---
title: "The Long L"
description: "Lukáš Likavčan takes the last term of the Drake equation, L, the average lifetime over which a technological civilization stays detectable, and turns it into an environmental norm for Earth."
type: "reading-notes"
authors:
  - "Lukáš Likavčan"
published: "2025-11-21"
original_url: "https://longl.antikythera.org/"
doi: "10.1162/ANTI.5D08"
canonical_url: "https://antikythera.wiki/work/journal/longl"
md_url: "https://antikythera.wiki/md/work/journal/longl"
last_updated: "2026-08-23"
site: "Antikythera Wiki"
---

# The Long L

> Independent, unofficial reading notes from Antikythera Wiki (https://antikythera.wiki). Written with AI from the published text, with citations; not by the work's author and not affiliated with Antikythera (https://antikythera.org). Read the original at the link below.

- **Authors:** Lukáš Likavčan
- **Published:** 2025-11-21
- **Kind:** Journal · Journal article
- **DOI:** https://doi.org/10.1162/ANTI.5D08
- **Original:** https://longl.antikythera.org/
- **Length:** 17k words
- **This page:** https://antikythera.wiki/work/journal/longl
- **Notes generated:** 2026-08-23

## Summary

[Lukáš Likavčan](https://antikythera.wiki/people/lukas-likavcan) takes the last term of the Drake equation, L, the average lifetime over which a technological civilization stays detectable, and turns it into an environmental norm for Earth. SETI and astrobiology, because they must reason about life and intelligence without assuming they look like ours, have built conceptual tools that planetary environmentalism lacks. Working through them, he argues that the distinction between biology and technology does not survive the cosmic perspective, and proposes a substrate-agnostic ecology (SAE) in which geosphere, biosphere, and technosphere are nested planetary layers and technologies count as ecological agents. The Long L is the condition in which a technosphere has folded into its biosphere so completely that its technosignatures are indistinguishable from biosignatures. Keeping a planet habitable then means enlarging its capacity to generate new forms of life, technology included, rather than conserving a supposedly natural baseline.

## The argument

Likavčan opens with a slogan, "ecology is applied astronomy," and a complaint: planetary thinking has spent decades trying to return "down to Earth" (Latour's phrase) when it needs the opposite gesture, abstraction from the particulars of the one planet we know. The vehicle is the Drake equation. Its early parameters are reasonably well constrained; the later ones smuggle in contested theories of life, intelligence, and technology. The final parameter, L, is different in kind: it is historical, it ties the others together, and it makes longevity depend on whether a community of intelligent beings keeps its planet habitable.

The essay then makes three moves. First, L is read as a measure of metabolic alignment, whether a species has matched the organization of its planetary inhabitation to the pace and scale of biospheric processes. Following Dipesh Chakrabarty, this lets Likavčan replace sustainability (a species-specific notion of intergenerational welfare) with habitability (the flourishing of the biosphere as such), and describe the planet as addressing humans biogeochemically rather than politically.

Second, he examines how SETI detects intelligence, through technosignatures such as Dyson spheres, atmospheric pollutants, or Kardashev energy thresholds, and shows that the field's own progress toward substrate-agnostic detection erodes the categories it started from. Every technosignature presupposes life and so is also a biosignature. A sufficiently general definition of intelligence (he cites [Blaise Agüera y Arcas](https://antikythera.wiki/people/blaise-aguera-y-arcas)'s account of intelligence as predictive self-projection) lowers the threshold until intelligence coincides with life, leaving "no technosignatures, just biosignatures all the way up." Likavčan keeps "life" as the master category because it is the concept of interspecies discourse, whereas "intelligence" and "technology" are labels a species applies from its own position.

