Doug's Darkworld

War, Science, and Philosophy in a Fractured World.

The Rare Earth Hypothesis…Are We Alone in the Universe?

with 12 comments

Not very likely. :(

The discovery of a (possibly) Earth-like planet nearly 20 light years away (in our back yard as galactic distances go) inspires me to write this basically pessimistic blog. Sadly in this case I think pessimism and realistic are synonymous. I think there’s an excellent chance that intelligent life such as ourselves is as rare as hen’s teeth in the universe. And that’s being generous, I think there’s an excellent chance that we are indeed…alone. I’d love to be persuaded otherwise, and my readers are welcome to do their best to convince me, but here’s the reasoning behind my bleak conclusion.

The first problem is the Fermi Paradox, which basically boils down to, where is everyone? If the universe is teeming with intelligent life, as so many people have concluded, why hasn’t anyone contacted us? Why do we see no evidence of intelligent life in the universe? So far the amount of empirical evidence for the existence of aliens is zero. Nada. Nil. Nothing. Granted there is some curious anecdotal evidence, but so far every UFO or alien sighting has a perfectly reasonable non alien explanation. And none has yielded a single artifact or sample of extraterrestrial origin.

As the wags say: “absence of evidence is not evidence of absence.” This is of a course a stupid truism like all truisms, why people think statements like this are logical arguments is a mystery to me. It’s a shame they don’t teach logic in the schools, we’d hear a lot fewer weak arguments like this. However, I digress. And I do have further reasoning to support my case.

My second argument is the rarity of intelligent life on Earth. Since the first cells divided in the primitive seas of earth there have been literally millions of different species on earth. Tens of millions possibly. How many of these species have evolved intelligence like humans possess? One, us. We do have a few cousins, but none that can play a game of chess, carry on a conversation, or anything even remotely close to the intellectual tasks that humans are capable at a few years of age. Signing apes are a sad joke, on Earth, we are indeed alone. Wishful and religious thinking aside, there’s no reason to assume our evolution was anything more than an unlikely fluke.

Thirdly, space exploration. More importantly, discoveries in our own solar system. At this point, it turns out that each and every planet and moon in the solar system appears to be unique. And I mean unique, the things we have discovered have vastly exceeded the imaginations of sci fi authors and scientists by incredible margins. In other words, the idea that there are “types” of planets and moons is silly at this point. Even the gas giants are each completely and utterly different. And when we go to other solar systems, it’s even worse. We aren’t finding anything like our own solar system, every new discovery makes our system appear like an oddball at best. The point I am making, is the idea that there is anything like a “normal” planet or solar system is more and more appearing to be wishful thinking at best.

So to me it appears that we have two incredibly unlikely events multiplied by each other. The likelihood of intelligence evolving on an Earth like planet appears to be very low. And the creation of a planet like earth appears to be very unlikely. Think of it this way, even with just a tiny handful of variables, there appear to be an infinite number of possible chess games. Yet despite a massive amount of study, the game has never been broken…there does not appear to be a sequence of moves that guarantees victory. Maybe at some point it will be discovered, but even then it will be one sequence of moves out of an infinite number of possible games.

To put it mildly, when it comes to the creation of planets and the evolution of life, there are vastly more variables than exist in a game of chess. When one starts to multiply huge improbabilities with other huge improbabilities, one gets numbers so large that they defy imagination. It is indeed entirely possible that the creation of an earth like planet with intelligent life on it may be so unlikely that there’s a good chance it won’t occur in the lifetime of the universe. No matter how many trillions of stars there are, we may be alone, we may represent an almost unimaginably unlikely lottery win.

I wish it were otherwise, and no one will be more thrilled than me if a flying saucer lands on the White House lawn. Until one does, or someone points out a flaw in my thinking, I’m betting that the bookies have a sucker bet at even 100 to 1 odds that alien intelligence will be discovered. And I’m apparently not the only one to reason this way, after writing this post I came across the Rare Earth Hypothesis. Sigh. Oh well, at least we still have our imaginations. Star Trek wouldn’t have been very exciting if on every planet Kirk visited he said “Beam me up Scotty, There’s no intelligent life down here.”

(The above image from Earth vs. The Flying Saucers is claimed as Fair Use under US copyright law. It is central to to illustrating the post and it is not being used for profit. It was also a classic movie for its era and I loved it when I was a young lad.)


Written by unitedcats

April 29, 2007 at 9:05 am

12 Responses

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  1. See The Drake Equation for some numbers on our intergalactic neighbors.

    World Famous John

    April 29, 2007 at 12:52 pm

  2. Hey, I want aliens. I want witty little shiny magic cuddly ETs to talk to. I agree with you mostly though. Contrarily, I would say that if intelligent life is like the game of chess, maybe it isn’t the surefire win that counts but just the win. And the game of chess has been won innumerable times. Hope springs eternal.


