, , , , , , , , , , , , , , , , , , , , ,

A recent academic paper seeks to explain the Fermi Paradox by asserting that all civilizations must either collapse or reach a point of homeostasis. The paper cites tensions between population growth, resource scarcity, limits to technical innovation, and ultimately political resistance to growth. The Fermi Paradox (FP) is the observation that by now, we should have detected or heard from an alien civilization if the universe has so much potential for intelligent life. But if those civilizations fail to advance beyond a certain level, they don’t develop the technical prowess to explore outside their own stellar neighborhoods or even become detectable from great distances.

The new paper, by Michael L. Wong and Stuart Bartlett (WB), says these outcomes might be the result of “asymptotic burnout” — followed by either civilizational collapse or a “homeostatic awakening”. Never has “get woke, go broke” been so palpable! Certain sections of the WB paper read like an encyclopedia of leftist apocalyptic speculation, dressed up in mathematics and assumed to generalize to any civilization of intelligent beings in the universe. The incredible vastness of outer space suggests that it might never be possible for us to detect these kinds of homebound, low-tech civilizations, whether constrained by scarcities and moribund technologies or hamstrung by their own politics. Similarly, they might not be able to detect us.

Great Filters

There are other, similar explanations of FP. All of those fall under the heading of “Great Filters”, and I’m not sure WB have come up with anything new in that regard except for the “woke” spin. Great filters can be extinction events, such as intra-planetary hostilities culminating in the reckless use of weapons of mass destruction. Or unfortunate collisions with massive asteroids, which are a matter of time. Malthusian outcomes have been discussed in the context of great filters as well. In the past, I’ve discussed the limitations imposed by collectivist social structures on a civilization’s potential to achieve interstellar travel. I’m not the only one. The kind of “awakening” posited by WB would certainly demand the centralization of economic decision-making, though they envision conditions under which the “awakening” is a rational and enlightened decision.

Grabby Civilizations

A bit of a digression here: one of the most interesting explanations for FP that I’ve heard is from economist Robin Hanson and several co-authors. Hanson, by the way, wrote the original paper on great filters. His more recent insight is the likelihood of an earth-bound selection bias: there must be reasons why we haven’t seen alien activity in earth’s backward light cone, assuming they exist. The light cone defines an area of space-time we have observed, or could have observed had we been looking. To have been within our light cone, an event coordinate’s distance from us in space must have been less than or equal to the time it takes for its light to arrive here. For example, we can see what happened on the surface of the Sun fifteen minutes ago because at the Sun’s distance, it takes just ten minutes for its light to reach us. However, an event on the Sun that occurred five minutes ago is still outside our backward light cone. Likewise, if a star is 100,000 light years away, we cannot see events that occurred there within the past 99,999 years.

Hanson and his co-authors focus on the timescales and “hard steps”, or critical evolutionary transitions, necessary for intelligent life to develop in a solar system. They construct a probability model suggesting that the birth of human civilization was likely on the early end of the time distribution of civilizational beginnings in the universe. That means there probably aren’t many distant civilizations we could possibly have seen in our light cone. We’d be more likely to detect them if they are sufficiently advanced to be so-called “grabby” civilizations, but that kind of technological development takes a long time. “Grabby” civilizations (or their machines) are capable of expanding their reach across the stars at high speed, some significant fraction of the speed of light. They can be expected to visibly alter the volume of space they control by settling, mining, building large structures, etc…. An interesting (and perhaps counterintuitive) result is that the faster such a civilization expands, the less likely we’d have seen them in our backward light cone. And we haven’t, which argues for a higher speed of alien conquest, all else equal.

In another post, Hanson estimates that the time until we meet another grabby civilization centers on about 1 billion years if we expand. So grabby civilizations are quite rare if they exist. That doesn’t rule out the possibility that we might detect or encounter a much less technically advanced civilization. Nevertheless, Hanson strongly believes in the reality of Great Filters and believes that human civilization is likely to encounter certain filters that we cannot even anticipate.