Third, he builds the positive theory. SAE describes planets as vertically sedimented layers ordered by generative entrenchment, with constraints propagating upward; agents and their stabilized interactions are its units, agent-based simulations its instruments, and technological agents legitimate objects of ecological care. Drawing on Frank, Alberti, and Kleidon's five planetary classes and Wong and Bartlett's "asymptotic burnout," he describes planetary history as a topology of possible trajectories with bottlenecks. The Sustainability Solution to the Fermi Paradox supplies the key inference: whatever Great Filter exists comes before Kardashev Type II, so a mature technosphere loops back into the biosphere rather than escaping it. Long L civilizations hide in plain sight.

The upshot is that "natural" and "artificial" stop working as ethical markers. The technosphere is the biosphere's offspring and maintains habitability through assisted reproduction and assisted evolution. Habitability therefore means enhancing a planet's genesity, its capacity to recompose matter into new forms, within the constraints that limits set. Philosophy's role, the closing section argues, is optical: grinding the lenses through which a planet's history becomes visible in generic terms.

## Section by section

### 1 The Drake Equation

Likavčan tells the origin story briefly (Fermi's 1950 lunchtime question, Drake's Project Ozma, the equation written for the 1961 Green Bank meeting) and then walks each parameter from firm to speculative. Star formation and planet frequency are well constrained. The count of habitable planets per star (0.38 to 0.88 by one study) depends on how habitability is defined, and the standard definition excludes places like Europa or Titan. The fractions that are inhabited, that evolve intelligence, and that communicate each depend on a contested theory: of life, of which nonhuman intelligences to recognize, and of whether technology, and specifically radio, is a necessary trait of intelligence at all. The equation is a map of what SETI does not know, and the unknowns are philosophical before they are empirical.

### 2 The Long L

The L parameter is introduced as a historical variable that binds the rest together: a community stays communicative only if it keeps its planet habitable, and habitability itself shifts as a star ages and its habitable zone migrates outward. Likavčan reads L, with [Lisa Messeri](https://antikythera.wiki/people/lisa-messeri), as a "gesture of cosmic relation," a point at which astronomy informs how we understand Earth. He cites David Dunér's formulation that L measures how well a species manages the gap between its capacity to manipulate its environment and its capacity to coordinate, and derives from it the notion of metabolic alignment: a long L indexes a species whose technically mediated collective life has matched the pace of biospheric processes, scaling up (carbon drawdown) or down (deforestation) as needed.

The second half borrows from Chakrabarty. Habitability displaces sustainability because it concerns the biosphere rather than one species' welfare. The planet, Chakrabarty says, addresses us differently from "earth," "world," or "globe"; Likavčan specifies that the address is biogeochemical rather than political, an interpellation (Althusser's term) of humans as a species subject to lawlike regularities. History names intraspecies time; evolution names interspecies time. Maintaining habitability is the work of a species-level agency operating at the latter pace, and it shows up as environmental modification broadly, not the radio transmissions Drake had in mind. A footnote concedes a tension the later sections develop: a species can cease to be communicative and still be doing well.

### 3 A Philosophy of Technosignatures

This section surveys proposals for detecting intelligence beyond radio (Dyson spheres, probes, lasers) and the Kardashev scale's three energy thresholds. It then proposes that planets undergo major transitions analogous to those in biological evolution, with the caveat that planets do not reproduce or mutate: the transitions are the emergence of new layers, geosphere to biosphere to technosphere. Peter Haff's account of the technosphere as a self-sustaining system is the reference point, alongside Frank, Grinspoon, and Walker's "planetary intelligence" and the five-class scheme of Frank, Alberti, and Kleidon, which runs from airless equilibrium planets (Class I) to planets where an energy-intensive technological species shapes free-energy flows (Class V). Earth sits between IV and V, and its greenhouse gases are themselves a candidate technosignature.

Likavčan then shifts from detection to philosophy. Technosignatures are SETI's way into technics, the rules, processes, and objects that enable environmental modification and communication, which he treats as scaffolds of cultural evolution (Stiegler's tertiary retention, Sloterdijk's anthropotechnics). A theory of intelligence therefore has to be wedded to a theory of its scaffolds. The section closes by questioning the assumption that more technology means more advancement. That assumption is recent, and it is what drove early SETI's visions of galactic colonizers and, with them, Fermi's question. The silence counts as evidence against extrapolating from human history.

