The Physics of Solids pp 3-20 | Cite as

# Basic Principles Summarized

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## Summary

The equilibrium state of matter in general (and condensed matter in particular) corresponds to the minimum value of its energy E (when \( {P_o} = T = 0 \)), or of its Gibbs free energy, \( G \equiv E + {P_0}V - TS \), (when P0 = const., T = const.), where P0 is the external pressure, T is the absolute temperature, V is the volume, and S is the entropy. This statement implies, among other things, that (when P0 = 0) the internal squeezing pressure due to the attractive forces among the elementary particles making up the matter is counterbalanced by the internal expanding pressure due to the perpetual motion of these particles. This, crucial for equilibrium perpetual motion, stems mainly or exclusively from the wave nature of matter and is summarized in the three basic principles of Quantum Mechanics (QM). For condensed matter, the forces are mainly electric and are characterized by the charge e, while the perpetual motion depends mainly on Planck’s constant, and the electronic mass,ħ me. Thus, properties of condensed matter depend on e, me and possibly on other physical constants. This observation together with dimensional considerations leads to several semiquantitative results.

## Keywords

Gibbs Free Energy Dimensional Analysis Coulomb Force Black Body Radiation Identical Fermion## Preview

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## Further Reading

- Landau & Lifshitz, Stat. Phys. [ST35], Chap. 20, pp. 59–63.Google Scholar
- Eisberg & Resnick, Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles [Q23], pp. 6–21.Google Scholar