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Order from disorder: do we need a new law of physics?
Graham Shields is a geologist at University College London.
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During decomposition, which amoebae called slime moulds (species pictured, Physarum polycephalum) speed up, entropy increases. Credit: iStock/Getty
Time’s Second Arrow: Evolution, Order, and a New Law of Nature Robert M. Hazen and Michael L. Wong W. W. Norton (2026)
Like evolution by natural selection, some ideas that start out as revolutionary can become so intuitive that they seem banal to future generations. Mineralogist Robert Hazen and planetary scientist Michael Wong must hope that the central idea behind their book becomes similarly mainstream.
Time’s Second Arrow explores how the natural world’s shift from humble beginnings to intricate order was inevitable. According to the authors, science has overlooked this “obvious truth” for too long. It is time to establish guiding principles that explain the complexity in all evolutionary systems — living and inert.
How the story of life and our planet unfolded — together
The authors open their case by outlining how laws of physics allow scientists to make predictions about how objects will behave anywhere in the Universe. The main rule in Hazen and Wong’s sights is the second law of thermodynamics. It describes how energy tends to dissipate over time, such that disorder (also known as entropy) always increases.
For example, a snowman melts because warmth loosens the hydrogen bonds that hold together its rigid ice crystals, turning the snow into messy liquid water. Similarly, when organic matter decays, its chemical bonds are broken and its atoms spread out into the soil, air and water.
This second law is often called time’s arrow because it lends all events a direction. A snowman’s fate on a warm day will always become a puddle, and summer’s green leaves all eventually turn brown. Hazen and Wong acknowledge this law. But they think that they have uncovered another: one that works in the opposite direction.