary system with a gas giant orbiting very close to the star. We know that such a planet cannot have formed in its observed location; it must have formed in the outer reaches of its solar system and then migrated inwards, demolishing everything else in the system on its way. But not in our case!—and that seems to be a very, very rare occurrence (look up the 'Grand Tack' theory for more information). In fact, in our case Jupiter's progression back to the outer solar system may have been crucial for Earth—this may have caused the Late Heavy Bombardment, which seems to have delivered the majority of Earth's current water via impacting comets. Additionally, the presence of the two gas giants in the outer solar system, Saturn and Jupiter, may have acted as a defensive shield since then—most incoming asteroids (from the Oort Cloud) get attracted to them rather than fall into the inner solar system. The result is that Earth has enjoyed a very, very long period without a truly planet-busting impact. (The Chixculub impact 65MYA was small beer, essentially....)
"Second, we underestimate the distance between stars. The possibility of intelligent beings travelling between stars seems to be effectively zero, just because of the distance.
"And then there's evolution. I'm happy with the idea that life could appear elsewhere, but there's no necessity for it to evolve towards intelligence. In the nearly four billion years that life has existed on Earth we are, as far as we know, the first species that has looked for evidence that we are not alone. I think that the probability of the existence other beings on other planets, capable of doing the same at a time when we could receive their messages, is vanishingly small."
Zyni: "This is good article but you are out by factor of 1,000: reasonable guess is 100 billion galaxies in observable universe and 100 billion (not million) stars per galaxy. Estimates vary though. Our galaxy is 100–400 billion stars. So a ~10^22 stars in observable universe, not ~10^19.
"And as you say, whole universe is bigger: if universe is spatially flat as it appears to be then unless global topology is peculiar (no reason for that) then universe is spatially infinite and so assuming cosmological principle (good assumption), number of galaxies, stars is infinite.
"Probably at least plausible assumption that earth-like planets are necessary for life though: carbon is unusual element and water is very unusual material so is at least plausible you need planets which sustain large bodies of liquid water. Are other possibilities like methane but methane is not as good as water, people think. So it is plausible but far from certain. This is why looking for exoplanets with lots of water is so interesting to do.
"There is however probably almost no chance any aliens ever could visit: distances between stars are big and there are many strong reasons to believe that the speed of light is a hard limit for speed of travel (and practically it is much lower). In particular, if you can send anything faster than light you can send a thing into your own past: you can violate causality. And this is not a hypothetical thing: if you show me a machine that can transmit, say, information even faster than light and give me much money, I can provide you a machine which will send information into your own past. With such a machine you can win all games of chance: there is no limit to the value of such a machine since one such game is called 'the financial markets.' We do not observe that people have machines that let them win the financial markets.
"All this means is likely no chance aliens ever will or ever have visited, or that humans ever will or ever have visited other habitable worlds."
"Finally, you are correct about absurd self-importance of civilisations: in our case we became able to meaningfully reason about the universe no earlier than 1915 (I have met people who were alive then!) and in fact probably not for a long time after that. And the chance we will still have a technological civilisation in 2115...currently looks tiny. So perhaps 200 years when we could even think about it. But we fantasize about civilisations which could undertake feats like interstellar travel which would likely take millions of years. Science fiction...is fiction.
"Probably we will detect life on exoplanets. Best chance of detecting 'civilisations' probably is to work out how to detect traces of dead ones. I have theory that the way to do this is to look for the signature of long-lived radioisotopes that are the result of large-scale nuclear war. This will be, I am sure, the way ours ends, as global warming drives vast migration, crop failures, nasty politics, and war (already, nuclear arms limitation is essentially gone)."
Mike replies: Thanks for the corrections Zyni. The chances of me writing a post like this and not getting a number wrong are about the same as the chance of successful interstellar travel.
JH: "Interesting (off)topic. As a person educated as an astronomer and physicist and avid reader of science fiction, I enjoy discussions like this. Yes, statistics would indicate that life exists on many planets in the universe. What we know of physical laws indicates that travel between locations many light-years apart is impossible today, but we do keep learning more about physical laws, so who knows? We have some interesting phenomena like entangled photons that indicate that faster than light communications may be possible, so maybe transportation or teleportation is not impossible.
