Where are they? Another solution to Fermi’s paradox.


Fermi’s paradox is the most frequent objection to the idea that there exists intelligent extra-terrestial life.

Now there’s appears to be a new solution to the paradox – perhaps the implicit assumption that populations of sentient beings will grow continuously and exponentially is wrong.

Two scientists at Penn State University suggest that:

“The problem is that this kind of growth may not be possible and they look at Earth as an example. For any expansion to be sustainable, the growth in resource consumption cannot exceed the growth in resource production. And since Earth’s resources are finite, it has a finite mass and receives solar radiation at a constant rate, human civilization cannot sustain an indefinite, exponential growth.

So we’ll have trouble colonising the galaxy, if we ever decide that’s necessary. At the very least, the spread of our civilisation will not be exponential, if it is possible at all.

Haqq-Misra and Baum say that this argument means that any extraterrestrial civilisation must be similarly constrained.”

Read the full article here.

Interesting idea. Certainly we can see how difficult it is to create sustainability in social organizations. Church congregations for instance seem to have at least four inherent population plateaus – at least in the Episcopal Church – according to research Arlen Rothage did back in the 70’s. It’s possible to overcome the plateau limit, but it takes a great deal of work.

Perhaps this same phenomenon is at work in the galaxy. Planetary civilizations might be limited in the degree that they can expand by technology and/or lifespan issues. Perhaps there are plateaus at the planetary, the planetary system level and at the interstellar level. Which would make sense – each scale involves multiple order of magnitudes scale changes.


I wonder if there’s a ubiquity or fractal distribution law at work? I’ve wondered that for some time about whether that exists for congregation sizes. We know that it exists for city sizes. Seems like the same basic resource and scaling plateaus that exist here on earth would exist in the galaxy as well.

The Author

Episcopal bishop, dad, astronomer, erstwhile dancer...


  1. Nicholas, your reflection here reminds me a bit of the dialogue in one of the later chapters in Lewis’ Perelandra, where Ransom contests the idea of a perpetual progressivism and unlimited growth for humanity. A finite universe must rule that out.
    I do think you are on to something with the fractals; though I think there is also an inherent brittleness in large systems. I’m preaching on that this Sunday given the “pride of the cedars of Lebanon” and the fall of Assyria > Babylon > Persia > Greece > Rome and (horrors) “the Church”! A lesson for the Anglican Communion…

  2. I had one of those early morning corrective thoughts, realizing it isn’t in Perelandra but in Out of the Silent Planet that the dialogue takes place.

  3. I think the aliens interface and evolve with thier nano, bio, info, technology and actually change states of being. They leave the cosmic egg, or fish bowl. All the talk you hear today about the coming technological singularitiy producing post-humans fits nicely with the fermi paradox, and Christianity. There is a better place in our future.

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