Free energy
# Free energy

Free energy may refer to:

## Science

* Free energy perturbation, a method based on statistical mechanics used in computational chemistry
* Free energy principle, a variational formulation of self-organisation in biological systems, applied in particular to neuroscience
* Free-energy relationship, a relationship in physical organic chemistry
* Principle of minimum energy, a thermodynamic formulation based on the second law
* Thermodynamic free energy, the energy in a physical system that can be converted to do work, including:
   * Gibbs free energy
   * Landau free energy (also known as grand potential)
   * Helmholtz free energy
* Variational free energy, a construct from information theory that is used in variational Bayesian methods

## Pseudoscience

* Free energy device, a hypothetical perpetual motion device that is supposedly capable of drawing energy from a hidden free energy field, which is unknown in science
* Free energy suppression conspiracy theory, in which advanced energy technologies are suppressed by governments or special interest groups
* History of perpetual motion machines, history of devices supposedly capable of drawing unlimited energy

## Other uses

* In economics, energy from sources that do not require an input which has to be paid for (usually a sub-set of renewable energy)
* Free Energy (band), a 5-piece rock band on DFA Records
