Maybe We Don’t Hear From Aliens Because They Choose To Go Silent

How will humanity meet its end?

That’s only a depressing question if you think that humanity will go on forever. Alas, nothing lasts forever, and if something could last forever, it probably wouldn’t be our struggling primate species.

But we’ll likely be around for a while yet, pondering things as we do. One of the things we love to ponder is: why don’t we hear from any other alien civilizations?

Any species that advances far enough to gain control of a planet and expand into space likely faces a similar set of existential conundrums in their continued survival. The “Great Filter” concept catches that idea. The Great Filter is an implication of the Fermi Paradox. The two fit together to try to give context to humanity’s situation.

The Fermi Paradox asks “If there are so many planets and possibilities for life to emerge, then where are all the aliens?” The Great Filter is one possible solution to the paradox. It says that as civilizations become more and more advanced, they face evolutionary hurdles they can’t clear. They collapse and become impossible to detect from great distances.

A pair of researchers have tackled these ideas in a new research article. Its title is “Asymptotic burnout and homeostatic awakening: a possible solution to the Fermi paradox?” It’s published in the Journal of the Royal Society Interface, and the authors are Michael Wong and Stuart Bartlett. Wong is a post-doctoral fellow at the Earth and Planets Laboratory at the Carnegie Institution for Science, and Bartlett is a Geological and Planetary Scientist at the California Institute of Technology.

At the heart of their work is this idea: Intelligent civilizations can realize their continued expansion is unsustainable and will lead to collapse, so they aim for a kind of homeostasis instead and become undetectable.

The authors invite us to think of life as systems where fluxes of mass and energy lead to the production of functional information that life utilizes and transmits. In this case, functional means it allows the living system to survive. Over time, lifeforms evolve to produce and use functional information better than their predecessors. But evolution isn’t steady. Life has become more complex due to a series of major transitions in the way it manages functional information. “Such transitions thus represent major shifts in the ways in which biological information is encoded and exploited,” the authors write. Obviously, being better at it is an evolutionary advantage.

From there, the idea expands to include cities, which in a manner of speaking are alive. The authors write that “In some ways, a city is a superagent composed of individual human agents analogous to a multi-cellular organism that is a superagent composed of individual cellular agents.”

Now consider a planet-encompassing civilization that is basically one big city. We’re not at that point on Earth, but we can see the possibility. Instead of lifeforms going through evolutionary transitions that allow them to continue to use energy and information effectively and overcome barriers to survival, global civilizations are in the same position.

Our cities are becoming larger and more interconnected. How far will that trend go? Lights from the United States glow in this night image based on data taken from the Suomi NPP satellite in April and October 2012. Credit: NASA Earth Observatory/NOAA NGDC

“So too has human society been shaped and reshaped by innovations that accelerate and widen the spread of information—most notably the inventions of the printing press, telecommunication, computers and the internet,” write Wong and Bartlett. And just as lifeforms have evolved to utilize other energy sources—microbes using geochemical energy, plants using sunlight, predators eating flesh—so have we. We’ve learned to use fossil fuels, we’ve developed nuclear energy, and we’re expanding our use of renewables like solar and wind.

So far so good for humanity, right?

But what happens as a globe-bestriding civilization continues to grow? Cities may behave like lifeforms in some ways, but obviously, they’re different. One of the ways they’re different, and the critical difference for the authors, is in their superlinearity.

A trend that’s superlinear is faster than a linear trend. The easiest way to understand superlinearity is to look at a graph of three lines, one linear, one sublinear, and one superlinear.

This graph shows the difference between linear, sublinear, and superlinear. Image Credit: Remi Louf, 2015.

Many aspects of a city are superlinear. Things like GDP, wages, crime, and disease are superlinear because they generate increasing returns with increasing size. Biological entities are different. Many aspects of biological life scale sublinearly, according to the authors. Some aspects of cities also scale sublinearly: total road surface, number of gas stations, and length of electrical lines, for example.

So some aspects of a city are sublinear and that’s desirable. That creates economies of scale which work in our favour. But some things in our envisioned global city are superlinear, and that, according to the authors, is the crux of the problem facing technological civilizations. Superlinearity leads to what the authors call singularities.

