## Zur Quantenmechanik II in Zeitschrift für Physik 35, 1926, pp. 557–615

Berlin: Vieweg und Springer, 1926. 1st Edition. FIRST EDITION IN ORIGINAL WRAPS OF BORN, HEISENBERG, & JORDAN’S “MONUMENTAL” THREE-MAN PAPER, ‘ON QUANTUM MECHANICS II’, THE FIRST COMPLETE STATEMENT OF MATRIX MECHANICS (Peacock, Quantum Revolution, 52).

In this work, Born, Heisenberg, and Jordan extend the methods Heisenberg presented in his initial 1925 paper and apply them to a number of important problems. “This paper definitively set forth [and first named] matrix mechanics — the version of quantum mechanics based on the algebraic manipulation of matrices that represent observable quantities such as position, momentum, and energy. Detailed calculations showed that the new matrix mechanics was very successful in predicting the anomalous Zeeman Effect, other forms of line splitting, and line intensities. The three authors even produced a new derivation of Planck’s Law” (ibid).

In the early 1920s there were fundamental difficulties in atomic physics. The quantum theory of atomic structure, founded by Bohr and largely developed by Bohr and Sommerfeld, did not describe the properties of complicated atoms and molecules. "In spite of its high-sounding name and its successful solutions of numerous problems in atomic physics, ‘quantum theory’, and especially the ‘quantum theory’ of polyelectronic systems, prior to 1925, was, from the methodological point of view, a lamentable hodgepodge of hypotheses, principles, theorems, and computational recipes rather than a logical consistent theory. Every single quantum-theoretic problem had to be solved first in terms of classical physics; its classical solution had then to pass through the mysterious sieve of the quantum conditions or, as it happened in the majority of cases, the classical solution had to be translated into the language of quanta in conformance with the correspondence principle?

In short, quantum theory still lacked two essential characteristics of a full-fledged scientific theory, conceptual autonomy and logical consistency" (Jammer, The Conceptual Development, 196). The work of Heisenberg, Born, and Jordan rectified these issues and marked the "starting point for the new quantum mechanics," also called matrix mechanics (DSB).

Heisenberg published his initial paper formulating his new quantum theory in 1925, but without reference to matrices. “Later the same year, Max Born and Pascual Jordan published a second paper that introduced the matrix formulation for the special case of one degree of freedom” (History of Physics: The Wenner Collection).

Finally, in early 1926, all three scientists collaborated on a third paper, this ‘three-man paper’, and extended the theory to an arbitrary number of degrees of freedom. In its final form, they argued, Heisenberg’s formulation of the new quantum theory is a matrix algebra of quantum operators that “predicts the radiation resulting from electron state transitions between energy shells in the atom without reference to how the transitions occur” (ibid). Item #848

CONDITION & DETAILS: Berlin: Vieweg und Springer. Large 8vo. (9 x 6 inches; 225 x 150mm). pp. 557-722. Complete issue, rebacked at the spine and housed in a handsome leather clamshell case gilt-lettered at the spine and on the front board. The front wrap has a red stamp and some minor soiling (see scans). The interior is bright and clean throughout. Very good condition.

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Price:
$2,800.00
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