75th Anniversary of `Existence of Electromagnetic-Hydrodynamic Waves'

TL;DR

This paper celebrates the 75th anniversary of Alfvén waves, highlighting their historical discovery, scientific significance in solar physics, and the evolution of understanding in MHD wave research over time.

Contribution

It provides a historical overview of the development and impact of Alfvén waves in space physics and discusses lessons about scientific modeling and discovery.

Findings

Alfvén waves are fundamental in solar and space physics.

Their detection advanced understanding of coronal heating and solar wind.

Historical perspective informs current scientific practices.

Abstract

We have recently passed the 75th anniversary of one of the most important results in solar and space physics: Hannes Alfv\'en's discovery of Alfv\'en waves and the Alfv\'en speed. To celebrate the anniversary, this article recounts some major episodes in the history of MHD waves. Following an initially cool reception, Alfv\'en's ideas were propelled into the spotlight by Fermi's work on cosmic rays, the new mystery of coronal heating and, as scientific perception of interplanetary space shifted dramatically and the space race started, detection of Alfv\'en waves in the solar wind. From then on, interest in MHD waves boomed, laying the foundations for modern remote observations of MHD waves in the Sun, coronal seismology and some of today's leading theories of coronal heating and solar wind acceleration. In 1970, Alfv\'en received the Nobel Prize for his work in MHD, including these discoveries. The article concludes with some reflection about what the history implies about the way we do science, especially the advantages and pitfalls of idealised mathematical models.