**Absolute zero** is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as 0. The fundamental particles of nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, **absolute zero** is taken as −273.15° on the Celsius scale (International System of Units), which equals −459.67° on the Fahrenheit scale (United States customary units or Imperial units). The corresponding Kelvin and Rankine temperature scales set their zero points at **absolute zero** by definition.

It is commonly thought of as the lowest temperature possible, but it is not the lowest enthalpy state possible, because all real substances begin to depart from the ideal gas when cooled as they approach the change of state to liquid, and then to solid; and the sum of the enthalpy of vaporization (gas to liquid) and enthalpy of fusion (liquid to solid) exceeds the ideal gas's change in enthalpy to **absolute zero**. In the quantum-mechanical description, matter (solid) at **absolute zero** is in its ground state, the point of lowest internal energy.

The laws of thermodynamics indicate that **absolute zero** cannot be reached using only thermodynamic means, because the temperature of the substance being cooled approaches the temperature of the cooling agent asymptotically, and a system at **absolute zero** still possesses quantum mechanical zero-point energy, the energy of its ground state at **absolute zero**. The kinetic energy of the ground state cannot be removed.

Scientists and technologists routinely achieve temperatures close to **absolute zero**, where matter exhibits quantum effects such as superconductivity and superfluidity. [Wikipedia]

**Russell**
**Absolute zero** is the lower limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reaches its minimum value, taken as 0. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, **absolute zero** is taken as −273.15° on the Celsius scale (International System of Units), which equates to −459.67° on the Fahrenheit scale (United States customary units or Imperial units). The corresponding Kelvin and Rankine temperature scales set their zero points at **absolute zero** by definition. Wikipedia, Absolute Zero

"Conversely, cold multiplies that memory which heat destroys. At **absolute zero**, polarity and conductivity are both more intense." [Atomic Suicide, page 186]

See Also

**Cold**
**Cycle of Temperature**
**Heat**
**Motion**
**Zero Point**
**Zero point energy**
**zero universe of rest**
**zero universe of stillness**