The Fermi Paradox

I’ve wanted to talk about the apologetic worth of the Fermi Paradox and the Drake Equation for sometime. Now a recent paper on arXiv ( gives me the excuse, and some fascinating numbers to motivate discussion.  First a warning though, this paper is a preprint.  While submitted to a reputable journal (Proceedings of the Royal Society of London A), it has not undergone peer review.  As such one should take the results cautiously as the community is still coming to terms with this topic, as the paper shows.

So what is the Fermi Paradox?  Originally posed by Enrico Fermi in 1950 it goes something like this.  First assume that the 4.5 billion years (Gyr) it took our planet to evolve to its current stage of development is the average amount of time it takes for an intelligent species to arise.  If this is the case then there should be plenty of opportunities for intelligent life to evolve elsewhere in the galaxy as the galaxy is approximately 9 Gyr old.  After all there are about 250 billion stars in the galaxy and plenty of time to fit in the 4.5 Gyr needed to get to our current state of affairs.  In addition to traverse all the stars in the galaxy would only take roughly 10-1000 Myr (million years) assuming sub-light travel speeds.  As such there is plenty of time for an intelligent species to traverse the galaxy multiple times over.  Given all this we should see signatures of alien intelligent life all over the place but we only see ourselves.  So where are they?

From the opposition direction comes the Drake Equation.  It tries to estimate how many intelligent space faring civilizations there should be in the galaxy.  By combining estimates of how many earth-like planets there are, how many have given rise to abiogenesis, how many have had organisms evolve to be intelligent, and so on you can get a ball park figure as to how many civilizations you would expect to find.

Both of these are classic SETI (Search for ExtraTerrestrial Intelligence)/astrobiology thought experiments.  I taught them both to undergrads in graduate school.  They are great thought experiments because both are exceedingly sensitive to your biases. This is because we lack hard data to back up the numbers plugged into the Drake Equation, and the Fermi Paradox causes all sorts of ideas as to why we don’t see aliens.

The paper I alluded to above by Sandberg, Drexler, and Ord, called “Dissolving the Fermi Paradox” takes a survey of all the numbers used for estimates of the Drake Equation and instead of picking one, gives a range of probable answers and sees how likely it is statistically that we are in a universe with alien life.  The name of the paper comes from the fact that the Fermi Paradox goes away if we find out its probably that there to be no life besides us in the universe.  After looking at a variety of options they come to this conclusion:

We have seen that a Fermi paradox arises if we combine a high and extremely confident prior for the number of civilizations in our galaxy with the absence of evidence for their existence. The high confidence that causes this clash typically results from applying a Drake-like model using point estimates for the parameters. These estimates, however, make implicit knowledge claims about processes (especially those connected with the origin of life) which are untenable given the current state of scientific knowledge.
When we take account of realistic uncertainty, replacing point estimates by probability distributions that reflect current scientific understanding, we find no reason to be highly confident that the galaxy (or observable universe) contains other civilizations, and thus no longer find our observations in conflict with our prior probabilities. We found qualitatively similar results through two different methods: using the authors’ assessments of current scientific knowledge bearing
on key parameters, and using the divergent estimates of these parameters in the astrobiology literature as a proxy for current scientific uncertainty.
When we update this prior in light of the Fermi observation, we find a
substantial probability that we are alone in our galaxy, and perhaps
even in our observable universe (53%–99.6% and 39%–85% respectively). ’Where are they?’ — probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable.
So by taking a look at the current state of affairs, they find it plausible that there is no life outside of Earth in the universe.  The numbers are even worse for intelligent life with it being very likely there is no intelligent life to be found else we would have encountered it already.  Thus it is a scientifically tenable conclusion that we are completely alone.
So why does this discussion make a good apologetic for Christians? After all, even if aliens were discovered it would not trouble the Christian.  Christians have historically had many interesting discussions on the topic of aliens as it makes for an interesting theological case study and the Scriptures are silent on the topic.  So regardless if the universe is teeming with life or constrained to just the Earth Christians have no problem.  Rather the results above pose a problem for the atheist.  The numbers here are damning and indicate that it is unlikely for life to arise by random chance. Observationally we can say fairly certainly that intelligent space-faring aliens do not exist else we would have seen them by now.
Even worse as we get better data for the variables in the Drake Equation (see the growing statistics on exoplanets and the emerging field of astrobiology) we may find that the Drake Equation would predict less than one civilization in the whole cosmos.  This would be an even worse paradox than the Fermi Paradox.  After all, we know for a fact that there is at least one intelligent civilization in the whole cosmos, our own.  If the Drake Equation were to predict less than one then we should not exist, yet we do.  This leads to a crisis as either we are the biggest statistical anomaly ever, or we are missing something.
As Christians we know the answer to this second apparent paradox, God created us and the whole cosmos. He is the explanation for why there is something rather than nothing.  We know who He is because He tells us about Himself in His Word by His Son Jesus Christ.  We do not need science to show us that there must be a God, we know there is one because He has told us so Himself.
All of this provides another argument in the back pocket of Christians against atheists.  This paper illustrates that there is a good chance that we are alone, even worse that we shouldn’t exist at all.  As Christians, we should pay close attention to these discussions as they continue to show the necessity of God as Creator and can be used to break down barriers to the Gospel.  That said we should be careful not to put to much weight on these numbers as they are still in flux, rather our foundation should always be on the Word and Christ’s Resurrection.  Nonetheless, it will be fascinating to see where research into both the Fermi Paradox and the Drake Equation goes in the future at it seems to be pointing to the inescapable conclusion that there is a God.

