Does the universe increase in complexity over time?

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Overview

Whether the universe becomes more complex with time is an open question that sits at the intersection of cosmology, statistical physics, information theory and biology. A growing number of physicists argue that complexity—understood loosely as structured, information-rich, far-from-equilibrium organization—does tend to rise in regions of the cosmos where energy flows are available [1]. Others point out that this trend may be temporary or local, vanishing as the cosmos gradually approaches thermal equilibrium [3].

Evidence for Increasing Complexity

• From the hot, almost featureless plasma of the early universe, successive phase transitions produced atomic nuclei, atoms, stars, galaxies and, on at least one planet, life and technology. Each step involves new layers of structure describable by more bits of information than the previous state [1].

• Quantitative approaches such as Eric Chaisson’s “energy rate density” track the amount of energy flowing through a system per unit mass per unit time; stars < planets < plants < animal brains < human societies, suggesting a long-term upward trend in localized complexity over 13.8 billion years [2].

• Recent theoretical work (e.g., Jeremy England’s dissipative adaptation framework) shows that driven, open systems can spontaneously select structures that absorb and dissipate energy more effectively, thereby increasing organizational complexity while still obeying the second law of thermodynamics [4].

How Complexity Can Rise While Entropy Also Rises

The second law demands that total entropy increase, but it does not forbid pockets of order. Continuous energy throughput (stellar radiation, chemical gradients, anthropogenic fuel use) allows local decreases in entropy at the cost of larger increases in the surroundings. In this view, complexity is a by-product of energy dissipation rather than a violation of thermodynamic principles [1][4].

Counterarguments and Conflicting Views

• Heat-Death Skepticism: Several cosmologists contend that any apparent growth in complexity is a transient spike. Eventually, star formation will cease, matter may decay, and the universe will drift toward maximum entropy, erasing intricate structures [3].

• Measurement Ambiguity: There is no universally accepted scalar for “complexity.” Measures based on algorithmic information, mutual information, thermodynamic depth or energy rate density often disagree, making empirical claims sensitive to the chosen metric. Some researchers therefore question whether the concept can be made rigorous enough to justify cosmological generalizations [1].

• Selection Bias: We observe complex phenomena (galaxies, life) precisely because observers arise in such regions, so the appearance of monotonic growth may be an anthropic illusion. Simulations of large-scale structure formation show both aggregation (complexity) and dissipation (simplicity) depending on location and epoch.

Current Research and Debate

The Quanta Magazine article reports new efforts to formalize “cosmic complexity” using computational models that treat the universe as an evolving information network [1]. Parallel studies examine whether black-hole thermodynamics set ultimate bounds on complexity storage, whether quantum effects can reverse complexity loss, and how fast intelligent civilizations can accelerate or impede cosmic trends.

In summary, a prominent school of thought argues that complexity does rise, at least in accessible epochs and locales, driven by energy flows and non-equilibrium thermodynamics [1][2][4]. A second camp counters that the pattern is contingent and will eventually reverse as cosmic free energy dwindles [3]. The discourse is active, and definitive empirical tests remain elusive, but the question continues to stimulate fruitful cross-disciplinary research.

Sources

https://www.quantamagazine.org/why-everything-in-the-universe-turns-more-complex-20250402/

Question

Does the universe increase in complexity over time?