“Superlinear scaling results in crises called ‘singularities’, where population and energy demand tend to infinity in a finite amount of time,” the authors write. The singularities are clashes between growth and expansion on one hand and the energy needed to sustain them on the other. “… a global civilization will march towards a singularity where energy resources can no longer sustain the trajectory of unbounded growth,” they write.

The solution to singularities is technological innovation or resets. Singularities arise more often as a planetary civilization continues to grow, and “… must be avoided by ever more frequent ‘resets’ or innovations that postpone the system’s collapse,” they write.

So tension sits at the heart of the civilization as it reaches global status. Singularities arise and are overcome by resets or innovations. But what if the time between these critical singularities keeps shrinking? At that point, the planetary civilization “… will face an ‘asymptotic burnout’, an ultimate crisis where the singularity-interval time scale becomes smaller than the time scale of innovation.”

This graph from the study shows how population growth leads to singularities that must be avoided by resets or innovations. Image Credit: Bettencourt et al.

Now the planetary civilization is in trouble. And that, say the authors, is why we don’t hear from any other civilizations. There are only two paths now.

One path is collapse. The asymptotic burnout that the authors talk about is kind of like the Great Filter. Every technological civilization that controls a planet eventually faces it. If there are or were other civilizations somewhere out there in space, maybe many of them slammed into asymptotic burnout and then just collapsed.

But others may not have. How did they avoid it? With homeostatic awakening.

In a homeostatic awakening, a global civilization becomes aware of its predicament and its trajectory. The civilization will “… have a window of time to affect a fundamental change to prioritize long-term homeostasis and well-being over unyielding growth—a consciously induced trajectory change or ‘homeostatic awakening’.”

That’s the authors’ potential solution to the Fermi Paradox and it tells us why we don’t hear from any more advanced civilizations. The lack of signal doesn’t mean they’re not there; it means they’ve “gone silent.” They’ve understood that their continued growth will doom them, and they stop expanding. In prioritizing homeostasis, they make themselves difficult to detect.

In tracing a civilizations path toward asymptotic burnout or homeostatic awakening, the authors lean on the idea of the dataome. The dataome “… encompasses the external recording and processing of information (in e.g. books, architecture and computers) as well as the coevolution of those infological organisms atop of a collection of biological organisms…” they write. We’re witnessing the dataome’s continued development right now, and we’re taking part in it.

This figure from the study shows three different scenarios for a civilization on an asymptotic burnout trajectory. The top civilization reaches burnout without realizing it in advance. The middle civilization sees burnout coming but is unable to reach homeostasis before burning out. The bottom civilization sees burnout coming and successfully reorients itself toward homeostasis. Image Credit: Wong and Bartlett 2022.

The dataome emerged and accelerated during the Agricultural Revolution, as more energy (food) became available and societies transitioned away from hunter-gatherer status and established cities. The emergence of a dataome leads to accelerated growth. We’ve seen that in our own history, and we’re watching as our society continues to accelerate. There are more and more of us, we produce and consume more goods, and we hunger for energy. And we’re headed for a singularity, where continued growth demands greater energy, but the climate can’t handle it.

Will we reset technologically? It’s within our power to do so and to avoid the climate change singularity. The authors look at a society that has managed to resist continual expansion and growth and prioritize other things.

Bhutan is a small mountainous kingdom between India and China. Bhutan’s government doesn’t bother with GDP, the measure that most nations use to gauge their progress and well-being. Instead, Bhutan maximizes their ‘Gross National Happiness.’ Bhutan’s GNH is based on four things:

  • sustainable and equitable socio-economic development
  • environmental conservation
  • preservation and promotion of culture
  • good governance.

So Bhutan has resisted the quest for growth and economic supremacy. The authors don’t claim that Bhutan’s case is necessarily relevant to avoiding asymptotic burnout, and the country’s an isolated case. But it does seem that Bhutan “… is unlikely to reach any kind of technological singularity in the near-future (burnout risk is relatively low at present).”

The authors mention examples of “mini-awakenings” where humans have realized they’re heading for big trouble and have changed their trajectory. The banning of ozone-depleting chemicals, the de-escalation of WMDs after the Cold War, and the moratorium on whaling are examples. Maybe, if we can live up to our climate change agreements, they’ll be in the same category.

