Most of us have seen the Drake equation, in one its many forms, which purports to put a number on how many alien civilizations have iPhones. There has been much discussion on the original and its variants since Drake first published in 1961. All attempts, I claim, share the same failing, as we’ll see. This is also related to the so-called Fermi paradox, also mentioned below.
Two fellows, Frank and Sullivan, have another go. The lite version of their peer-reviewed paper is in (appropriately) the New York Times with the title “Yes, There Have Been Aliens“. The full version is the “A New Empirical Constraint on the Prevalence of Technological Species in the Universe” in Astrobiology.
From the Times:
Instead of asking how many civilizations currently exist, we asked what the probability is that ours is the only technological civilization that has ever appeared. By asking this question, we could bypass the factor about the average lifetime of a civilization. This left us with only three unknown factors, which we combined into one “biotechnical” probability: the likelihood of the creation of life, intelligent life and technological capacity.
You might assume this probability is low, and thus the chances remain small that another technological civilization arose. But what our calculation revealed is that even if this probability is assumed to be extremely low, the odds that we are not the first technological civilization are actually high. Specifically, unless the probability for evolving a civilization on a habitable-zone planet is less than one in 10 billion trillion, then we are not the first.
You can already see that abuses of probability are coming up. From the paper:
We define the “A-form” of the Drake equation, which describes the total number of technological species that have ever evolved anywhere in the currently observable Universe:
A = [N* fp np][fl fi ft]
…where N* is the total number of stars [the asterisk is a star, not multiplication], fp is the fraction of those stars that form planets, np is the average number of planets in the habitable zone of a star with planets, fl is the probability that a habitable zone planet develops life, fi is the probability that a planet with life develops intelligence, and ft is the probability that a planet with intelligent life develops technology (of the “energy intensive” kind such as that of our own civilization).
After this comes manipulations of the equation which aren’t especially interesting. There are no insurmountable problems in the leading elements of this (or modifications of this) equation. But there is a universe of trouble with the terms in the brackets, [fl fi ft].
All of these elements are said to be probabilities. So, focus on probability’s Golden Rule: All probabilities are conditional. From that simple and honest truth flows everything, including the proof that the Drake equation, modified or no, has no meaning as it stands.
Let’s step through each probability.
The first, fp, is also the least: the fraction of stars with habitable planets. Least trouble I mean, because scientists can be confident (not that they’re right, just confident) they have a handle on the causes behind the creation of these planets. So natural will be giving a number to this one, with strong tacit premises on planet formation, that it won’t even seem like a probability to most scientists.
Then comes fl, the probability a planet develops life. Since nobody knows scientifically how life began (on Earth), premises which can fix fl are hard to come by. One can make up a number here, and anywhere, based on gut feelings, of course. But what does that number mean? It is the premises in any probability that are important, and here there are only vague notions. If we knew, and were not bluffing about knowing, how biogenesis occurs, then we’d be on solid ground. We do not know, so aren’t.
The next element, fi, is the probability of something like “Rational creatures on other planets exist”. Proponents must therefore have some kind of causal theory of how rational creatures, i.e. animals with intellects and wills, came to be. You further need a strict definition of mind, consciousness, intellect, and will. Naturally, one working theory about all this is denied by many scientists.
So, seeking elsewhere, in order to calculate fi, we would need a list of accepted premises that unambiguously lead to a unique number, or at least to a tight interval. None exist: none that are acceptable and agreed to by all, I mean. Plentiful premises exist that might be used, of course. You might say, “7 out of 10 planets with life develop rational creatures” and thus fi = 0.7. But who would agree to these premises? It is mere whim.
Finally, ft, “the probability that a planet with intelligent life develops technology (of the ‘energy intensive’ kind such as that of our own civilization).” What might the premises be? Specifically, and in the detail required to give ft.
For man, given (conditionally on) we have observed such development, the probability is 1. For aliens? You have to have a causal theory of civilizational development in alien minds. State it.
But forget all that. I think most who wield the Drake and its variants cherish the probability 1. That is, I’d wager at least a majority of those who study Drake already believe other “intelligent civilizations” exist, and want to make that belief appear more scientific, hence the need to put numbers to their belief: modern science rests on numbers. Their real interest is not estimating whether ICs exist, but how many exist, a number which is believed to be above one.
Which leads to the Fermi paradox. It takes (sort of) the Drake as a premise and asks, if ICs “evolved”, given the apparent age of the universe, and assuming technological progress must on average increase, then where are all the aliens? We appear to be alone. The “paradox” shares the same premises as the Drake, all of which combined say that development is inevitable.
