Thermodynamics

Metastability denotes the phenomenon when a system spends an extended time in a configuration other than the system's state of least energy.

The four laws of thermodynamics define fundamental physical quantities (temperature, energy, and entropy) that characterize thermodynamic systems at thermal equilibrium.

Thermal insulation is the reduction of heat transfer (the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence.

Temperature measurement describes the process of measuring a current local temperature for immediate or later evaluation.

(For the infectious disease, see Common cold. For other uses, see Cold (disambiguation).) Cold is the presence of low temperature, especially in the atmosphere.

In physics, a free surface is the surface of a fluid that is subject to zero parallel shear stress,such as the boundary between two homogeneous fluids,for example liquid water and the air in the Earth's atmosphere.

In thermal physics and thermodynamics, the heat capacity ratio or adiabatic index or ratio of specific heats or Poisson constant, is the ratio of the heat capacity at constant pressure (CP) to heat capacity at constant volume (CV).

In probability theory and information theory, the Kullback–Leibler divergence, also called discrimination information (the name preferred by Kullback), information divergence, information gain, relative entropy, KLIC, KL divergence, is a measure of the difference between two probability distributions P and Q.

A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle.

Dissipation is the result of an irreversible process that takes place in inhomogeneous thermodynamic systems.

Refrigeration is a process of moving heat from one location to another in controlled conditions.

A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.

Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere.

The Boltzmann constant (kB or k), named after Ludwig Boltzmann, is a physical constant relating energy at the individual particle level with temperature.

Dew point is the highest temperature at which airborne water vapor will condense to form liquid dew.

The first law of thermodynamics is a version of the law of conservation of energy, adapted for thermodynamic systems.

The heat death of the universe is a possible ultimate fate of the universe in which the universe has diminished to a state of no thermodynamic free energy and therefore can no longer sustain processes that increase entropy (including computation and life).

In physics, heat is energy that spontaneously passes between a system and its surroundings in some way other than through work or the transfer of matter.

Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to (or removed from) an object to the resulting temperature change.

In thermodynamics, a heat engine is a system that converts heat or thermal energy—and chemical energy—to mechanical energy, which can then be used to do mechanical work.

The heat of combustion is the total energy released as heat when a substance undergoes complete combustion with oxygen under standard conditions.

Joule heating, also known as ohmic heating and resistive heating, is the process by which the passage of an electric current through a conductor releases heat.

In the physical sciences, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform.

The second law of thermodynamics states that the total entropy of an isolated system always increases over time, or remains constant in ideal cases where the system is in a steady state or undergoing a reversible process.

Spontaneous combustion or spontaneous ignition is a type of combustion which occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self heating which rapidly accelerates to high temperatures) and finally, ignition.

Standard conditions for temperature and pressure are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data.

In thermodynamics, a state function or function of state is a function defined for a system relating several state variables or state quantities that depends only on the current equilibrium state of the system.

Thermal physics is the combined study of thermodynamics, statistical mechanics, and kinetic theory.

Vapor pressure or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system.

A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases occur and coexist at equilibrium.

Scale of temperature is a way to measure temperature quantitatively.

The Arrow of Time, or Time's Arrow, is a concept developed in 1927 by the British astronomer Arthur Eddington involving the "one-way direction" or "asymmetry" of time.

In thermodynamics, a critical point (or critical state) is the end point of a phase equilibrium curve.

In classical statistical mechanics, the equipartition theorem is a general formula that relates the temperature of a system with its average energies.

In physical science, an isolated system is either of the following: 1.

In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect, Kelvin–Joule effect, or Joule–Thomson expansion) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is forced through a valve or porous plug while kept insulated so that no heat is exchanged with the environment.

The kinetic theory describe a gas as a large number of submicroscopic particles (atoms or molecules), all of which are in constant rapid motion that has randomness arising from their many collisions with each other and with the walls of the container.

Space-based solar power (SBSP) is the concept of collecting solar power in space (using an "SPS", that is, a "solar-power satellite" or a "satellite power system") for use on Earth.

The Stefan–Boltzmann constant (also Stefan's constant), a physical constant denoted by the Greek letter σ (sigma), is the constant of proportionality in the Stefan–Boltzmann law: "the total intensity radiated over all wavelengths increases as the temperature increases", of a black body which is proportional to the fourth power of the thermodynamic temperature.

The Stefan–Boltzmann law describes the power radiated from a black body in terms of its temperature.

A supercritical fluid (SCF) is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist.

Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible.

Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter.

A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity.

In electric power generation a combined cycle is an assembly of heat engines that work in tandem from the same source of heat, converting it into mechanical energy, which in turn usually drives electrical generators.

Thermodynamic diagrams are diagrams used to represent the thermodynamic states of a material (typically fluid) and the consequences of manipulating this material.

In thermodynamics, the exergy (in older usage, available work and/or availability) of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir.

An ideal Bose gas is a quantum-mechanical version of a classical ideal gas.

In electrochemistry, the electrochemical potential, μ, sometimes abbreviated to ECP, is a thermodynamic measure of chemical potential that does not omit the energy contribution of electrostatics.

In building design, thermal mass is a property of the mass of a building which enables it to store heat, providing "inertia" against temperature fluctuations.

Heat transfer physics describes the kinetics of energy storage, transport, and transformation by principal energy carriers: phonons (lattice vibration waves), electrons, fluid particles, and photons.

Thermal conduction is the transfer of heat (internal energy) by microscopic collisions of particles and movement of electrons within a body.

Convective heat transfer, often referred to simply as convection, is the transfer of heat from one place to another by the movement of fluids.

Waste heat is by necessity produced both by machines that do work and in other processes that use energy, for example in a refrigerator warming the room air or a combustion engine releasing heat into the environment.

In thermodynamics, a quantity that is well defined so as to describe the path of a process through the equilibrium state space of a thermodynamic system is termed a process function, or, alternatively, a process quantity, or a path function.

The principle of minimum energy is essentially a restatement of the second law of thermodynamics.

A thermodynamic instrument is any device which facilitates the quantitative measurement of thermodynamic systems.