Magnetic World: The Historiography of an Inherently Complex Science, Geomagnetism, in The 20th Century

The 20th century witnessed a succession of remarkable developments in the history of geomagnetic research. After 1900, geomagnetic researchers increased their activity as they adopted theories by C. F. Gauss and J. C. Maxwell and developed means to bridge the gulf between these theories and masses of data of global phenomena. This paper outlines three main streams in 20th-century geomagnetic research: investigations of processes deep inside the Earth that produce the main geomagnetic field, examinations of crustal magnetism, and research into processes on the edge of space, where Earth's magnetic field interacts with the interplanetary environment. This discussion places these research streams in the historiographic context of disciplinary specialization and transformation. In the early 20th century, geomagnetic researchers thought of their domain as all of Earth's magnetic and electric phenomena. In mid-century, however, many researchers began to narrow their gaze to one problem area or another. This specialization contributed to a period of dramatic developments in the latter half of the century: geodynamo theory, paleomagnetic evidence of plate tectonics, computer modeling of magnetic reversals, and discovery of the solar wind, radiation belts, and magnetic substorms. But there was more to this period than simple specialization. As researchers gradually shifted their research programs, their methods, instruments, and theories moved from one program to another, researchers sometimes going with them. Chameleons and opportunists frequently left one research program for another, more promising one. This paper closes with a discussion of the possibility of "re-connection" among these specializations, as researchers have begun once again to communicate across inter-field lines.