Drake’s Equation

Earth Mostly HarmlessThe other day I was Wiki Walking and ended up reading about the Rare Earth Hypothesis in reference to the Fermi Paradox and the Drake Equation. We’ve discovered that most stars in our galaxy appear to have planets of some kind, although ones with human-friendly environments may be quite rare.  The presence of a plethora of planets presumably provides a potentially large factor for at least one part of the professor’s pretty problem.

But it’s possible that some of its other factors are extremely small. They may be much smaller than anyone had imagined. They may be so small as to ensure that we are alone in the galaxy.

It’s even possible we are alone — or nearly alone — in the universe!

Science fiction fans may be familiar with the Drake Equation (DE).  It dates back to 1961, and was created by Frank Drake as a way to quantify the number of civilizations in the galaxy. Essentially, the equation starts with the total count of stars and multiplies that against several reducing factors. The final result is a (possible) count of planets with intelligent life.
Drake Equation

The reducing factors take into account things like: not all stars have planets, not all planets are in habitable zones, life may not develop on all habitable planets, intelligent life may not always develop.  (See the Wikipedia article for the specific factors.)

A great deal of science fiction assumes the DE results in lots of intelligent alien races scattered throughout the galaxy. TV science fiction often tends to assume most of them look somewhat like us, but that is more a limitation of special effects (and perhaps a failure of imagination).

Prometheus Engineer

Let there be life!
(And a sequel.)

Some stories have used the idea that the galaxy was somehow seeded by a race, and that’s why so many aliens look humanoid: they’re all based on the same basic model. Star Trek used the idea (in the TNG episode, The Chase, season six), and the movie Prometheus is based on the idea.

There is also a scientific concept, panspermia, which suggests that simple life forms could live in space and seed planets via falling meteors.  The DE, and ideas like panspermia, are what gives hope to missions like SETI and the Arecibo Message.

And as I’ve mentioned before, I long for alien contact!

But the Rare Earth Hypothesis (REH) may dash all those hopes.  (And, sadly, SETI has turned up nothing in a search that has been ongoing in some fashion since the 60s and has been in high gear for almost 20 years.)

The REH is one answer to the Fermi Paradox, which asks the obvious question: Okay, so if alien life exists… where is it?


I hope they’ve heard of the Prime Directive!

The Paradox has many potential answers. A classic one is that aliens deliberately leave us alone until we’re “ready” or “worthy.” But generally speaking, it’s not unreasonable to believe that if aliens did exist, we would have seen some clear sign.  (Isn’t it funny how the UFO craze seems to have evaporated now that just about everyone carries a video camera with them at all times?)

Given human nature, it seems unlikely that all aliens would go along with a program of leaving us alone. But as I’ve pointed out before, even in the 60s we understood the value of a “Prime Directive” (even if Kirk did violate it more often than not).  By the time Picard came along (late 80s), we were much clearer on the idea.  Perhaps by the time we actually (seriously) reach space, we’ll have grown up even more and will fully embrace such principles.

Or it could work like the opening to Hitchhiker’s Guide to the Galaxy, and we’ll be wiped out for merely being in the way and too unintelligent and primitive to get out of the way.

Arecibo message

Arecibo message, our email to any listening alien civilizations!

Our galaxy is billions of years old.  A space-faring species could explore and colonize the entire galaxy easily within a million years using technology we can foresee today (specifically: no faster than light travel).  Certainly if life is common one would think we’d have seen some indication.

The REH suggests that life is extremely uncommon. It may be so uncommon that we are alone in the galaxy (which is why we’ve seen no signs of other life).  It’s possible that the probability of life in an entire galaxy is less than 1.  We happened to beat the odds, but other galaxies may be devoid of complex, let alone intelligent, life.

It may turn out that single-cell life is somewhat common. Here on Earth we find life everywhere, even in extreme places such as deep-sea vents and volcanic pools.  Bacteria have been found deep in the Earth.  (I have some doubt even on this. To me, RNA is one hell of a jump up from organic chemistry.  I have not heard a good account of how amino acids evolved into RNA.)

