Summary
The Second Law of Thermodynamics states that entropy in a closed system tends to increase over time, providing a universal directionality to physical processes.
Observation / Fact
Across all observed physical systems, ordered energy gradients dissipate into disorder unless constrained by external conditions. This principle has been verified experimentally at every accessible scale.
Why This Is Non-Trivial
The law is not probabilistic in everyday contexts; macroscopic violations are never observed. Its universality demands an explanation for any large-scale system exhibiting sustained order.
What It Implies
If entropy always increases, then any system with low entropy must have begun in an even lower-entropy state. Applied cosmologically, this implies the universe started in a highly ordered condition.
Related
- Entropy as the Arrow of Time
- Low-Entropy Big Bang