I'm not convinced there is intelligent life here either. I always have to question the idea of human intelligence whenever I hear about the Drake Equation. You've probably heard of this equation before, but if not, Wikipedia describes it:
The Drake equation is a probabilistic argument used to arrive at an estimate of the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. The number of such civilizations, N, is assumed to be equal to the mathematical product of (i) the average rate of star formation, R*, in our galaxy, (ii) the fraction of formed stars, fp, that have planets, (iii) the average number of planets per star, ne, that can potentially support life, (iv) the fraction of those planets, fl, that actually develop life, (v) the fraction of planets bearing life on which intelligent, civilized life, fi, has developed, (vi) the fraction of these civilizations that have developed communications, fc, i.e., technologies that release detectable signs into space, and (vii) the length of time, L, over which such civilizations release detectable signals...
Now, there is nothing inherently wrong with this. If you want to know how likely something is, you can express that by multiplying out the odds of all necessary factors. That's how probability works.
The problem with the Drake Equation isn't the equation itself, but rather, how people misuse the equation to support all sorts of pseudoscientific nonsense. It's particularly bad as scientists are often the ones who do it, and what they do is almost always the same thing - make some key assumption their results will depend upon and gloss over it like it is nothing. Today, I've found the best example I've seen of this yet.
Before I get to the that, I should give credit to the blogger Anders who wrote a post about this paper (or rather, about a blog post referencing this paper). I wouldn't have seen this paper except I happened to glance at his blog to see if he was discussing anything interesting and saw this during my quick skim:
The article made some interesting points. Current exoplanet statistics suggests that it’s extremely unlikely that we are the only technologically advanced civilisation to have ever developed.
Now, I didn't find the rest of Anders's post interesting. I didn't find the blog post it was about interesting either. This claim is the only thing that caught my eye. It's such an incredible claim I wanted to know what sort of basis there was for it. It turns out the answer is, "None." It all turns on a remarkable example of begging the question.
(As a quick aside, I should point out "begging the question" is not the same as "raising the question." Raising a question would mean bringing it up. Begging a question is a logical fallacy in which one assumes something in order to prove it is true. A reader recently reminded me people often misuse this phrase so I thought I'd make sure we all know what it means.)
The trick to the paper Anders relies upon for his claim comes in an incredibly simple form. It's easy to miss though as the authors of the paper modify Drake's Equation in a few largely unimportant ways. First, rather than look at the probability intelligent life that we could communicate with exists right this moment, it looks at the probability (non-human) technology-inventing intelligent life has existed at all. This simplifies the equation a bit, and it is represented with the variable A.
The next change the authors make is to simplify the factors by grouping them. Factors which involve planets and the odds of them being habitable are grouped into one variable (Nast). Factors which involve the origination of life, its evolution into an intelligent form and the odds of that intelligent life developing technology are grouped into a second variable (fbt). This gives us the equation:
A = Nastfbt
The authors discuss how new data allows us to get better estimates for Nast, improving our ability to come up with an estimate for A. This isn't an impressive development though as the factors that variable include have never been great sources of uncertainty for the Drake Equation. How many planets are habitable is far less uncertain than how likely a planet is to develoo intelligent life. The authors recognize that by saying it:
is extremely uncertain, basically because (a) we have no theory to guide any estimates, and (b) we have only one known example of the occurrence and history of life, intelligence and technology. We Leave fbt as simply statistically unknown at this time and examine the consequence of it taking on various values depending on one's pessimism or optimism.
That's right. The authors admit to having no idea what one half of their equation is. Despite that, they draw a variety of conclusions, with one author writing in an article:
There is no reason we can't take the same approach with the astrobiology of the Anthropocene. Earlier this year, Woody and I used the amazing exo-planet data (and some very simple reasoning) to set an empirical limit on the probability that we are the only time in cosmic history that an advanced civilization evolved. It turns out the probability is pretty low — one in 10 billion trillion. In other words, one can argue that the odds are very good that we're not the first time this — meaning an energy intensive civilization — has occurred. With that idea in hand, you can take a theoretical jump and ask a simple question: How likely is it that other young civilizations like our own have run into the kind of sustainability crisis we face today?
That's complete nonsense though. The "empirical limit" they come up with is nothing more than, "We assume there's this particular limit, therefore there's this particular limit." We can see this by examining how they came up with their estimates. If they don't know two of the three variable (A or fbt), how could they come up with any estimate? They explain:
To address our question, A is set to a conservative value ensuring that Earth is the only location in the history of the cosmos where a technological civilization has ever evolved. Adopting A = 0.01 means that in a statistical sense were we to rerun the history of the Universe 100 times, only once would a lone technological species occur. A lower bound fbt on the probability is then...
That's right. This equation was created to describe the probability intelligent, technology creating life would come to exist in our universe. In examining it, the authors set that value to 1%. Having arbitrarily decided what the probability is, they then plug it into their equation and generate some numbers.
But why did they choose 1%? The authors offer no explanation for that value. All they say on the issue is the value is "a conservative value." Says who? Why should anyone think the probability of life like that of humans coming into existence is 1%? Why is 1% any better than 10% or .0001%?
It isn't. The authors had no basis for that assumption. They could have just as easily assumed any other value and gotten entirely different results. They could have found the odds other life like ours has existed at some point in the universe are greater than they say by changing 1% to 10%. The opposite is true as well. If we assume human life is an incredible fluke which only had a 0.0000000000000000000000000000000000000000000000000000001% chance of happening, then the numbers they came up with would shrink dramatically.
It is embarrassing this got published. The entire paper is nothing more than, "If we assume the odds of something happening are X without any basis or explanation, then the odds of something else happening are Y! Aren't we smart!?" It's the sort of a high school student would be slammed for doing in an essay. That scientists would do it is sad, and that they could get it past peer-reviewers is just embarrassing. It's a disgrace to science as a whole.
There are a variety of points that could be made here, particularly with comparisons to climate science since Anders is mostly known as a climate-blogger and he seems to support this sort of work. I'm not interested in thinking through those though. Instead, I'm just going to close this out with a simple observation.
Nobody knows how big the universe is. We often talk about the "universe" in reference to what we can see, but the reality is the visible universe we're aware of is not the entire universe. We have no idea how far the full universe might extend. The visible universe may comprise a large portion of the full universe, or it might just be an infinitesimal speck in the middle of something larger than we could hope to comprehend.
The authors of this paper list their estimate for the number of stars in the universe, and they take note of the fact the size of the region being considered will affect any probability estimates. What they never make clear is since we have basically no idea how large the universe is, we cannot possibly hope to estimate the odds of other intelligent life existing or having existed in it.
All we can do is say in our (small?) corner of the universe, there are no signs of intelligent life.