### thermodynamic equilibrium

**(TE)**
(state of a system with no net heat flows)

**Thermodynamic equilibrium** (**TE**) is the state of a
thermodynamic system (e.g., a gas cloud) such that there
is no net heat flow, e.g., everything in it being the same
temperature.
It is a theoretical state, but is useful in modeling, e.g.,
the limit of "if there were less heat
flow, what conditions would be approached".

Local thermodynamic equilibrium (LTE) is
state where conditions in region(s) within the
system are such that the temperature is virtually
the same as far as a particle or photon
is likely to reach in a single hop.
Given the complications of including the effects of heat flow,
presuming LTE can simplify models such as those for
radiative transfer, making them tractable.

Thermodynamic equilibrium (or local thermodynamic
equilibrium) is the condition that produces
black-body radiation and the internal characteristics
of a black body.

(*physics*)
**Further reading:**

http://en.wikipedia.org/wiki/Thermodynamic_equilibrium

**Referenced by pages:**

black body (BB)

black-body radiation

Boltzmann equation

Bose-Einstein statistics

decoupling

Kirchhoff's law of thermal radiation

local thermodynamic equilibrium (LTE)

particle

recombination

reheating

Rosseland mean opacity

equation of radiative transfer (RTE)

Saha equation

temperature

thermal emission

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