The explanation for FP offered by Hanson, et al is nuanced, and it is my favorite, given my fascination with the possibility of extraterrestrial life. Even if the development of human civilization is not especially “early”, the number of interstellar civilizations, grabby or not, is probably still quite small at this juncture. And no doubt space travel is tough! These civilizations and their interstellar pioneers might not endure long enough to cover the distances necessary to reach us. Even more pertinent is that we’ve really only been “looking” in earnest for maybe ten decades at the most, and without complete coverage or much precision. Alien origins or spatial conquests within the last 100 years at distances exceeding 100 light years would not yet be visible to us. And again, it’s remotely possible that there is a grabby civilization whose expansion will intersect with us sometime in the near future, but it is still too distant to be within our backward light cone. If closing on us fast enough, it could have been within a single light year six months ago and we would not yet know it!

Do Civilizations Scale Like Cities?

Now let’s return to the kind of great filter put forward by WB. They first appeal to the observation that cities scale superlinearly. That is, in cross-sectional data, the relationship between city population and various measures of income or output (and other metrics) are linear in logs with a coefficient greater than 1. That means a city with twice the population of another would generate more than twice as much income.

There are reasons why we’d expect city size to be associated with greater productivity, such as an abundance of collaborative opportunities and economies of agglomeration. However, WB assert that it is impossible for a city to sustain a superlinear growth relationship over time, requiring “unbounded growth”, without periodic bursts of innovation. Otherwise, a city encounters a growth “singularity”. WB maintain that the inability of innovation to sustain unbounded growth manifests in a cascade of failure in such a city, or at least homeostasis.

WB go on from there to claim that a civilization, as it advances, will become so interconnected via technology that it can be treated analytically like a single super-city. This assumption, that whole worlds scale like cities, offers WB an analytical convenience. They assume that population growth outstrips the supply of finite resources with an inadequate pace of innovation. WB further propose that civilizations confronting these barriers might undergo “awakenings” under which zero growth is accepted as a goal.

Of course, the growth of a city will stagnate when its size overwhelms its ability to meet demands. A city might be under severe resource constraints. There are external phenomena that can cause a city to languish. All this depends upon the unique vulnerabilities of individual cities. Certainly a widespread dearth of innovation could do the trick. A planetary civilization might be subject to similar constraints or limiting events. Some planets might be resource poor or have especially hostile natural environments. Aliens unfortunate enough to be there will not and cannot become “grabby”. But WB’s hypothesis amounts to the assertion that no civilization can hope to achieve “grabbiness”.

Faults In the Clouds of Delusion

The WB argument is misguided on several levels. First, there is only limited evidence that the scaling of cities is time invariant — that the relationships hold up as cities grow over time —no singularity required! After all, the super-linear relationship referenced by WB is based almost entirely on cross-sectional data. Moreover, the scaling assertion is atheoretic. Rationales are offered based on human social connections and presumed, fixed technical relationships between city population and such things as energy use and infrastructure requirements. However, the discussion is completely devoid of the equilibrating processes found in market economies and the guidance of the price mechanism. Instead, growth simply rages on until the pace of innovation and limited resources can no longer support it.

WB appear to assume that a planet’s finite pool of resources places a hard limit on the advancement of civilization. This is more than a bit reminiscent of the Club of Rome and it’s “Limits to Growth”, or the popular understanding of Thomas Malthus’ writings. That understanding is based on a purely biological model of human needs. which was spectacularly wrong in its prediction of worldwide famine. But that was only a starting point for Malthus, who believed in the power of markets. And even in primitive markets, the very scarcity with which biological needs conflict is what incentivizes greater efficiencies and substitutes. When something gets especially scarce, the market signals to users that they must conserve, on one hand, and it also incentivizes those able to commandeer resources. The latter act to fill the need with greater supplies, close substitutes, or inventive alternatives. Again, these kinds of equilibrating tendencies don’t seem to be of any consequence to WB.

