Does the universe increase in complexity over time?
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Short answer
The observable universe shows a long-term trend toward the emergence of more intricate structures—atomic nuclei, stars, planets, living cells, brains and cultures. Most contemporary physicists and complexity theorists therefore speak of a statistical increase in local complexity, even though the global entropy of the universe is always rising. In that qualified sense, yes: complexity has tended to grow over time [1][3][5].
What do we mean by “complexity”?
There is no single metric, but widely used proxies include:
- number of distinct parts and the richness of their interactions
- informational (algorithmic) compressibility
- free-energy rate density (energy used per unit mass per unit time) [4].
All capture the intuitive notion that a star or a living cell is “more structured” than a hydrogen cloud.
Evidence for a long-term rise
- 10-32 s after the Big Bang, symmetry-breaking produced a zoo of fundamental particles from a uniform quantum field [5].
- By 380,000 years, atoms formed; by a few hundred million years, gravity condensed matter into the first stars and galaxies [5].
- Stellar nucleosynthesis built heavy elements, enabling planetary systems and organic chemistry [1].
- On at least one planet, chemical networks crossed the threshold to self-replication and evolution, generating life and, later, technology-using intelligence [3].
Computer models of dissipative systems show that when energy flows through matter far from equilibrium, self-organized structures that harvest that flow tend to arise, a principle sometimes called “dissipative adaptation” [3].
Why higher complexity does not violate the second law
The second law of thermodynamics applies to closed systems. Local pockets can lower their entropy if they export greater entropy to their surroundings. Stars, living organisms and societies are all open systems driven by energy gradients (sunlight, geothermal heat, fossil fuels). Their local ordering is paid for by a larger increase in environmental disorder, keeping the cosmic entropy budget positive [5].
Limits and counterarguments
- Cosmologists note that complexity may only rise until usable free energy runs down (the “heat death”) [5].
- Some argue the trend is selection bias: we observe complexity because we are complex observers [4].
- Others find no universal quantitative law—certain epochs (e.g., the peak of star formation ~10 Gyr ago) may already lie behind us, so the future trajectory could plateau or reverse [4].
Public discourse and historical perspectives
Pierre Teilhard de Chardin popularized the idea of a cosmic “complexification” culminating in an “Omega Point,” blending science and theology [2]. Modern complexity scientists echo his empirical narrative while bracketing the teleology. The Quanta Magazine article [1] frames the debate in non-spiritual terms, stressing that increasing complexity is a probabilistic outcome of energy flows, not an inevitable march toward perfection. Critics caution against conflating descriptive science with progress narratives but generally agree that, so far, the universe has produced ever richer patterns.
Suggested Sources
(Community members: please add links, papers, datasets or books that clarify definitions of complexity, present contrary evidence, or quantify trends in astronomical or biological systems.)
Sources
[1] Why Everything in the Universe Turns More Complex, Quanta Magazine, 2 Apr 2025. https://www.quantamagazine.org/why-everything-in-the-universe-turns-more-complex-20250402/ [2] Pierre Teilhard de Chardin, The Phenomenon of Man (1955). https://archive.org/stream/ThePhenomenonOfMan/phenomenon-of-man-pierre-teilhard-de-chardin_djvu.txt [3] Jeremy England, “Statistical Physics of Self-Replication,” J. Chem. Phys. 139, 121923 (2013). doi:10.1063/1.4818538 [4] Charles Lineweaver, Paul Davies & Michael Ruse (eds.), Complexity and the Arrow of Time, Cambridge University Press, 2013. [5] Sean Carroll, From Eternity to Here: The Quest for the Ultimate Theory of Time, Dutton, 2010.