Definition

1. Noun:
   • (Thermodynamics): A thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work. It is a measure of the disorder or randomness in a system.
   • (Information Theory): A numerical measure of the uncertainty or randomness associated with a set of possible outcomes or a message.

Usage Examples

• Thermodynamics:
  • The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time.
  • As the ice melted, the entropy of the system increased.
• Information Theory:
  • The encryption algorithm relies on high entropy to ensure security.
  • A compressed file has lower entropy than the original data.

Advanced Usage

• "Entropy of mixing": The increase in entropy when two different substances mix.
  • The entropy of mixing explains why gases spontaneously diffuse into each other.
• "Maximum entropy": A state of greatest disorder or a principle used in statistics and information theory to find the least biased distribution.
  • The maximum entropy principle is used to make predictions when information is incomplete.

Variants and Related Words

• Thermodynamic entropy (n): The classical physics concept related to energy dispersal and disorder.
  • Thermodynamic entropy is central to understanding heat engines.
• Information entropy (n): The concept from information theory quantifying uncertainty.
  • Claude Shannon developed the mathematical theory of information entropy.
• Entropic (adj): Relating to or characterized by entropy.
  • The process is driven by entropic forces.

Synonyms

• Disorder: Lack of order or predictability (in thermodynamics).
• Randomness: The quality of lacking a pattern or predictability (in information theory).

Related Phrases

• Entropy generation (n phr): The production of entropy within a system, often associated with irreversible processes.
  • Friction leads to entropy generation.
• Entropy change (n phr): The difference in entropy between two states of a system.
  • Calculating the entropy change is essential for this thermodynamic cycle.

Related Idioms

• "Heat death of the universe": A theoretical fate of the universe linked to the concept of maximum entropy, where no energy is available for work.
  • Some cosmologists discuss the heat death of the universe as the ultimate triumph of entropy.

Noun

1. (thermodynamics) a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work
   • entropy increases as matter and energy in the universe degrade to an ultimate state of inert uniformity
2. (communication theory) a numerical measure of the uncertainty of an outcome
   • the signal contained thousands of bits of information