Pauli exclusion principle

(pow -lee) The principle that no two particles can exist in exactly the same quantum state. It is obeyed by fermions but not by bosons. The existence of white dwarfs and neutron stars is a consequence of this.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Pauli exclusion principle

[′pȯl·ē ik′sklü·zhən ‚prin·sə·pəl]

(ecology)

exclusion principle

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Pauli Exclusion Principle

a fundamental law of nature according to which two identical particles with half-integral spin (in units of Planck’s constant ħ) cannot simultaneously exist in the same state. The principle was formulated in 1925 by the Swiss physicist W. Pauli for electrons in the atom; it was later extended to all particles—elementary particles, nuclei, atoms, or molecules—with half-integral spin (fermions). Pauli subsequently showed that the exclusion principle follows from the relation between spin and statistics that exists in relativistic quantum mechanics: particles with half-integral spin obey Fermi-Dirac statistics. In particular, the wave function of a system of identical fermions must be antisymmetric with respect to an interchange of any two fermions. Thus, no more than one fermion can occupy a given state.

The Pauli exclusion principle played a decisive role in understanding the regularities underlying the filling of the electron shells of the atom. It served as the starting point for an explanation of atomic and molecular spectra. In the quantum theory of the solid state, the application of the principle led to Fermian statistics for an electron gas. The explanation of most thermal, electric, and magnetic properties of a solid is based on Fermian statistics. The exclusion principle has an important place in nuclear theory—for example, it provides the foundation for the nuclear shell model. It also has a considerable role in the theory of nuclear reactions and reactions between elementary particles.

REFERENCE

Teoreticheskaia fizika 20 veka (in memory of W. Pauli, translations). Moscow, 1962.

V. P. PAVLOV

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References in periodicals archive

Relying on this nuclear physics example, one deduces that the Pauli exclusion principle is completely consistent with three identical fermions in a [J.sup.[pi]] = [3/2.sup.+] and I = 3/2 ground state.

The discussion presented above shows that there is no need for introducing a new degree of freedom (like color) in order to settle the states of [[DELTA].sup.++], [[DELTA].sup.-] and [[OMEGA].sup.-] baryons with the Pauli exclusion principle. Hence, there is no reason for the QCD invention.

On the quantum mechanical state of the [[DELTA].sup.++] baryon

In the following sub-sections, three areas are discussed: The Pauli exclusion principle, chemical reactivity and chemical bonds.

The Pauli Exclusion Principle is an extremely important principle in science [10].

A quantum theory of magnetism

The Pauli exclusion principle stands at the basis of the structure and stability of matter.

Violating a not-so-exclusive exclusion principle

In the way they build the superstructures of atoms and in the way they prevent atoms from collapsing, electrons obey a rule called the Pauli exclusion principle. The exclusion principle forces them to follow the Fermi-Dirac statistical law, under which their wave functions can be positive part of the time and negative part of the time.

Schrodinger goes to Monte Carlo; the 'adaptive Monte Carlo' method seeks solutions for chemical and condensed-matter structures