Evolution of ideas in solar‐terrestrial physics

Summary. This essay is an attempt to follow, from the beginning of this century, the evolution of various concepts developed in the field of the solar activity‐magnetospheric disturbance relationship, but is not merely a chronological description. In most scientific fields, as observed by Thomas S. Kuhn, there is a strong tendency for scientists to have a high degree of agreement on theoretical assumptions establishing a coherent tradition of research, defined as a ‘paradigm'. Some paradigms are often initiated by a simple, qualitative intuition. However, once established, they are articulated and elaborated to the point that observational or theoretical anomalies are treated not as refuting the underlying theory, but as solvable puzzles by ad hoc modification to the original theory. Solar‐terrestrial physics is no exception in this regard. We examine the evolution of various disciplines in solar‐terrestrial physics from this particular point of view in the following disciplines: (1) the solar wind generation, (2) the source regions of the high speed streams, (3) solar flares, (4) the magnetosphere formation, (5) the morphology of magnetospheric disturbances, (6) the solar wind‐magnetosphere energy coupling, and (7)auroral particle acceleration. It is also pointed out that the tendency toward increasing specialization in various disciplines tends to create a gap among interrelated disciplines. This is particularly serious in solar‐terrestrial physics, since a study of the north‐south component of the interplanetary magnetic field has fallen into the gap between solar physics and magnetospheric physics.