PlanetPhysics/Temperature

Temperature, $T$, is a [[../Vectors/|scalar]] [[../Thermodynamics/|Thermodynamic]] variable related to the amount of [[../KineticEnergy/|kinetic energy]] that a [[../SimilarityAndAnalogousSystemsDynamicAdjointnessAndTopologicalEquivalence/|system]] of either atoms/molecules or [[../QuarkAntiquarkPair/|spins]] have. The proportionality constant, $k$, beween the kinetic energy and temperature $T$ of the system is called the Boltzmann constant .

For an atomic or molecular system, $T$ is usually measured with a calibrated thermometer; in the case of an ensemble or system of spins, $T$ is called the spin temperature of the system, and is typically measured through [[../MagneticInductionVector/|magnetization]] transfer experiments at [[../ThermalEquilibrium/|equilibrium]]. The [[../ThermodynamicLaws/|absolute temperature]], or Kelvin scale, has only values that are greater than, or equal to, zero. One notes, however, that according to [[../QuantumParadox/|quantum mechanics]], even at zero degrees Kelvin there are still [[../CosmologicalConstant/|motions]] present in any atomic or molecular system--the zero-point vibrations, yielding an absolute minimum zero-point vibration [[../CosmologicalConstant/|energy]] $E_o^v>0$.

For crystalline systems, their entropy--which is a measure of the degree of disorder present in any thermodynamic system-- tends to zero when temperature tends to absolute zero (the Third Law of Thermodynamics).