SETI's Problem: The Fermi Paradox

I have always considered SETI a noble yet misguided pursuit.  On the one hand, the upside is huge:  the discovery of intelligences outside our own solar system.  On the other hand, the odds of success are statistically almost non-existent.  But as long as private individuals and corporations were looking for a project to throw a relatively small amount of money at, I considered the exercise valuable if for no other reason than we were getting really good at scanning the RF spectrum.

I mean no disrespect to the legion of scientists and technicians who gave their careers to the project, and I certainly don’t want to come off as kicking these scientists and technicians when they’re down, but now that the cold water has been splashed on SETI’s plans, it’s probably a good time to explain why I believe SETI was a noble waste of resources from the start.

You see, SETI’s biggest problem is not funding, or technical ability, or public support.  SETI’s biggest problem is The Fermi Paradox.  This paradox, first presented by physicist Enrico Fermi in 1950, makes a very good point:  If intelligent life is common in our galaxy, then we should see signs of it everywhere.  Now, that sounds simplistic, and the common rebuttal argues that space is huge, so even a large number of intelligent species would be separated by massive distances.

The problem is that this counter-argument, though it takes into account the hugeness of space, completely ignores the hugeness of Deep Time.  The galaxy - heck, the universe - is ancient.  Humans are not wired to completely grasp the timescales involved.  Intelligent species would not only have to exist across space, but they would also have to exist across time.  And the odds of multiple intelligent species existing relatively simultaneously in the same general volume of space during the same general time does not appear to be statistically possible.  Let’s run some numbers.

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Geologic Time

The Earth is 4 billion years old, more or less.  For 3.999 billion of those years, not a single intelligent, tool-using, technologically-capable creature evolved.  Then, along came some smarter-than-average apes who started manipulating their environment.  A few hundred thousand years later came language.  Art.  Agriculture.  And then, about 100 years ago, radio.  100 years.  4 billion years.  If you took a human lifetime and divided it into seconds, you’d come out with about 2 billion.  That means if the history of the world were compressed into a human lifetime, humans have been using radio for about as long as it took you to read this paragraph.

So, let’s define “intelligent life” by SETI’s requirements.  For SETI to identify an intelligent species, that species would have to be at least radio-capable.  Humans have been inside this window for a bare 100 years.  Now, the other big question, and one we really can’t answer, is how long a species remains radio-capable?  How long, in essence, is an intelligent species around?  I submit that this may seem like an important question, but it really is irrelevant, because the answers are all mutually exclusive.  If an intelligent species sticks around only for a thousand years or so, that is such a tiny sliver of cosmic Deep Time that it is unlikely in the extreme that two species would exist inside that 1000-year window in a volume of space small enough for them to be detected by each other.  On the other hand, if intelligent species exist for eons, then we should see evidence of them everywhere.  The RF spectrum should be screaming with intelligence.  Everywhere we point telescopes we should see evidence of intelligent civilizations.   Life has invaded every niche on Earth, and it’s safe to assume that intelligent life should invade every niche in space.  For it to be long-lived and successful, it would have to!


As Humans,  we have evolved to be explorers, to search out others like us, to make connections.  We are a social species, and there’s something deep inside all of us that want to believe that there are other species not too different from us populating the stars.  But we are also a logical species.  We are engineers, mathematicians.  Our challenge is that these two sides compete with one-another.  And it is our constant struggle to filter our wishes and fantasies, to remain rational in the face of emotion.  



Our logical side looks at the cosmos and sees nothing but a completely indifferent universe. That is a lonely thought.  It triggers that part of us that wants to belong.  But wanting something does not make it reality.  A part of me will miss SETI and the ideological vigor with which it pursued its goal.  But the logical, rational side of me must accept that it’s time to move on.



The universe may be empty of intelligence, but it is filled to the brim with mysteries.  I take solace in that, in the idea that, in the words of Carl Sagan, “Somewhere, something incredible is waiting to be known.”