About Dr. Paul Edmon

Dr. Paul Edmon is from Seattle, Washington and now resides in Boston, Massachusetts. He has his B.S. in Physics from the University of Washington in 2004 and Ph.D. in Astrophysics from the University of Minnesota in 2010. He is professional staff at Harvard University and acts as liaison between Center for Astrophysics and Research Computing. A life long Lutheran, he is formerly a member of Messiah Lutheran Church in Seattle and University Lutheran Chapel in Minneapolis. He now attends First Lutheran Church (FLC) of Boston where he teaches Lutheran Essentials. He sings bass in the FLC choir and Canto Armonico. He was elected to the Concordia Seminary St. Louis Board of Regents in 2016. He is single and among his manifold interests are scotch, football, anime, board games, mythology, history, philosophy, and general nerdiness. The views expressed here are his own and do not represent Harvard University or Concordia Seminary. Twitter: @pauledmon


The Fermi Paradox — 11 Comments

  1. Forgive my snark, but it sounds to me like evolutionary science is the only thing that can be definitively proven to have come come from nothing, and is evolving into chaos. This is very helpful. Thank you!

  2. Dr. Edmon, this reminds me of C.S. Lewis, who somewhere (in his book Miracles, I think) mentioned how, in his own lifetime, BOTH the “We are alone in the universe” argument AND the “Life is everywhere in the universe” argument were trotted out as arguments against Christianity. Either “The idea of a loving God is obviously absurd because intelligence only exists in one tiny corner of a vast, lifeless cosmos,” or “It’s parochial to think that God would care about our insignificant species out of all the countless forms of life populating the universe.”

    I know you are aware there are numerous proposed solutions to the Fermi Paradox besides “There’s no one out there.” Speaking of C.S. Lewis again, he (in his fine trilogy of space novels) proposed that the reason we don’t hear from ETI’s is that God has quarantined Earth because of humanity’s fall into sin. In other words, maybe God doesn’t want our sin and its effects to spread to other (unfallen) races!

    I hate to disagree with you, but I’m not sure your “The unlikelihood of life in our universe is evidence for a Creator” argument works. I think there are probably plenty of atheists who would simply say, “Sure–the origin of life happened by chance in a one-in-a-jillion combination of circumstances. That just shows life is one great big accident!” I think (if I understand him) this was biochemist Jacques Monod’s view.

    I appreciate what you said about “…we should be careful not to put to [sic] much weight on these numbers as they are still in flux, rather our foundation should always be on the Word and Christ’s Resurrection.”

    Or, as C.S. Lewis said in his essay, “Religion and Rocketry” (1958), “Each new discovery, even every new theory, is held at first to have the most wide-reaching theological and philosophical consequences. It is seized by unbelievers as the basis for a new attack on Christianity; it is often, and more embarrassingly, seized by injudicious believers as the basis for a new defense.

