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Chapter
Change of State with Time
Let the wave function ψ(x, 0) which describes the state of an ensemble of particles (x denoting all the co-ordinates of a particle) be given at some instant t = 0. By means of this wave function we may calculate ...
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Chapter
The Relation between Quantum Mechanics, Classical Mechanics and Optics
Ehrenfest’s theorems proved in Section 32 assert that in any state Ψ the mean values of mechanical quantities obey the quantum Newton’s equation1:
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Chapter
Perturbation Theory
The problem of finding the quantum levels of a system (i.e. of finding the eigenvalues and eigenfunctions of the energy operator H) can be solved by means of known mathematical functions in only a very few cases....
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Chapter
Multi-Electron Atoms
The helium atom, the second in the periodic system, is the simplest multi-electron atom, but even here classical mechanics failed completely. Attempts at calculations using classical mechanics (with Bohr’s qua...
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Chapter
Conclusion
In this exposition of the fundamental ideas of quantum mechanics no attempt has been made to preserve a strict sequence of deduction. The orderly logic of a deductive account would inevitably involve some degr...
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Chapter
Foundations of Quantum Theory
The development of quantum mechanics was preceded by that of the quantum theory of light. At the end of the last century it seemed that in the contest between the corpuscular and wave theories of the nature of...
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Chapter
Representation of Mechanical Quantities by Operators
As we have seen, in the quantum region there are no states in which the momentum and co-ordinate of particles have definite values simultaneously. This fact is reflected in the formalism of the theory: the mat...
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Chapter
Intrinsic Angular Momentum and Magnetic Moment of the Electron. Spin
The theory of the motion of a charged particle in a magnetic field as given in the preceding chapter is by no means complete. The reason is that, in addition to the angular momentum and magnetic moment due to ...
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Chapter
The Passage of Microparticles Through Potential Barriers
If there are two regions of space in which the potential energy of a particle is less than on the surface separating the regions, then such regions are separated by a potential barrier.
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Chapter
Simple Applications of the Theory of Motion of Many Bodies
In discussing the motion of the optical electron in an atom we have assumed the nucleus of the atom to be at rest, regarding it as a source of central forces. This approximation is a good one when the mass m of t...
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Chapter
Formation of Molecules
Let us now consider the hydrogen molecule H2 in terms of quantum mechanics. This molecule has a typical homopolar bond. Thus from this simple case of a homo-polar molecule we can hope to elucidate the nature of t...
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Chapter
Foundations of Quantum Mechanics
The physical significance of the waves which, according to de Broglie’s concept, are related to the motion of particles was not discovered immediately. Attempts were made at first to regard the particles thems...
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Chapter
Theory of the Motion of Microparticles in a Field of Potential Forces
In this chapter we shall consider some simple problems of atomic mechanics concerning the motion of particles in the field of potential forces. Generally speaking, if the forces are independent of time, the ba...
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Chapter
Collision Theory
The theory of the collision of microparticles has become a very extensive branch of atomic mechanics.1 It is not possible to give a detailed account of this theory in the present book, and we shall merely describ...
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Chapter
Emission, Absorption and Scattering of Light by Atomic Systems
Problems concerning the interaction of light and microparticles are in some respects outside the scope of quantum mechanics. They cannot be discussed without the use of supplementary ideas relating to laws of ...
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Article
Causality in present-day field theory
The form of causality used in present-day theory follows from basic space-time concepts.
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Article
Geometric optics of elementary particles
It is shown that the nonlocal potential deduced from quantum field theory may be replaced by a local, complex refraction index for large wave numbers.
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Article
On elastic pion and nucleon scattering at high energies
It is shown that under rather general assumptions the largea ngle elastic scattering cross-sections must decrease as 1/E 0 (E 0 is the energy of an incident particle in the laboratory system).
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Article
A fast-neutron pulse reactor
In June, 1960, criticality was reached on the fast-neutron pulse reactor constructed at the United Institute of Nuclear Studies.
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Article
Five years of activity of the Joint Institute for nuclear studies
In March of this year, the Joint Institute for Nuclear Studies, the international scientific organization of the socialist countries, completed five years of existence. On this occasion, the Editorial Board pu...
