Monday, May 17, 2010

Resolving Fermi's Paradox

If intelligent life exists elsewhere in the universe, where is everyone? Enrico Fermi’s 1950 question has elicited many theories in the sixty years since. If advanced life was as commonplace as Frank Drake or Carl Sagan believed, it seems unlikely that not a single extraterrestrial civilization would have made itself known to us.

Some, like futurist Ray Kurzweil, believe that this means that we are alone in the universe: the product of a series of astronomically unlikely occurrences. Kurzweil reasons that any advanced civilization would use all the matter of its own planet for computing, then radiate outward from their home world. The fact that no one seems to have done this already is supposedly evidence that we are alone.

I think this is a remarkably anthropocentric view of the universe. Both Fermi’s Paradox and Kurzweil’s reasoning employ the same faulty assumption that extraterrestrial life would act the same way that humans might. How can we possibly guess the goals of an extraterrestrial civilization when we don’t even know how our own civilization will act in the future? Why should we assume that extraterrestrials will be expansionists, desiring to conquer (or even communicate with) the rest of the universe? This is a remarkably human trait to project onto other potential civilizations. It’s entirely possible that extraterrestrial life does exist, but is simply not interested in interacting with us, content with not venturing far from their home worlds. Any civilization capable of interstellar travel or communication will almost certainly have access to anything it wants at home, and perhaps would have no particular reason to be interested in a pale blue dot populated by bipedal apes.

There is another, darker explanation for the lack of contact with extraterrestrials. If advanced civilizations tend to eliminate any inferior civilizations with which they come in contact, then we will have no evidence of them until immediately before our extinction, if at all. The fact that we have not yet been eliminated, then, simply means that no other advanced civilizations are aware of our presence yet. We can employ the Anthropic Principle here: We would not be here to speculate about Fermi’s Paradox if we had been discovered by another civilization.

These are the explanations for Fermi’s Paradox which seem the most plausible to me. The least plausible explanation is the one Kurzweil suggests: That we are alone. Even if advanced life developed in only one in a billion solar systems, there would be trillions of civilizations in the vastness of our universe. Finding them, however, may be much more difficult. Perhaps a truly intelligent civilization would leave no evidence of its existence at all.


  1. Your assumption is that not one single alien species will behave the same as humans, not even one out of millions of alien species.

    Because if even one species behaves like us it would only take them a few million years to explore the galaxy using robotic spaceships and they would be here.

  2. Hi Sean,

    Thanks for your input!

    I'm not sure that assumption is unreasonable. Perhaps expansionist civilizations disproportionately go extinct; it seems likely to me that civilizations bent on conquest would tend to destroy themselves. Or perhaps they defeat their expansionist tendencies long before they're capable of exploring the galaxy.

    Think of our own civilization, for example. It's possible that within a few decades, we'll have the ability to create full-immersion virtual worlds for ourselves. Once we do that, will we necessarily need to be expansionists? We'll have everything we need in our virtual worlds.

    Eventually it might be necessary as our solar system gradually became uninhabitable, but even then the amount of expansion we'd need to do would be very small...possibly to only one other star system.

    It seems to me like expansionism is an extremely human characteristic, and there's no reason to think that even one out of millions of species would share that trait. There's not even any reason to think our own descendants will share that trait IMO.