    April 29, 2007 at 8:32 pm

  3. The Drake equation is a neat stab at the problem, but since we have no clue what the variables are, one can plug in the numbers one wants to get the results one wants. And unfortunately it’s looking like some of those numbers are vastly smaller than Drake’s original optimistic guesswork. I would still love to find our brothers and sisters among the stars, and I think more money should be spent on the search…I mean, it’s not really very much money. However, I don’t think we are going to find anything.


    April 30, 2007 at 7:39 am

  4. It doesn’t matter if we’re alone in the universe or not. Getting all worked up about an issue like that is overlooking how you’ll be dying all alone sometime inevitably.

    Richard Warwick

    April 18, 2008 at 4:51 am

  5. Well, no disrespect intended, but that argument could be used as an argument against getting worked up about anything. I think life is more than simply waiting for the clock to run out, and I’m going to get worked up about some things because at the very least, it makes life more interesting. Granted though, in the greater scheme of things, I’m not going to get too worked up about this particular issue.


    April 18, 2008 at 6:36 am

  6. I would have to agree with you… the only thing I would add is that in the future we will likely find many other “habitability factors” that make the probability of finding an intelligent life bearing planet like Earth even lower than was hypothesized in “Rare Earth”…. I believe the likelihood for our existence will be found to be practically a miracle…. I already think it is but I never had faith in blind chance anyways… we’ll just wait and let science progress and over time I think people with faith in blind chance will be left with a choice that they will find hard to swallow…

    Peter Tong

    July 23, 2008 at 8:02 am

  7. You see its alright trying to pick up transmissions from Extra terrestials ,but do they have the same equiptment as us , in the last 100years weve seen our communications develop from crude short wave morse equiptment and crude baird Television to DAB radio and H.D. t.v and whats to come in the next 100 years .. On another planet they may be hundreds of years ahead of us in Communications Technology,so we cannot recieve their transmission and they ours. Alternately their civilisation may be only in our equivalent to the 17th century and any kind of radio or television hasnt been invented yet., its probably unlikely that they are on the same time scale as us. You have the equivalent of trying to play a 78rpm record on a C.D. player ……… you cant . thats the answer .


    September 30, 2008 at 1:30 pm

  8. A interesting view of whether we are indeed alone in the this universe. I think it is sometimes a good idea when faced with this question to step back and admire the wonder that is our solar system.

    You see, my point against your argument, is that currently we do not know how big the entire space mass actually is. Some consider that space is infinitive others view it as a measurable expanse but in essence we do not know what we are up against in terms of sheer scale.

    Sure, what we do know is that from what we can see (or what the hundreds of deep space probes have shown us) is space is enormous (or at least it is from our perspective) and is filled with many planets which, as you quite rightly mention, are significantly different to our own in terms of climate and habitation. As is quoted in one of my favorite films “if we are alone, it is an awful waste of space”, meaning at present our own existence cannot be in isolation if not because we cannot begin to calculate the sheer size of the unknown mass of space. In my view we cannot begin to make judgment upon our own existence in the universe until we have a better idea of the calculus involved.

    Alien Sightings

    January 11, 2009 at 2:06 pm

  9. The sad application of logic in this matter leaves us empty inside. I no longer even offer my view when the subject comes up. I used to point everyone to Ward and Brownlee’s work and smugly offer how futile their hopes were. Told my friend how futile his membership in the Planetary Society was and that SETI at Home was a waste of his computer’s clock cycles.

    I don’t do that anymore.

    I’ve come to the conclusion that life is just too short and most people desperately need to cling to their hopes and dreams. It gives them comfort. For what it’s worth, I also apply the same approach to those who are religious.

    Sam Clark

    February 16, 2009 at 8:00 am

  10. […] right along, I’ve already made my unpopular arguments that we might indeed be alone in the Universe, so let’s for grins assume that […]

  11. Ok, I have issues with your claim that the phrase, “absence of evidence is not evidence of absence” is not a logical statement.

    Claiming the opposite, “absence of evidence is evidence of absence” would be the fallacy of Argument of Silence.


    May 26, 2010 at 8:59 pm

  12. Well, the argument from silence is a valid argument in many contexts. It would have been more accurate to say that in this context, I don’t think it is. The utter lack of evidence for alien intelligence doesn’t prove they don’t exist, but it’s a reasonably strong argument that they must be very rare at the least. And this argument can’t simply be dismissed by saying “absence of evidence is not evidence of absence.” At the very least it’s a paradox, the Fermi paradox to be specific.


    May 26, 2010 at 9:49 pm

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