PlanetPhysics/Principles of Thermodynamics
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This is a contributed entry on Thermodynamics principles and/or laws; the latter are defined as those primary [[../Predicate/|propositions]] that are fundamental to the logical and mathematical development of [[../Thermodynamics/|Thermodynamics]] in accord with all experimental findings in classical molecular physics. Thus, thermodynamics has its historical roots in studies of [[../Heat/|heat]] and Molecular Physics.
In particular, such thermodynamic laws impose essential constrains on the equations of state and state functions that are employed to describe all closed thermodynamic [[../GenericityInOpenSystems/|systems]]. However, the thermodynamic treatment of open systems is not yet a `closed book'. One also notes that such thermodynamic laws that hold for all closed systems may still be further derived from statistical mechanics.
Principles of Thermodynamics
Basic Concepts
{Thermodynamic systems}: Closed vs. Open systems.
Thermodynamic Processes: Reversible vs. Irreversible := [[../ThermalEquilibrium/|equilibrium]] vs. Non-equilibrium
The Zeroth Principle
Thermal Equilibrium definition. Temperature and Molecular Motions
[[../BoltzmannConstant/|Temperature]] is a measure of the degree of molecular [[../CosmologicalConstant2/|motion]]: the higher the average [[../AbsoluteMagnitude/|magnitude]] of [[../Velocity/|velocities]] in a system measured at equilibrium with the system, the higher the temperature is (the hotter the system is).
[[../BoltzmannConstant/|absolute temperature scale]]
[More to come...]
Whereas absolute temperatures of molecular systems can only take on positive values, [[../QuarkAntiquarkPair/|spin]] temperature--or spin-lattice temperature-- for example, may take on `negative' values as a result of spin population inversion through [[../FluorescenceCrossCorrelationSpectroscopy/|Polarization]], or cross-polarization.
Such cross-polarization processes might be thus utilized in designing and operating [[../CategoriesOfQuantumAutomataAndQuantumComputers/|quantum `computers]]' or quantum nano-robots.
The First Principle
Total \htmladdnormallink{energy {http://planetphysics.us/encyclopedia/CosmologicalConstant.html} Conservation}
The Second Principle
During any thermodynamic process the entropy of a closed system always increases if the closed system is not at equilibrium (when the latter becomes constant), [or, equivalently, that perpetual motion machines are impossible].
The Third Principle
The entropy of any crystalline system tends to zero in the limit of absolute zero temperature.
Discussion
Suggested Fourth Principle: the Onsager reciprocity \htmladdnormallink{relations {http://planetphysics.us/encyclopedia/Bijective.html} for non-equilibrium, open systems}
Remark: Commonly, the four principles of reversible thermodynamics are also known as "the four thermodynamic laws ".