The Origin and Development of Astrophysics

Abstract

The two great nonclassical physical theories, the quantum theory and the theory of relativity, that led to the nuclear model of the atom, also led to astrophysics, and to a rational cosmology. Astronomy began to change from a discipline concerned with the study of the positions, the motions, and the clustering of stars to the study of the structure of stars, to “astrophysics,” which is the application of the laws of physics to the analysis of stellar structure. The aim here was, and still is, to lay down the blueprint for the theoretical structure of a model of a star. Because stars differ considerably in their physical features, a single stellar model cannot describe all kinds of stars. Astronomers, clearly recognizing this, understood the need to find those common physical characteristics that can be represented by a single stellar model. To this end they began to classify stars into groups with the idea that all the stars in a single group can be described by a single stellar model. Thus they reasoned they could construct a correct model of the sun and that that model would describe all stars like the sun. The classification of stars had already been begun on a simple scale with the introduction of the magnitude (apparent brightness) scale by Hipparchus and Ptolemy.

Silently one by one, in the infinite meadows of heaven Blossomed the lovely stars, the forget-me-nots of the angels.

—Henry Wadsworth Longfellow