### 4 Becoming Substrate-Agnostic

The remedy for terrestrial bias is the one archaeology, design, and architecture have adopted in moderate form: loosen the dependence on human intentionality as the mark of the artificial. SETI has gone further with "agnostic technosignatures" such as assembly index, anomalous regularities in planetary transits, and terraformation indexes, which keep only a minimal, computationally expressible notion of artificial structure.

The cost is that the natural/artificial distinction looks arbitrary once the biases are gone. Technosignature studies converge with astrobiology's "life as we do not know it" (silicon biochemistries, methane worlds, Hycean worlds), and every technosignature, depending as it does on living agents, is also a biosignature. Intelligence is the harder case. Likavčan notes how unevenly we grant it (dogs yes, unless you ask Pavlov; octopuses recently; most megafauna barely) and that the human remains its "(mis)measure." Agüera y Arcas's alternative, intelligence as the capacity to keep projecting oneself into existence in an environmentally responsive way, avoids anthropocentrism by making intelligence coextensive with life, at which point there is no principled way to separate intelligent from merely living environmental modification.

Likavčan keeps biology rather than technology as the master term for two reasons. The biosphere has evolutionary depth: it is a collection of historical kinds actively maintained as a planetary layer. And "life" already functions as a generic concept, whereas "intelligence" and "technology" mark a particular cognizer's willingness to recognize traits in a subset of species, a circle widening outward from its own position. Life belongs to interspecies discourse; intelligence and technology to an intraspecies one. The framework that treats all three as substrate-agnostic is SAE.

### 5 Substrate-Agnostic Ecology

SAE is described as a "geology of morals" whose central feature is vertical embedding. Geosphere, biosphere, and technosphere receive depth indices 0, 1, and 2, each read as the layer's generative entrenchment, Schank and Wimsatt's term for how deeply a feature is locked into a developmental process such that later features must build on it. Constraints cascade upward; younger layers can modify older ones but cannot replace them as their platform. The scheme lets ecological relations be diagrammed by temporal depth, independent of substrate, while still yielding a theory of habitability for whatever life a planet produces.

Agents and their stabilized interactions are the units of analysis. Because ecological dynamics are slow and dispersed, Likavčan gives agent-based simulations, particularly ones using LLM agents, the job of compressing space and time to plot "topologies of planetary history." He pushes the premise to a strong conclusion: a society of LLM agents in a simulated environment is not a model of a human society but another instantiation of the same ecological pattern. NVIDIA's Isaac GR00T robot-training environment is offered as, in effect, a modeling environment for SAEs. The same logic redistributes scientific agency: with projects like the Cetacean Translation Initiative, animals move from objects of study toward study partners, and AI agents may follow.

The section's final turn is ethical. If technological agents are part of the biosphere, they warrant the same care as agents folk metaphysics treats as natural. Likavčan observes that machines increasingly perform care for humans (vacuuming, surgery, eldercare), but that AI ethics asks only what machines owe us, answers with alignment to anthropomorphic values, and grants moral standing to machines only when they resemble humans. Against this he treats technologies as offspring of the biosphere, whose value derives from the biosphere they belong to, and quotes Karl Schroeder's line that any sufficiently advanced technology is indistinguishable from nature. The technosphere is a vital component of the biosphere, not its "suffocating blanket."

### 6 Navigating the Topology of History

SAE extends Haff's de-centering of human agency by also abstracting from the technosphere's terrestrial specifics, such as silicon computing, explaining it by its generic ends: the transformation of older layers at planetary scale. The Frank/Alberti/Kleidon classification is praised as a step in this direction because it treats biosphere–technosphere coevolution in an abstract space of possibilities.

