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April 10, 2024

As sketched in the previous post, I believe modernity to be an unsustainable flash that will not persist into future millennia. Uncomfortable with untethered speculation, I have said little about what might come after, but feel I owe something in this vein. Semantically, what follows the modern age must be the post-modern age, right? Except that name is already taken by a rather inane school of thought that may be even worse than modernist thought (it actually does not fundamentally refute modernism anyway, just throws sand into any conversation).

Despite my disdain for post-modernism, I will appropriate the term for what it will likely come to mean in centuries hence (long after people have finally forgotten the silly modern version of post-modernism). I feel better already.

The simplest explanation for why I have not written much on post-modernity is that I don’t feel I have much to say. The range of possibilities is quite large, and I would be a fool to pretend that I—or anyone, really—can paint a credible picture. I’m virtually certain I know how humans will live on the planet tomorrow, fairly sure I could paint an accurate picture for life one year from now, reasonably confident about a decade out, pretty damned fuzzy on a century from now, perhaps a little more clear a millennium into the future (as most of modernity has melted by then), have a decent guess for several million years hence (less likely to still have homo sapiens), and am increasingly certain when the number turns to billions of years (complex life on Earth extinguished). For me, the hardest part is the century scale: the messy, chaotic transition likely characterized by de-industrial scavenging.

Ignoring my discomfort of wading deep into the unknown, it may at least help some folks to get a screenshot of my fuzzy imaginings in this space.


I find it easiest to start by eliminating vast tracts of “parameter space” by elucidating modes of life that I deem to be either impossible or too unlikely to take seriously. I will confess that as I write this, I have no real idea where it’s going, so we’re both in for a ride of discovery.

Nothing is Forever

Let’s get this one out of the way at the start. The universe is 13.8 billion years old, and it isn’t what it used to be. I would say that the universe is somewhat like a middle-aged adult, approaching old age. Maybe that’s just me, projecting. Anyway, abundant stores of gas and dust in its youth led to rapid star formation, galaxy formation and mergers, supernovae, quasars, and many other signs of vigor. Many of those stores are now spent or dispersed. Present-day galaxies tend to be large, symmetric, stately, and relatively gas-poor compared to the youngsters of yester-eon still figuring out who they were (common features of young galaxies were pink hair, piercings, and tattoos; some of them smoked).

The point is, the universe goes through a golden age of star/planet formation, supporting a vibrant middle class of life (presumably not rare in this enormous space). Like every star, ours will spend its fuel and power down. Eventually the universe becomes darker, colder, and—as far as we understand things—accelerates expansion until galaxy remnants are isolated. This is called the “heat death” of the universe. Deal with it. Nothing lasts forever, just as life loses meaning without death.

Within a billion years, our slowly-shrinking sun gets hotter, and more luminous to the point that the oceans evaporate in a runaway greenhouse (Venus) event. On that time scale, whatever complex life still exists on the planet will likely evaporate with the oceans. I suspect humans will be long gone by then, anyway (and not into space, silly).

Species Longevity

Homo sapiens has been around for 200–300,000 years, and genus Homo for about 2.5–3 million years. The great ape line is about 20 million years old. This provides some sense of timescales for species longevity. Some designs last a long time, while others flit in and out of the scene in well under a million years.

It would raise eyebrows to expect our species to have a run well outside of the few-million-year mark. A short expectation is especially true for a species who effects so much destruction of ecological health. I am not one to buy into unsubstantiated beliefs of transcending our animal status via complete mastery so that we come to operate outside the normal and harsh rules of evolution.

No Space

I also restrict my thinking to Earth. I can’t prove we won’t colonize space any more than I can prove you won’t roll 10 sixes at once on a set of dice. It’s just phenomenally unlikely given the stack of low-probability conditions that would need to be met. I need to watch my word count here (I elaborate on the juvenile fantasy elsewhere), so will attempt a short-hand list of fundamental barriers. Like rolling a die, each in isolation might not seem like “game over,” but in aggregate, it stacks up to a pretty outlandish prospect.