Multi-cellular life seems to need mitochondria to provide the necessary energy, and one theory is that mitochondria were a very low-odds accident where a smaller single-cell critter became a symbiote to a larger single-cell critter, and over time the relationship became permanent.

Moonrise (STS35)

A long way up from those ancestral tidal pools!

Many believe that our large moon was a key factor in the development of life. The moon creates strong tides, which means tidal pools. Life adapting to the daily transition may have been thus encouraged to make the jump from ocean to shore. However, others point out that the process (we think) that formed our moon — debris gathered in the Lagrange points — is a common phenomenon.  Moons, obviously, are common in our Solar system.

So the REH says we don’t see evidence of other life, because there isn’t any other life.

A rather disturbing answer to the Fermi Paradox is that intelligent life always ends up killing itself off.  Or possibly dying off due to apathy when individuals become too engrossed in their TWITs and Angry Birds and no one learns the skills necessary to ‘keep the train running.’  (Does that sound like a civilization you might have heard of?)

Ark B

“We’re right behind you!”

One of my favorite bits in the aforementioned Hitchhiker’s Guide to the Galaxy concerns the planet of Golgafrincham. The people there decided to rid themselves of the “useless” one-third of the population: the insurance salesmen, management consultants, hairdressers, telephone sanitizers, etc.  They concocted a story about a threat to the planet and built three “Ark” spaceships, packed those folks into the B-Ark and sent them off with promises that the rest would follow in the other two arks.

The rest of Golgafrincham heaved a sigh of relief and got on with life. Only to die out shortly thereafter from a deadly disease spread via dirty telephones.

telephone sanitizer

telephone sanitizer

(It turns out that the B-Ark crash landed on an “utterly insignificant little blue-green planet” circling a “small unregarded yellow sun.”  Yep, that’s right. We’re the descendents of the useless Golgafrinchams!)

As I look around at the world today, I have to say: I can’t help but wonder if self-destruction isn’t in our future.  We muddle along with a value system that doesn’t seem designed to insure survival.

Some days I think the only real question is: what form will our self-destruction take?

I’ve got $500 riding on “Virulent Disease” but, win or lose, I’m not sure how one ends up collecting on that bet.

About Wyrd Smythe

The canonical fool on the hill watching the sunset and the rotation of the planet and thinking what he imagines are large thoughts. View all posts by Wyrd Smythe

6 responses to “Drake’s Equation

  • Lady from Manila

    I’ve always been highly skeptical of UFO sightings. Similar to ghosts, supernatural stuff, and even religion, I believe man’s overactive imagination is largely at work here. Our mind always finds a way to explore unceasingly the concepts we need to make our lives more interesting.

    However, it’s difficult for me to agree with the probability we are alone in the universe. If earth could happen in our single solar system, what more in the billions of other similar systems that are out there in the universe. I don’t think it has to be the same as our planet’s make-up and physics, though. It may sound a bit preposterous but I already mentioned to you how I’ve conjured up alien creatures with physical features totally different from us, like in liquid or even gas frame. And what if they also possess an unfathomable kind of intelligence – what if their minds work utterly dissimilar from ours?

    Nobody knows for sure what’s out there – and that’s what makes it at all times a stirring mystery.

    As to “if aliens did exist, we would have seen some clear sign”, the REH statement that there isn’t any other life, and the Fermi paradox question asking where alien life exists – how can we easily detect life forms that are so so so far away from us, most probably located in other galaxies spread throughout the entire infinity? If we can’t find them, it’s more likely they can’t find us either.

    That we’re the descendants of the useless Golgafrincham’s B-ark spaceship :-D; Now that explains my obsession to wipe clean before and after every use every landline phone I touch.

    I’m glad to see you writing again and I do appreciate fascinating and informative posts – like this one – from you, Wyrd.