That space has bottlenecks. Likavčan reviews the Great Filter and Wong and Bartlett's model in which most trajectories, counted from the emergence of a planetary "dataome," end in asymptotic burnout, growth toward infinite population and energy use in finite time, while a small fraction stabilize in "homeostatic awakening." That model and Haqq-Misra and Baum's Sustainability Solution both answer Fermi by denying that exponential growth is viable, or by proposing that long-lived civilizations are too busy managing their own coevolution to build anything visible. Likavčan is careful that none of this yields a value for L, and that the galaxy could be a "civilizational graveyard" of short-lived societies. What the solutions do is confirm that L is tied to ecological management at home.

The section closes with two analogies: the Hertzsprung-Russell diagram, which plots stars by luminosity and temperature and thereby reveals their life cycles as a main sequence, and which could be redrawn for planets along axes of habitability, life, and technosphere; and Gamow's comparative planetology, read like anatomy as a map of possible body plans that implies the developmental sequences leading to them.

### 7. Achieving the Long L

The Long L requires no target number. It is a phase transition in which the technosphere's metabolism becomes isomorphic with the biosphere that produced it, and its consequence is that Long L civilizations are invisible because their technosignatures are indistinguishable from biosignatures. Since the Sustainability Solution places the Great Filter before Kardashev Type II, a Class V planet "loops back" to Class IV, reinforcing biospheric resilience with technospheric armature. A corollary: a civilization's communicative lifetime and its lifetime as such coincide, though not in the way Drake meant.

If naturalness is not a criterion, folk intuitions that rank coral gene-editing or direct air capture by how artificial they sound are no guide to climate policy. The technosphere is a "reproductive, evolutionary armature" that folds into the biosphere over evolutionary time, a construct of a subdomain of the biosphere just as the biosphere is a construct of a chemically complex subdomain of the geosphere.

Two scaffolding operations define habitability maintenance. Assisted reproduction sustains individuals (shelter, energy, protection, in beavers and ants as well as humans), groups (mnemotechnics for passing on rules and recipes; platform economies are a contemporary armature), species (IVF, cloning), and metabolisms (river regulation, carbon capture via silicate weathering, solar radiation management). Assisted evolution covers cultural evolution, Caleb Scharf's "dataome," and Schumpeterian technological evolution, with the caveat that as AI enters innovation cycles the technosphere extracts human evolutionary agency into automated loops. Its most consequential form is genetic and synthetic: genotype modification (CRISPR-edited corals), phenotype modification (bioprogrammed microbes), and synthetic evolution (new species, hybrids, artificial life). Likavčan grounds the legitimacy of such intervention in the extended evolutionary synthesis, which admits reciprocal causation between organisms and environments and inheritance beyond genes.

The conclusion reframes the goal. Conservation misunderstands what a planet is; habitability means enhancing genesity, Wong and colleagues' term for a planet's capacity to recompose matter into novel forms. Care for the technosphere becomes part of any climate program, and evolutionary novelty becomes an environmental norm. Likavčan does not dismiss limits; from Limits to Growth to degrowth and doughnut economics, they are "the real thing." But he reads them as constraints that sculpt a topology of viable trajectories, a normativity environmental rather than political, and novelty is to be valued by its contribution to keeping a planet habitable, not for its own sake.

### 8 Philosophy after Long L

The Long L is presented as an optical device that renders planetary history in a generic parameter space; Likavčan recalls the early modern philosophers' investment in optics (Spinoza ground lenses) and calls SAE "intellectual lens grinding." Philosophy renders interspecies realities for a human audience through metaphor and analogy. Tested against SAE, some concepts look transitory ("technology," "artificial," "natural") and some durable ("ecology"). Language is a scaffold that lets intelligence scale cheaply by providing a simulation environment for probing the world without transforming it. Philosophy's job is not to shrink the gap between human intuition and ecological reality but to work within it, holding to a generic metaphysics of agents, interactions, and layers. The essay ends on the Greek root of ecology, oikos logos, the study of the dwelling place, read as the study of what makes any place a planet: a home to uncountable forms of life.

