The most widely used term for the opposite of entropy is negentropy, short for “negative entropy.” It describes the tendency of a system to become more ordered, more structured, and less random. While entropy measures how much a system has moved toward disorder and equilibrium, negentropy measures how far a system sits from that disordered state.
Negentropy: The Core Concept
Negentropy is defined as the specific entropy deficit of an ordered subsystem compared to the surrounding chaos. In plain terms, if you look at something highly organized, like a crystal, a living cell, or a neatly sorted library, it has less entropy than its surroundings. That gap between its low entropy and the high entropy around it is its negentropy.
Erwin Schrödinger, the physicist best known for his thought experiment with a cat, introduced the idea in his 1944 book “What Is Life?” He argued that living organisms sustain their internal order by extracting negentropy from the environment. A plant absorbs low-entropy sunlight and uses that energy to build complex molecules. An animal eats structured food and breaks it down to power its own organization. In Schrödinger’s words, “the essential thing in metabolism is that the organism succeeds in freeing itself from all the entropy it cannot help producing while alive.”
Negentropy has formal thermodynamic principles that mirror the familiar laws of entropy. There is a negentropy principle for the existence of ordered systems and a principle of maximum negentropy production that describes how those systems evolve. These are direct counterparts to the entropy principle and the law of maximum entropy production.
Why This Doesn’t Break the Second Law
The second law of thermodynamics says that in an isolated system, one where nothing gets in or out, entropy either stays the same or increases. The universe as a whole trends toward disorder. So how can anything become more ordered?
The key distinction is between isolated and open systems. Almost nothing you encounter in daily life is truly isolated. Your body, a plant, a city, even Earth itself constantly exchanges energy and matter with its surroundings. An open system can decrease its own entropy, becoming more ordered locally, as long as it increases entropy somewhere else by at least the same amount. A refrigerator makes its interior colder and more ordered, but it pumps heat into your kitchen, increasing total entropy. Life works the same way: low-entropy photons from the sun pour down on Earth, providing an endless source of negative entropy that organisms use to build and maintain their complex structures.
The total entropy of the universe still goes up. Negentropy is always a local phenomenon, paid for by greater disorder elsewhere.
Free Energy: The Practical Currency
In chemistry and biology, the concept most closely related to negentropy in everyday use is Gibbs free energy. This measures the energy available in a system to do useful work, including the work of building and maintaining order. The relationship is captured in a simple equation: free energy equals the total energy content minus the product of temperature and entropy.
When free energy is negative for a given process, that process happens spontaneously. When you need to push free energy in the positive direction, like assembling a protein from amino acids, you need an energy input. Cells use ATP, their universal energy molecule, to power exactly these kinds of order-building reactions. The ATP-producing steps of basic sugar metabolism illustrate how cells continuously harvest energy from food and channel it into maintaining their low-entropy internal state.
Life depends on this continuous input of energy because cells require constant assembly, maintenance, and selective destruction of complex structures: DNA, proteins, membranes, and organelles. Without a steady supply of free energy, these structures would degrade, and the organism would reach equilibrium. In thermodynamic terms, equilibrium for a living thing is death.
Gravity and Cosmic Structure
Negentropy shows up at scales far larger than biology. In cosmology, gravity plays a surprising role. You might expect that as the universe ages and entropy increases, everything should spread out into a featureless haze. But gravity pulls matter together, forming stars, galaxies, and galaxy clusters. This increasing clumpiness reflects increasing gravitational entropy, yet it simultaneously creates pockets of extraordinary local order: stars with nuclear furnaces, planets with stable surfaces, and the conditions for complex chemistry.
Research into gravitational entropy has shown that the formation of cosmic structures follows specific patterns, producing a nested hierarchy of bound structures at particular mass and size scales, from subatomic particles all the way up to superclusters of galaxies. Gravity, in a sense, is one of nature’s most powerful engines of local negentropy.
Dissipative Structures
In the 1960s and 1970s, the chemist Ilya Prigogine developed a framework that explains how complex, ordered patterns can arise spontaneously in systems far from equilibrium. He called these “dissipative structures” because they maintain their organization by continuously dissipating energy.
A hurricane is a dissipative structure. So is a convection cell in a pot of boiling water, or the intricate chemical oscillations in certain reactions. These systems are not at rest. They exist only because energy flows through them. Cut off the energy supply and the structure collapses back into disorder. Prigogine’s insight was that the classical thermodynamics of the 19th century, focused on equilibrium and reversible processes, simply could not explain these phenomena. He reformulated thermodynamics as a theory of processes rather than a theory of states, earning a Nobel Prize for the work.
Dissipative structures offer a bridge between physics and biology. Living cells, ecosystems, and even weather systems all maintain their organization through the same basic mechanism: they import low-entropy energy, use it to build and sustain internal order, and export high-entropy waste heat to their surroundings.
Extropy: A Different Kind of Opposite
Outside of physics, you may encounter the term “extropy.” In information theory, extropy is a formal mathematical complement to entropy. For a simple two-outcome probability distribution (like a coin flip), extropy and entropy are identical. But for distributions with more than two outcomes, they diverge into distinct paired measurements that together give a fuller picture of the uncertainty in a system.
The term also has a separate, philosophical life. In transhumanist thought, extropy refers broadly to the tendency toward increasing order, intelligence, and complexity in systems, essentially a philosophical counterpart to entropy’s arrow toward disorder. This usage is more of a worldview than a physical law, but it draws on the same intuition: that entropy has a meaningful opposite, and that the universe’s most interesting features emerge from the interplay between the two.
Negentropy in Everyday Terms
You experience negentropy every time you clean your house, organize files on your computer, or cook a meal from raw ingredients. Each of these acts reduces local disorder. And each requires energy: your metabolic energy, electrical power, or heat from a stove. The pattern is universal. Order is never free. It always requires energy flowing through a system, and it always produces waste entropy that gets exported somewhere else.
This is why perpetual motion machines are impossible, why your desk gets messy if you stop tidying it, and why every living thing must eat. Negentropy is the ongoing, energy-intensive project of building and maintaining structure in a universe that constantly pulls toward randomness.