Scientific

Entropy

Definition

Entropy is a thermodynamic quantity measuring the degree of disorder or randomness in a system, expressed in joules per kelvin (J/K).

Explanation

The Second Law of Thermodynamics states that total entropy of an isolated system always increases over time. An ice cube melting in a warm room increases entropy as ordered crystal structure becomes disordered liquid. Entropy also underpins information theory: Claude Shannon borrowed the concept to quantify uncertainty in data, where 1 bit of entropy represents a 50/50 choice.

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