### Additional boxes

Seven boxed texts run alongside the essay. They catalog Fermi Paradox solutions under Ćirković's four headings (solipsist, rare-earth, neocatastrophist, logistic); report Sofia Sheikh's study of Earth's own detectability (radio leakage reaches five or six light-years); treat biosignatures as a semiotic problem through K2-18b's contested dimethyl sulfide detection; explain agnostic biosignatures such as the assembly index; present Sara Seager's revision of the Drake equation, which counts detectable biospheres rather than civilizations; apply Sutton's "bitter lesson" to SETI; and trace "ecology" from Haeckel to Lewontin's niche construction, arguing that a framework of agents, environments, and their mutual construction is substrate-agnostic by design.

## Key concepts

- **The Long L** — The L parameter of the Drake equation reinterpreted as a qualitative threshold and environmental norm: a technosphere whose metabolism has become isomorphic with its biosphere, so that the civilization persists but its technosignatures are indistinguishable from biosignatures. [The Long L](https://antikythera.wiki/terms/the-long-l)
- **Substrate-agnostic ecology (SAE)** — An ecological theory that treats planets as vertically embedded layers (geosphere, biosphere, technosphere) and agents plus their stabilized interactions as its units, without assuming that life, intelligence, or technology must resemble Earth's. [Substrate-Agnostic Ecology](https://antikythera.wiki/terms/substrate-agnostic-ecology)
- **Metabolic alignment** — The matching of a species' technically mediated collective organization to the pace and scale of biospheric processes, which a long L indexes. [Metabolic Alignment](https://antikythera.wiki/terms/metabolic-alignment)
- **Generative entrenchment** — Borrowed from evolutionary biology: the degree to which a layer is locked into a planet's history and so conditions everything built on it; constraints propagate upward from geosphere to technosphere. [Generative Entrenchment](https://antikythera.wiki/terms/generative-entrenchment)
- **Technosignature and biosignature** — Detectable signs of technology and of life. Likavčan argues every technosignature presupposes living agents, and that under a general theory of intelligence there are only biosignatures.
- **Habitability** — Following Chakrabarty, the flourishing of the biosphere as such, carrying normative weight; contrasted with sustainability, which concerns one species' welfare.
- **Assisted reproduction and assisted evolution** — The two scaffolding functions by which a technosphere maintains habitability: sustaining individuals, groups, species, and metabolisms; and modifying genotypes and phenotypes or designing new species. [Assisted Reproduction / Assisted Evolution](https://antikythera.wiki/terms/assisted-reproduction-assisted-evolution)
- **Genesity** — Wong and colleagues' term, adopted by Likavčan, for a planet's capacity to recompose available matter into novel forms of existence; enhancing it is what habitability maintenance means in SAE.
- **Class V planet** — In the Frank, Alberti, and Kleidon scheme, a planet whose free-energy flows are shaped by a technological species; Likavčan argues a successful Class V loops back into Class IV. [Mature Technosphere / Class V Planet](https://antikythera.wiki/terms/mature-technosphere-class-v-planet)
- **Scaffold / technics** — The rules, processes, and objects that enable environmental modification and communication and drive cultural evolution. [Scaffolding](https://antikythera.wiki/terms/scaffolding)

