Landauer’s Principle is a foundational concept in the physics of information, stating that erasing one bit of information in a computational system has an unavoidable minimum thermodynamic cost. Specifically, it requires the dissipation of at least
k T ln 2 joules of heat,
where k is the Boltzmann constant and T is the temperature of the surrounding environment (in kelvins).
This principle links information theory and thermodynamics, showing that information is physical—and processing or deleting it has real energetic consequences.
Key Insights:
- Only logically irreversible operations, such as erasing a bit or merging data paths, incur this cost.
- The principle sets a fundamental limit on energy efficiency in computation.
- It underpins the second law of thermodynamics in information systems, ensuring no process can reduce entropy without an energetic cost.
Examples:
- In digital computers, resetting a bit to 0 regardless of its current state is an irreversible action that must generate heat.
- Reversible computing (where computations avoid erasure) is being explored to approach these thermodynamic limits.
- Landauer’s principle plays a role in understanding the thermodynamics of computation, quantum information, and even black hole physics.
Landauer’s Principle highlights that processing information isn’t free—even the smallest act of forgetting comes with an inescapable energy cost.