The focus on super-linearity and the relationship between population and economic and other metrics obscures another reality: global fertility rates have been declining for decades and are now below replacement levels in many parts of the world. In addition, we know that birth rates tend to decline as income rises, which directly undermines WB’s concern about super-linearity. The unsustainable population growth envisioned by WB is unlikely to occur, much less overwhelm the ability of resources and innovation to provide for growth in human well-being. WB also ignore the fact that in-migration to cities is a primary contributor to their population growth, whereas in-migration has not been observed at the global level… at least that we’re aware!

What is never in short supply is human ingenuity, if we allow it to work. It enables us to identify and extract new reserves of resources previously hidden to us, and every new efficiency increases the effective reserves of resources already available. Mankind is now on the cusp of an era in which mining of scarce materials from the moon, asteroids, and other planets will be possible.

WB are correct that there are obstacles to urban growth, but they seem only dimly aware of the underlying reasons. Cities must provide myriad services to their residents. Many of those services will experience meager productivity gains relative to goods production, and consequently increased costs of services over time. This is an old problem known among economists as Baumol’s disease, after William Baumol. While it is not limited to cities, it can be especially acute in urban areas. The cost escalation may be severe for services such as education, health care, law enforcement, and the judicial system, which are certainly critical to the economic viability of cities. However, there will be future innovations and even automation of some of these services that boost productivity. Still, they are bound to mostly rise in cost relative to sectors with high average growth in productivity, such as manufacturing. Baumol’s disease is unlikely to tank the world economy. It is simply a fact of economic evolution: relative prices change, and low productivity sectors will suffer cost escalation.

The kind of “awakening” WB anticipate would only occur if individuals are willing sacrifice their liberties en masse, or if elites coerce them to do so. Perhaps there are beings who never imagine the kinds of liberties humans expect, or at least wish for. If so, I’d wager their average intelligence is too low to accomplish space travel anyway. We’ve learned from theory and history that socialism imposes severe constraints on growth. That’s why I once proposed that civilizations capable of interstellar travel will have avoided those chains.


Wong and Bartlett attempt to explain the Fermi Paradox based on the “asymptotic burnout” of civilizations. That is, they believe it’s extremely unlikely that any civilization can ever advance to interstellar travel, or as Hanson would put it, to be “grabby”. WB rely on an analogy between the so-called super-linearity of city scales and the scales of planetary civilizations. They generalize super-linearity to the time domain. In other words, WB make the heroic assumptions that the economic aggregates of planetary civilizations scale over time as cities scale cross-sectionally.

WB then claim that civilizations will confront limits to advancement based on their inability to sustain their pace of innovation. This amounts to Malthusian pessimism writ large. Today, human civilization, while not without its problems, is nowhere near the limits of its growth, and we are nearly ready to reach out beyond the confines of our planet for access to new stocks of resources. There are vast stores of unexploited energy even here on earth, and there are a number of relatively new energy technologies that are either available now or still in development. And there will be much more. Like the Club of Rome, WB lack an adequate appreciation for the power of markets and incentives to solve economic problems, which includes spurring innovation.

Finally, WB make the wholly unsupported conjecture that some civilizations will undergo “awakenings”, choosing to adopt homeostasis rather than growth. WB might or might not realize it, but this implies an abandonment of market institutions in favor of centrally-planned stagnation, and not a little coercion. Perhaps we should view WB’s hypothesis as a cautionary tale: get woke, go broke! Certainly, a homeostatic civilization that relies upon the ignorance of central planners will never develop the capacity for interstellar travel. It simply cannot generate the wealth or expertise necessary to do so. In fact, they are more likely to suffer bouts of mass starvation than any sort of middling prosperity. We probably haven’t seen other civilizations yet, and maybe we’re “early” on the development time-scale for civilizations, but when and if aliens arrive, it won’t be thanks to socialist “awakenings”. WP are at least correct in that regard.