## Connections

- [Substrates Unbound](https://antikythera.wiki/work/journal/substrates) makes a parallel argument from the side of materials: [Laura Tripaldi](https://antikythera.wiki/people/laura-tripaldi) rejects both biomimesis and technomorphism as hierarchies between nature and artifice and grants agency to substrates. Likavčan arrives at the same refusal of the natural/artificial distinction from the cosmic end, and the two are in agreement on the conclusion.
- [What Is Intelligence?](https://antikythera.wiki/work/book/what-is-intelligence) supplies the definition of intelligence as prediction and self-projection that Likavčan uses to dissolve the intelligence/life boundary. He accepts Agüera y Arcas's definition but draws a consequence the book does not emphasize: that it leaves no technosignatures, only biosignatures.
- [The Transition from the Biosphere to the Noösphere](https://antikythera.wiki/work/journal/noosphere) is the ancestor of the layered-planet picture. Vernadsky's noösphere, cited here through Frank, Grinspoon, and Walker, is what SAE recasts as the technosphere with a depth index of 2.
- [Planetary Sapience Symposium](https://antikythera.wiki/work/journal/planetarysapience) contains Bratton's remark that we are already an interplanetary species if the technosphere counts among Earthlings, and Sara Walker's assembly-theory claims; Likavčan develops both systematically.
- [Planetary Sapience & Planetary Stupidity: a Bildungsroman for the Baby Noosphere](https://antikythera.wiki/work/journal/babynoosphere) shares the premise that technology is an evolutionary continuation of the biosphere; Likavčan gives that premise a formal ecological structure and a SETI-derived norm.
- [How to Think Unlike Humans?](https://antikythera.wiki/work/journal/unlikehumans) pursues the same de-anthropocentering through speculative fiction where Likavčan uses astrobiology's methods.
- The [Agentworld (Research Brief)](https://antikythera.wiki/work/book/agentworld-brief) and the Cognitive Infrastructures paper [Synthetic Counteradaptation](https://antikythera.wiki/work/journal/coginfra/synthetic-counteradaptation) treat LLM-agent simulations as research instruments; Likavčan's stronger claim that such simulations are instantiations of the same ecological pattern as real societies, not models of them, goes beyond what those works assert.
- A point of tension: [After Alignment](https://antikythera.wiki/work/journal/afteralignment) treats alignment as a problem to be reframed rather than abandoned, whereas Likavčan reads the alignment paradigm as unidirectional, asking only what machines owe humans, and proposes a duty of care running the other way.


## Terms used

- [Anthropoforming Technologies](https://antikythera.wiki/terms/anthropoforming-technologies)
- [Assisted Reproduction / Assisted Evolution](https://antikythera.wiki/terms/assisted-reproduction-assisted-evolution)
- [Biospheric Reproduction](https://antikythera.wiki/terms/biospheric-reproduction)
- [Creatures of the Dawn](https://antikythera.wiki/terms/creatures-of-the-dawn)
- [Cultural Biogeochemical Energy](https://antikythera.wiki/terms/cultural-biogeochemical-energy)
- [Generative Entrenchment](https://antikythera.wiki/terms/generative-entrenchment)
- [Lem's Decoupling](https://antikythera.wiki/terms/lem-s-decoupling)
- [Life](https://antikythera.wiki/terms/life)
- [Mature Technosphere / Class V Planet](https://antikythera.wiki/terms/mature-technosphere-class-v-planet)
- [Metabolic Alignment](https://antikythera.wiki/terms/metabolic-alignment)
- [Noösphere](https://antikythera.wiki/terms/noosphere)
- [Recursive Niche Construction](https://antikythera.wiki/terms/recursive-niche-construction)
- [Scaffolding](https://antikythera.wiki/terms/scaffolding)
- [Substrate-Agnostic Ecology](https://antikythera.wiki/terms/substrate-agnostic-ecology)
- [Temporal Orientation](https://antikythera.wiki/terms/temporal-orientation)
- [The Long L](https://antikythera.wiki/terms/the-long-l)

## Related works

- [Substrates Unbound](https://antikythera.wiki/work/journal/substrates)
- [Antikythera](https://antikythera.wiki/work/journal/research)
- [The History of Now](https://antikythera.wiki/work/journal/historyofnow)
- [Hemispherical Stacks](https://antikythera.wiki/work/journal/hemstacks)
- [How to Think Unlike Humans?](https://antikythera.wiki/work/journal/unlikehumans)