The one obvious answer is to Fermi that we are alone is usually rejected. Not on logical grounds, but aesthetic.
The Drake and Fermi are not flawed logically: one can put probabilities to any question. But they are largely circular, since the goal of most who use them to is justify their pre-existing beliefs.
An earlier and much worse version of this post appeared originally on 30 June 2016.
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The other bookend paired with the Drake/Fermi speculations is Evolution. In this January’s edition of First Things Magazine comes a letter to the editor titled Evolution is Not God. He says, based on what we now know about DNA, that evolution by mutation cannot not lead to “supermen” rather to devolution from “an original state of perfection, just as God revealed in the sacred history of Genesis.”
As it turns out, the part of the DNA labeled as “junk DNA” in the 1970s is actually packed with many, interwoven, sets of instructions depending on whether it is read forward, backwards, using various sequential patterns and so forth. It seems here that Our Lord has had both the first and last words. Let there be light!
There may or may not be extraterrestrial life, but if we ever see some, I suspect there will be surprises. Even on our one planet, there are many different varieties of life and there have been many different kinds in the past as well. Even the animals that we are most familiar with perceive and experience the world in substantially different ways.
As pointed out in the post, not only do we not have a theory about how life might arise, we do not have a comprehensive theory about what forms life can take on. For that matter, what is intelligent life? Whether this is conceived of in an Aristotelian/Thomistic manner or some other way, it is not unreasonable to think that there are different ways that reasoning capability can exist in biological creatures.
And likewise, why should technologies be the same? In the pre-modern era, there were similarities, but also significant differences in science and technology among different civilizations. The reason for the similarity now is that communication and transportation allows people to adopt technologies more rapidly. But if we are talking about planets separated by vast distances, there is every reason to believe that another species might come up with technologies we can’t imagine (and vice versa).
As far as the Fermi paradox, maybe the distances are just too far. Feasible faster than light travel is purely hypothetical and even something like a generation ship is fantastically difficult. One of the longest-lived and most conservative civilizations known was ancient Egypt, lasting for around 3,000 years. To have a generation ship, you basically need a civilization as stable or more, but in space, and with technological capabilities far beyond ours. It could theoretically happen, but human beings are nowhere near being able to accomplish it.
“The Drake and Fermi are not flawed logically: one can put probabilities to any question.”
The Drake equation always struck me as “numbers I pulled straight out of my butt.” We have no idea the frequency of any of these conditions. We’re working on a sample size of one. They are based on nothing other than sounding really large, while not producing a number so large that it exceeds the number of stars in the universe.
The whole “yes, there have been aliens” is even worse. It is entirely unknowable. Yet they say it with such confidence.
even when figures relate to observations, mathematics can only help with finding errors in equations — against measured data. so, consider the slant height of some very large megalithic buildings (at giza plateau) and use ancient units: then the slant height from one building is 342½ cubits and another slant height is 399½ cubits; now using cubits as lunations, together that are ? 742 lunations: this is about 32 tropical orbits of Mars and also also 28 synodic orbits of Mars; and with ± 1 lunation precision this also about 60 tropical years and about 3×(1×Metonic period + 1×Lunar year) ? 3×20 tropical years.
now the questions is: was this the intention (or coincidence) by the ancient architects? all these periods can be validated against recent observations and therefore weigh as empirical facts; IMO if the message of equations cannot be trusted for our solar system, why then for the cosmos of Drake?
Seems to me the obvious reason for the state of the world as we see it is that aliens are here and running things not for the benefit of humans.
The Drake Equation, like Da Theory of da Evolution, and Relativity Math-a-Magics with Time-pretzel-balloons, all exist to keep Atheism afloat by covering up uncomfortable realities that the Church might actually be better at this science-stuff than they are.
Many people might be deluded into following any number of hypothetical fake-religions that are handed down to them… but atheists are the only tribe of bright-bulbs stupid enough to believe in bull$#!^ they literally KNOW they made up on the spot! And they continue to make it up as they go! And oh-boy, do they really hate being held up to their own standard!
Now we have secular atheist state-celebrated sodomy and transgenderism pushed by the same academics that believe in a magical rock in the sky, that fell down, somehow got electrocuted, and then released little fishies into the sea foam that just happened to be there…
It’s always amusing when you find this same sort wringing their hands about race-mixing their glorious whiteness with the darky brutes despite proudly believing they have literal apes and chimpanzees swinging around on their ancestry tree. You’d think they’d respect their forefathers!