    But usually, when the popular hubbub has subsided and the novelty has been chewed over by real theologians, real scientists and real philosophers, both sides find themselves pretty much where they were before…So, I cannot help expecting, it will be with the discovery of ‘life on other planets’ if that discovery is ever made.”

    Thanks for a thought-provoking piece.

  3. @James Gibbs #2

    “I hate to disagree with you, but I’m not sure your “The unlikelihood of life in our universe is evidence for a Creator” argument works. I think there are probably plenty of atheists who would simply say, “Sure–the origin of life happened by chance in a one-in-a-jillion combination of circumstances. That just shows life is one great big accident!” I think (if I understand him) this was biochemist Jacques Monod’s view.”

    Which is a fair answer to be honest. After all you only need to have it work once. However, I’m not sure how many atheists will be comfortable with that solution. More to the point the idea is to seed doubt in their own stance and to add credence to what you are saying. To me that’s the point of apologetics. I’ve never seen a slam dunk apologetic argument that one could not finagle ones way out of if one were committed to their worldview.

    I find the Fermi Paradox such a fascinating idea though because it really does illustrate what your bias is. So I think its a fun apologetic tool to use because its a bit out of the norm and can get people to think and reconsider. Plus its just a fun thought experiment. I always enjoyed teaching this section in class because it always spurred interesting ideas.

    To be sure though as many apologetic/logical arguments we can make it will never convince someone of Scripture’s validity. That is the work of the Holy Spirit. Heck even if you managed to convince someone to be a Theist, they still don’t have saving faith. Thus we have to always make sure we rely on Scripture and the work of Christ rather than our own arguments, as convincing as they may seem to us.

  4. Dr. Edmon, the Sept. 2018 issue of Scientific American has an article about this very issue–arguing that “We are (probably) alone in the universe.” Interesting!

    Btw, I loved reading the Wikipedia article on the Fermi paradox.

    My favorite “solution” to the paradox (in that article) is “They are too alien.”

    People have tried to come up with an estimate for how likely is life “as we know it” on other planets, but I always wonder, “How would we recognize ET life that was TRULY alien–NOT “as we know it”? Funny how the aliens on Star Trek are always so…humanoid! (I guess the makeup budget has its limits–ha!)

    I am a TOTAL agnostic on ETI, personally. Being a big sci-fi fan, I secretly hope ETI’s exist, but I know of no evidence they do. So, my personal inclination is to lean toward the ideas that (a) space is vast, (b) radio astronomy only goes back to the 1930s (right?), so (c) we just haven’t detected anything–yet! 😉

    Lots of people tie ETI’s to evolution and abiogenesis (“If conditions for life exist on other planets,” etc.), but I don’t think they have to go together. Why couldn’t God have created (without evolution) intelligent beings on innumerable planets?

    I see what you mean by there’s no such thing as “a slam-dunk apologetic argument.” But, at the same time, if I as a Christian think a particular argument doesn’t hold water, I wonder how effective it could be for an unbeliever. It’s hard to judge how persuasive an argument is, as you kind of said at the end there.

    I know Francis Collins found the moral argument for God’s existence very convincing, but I’m sure other Christians would kind of go, “Eh.” I personally have never understand the appeal of the ontological argument (Anselm)!

  5. Oddly I really like Avicenna’s argument (necessary existent) even though he’s Muslim. I think it fits well with the Lord’s self revelation as I AM. So I’m happy to steal that argument from that heathen :).

    As noted, Scripture is silent on the topic of life outside of Earth. Thus as Christians its more of a fun exercise, though interestingly we did have an actual case of this when the New World was discovered and the pope had to rule that the people in the Americas were human and thus in need of Christ. To me this is the more interesting debate with aliens is will they need Christ or not? As you pointed out C. S. Lewis has done some thinking on this in his Space Trilogy (which I hgihly recommend). Other Christians have historically as well.