"But I do have an interesting story. While there have been stories and art that might indicate alien visits over recorded history, the level of activity seems to have increased since we began experimenting with atomic physics, especially the bombs.
"In the early '70s, I worked for several years for companies in Oak Ridge, Tennessee. Oak Ridge National Lab was where the material for atomic bombs was manufactured during WWII. I lived in a small government built house on a ridge on the eastern side of town near the railroad tracks that were built to supply the town and take away the bomb materials.
"The guy who installed our phone grew up in a house nearby—his father and mother worked at the labs. He told us that as kids they would sit on the back porch at night and often see fast-moving lights zipping back and forth around the labs. I asked others who grew up there about the UFOs and stories like that were common knowledge.
"Similar stories circulate about Alamogordo, New Mexico, and the Nevada Test Site where bombs were tested.
"Now we know more and more about nuclear physics, but did that work create some signal that was detected by another civilization that came to investigate?
"Oh, and remember the entry for Earth in The Hitchhiker's Guide to the Galaxy revised the description from 'harmless' to 'mostly harmless.'"
Mike replies: To the three of you, I would ask: given the numbers of stars in the universe, and assuming that a solar system like ours with one planet with carbon and liquid water is as rare as one in ten million, then how many such planets would there be? The closest I can come blundering around in the dark is that 10^22/10,000,0000 is 1e15 or 1,000,000,000,000,000, or one quadrillion, or one thousand trillion. Is that right? So this would be the number of theoretically life-sustaining planets in the Universe if the chance of an earth-like planet existing is one for every ten million stars. Slot in even very high values for the chances, and you still have a very large number of earth-like planets. If, as Zyni says, there are 100 billion stars in the Milky Way, then if the chances of an earth-like solar system is as rare as one in one hundred million, or 100,000,000, then there would still be a thousand earth-like solar systems just in the Milky Way. (My arithmetic might be way off; I'm innumerate.) Then you also have to factor in time. If we exist as a species for 300,000 years, which is essentially as brief as the flash of a strobe on the cosmic scale, then how many opportunities have their been for a species like us to come and go on such planets, in the billions of years the universe has existed? This is a semblance of the argument that carbon-based life either has, does, or will exist elsewhere, and not in small numbers.
Bear in mind that I am not a thinker on this subject, not educated at all, just a total ignoramus applying simple (perhaps even simpleminded) logic!
Farhiz Karanjawala: "Very interesting, but what triggered this?"
Mike replies: You know, someone else asked me that too, and I don't recall. It wasn't for the sake of the links: those were an afterthought.
I feel I've been writing too long recently, and resolved to try to write shorter, friendlier posts, either newsy or amusing, and this was intended to be one. But then I "got writing," as a I do (time goes into suspension), and continued to rearrange and polish it...as I do. When something emerged, this was it. Maybe it was an encounter with a random news blip about one of those hopelessly sincere people who fervently believe the Earth is flat; I remember idly mulling that over recently, at the pool table. (Shared reality and our departure from it being a pertinent topic recently—for instance, in a recent survey [go to this link and scroll down to #5], only 23% of Republicans consider climate change a major threat.) But I really don't know what possessed me. :-)
Benjamin Marks: "I am a fan of speculative fiction. I understand the gist of the math arguments. But I am always puzzled why folks who speculate about the numbers above assume that non-human visitors would use a version of our technology moving through physical space and though time.
"Just because we are barely evolved apes who have learned some tricks with steam and rockets doesn't mean that these qualities are universal, if you'll pardon the term. If a life form wasn't carbon or water-based, why would they have to stick to the low speeds of our chemical rockets? If they could manipulate energy on a large enough scale, why assume that they couldn't fold physical space, or move through time in ways that made travel across large distances trivial?
"We are limited to our solar system because we are what we are physically and, as pointed out in Mike's post, pretty young. But what if this current phase is just our adolescence? I understand that once you take the lid off what's known and understood that anything can fit into that 'deus ex machina' box. But every single time in human history that we have thought we understood the world and the heavens well, we have been wrong. Why not assume that our current understandings are just a placeholder and that our children's children will look at our current ideas the way we look at geocentric notions of the universe: as a quaint stopping point on a search for a better, more accurate truth?"
