Definition
The Second Law of Thermodynamics states that the total Entropy of an isolated system can never decrease over time; it can only remain constant or increase. In simpler terms, energy naturally tends to spread out and become less usable, leading to a state of maximum disorder.
Why It Matters
The Second Law is the ultimate “boundary of the possible.” it defines the Arrow of Time and dictates that all order in the universe is temporary and expensive. It is the reason perpetual motion machines are impossible and why life—which is a state of extreme order—requires a constant influx of energy to survive.
Core Concepts
- Entropy: The measure of a system’s disorder or the number of ways it can be arranged while appearing the same at the macro-level.
- Negentropy (Negative Entropy): The state of order or information that living systems and machines create locally at the cost of increasing entropy globally.
- The Arrow of Time: Because entropy increases, the past and future are distinct; a broken glass does not spontaneously reassemble.
- Heat Death: The theoretical end-state of the universe where all energy is evenly distributed and no further work can be performed.