PNAS Nexus · 26 August 2026 · From issue 27

Is entropy objective? rethinking the foundations of irreversibility and the second law

Entropy and disorder may depend on what an observer chooses to measure.

Juan M R Parrondo.

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Also in issue 27 15 papers

An eye scan predicted age within 2.85 years and flagged disease risk differently in men and women.
Nature Communications
Patterns across connected brain regions, not just single spots, predict memory accuracy.
Proceedings of the National Academy of Sciences
Long-lived bats evolved gene changes that fight viruses and may also block cancer and ageing.
Nature
Teams of ocean bacteria fully break down tough algae sugars that single microbes cannot handle alone.
Nature
Charged water drops can break protective coatings and cause metal to rust.
Nature
Humans predict words better than AI models, and voice tone boosts both humans and AI.
Proceedings of the National Academy of Sciences
Classroom friendship patterns predict student well-being and grades better than family background alone.
PNAS Nexus
A rare particle breakup was seen for the first time, confirming a strange particle's hidden double nature.
Physical Review Letters
A dead star's leftover core lit up in radio waves years after it exploded.
The Astrophysical Journal
Light can be tuned to build two different rigid ring shapes from one starting material.
Nature Chemistry
Gut disease shares the strongest genetic link with depression among four illness types studied.
Nature Genetics
After diabetes starts, men get heart and kidney disease more, women get mental health problems more.
PLOS Medicine
In a lab test, electricity made droplets form, move, and dissolve nonstop without producing waste.
Nature Communications
In single-celled sea creatures, an eye-like part lost its food-making tool but may still sense light.
PNAS Nexus