    • Wyrd Smythe

      Prior to Sputnik, people reported seeing “angels” and “demons,” but afterwards they reported UFOs and “little green men.” (But, as I mentioned, now with the ubiquitous cameras such reports have really dropped off.)

      Astro-biologists and science fiction writers (and you and I) have imagined some pretty wild possibilities, so I think we’ll recognize life when we see it. There are attributes to look for: patterns (particularly of being), energy transfer (“fuel” in, “waste” out), and replication (making more). Information storage is probably also an attribute (memories, DNA). I think we have a good shot at recognizing those things in unusual places.

      I also think intelligent life will share certain attributes. Mathematics is universal. If they count, they should have math. If they have math, we can communicate. (I suspect math is one of the dividing lines between intelligent and non-intelligent. Complex language is another.)

      It’s true that the odds are against being able to see other civilizations at a distance. We’ll just have to see, if we survive long enough to get out there.

  • The Color of Lila

    Wyrd, pffft. The Prime Directive is well understood by sci-fi fans and probably by folks like anthropologists, but you can bet that if we ever find a planet that could actually support human life, the aliens better hope they are more advanced than we are… or the story will play out more like Europe finding the New World. Whether we “conquer” them intentionally by force to get their resources (including, by that time, mere living space), or unintentionally by simply overrunning them with our curiosity, selfishness, and obliviousness – we are going to be a problem.

    • Wyrd Smythe

      That’s certainly one scenario, and it may depend a great deal on whether they have something we really want (or worse, perceive we need). It might not go that way… Construction efforts are still sometimes stymied by ecological or political concerns. We do have some sense of the logic that underlies the Prime Directive. As I say, it may boil down to whether we see them as purely a research effort or as “Hey, look at all that gold!” (Or oil, or iridium, or whatever.)

      Stephen Hawking is convinced that a truly superior race meeting a lesser one will even unintentionally be bad for the lessor one (he cites how that’s usually the case on Earth). Perhaps I’m overly optimistic about possible futures (too much Star Trek, maybe), but I think that it’s at least possible — given the enormous requirements of space travel — that we’ll advance to being responsible galactic citizens.

      Or maybe we’ll end up being the Klingons or Romulans… the villains of the galaxy!

  • bronxboy55

    One factor that tends to get overlooked is the idea of timeframe. If Earth has been around for four billion years, human existence is a thin sliver of that. And the time when we’ve possessed technology advanced enough to either detect life elsewhere or make our existence known is much thinner still. If the Milky Way is 13 billion years old, probability seems to suggest that our thin slice of time will not line up with the thin slice of whoever is out there. And that doesn’t take into account that whoever is out there may be alien dolphins or bumble bees — too busy breaching and pollinating to be bothered with the rest of the galaxy. And then there’s that stifling speed-of-light limit.

    Another great post, WS. By the way, I’m putting $500 on Asteroid Strike. We could probably avoid it, but we’ll be too busy watching American Idol, or whatever it is people watch.

    • Wyrd Smythe

      Thanks. I simplified it to make it simple, but the Drake Equation’s first factor, “R*“, is actually the rate of star formation in our galaxy. In the abstract, the Drake Equation is really about the chances of intelligent life during the life of the galaxy.

      That said, you’re quite right about the chance of missing the “window” of some putative intelligent race’s time in space. One guess at things is that intelligent civilizations tend to self-destruct, and that would make the window fairly narrow and easy to miss. But another guess (and it’s all guesses) is that, once you achieve space travel, you have enough options to keep going. On that account, once a race achieves space, they’re likely to be around for a while. Given that colonization of the galaxy is feasible within 200,000 to 1,000,000,000 years using ordinary space travel, you have to wonder. (Another guess is that it takes roughly 10 billion years for intelligence to evolve, so any other race is about where we are technologically.)

      You’re also right that another guess that explains the silence is that other races simply may not have the drive we do to explore (and conquer!). And science fictions authors have pointed out that, in a dangerous forest, smart critters keep silent and don’t attract attention. Who knows,… maybe there are galactic bears out there!

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