Contextual hardships of living in space include:

  1. Nothing to breathe: we’re adapted to Earth’s atmosphere and need oxygen.
  2. Nothing to drink: water is thin on the ground out there.
  3. Nothing to eat: we eat biology—not rocks—and that’s all on Earth, as far as we know.
  4. Distances defy intuition: the moon is about 1,000 times farther than the space station and Mars is 600 times farther than the moon, on average.  The next star is 200,000 times the distance to Mars.
  5. Cosmic radiation is about 100 times higher outside Earth’s magnetosphere, so Moon or Mars means cancer is likely within a year or so.
  6. Space travel eats our planet’s resources like crazy, effecting a large environmental cost to Earth: a person in space is doing the equivalent of driving sixty diesel buses at once.
  7. Relating to the prior point, the fastest way to destroy Earth is to try to leave it—only to land somewhere more “destroyed” than Earth in its suitability to support life.
  8. The International Space Station has not solved closed-cycle living and depends on monthly resupply from Earth’s surface (for oxygen, etc.) at $100M a pop (high rent).
  9. Mars’ atmosphere is 95% CO2, while a 0.01% increase in atmospheric CO2 on Earth (from 0.03% to 0.04%) has us stymied.
  10. Our solar system is a desolate, barren wasteland in the context of providing human needs: living on Mt. Everest or the ocean floor is far easier, but still prohibitively hard.
  11. We have not succeeded in creating an artificial environment capable of supporting human life even on Earth where it would be far simpler and cheaper than trying in space. What took evolution billions of years to sort out is not easily replicated or even fully understood.
  12. Interstellar travel brings in a new list of even crazier insanity. Really. It’s insane. Proponents need serious help relocating grounded reality.

The first three translate to minutes, days, and weeks for survival. In short, Earth is our context, surrounded by a biodiverse ecology. Don’t succumb to the mental disease of taking anything else seriously. Isolated internal logic and the rare space stunt are nothing to context.

Non-Renewable Resources

We are ripping through key deposits and concentrations of non-renewable resources (fossil fuels, aquifers, minerals, metals, fertile soils) on a centuries or even decades timescale. It’s all anyone alive today has ever known, although the scale is substantially higher today than our elders experienced as kids. Nothing like this can persist into even the intermediate future. Certainly on civilizational timescales (10,000 years since we began agriculture, then cities), the gig is up. Technically, some of these things may be said to be renewable (eventually and slowly replaced), but at nothing near the rate at which modernity consumes (requires) them.

As with most of these elements, I can’t rule out beyond the shadow of a doubt that recycling might advance to the point that mining is no longer necessary while still having access to as much material as modernity wants, but this high-tech imagined future runs afoul of too many other considerations (e.g., ecological) to seem realistic.

We’re left with dependable renewable resources like wood, fibers, skins, and bones. I have a hard time arguing against rocks, dirt, and clay as well, as these are at-hand and in circulation on the surface.

Ecological Isolation

I don’t consider it feasible that we could skate through ecological collapse, living as an “island” species perhaps along with select domesticated animals and plants. To me, it’s similar to imagining that all we need as humans is a brain and a heart—or equivalent contraption—to deliver blood/oxygen to the brain. Such “disembodied” thinking flies in the face of the only examples we have. In reality, we appear to need even stuff we don’t fully comprehend. We also need gut bacteria, so that a human being isn’t even a single stand-alone species.

Humans got here in an ecological context surrounded by uncountable and unknowable interdependencies. It’s enormously risky to let our ecological ignorance suggest that we don’t need what we don’t understand—especially when we have ZERO evidence that humans can survive in a world depleted of its biodiversity. I get angry thinking about people who blithely make such a counterfactual and irreversibly devastating assumption.

Nor should we imagine ourselves as being able to survive the sixth mass extinction we have initiated. Animals higher on the food chain have a harder time in such epochs. Humans are voracious (big brains to feed and a lot of un-furry surface area to keep warm), and therefore are ecologically expensive. If the Earth tightens its belt, don’t assume that humans will fare well. We are summer children borne of “good” times, where “good” translates to “biodiverse.” Cleverness is no guarantee against starvation, as countless clever humans who have starved can’t tell you. Speaking of cleverness…congratulations, by the way, on kicking off the sixth mass extinction. Something to be proud of!

What’s Left

Damn. I’ve done it again. I spent many words rehashing what we can’t expect to do, short-changing those interested in what’s left. But I think these constraints are important to spell out. Mirroring the preceding impossibilities (at least practically so), we would need the post-modernity future of humanity on Earth to:

  1. Accept that time is both precious and immense. As such, we should: A) revere the deep past that got us here; B) appreciate the present; C) actively avoid harming the future.
  2. Stick to Earth: it is our only home; our complete context; our creator. We need to treat it accordingly, as it is our everything.
  3. Get by using only renewable (principally biological) resources, and at a rate that is ecologically sustainable.
  4. Recognize the value of ALL life, and that we are one (small) part of a whole—lucky and privileged to be here at all.
  5. Renounce the Human Reichhuman supremacy in concert with our capability is (disastrously) pulling us out of ecological context.
  6. In short: treat the more-than-human world at least as well as we treat ourselves.

