Thermalisation

In physics, thermalization (in Commonwealth English "thermalisation") is the process of physical bodies reaching thermal equilibrium through mutual interaction. In general the natural tendency of a system is towards a state of equipartition of energy and uniform temperature that maximizes the system's entropy. Thermalization, thermal equilibrium, and temperature are therefore important fundamental concepts within statistical physics, statistical mechanics, and thermodynamics; all of which are a basis for many other specific fields of scientific understanding and engineering application.
Examples of thermalization include:
The hypothesis, foundational to most introductory textbooks treating quantum statistical mechanics, assumes that systems go to thermal equilibrium (thermalisation). The process of thermalization erases local memory of the initial conditions. The eigenstate thermalization hypothesis is a hypothesis about when quantum states will undergo thermalization and why.
Not all quantum states undergo thermalization. Some states have been discovered which do not (see below), and their reasons for not reaching thermal equilibrium are unclear .
Theoretical description.
The process of equilibration can be described using the H-theorem or the relaxation theorem, see also entropy production.
Systems resisting thermalization.
An active research area in quantum physics is systems that resist thermalization. Some such systems include:
, the mechanism for neither of these phenomena is known.
Other systems that resist thermalization and are better understood are quantum integrable systems and systems with dynamical symmetries.