Does the universe increase in complexity over time?

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Short answer

Most cosmologists, biologists and philosophers agree that pockets of the universe have grown more complex since the Big Bang, but they disagree on whether this is a universal, inevitable trend or a contingent by-product of thermodynamic processes. In other words, complexity increases locally, while global entropy still rises. [1][3][4]

How “complexity” is defined

Physical/thermodynamic: number of possible micro-states, algorithmic information, energy-rate density.
Biological: hierarchical organisation, diversity of differentiated parts, genetic information.

Because the word can mean different things, debates sometimes talk past one another. [1][4]

Physical mechanisms that allow local complexity

Expansion of the universe created temperature gradients between hot stars and cold space, permitting free-energy flows that can build structure. [1]
Non-equilibrium thermodynamics (Prigogine, England) shows that driven systems form “dissipative structures” such as hurricanes, convection cells, and eventually life, because such structures maximise the rate at which they dissipate the imposed energy gradient. [1][5]
Stellar nucleosynthesis and supernovae produced heavier elements, enabling chemistry and planets with far richer organisational possibilities than the primordial plasma. [4]

These mechanisms are consistent with the second law of thermodynamics: total entropy rises, but local order can form as long as more entropy is exported to the surroundings. [1]

Historical and philosophical perspectives

Pierre Teilhard de Chardin (1955) proposed a teleological “complexification” leading from matter to life to mind (“noosphere”). He saw complexity as the universe’s main axis of evolution. [2]

Modern “cosmic evolution” frameworks (e.g., Eric Chaisson) replace Teilhard’s theology with quantitative measures (energy-rate density) yet keep the core narrative that galaxies → stars → planets → life → technology reflect a long-term rise in complexity. [4]

Stephen Jay Gould objected that the apparent trend is a statistical artifact. If life begins at a minimal complexity (“left wall”), random diffusion in complexity space will produce more complex forms over time without any directional force. For Gould, bacteria remain dominant in biomass, so no net trend exists; we just notice the tail. [3]

Areas of agreement

Nobody disputes that galaxies, stars, planetary atmospheres, biospheres and technological societies are more structurally intricate than the primordial fireball.
All sides concur that free energy flow makes local complexity possible.
All accept that the second law is not violated; entropy increases overall.

Areas of disagreement

Inevitability: Teilhard and some cosmologists think complexity is quasi-law-like or even teleological [2][4], while Gould and others see it as contingent. [3]
Metric: Physicists favour energy, information or algorithmic complexity; biologists often focus on morphology or genomic length. Different metrics can show plateaus or even declines in certain eras.
Future: Some argue complexity will keep rising toward a technological “singularity” or “Omega Point” [2], whereas pessimists note cosmic expansion will eventually dilute energy flows and limit further growth.

Open questions

Is there a universal, quantitative measure of complexity valid from atoms to societies?
Will accelerating cosmic expansion or proton decay terminate complexity?
Can artificial intelligence create qualitatively new layers of organisation, or is it just rearranging existing complexity?

Sources

[1] Natalie Wolchover, “Why Everything in the Universe Turns More Complex,” Quanta Magazine, 2 Apr 2025. [2] Pierre Teilhard de Chardin, The Phenomenon of Man (1955), online text at Internet Archive. [3] Stephen Jay Gould, Full House: The Spread of Excellence from Plato to Darwin (1996). [4] Eric J. Chaisson, Epic of Evolution: Seven Ages of the Cosmos (2006). [5] Jeremy L. England, “Statistical Physics of Self-Replication,” J. Chem. Phys. 139, 121923 (2013).

Sources

https://www.quantamagazine.org/why-everything-in-the-universe-turns-more-complex-20250402/ https://archive.org/stream/ThePhenomenonOfMan/phenomenon-of-man-pierre-teilhard-de-chardin_djvu.txt

Question

Does the universe increase in complexity over time?