Schrödinger, long before any knowledge of DNA, posited an intriguing thesis: some form of order must confront the chaos and uncertainty inherent in entropy. Let us begin by reviewing some basic concepts.
According to the second law of thermodynamics, the entropy of a closed system can only increase or remain constant. To decrease entropy, work must be performed; an increase occurs spontaneously, while a decrease does not.
Entropy is closely related to microstates. Consider a gas composed of n atoms: these atoms can be arranged within a grid, with each atom occupying one block. However, the arrangement is determined not only by position, but also by energy and direction, effectively forming a three-dimensional grid.
Given the astronomical number of atoms in a liter of gas (approximately 2.69 × 10²²), the number of possible microstates—unique configurations of these atoms at any given moment—is immense.
If, in a closed system, we remove a partition and allow a gas to expand to double its original volume, the number of microstates also increases, as the atoms have more available positions. If the partition originally separated the same gas at two different temperatures, its removal allows both portions to interact, eventually reaching thermal equilibrium. We must note that entropy arises here because microstates with higher average internal energy were initially confined to one partition, while those with lower internal energy were in the other. Upon mixing, these distinctions dissolve, resulting in a greater number of microstates where atoms with varying internal energies are more evenly distributed.
All of this occurs within the confines of a modest closed system in the laboratory. But what happens when the entire universe is considered as a single closed system? According to the second law of thermodynamics, the universe’s entropy must continually increase, progressing toward a hypothetical state of maximum entropy: the thermal death of the universe. This state represents absolute equilibrium—devoid of movement, temperature gradients, and, ultimately, change.
However, astronomical observations suggest a different reality. Some form of order appears to counteract entropy. Planetary systems exhibit properties that combine entropic uncertainty with structured order.
On a smaller cosmological scale, life on Earth also grapples with uncertainty. Achieving order amid disorder requires rethinking the fundamental concept of entropy and recognizing the central role that information plays in regulating disorganization. Hermann von Helmholtz coined the idea of thermal death, although it was not widely adopted; thermodynamic forefathers certainly were aware of it. Although rather extreme and pessimistic, the concept of thermal death arose from the ever-increasing theoretical entropy in opposition to the order and certainty observed in daily life.
One of the earliest attempts to address this conundrum was the thought experiment of Maxwell’s demon, proposed by James Clerk Maxwell in his 1867 text Theory of Heat. The central question it raises is: can entropy in a closed system be reduced without performing external work? According to thermodynamic law, the answer is no. Yet, such systems—seemingly able to decrease internal entropy—exist everywhere. Any biological system, for instance, maintains a state far from equilibrium with its environment.
To be alive implies many things, but foremost among them is the capacity to establish a boundary between the organism and its environment. This barrier is essential to maintaining homeostasis despite fluctuating external conditions. Such a structured order, complex and persistent amid chaos and uncertainty, requires regulatory mechanisms.
Far from living complexity, Maxwell proposed the famous demon: a creature capable of controlling the flow of atoms in a closed system separated by a partition. The demon could rapidly control a microscopic door in the partition and let lower- or higher-energy atoms slip between compartments. The goal was to group fast-moving particles at one end and slow-moving (less intslower particles on the other, the demon would effectively decrease the system’s entropy—without performing any observable work and, ostensibly, without violating the second law of thermodynamics.
This demonic ability raises numerous questions: How does the entity detect atomic speed? By what mechanism does it control the partition door? While we need not delve into these technical nuances, the philosophical implications of the thought experiment are worth exploring.
To begin with, the term demon—evocative and often misunderstood—is associated with intelligent capabilities. It was not Maxwell but his colleague William Thomson (later Lord Kelvin) who coined the term thermodynamic demon. For Maxwell, the being he envisioned was a microscopic, intelligent agent. The term demon in this context is not biblical, but rather Socratic in nature. More precisely, the word daemon refers to a supernatural intermediary, a messenger of the divine, or an inner moral voice with ethical dimensions.
Although later interpretations suggest a biblical or exorcistic association, a more accurate inference would be a Luciferian interpretation, not in the satanic sense, but as a figure of intellectual rebellion and autonomy. Maxwell’s demon is, after all, a mental construct that defies the constraints of physical laws, suggesting reflections on freedom rather than notions of curse or malice.
Calling such an entity intelligent invites further etymological insights: the Latin intelligere means comprehending or discerning. Comprehension implies both perception and intentionality—means and ends, or a kind of teleology. For this reason, many physicists today avoid philosophical connotations and instead use the more neutral term automaton to describe similar constructs.
Returning to the central issue: if a demon or automaton must involve some form of heat transfer in the process of separating atoms, it would indeed violate the second law of thermodynamics. To resolve this paradox, the concept of entropy must be refined. If entropy is understood as a measure of uncertainty—a concession to our increasing ignorance of the microscopic changes underlying macroscopic states—then an increase in entropy also signifies a loss of information.
Consider a monoatomic gas placed in a two-grid microstate. If the atom occupies the first block, its position is true (1); if not, it is false (0). Thus, the most fundamental microstate corresponds to a bit of information. As the volume or temperature of the gas increases, so too does the number of possible microstates, thereby reducing our knowledge of the atom’s position, energy, or direction.
In this revised framework, the demon functions as a memory device, recording information about microstates and their transitions. In 1961, Rolf Landauer resolved the demon’s paradox: at some point, the demon’s memory will reach capacity, and the erasure of information inevitably results in heat dissipation into the environment, thereby preserving the second law of thermodynamics.
What does this imply for living systems? If entropy entails a loss of information, then Schrödinger’s concept of negative entropy—or negentropy—becomes more intelligible. In contrast to decay, change, and randomness, living organisms maintain order by acquiring information from their environment. Through this informational input, they metabolically adapt, solve problems, and resist the tide of entropy.
The linkage between life and information opens a new dimension in our understanding of what it means to be alive. This act of freedom—implied in the condition of being alive—encompasses not only the bioenergetics of metabolism but also the bioinformatics of gathering, processing, and responding to information. This perspective introduces the overarching concept and objective of these three short essays: niche construction.
First, Schrödinger’s notion of negative entropy offers the idea of a counterforce to disorder. Then, Maxwell’s demon refines this by framing entropy as a form of information loss. Life, viewed through this lens, becomes a battleground—a stoic endeavor to persist against the forces of disintegration. In this battle, only information can guarantee survival, or at the very least, a temporary equilibrium.
Genetic information, encoded in DNA, provides the foundation for adaptation. Yet the deterministic regime of genes is complemented by another form of information: that which the organism actively acquires through perception, interaction, and learning. This acquired information empowers the organism not only to respond to its environment but also to alter it. This dynamic interplay is what defines niche construction—the process by which life shapes the very conditions of its own evolution.
References
Leff, Harvey S., y Andrew Rex, eds. Maxwell’s Demon: Entropy, Information, Computing. Princeton Legacy Library. Princeton, New Jersey: Princeton University Press, 2014.
Odling-Smee, J. C. Niche Construction: How Life Contributes to Its Own Evolution. Cambridge, Massachusetts: The MIT Press, 2024.