All of this leads us back to the Fermi Paradox. The question at the heart of the Fermi Paradox is “In a universe that seems amenable to abiogenesis and the evolution of life leading to technological civilizations, why haven’t we seen definitive evidence of extraterrestrial civilizations?” Wong and Bartlett say that the question itself is a paradox. That’s because “… there is an implicit assumption that the trajectory of progress can be extrapolated from the past, i.e. that the future is a linear extension of past and current trends.”

The assumption behind the Fermi Paradox is that civilizations will continue to harness more energy and expand. That assumption is expressed in the Kardashev Scale, which measures a civilization’s technological advancement based on its energy consumption. In the Kardashev Scale, civilizations grow until they harness all the power of their star with massive engineering megastructures called Dyson Spheres. Once they’ve harvested the energy of their solar system, they spread throughout the galaxy as a Type III civilization and should be detectable.

The Kardashev Scale is fun but simplistic. It ignores the fact that evolution isn’t linear, and it ignores superlinearity and the crises that singularities create.

The authors say that Type III civilizations may be unattainable. Instead, civilizations either burn out and potentially collapse, or they reach homeostatic equilibrium and are undetectable.

This figure from the study shows that Type III civilizations may be out of reach and that civilizations are bounded by collapse and homeostasis. Image Credit: Wong and Bartlett 2022.

Other solutions to the Fermi Paradox talk about potential bottlenecks in a civilization’s technological advancement up the Kardashev Scale. Thinkers attach probabilities to those bottlenecks, like in the Drake Equation. But this idea is different. According to the authors, it’s inevitable that a civilization will come up against singularities. “The solution we propose here is of a different kind: it is an inevitable barrier, emergent from the dynamics of energy and information flows within a living system, that civilizations will either meet or learn to redirect themselves around.”

If the authors are correct, then homeostatic civilizations will last much longer than burnout civilizations. The civilizations that slam into the singularity barrier will collapse.

This figure from the study shows that homeostatic civilizations will last much longer than others. But it’s impossible to know how many, if any, might make it to that point. Image Credit: Wong and Bartlett 2022.

The authors are merely presenting their idea for discussion. They make no claim that it’s true, but point out that it’s based on things we know about life and biology on Earth. “Like so many other astrobiological hypotheses, there is no evidence yet that this idea is true, other than its rooting in the laws of life that seem to govern biological organization on Earth,” they write.

For those of us who are interested in all things space-related, including our own civilization, this idea is sort of like a life-preserver. Many of us grew up watching one of the iterations of Star Trek, where humanity is more or less unified and we’ve gone out into space to meet our neighbours. It’s a great and inspiring vision, at least until it runs into things like the Fermi Paradox and the Great Filter.

But maybe there’s hope. Maybe our civilization will be one of the ones that can see singularities coming and can reorient itself towards homeostatic equilibrium.

Looking around at the world today, it can seem unlikely. But humans can be very good at generating solutions. Maybe we can overcome some of the singularities that are coming our way. Maybe we’ll figure it out one day. People criticize the capitalist mindset by saying perpetual growth is unattainable. The usual comeback from space-knowledgeable people is that we can expand into space and preserve the biosphere’s health. We can have moon bases, a presence on Mars, asteroid mining, etc.

The paper’s authors leave it to the rest of us to wonder about those aspects of humanity’s future. They also leave it to other researchers to explore and test their ideas. “We hope that future work will test the assumptions outlined above,” they write in their conclusion. “Specifically, we encourage the collection and analysis of global datasets to quantify how growth, productivity and other social metrics have changed over time.”

Earth. Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill.

“Regardless of whether the burnout–awakening hypothesis does or does not describe a universal trajectory for life in the universe, it is critical to know whether humanity is in danger of suffering from an asymptotic burnout,” they explain.

Humanity’s future is up in the air. Will our distant descendants have the wisdom to see singularities coming? Can we create a global political system to deal with singularities effectively? Who knows.

But there’s a melancholy aspect to both asymptotic burnout and homeostatic awakening. In both cases, we’ll never meet the neighbours.


Evan Gough

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