    My own personal bias is that life doesn’t exist outside of Earth or if it does it will not be intelligent. I see this as a confession of the unique place of Earth in the Lord’s Creation, as well as the fact that Universe is vast and a place that we are to subdue. After all we were intended to live forever, and if we kept procreating at a reasonable rate, we would have to move out to the stars. Think of it Adam and Eve in Space, now there is a fun one. That said if life is discovered I won’t be concerned, just meant my bet was wrong and I’m out a case of beer.

    With respect to the effectiveness of the apologetic of the Fermi Paradox, I think it does have some merit. I’ve read in several places evolutionists basically expecting life existing everywhere because their worldview demands it. After all they don’t like statistical anomalies. So if we are shown to be a massive anomaly I think that’s a pretty powerful thing and can help motivate them to reconsider their suppositions. If I can get that then the apologetic has done its job.

  6. I’m not familiar with Avicenna’s argument, but will look it up later. The tiny bit I absorbed from “Professor Wikipedia” looks interesting!

    Don’t see why a Muslim couldn’t come up with as good of a rational argument for God’s existence as a Christian. After all, bare theism is all reason can prove! As far as “heathen” thought, I have personally found some of the writings of Harold Kushner (a pretty liberal rabbi) very profound, especially his When Bad Things Happen to Good People and his later volume on the Book of Job.

    Glad to hear you like the Perelandra trilogy!

    Have you ever seen the 1955 movie Conquest of Space? There’s an interesting conversation between the leader of the first trip to Mars and his first officer, where they argue about the morality of space exploration. (You can read that bit of dialogue on IMDb.) Pretty profound stuff for a Fifties space opera!

    As far as “what if ET shows up”–I don’t know. What I worry about is guys like Ken Ham who argue ETI’s can’t exist because Scripture says so. Well, what will he do if ET shows up? Will it provoke a crisis of faith in everyone who bought what he was selling? I agree with you–Christians have nothing to worry about as far as hypothetical aliens.

    Back to the Fermi Paradox–you’re right. If it (that new paper) helps even a few unbelievers be more open to the Gospel, how can I be against it?

  7. Philosophers have always done interesting work on metaphysics and the attributes of God. Avicenna is certainly part of that tradition. The probably always comes in when you try to put philosophy above theology rather than theology above philosophy. After all revelation always trumps reason. Still many interesting and informative arguments exist on the topic so I am happy to steal from the heathens when they have good ideas that conform to Scripture.

    I have not see Conquest of Space but I will have look into it.

    While I can maybe understand why one might hypothesize there is no life outside of Earth, there is no firm evidence that Scripture says either for or against. I’m sure its a similar argument like those who would say that Scripture demands geocentrism. I’m fine with people having their own opinions on the matter, but there is no way you can doctrinally bind some one’s conscience on it. To do so is dangerous as it goes beyond what Scripture says.

  8. “…I am happy to steal from the heathens when they have good ideas that conform to Scripture”–all truth is God’s truth, right? As George MacDonald said, “Truth is truth, whether from the lips of Jesus or Balaam.”

    What do you think of the idea that, being human beings endowed with reason, and God’s revelation being bound to the written Scriptures, we have to use reason even to understand revelation? Just throwing that out there…

    I totally agree with you about not binding consciences to extra-Biblical speculation.

    As far as geocentrism, I view it as pernicious. It’s certainly not as harmful a view as, say, “All vaccines are evil,” but any time people ignore something so clearly established as heliocentrism, to me, that just reinforces a tendency to accept fringe-y views.

    I guess I would say it’s not a sin to believe in geocentrism, but I would be concerned for the rationality of a loved one who embraced it!

  9. Certainly we aren’t relativists, so truth is truth no matter where you find it. The question is how do you discern the truth. With heathens one must always be on higher alert. That said there are many pernicious things said by Christians as well that masquerade as the truth but are not.

    Sanctified reason is certainly the lens through which we look at a great many things. However what makes reason sanctified is the Lord and sanctified reason would never put itself above or against what God’s Word clearly teaches. Thus reason is certainly subservient to faith, but it doesn’t mean that reason, or faith for that matter, are blind.

    As an astronomer I always find it confounding that people still believe in a flat earth or geocentrism. I mean these days its easy to prove otherwise. It really does no favors to the Christian witness (see: Let the world mock us for the other ridiculous things we believe (of which there are many), this one isn’t really up for debate anymore.

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