As I’ve said before, no other species needs to exercise the self-restraint embodied in these “rules.” Other species—and some human cultures—appear to operate within their original ecological context in a mode of “fair play.” By rapidly depleting non-renewable resources and initiating a mass extinction, we have earned a special “probationary” set of restrictions. Our capabilities exceeded what evolution prepared the ecosphere to tolerate, so that it’s a matter of deliberately tucking back into ecologically viable profiles, or else let the ruthless process play out, come what may.

Unlikely Accoutrements

At this point, we can rifle through elements of modernity that fail to meet the criteria for long-term sustainable living. Consequences of the renewable-only provision are the easiest to examine. We probably don’t have skyscrapers, paved roads, cars, tractors, airplanes, solar panels, wind generators, electricity, computers, phones, appliances, guns, plastic crap, and depending on where you’re sitting most of the things in your field of vision (except perhaps out the window, depending on how much nature is left where you are).

Whoa, whoa, whoa, you might say. To many, it will seem preposterous to write off such a sweeping list that seems to encompass practically everything familiar. We mistakenly attribute temporary material excess to human innovation, and imagine that the key step is one of conception, which is immune to erasure. I would say that difficulty accepting the removal of all these staples of modernity is a consequence of living in a highly skewed period of time. To flip the cube perspective, what’s preposterous is having these things at all, right now. It’s certainly unlike anything Earth has seen for its entire 4.5 billion year history, is causing rapid imbalance in what evolved ecologies can handle, and is far more likely to manifest as a flash than as a new normal (for reasons summarized in the last post).

In any case, eliminating such things dramatically changes the madcap life we know. But we’ve only had most of those things for a time that is brief even against the age of agriculture (itself an ecological/evolutionary flash). Meanwhile, things like pottery, leather, clothing, boats, bows, arrows, spears, chairs and tables are okay. It’s not as bad as the crass idiom, in that we will still have a pot to piss in.

Proper attention to ecological health probably eliminates agriculture. Otherwise ecology eliminates us: not really a choice, you see. Despite the fact that we’ve been doing it for a while, a variety of ills accumulate (e.g., nutrient depletion, salt buildup, erosion, desertification) so that fields do not remain viable for very long on relevant timescales. It is possible that agriculture can persist in some regions (like in flood plains that are continually refreshed) and at small scale. More likely, horticulture can survive the longer haul. The difference is that ecologically-viable horticulture tends to plants that already exist in a region, so that the complex web of life in place is already adapted to “service” the plant—just as the plant services its environment in return.

Whether or not we maintain domesticated animals is difficult to predict. Dogs voluntarily built mutual associations with humans in a non-captive capacity prior to agriculture’s appearance. Cats half-heartedly joined once we had grain storage (and thus rodents), so maybe they don’t persist as companions if we abandon the surplus/storage model for food. Draft animals are certainly an agricultural concept. Captive livestock for eating (lazy hunting) may continue to be practiced, but just as human slavery is morally reprehensible to us today (noting that we did not go so far as to raise slaves to eat, as far as I know), animal enslavement might well be rejected as disrespectful of animal “sacredness” in a world where we value all life and do not see ourselves as masters. I don’t know for sure, and would not want to place bets either way.


Am I simply describing a reversion to hunter-gatherer lifestyles? Not deliberately. Everything I have outlined certainly accommodates hunter-gatherer lifestyles. This is no coincidence, since pre-modern ways of living were not demonstrably unsustainable. Megafauna extinctions did accompany the initial migration of humans out of Africa, but the co-evolved megafauna in Africa survived long enough to suffer the modern holocaust.

Hunter-gatherers, therefore, provide an essential data point. Hunter-gatherer humans can likely survive and enjoy themselves (yes, they do) for timescales consistent with the normal course of evolution—and perhaps pave the way for the next adaptation. It’s a safe bet that it could work. For me, this is the baseline, or fallback. If you consider this to be a terrible outcome, then I suspect that you value an unsustainable aberration—a fleeting failure mode—more than the amazingness of humans in full ecological context: worth some introspection and value assessment.


Building up from the hunter-gatherer default, horticulture allows a hybrid existence, where something akin to “crops” are tended, but without plowing and eliminating all but the desired plant. Such practices might not favor settlements the way monoculture fields did, instead supporting seasonal migration. Harvest is not greedy: it’s not all for us. Enough is left to share with other life and to re-seed itself for long-term success. Hunting (rather than slaughtering enslaved animals) would remain part of our practice as occasional treats.


The previous two modes are not unknown to the pre-modern (pre-agricultural) world, and therefore seem pretty viable. But what else can we imagine? It seems most likely to me that what actually happens in the future is not a return to prior ways as if modernity never happened. Something that profound will leave a mark. But what kind of mark?

Will we suffer a collective amnesia and forget everything that came before? I’m not sure how that would happen, exactly. Oral traditions alone will carry things we’ve learned far into the future. It would be hard to erase the now-common knowledge that Earth is round, that the sun is a star Earth travels around annually, that life evolves by a simple selection rule of success and failure, and that all life is related in a colossal family tree. While oral stories alone can keep such understandings alive, it seems plausible to me that written language will be preserved (not intrinsically unsustainable, and darned handy). A literate version of hunter-horticulturalists is mind-boggling to contemplate.

Whether oral or written, maintained knowledge would ideally help future humans understand the value and kinship of all life, while perhaps contributing to appropriate humility that we just happen to be here and that Earth was not prepared for our dominion over it. I would hope that we carry cautionary tales of the mentalities and practices that led to destruction, so that we might avoid falling into a similar trap again—not that it would be possible to fully repeat, as easily-accessed non-renewable substances have been depleted.

We can also imagine preserving basic germ theory and being able to manage outbreaks better by being careful about contamination via water, air, or insects. Maybe we won’t call such transmission agents “vectors” (I hope not, actually), but the basic idea might survive.


What else might we do? How much of our craftsmanship might remain? What hard-won techniques might we keep? In the nearer-term, metals will still be around and certainly used. Long term, it’s less clear after most surface metals have corroded. I’m rooting for bone tweezers. We’re a clever species, and likely to improvise new versions of past innovations given the materials at hand, and hopefully some wisdom of restraint that comes from placing priority on the health of other species and their ecological relationships.

I’m running out of steam because I’m not comfortable with this degree of speculation. It is very hard to anticipate the constraints and the surprises. Whatever unfolds in the future, I suspect it will involve more happenstance than design.

Terra Firma

What I do know is that basic built-in traits and behaviors of humans will be ever-present. Human animals will always breathe, drink, eat, sweat, pee, poop. Humans will maintain sophisticated languages and oral traditions. They/we will laugh at each other, at animal antics, at irony, and at witty connections (puns, surely). Humans will always cry at loss and pain. We will love, tell stories, raise children, care for elders, celebrate important events, and honor the lives and deaths of loved ones. We will be keen observers of the ways of the world and of its inhabitants. We will marvel at sunsets, starry skies, rainbows, fragrances, and awesome weather events. We will make music, sing and dance, and create works of art. We will muse over origins (lots of speculation about the remnants of modernity) and try to puzzle out the future. We will discuss and debate mental models of the world and their limitations in capturing the fully contextualized reality.

All of these things are built into our anatomy, brain structures, and social heritage. The list above doesn’t sound so bad, to me. In this light, the question of what technology we manage (or decide) to keep seems far less important—or even interesting. It’s incidental: non-essential—fetishism, even. The earth and its ecology is (or at least once was) capable of providing humans with all they need to thrive. High-tech bells and whistles are superfluous noise.

We ought not mourn the loss of something that is unsustainable, devastating to life, and that is destined to fail. Surely, many Germans were distraught by the fall of the Third Reich, while the vast majority of humans were overjoyed at its demise. Likewise, many humans will doubtless lament the failure of modernity, but the greater community of life will start to breathe again—to the enduring benefit of all humans and all life. Modernity: bad. Post-modernity: could be good if we can give it a chance.

Tom Murphy

Tom Murphy is a professor of physics at the University of California, San Diego. An amateur astronomer in high school, physics major at Georgia Tech, and PhD student in physics at Caltech, Murphy has spent decades reveling in the study of astrophysics. He currently leads a project to test General Relativity by bouncing laser pulses off of the reflectors left on the Moon by the Apollo astronauts, achieving one-millimeter range precision. Murphy’s keen interest in energy topics began with his teaching a course on energy and the environment for non-science majors at UCSD. Motivated by the unprecedented challenges we face, he has applied his instrumentation skills to exploring alternative energy and associated measurement schemes. Following his natural instincts to educate, Murphy is eager to get people thinking about the quantitatively convincing case that our pursuit of an ever-bigger scale of life faces gigantic challenges and carries significant risks. Note from Tom: To learn more about my personal perspective and whether you should dismiss some of my views as alarmist, read my Chicken Little page.