Rikitake Yasushi | CONFIRMED • 2025 |

Rikitake Yasushi (力武 常, 1921–2015) was a prominent Japanese geophysicist best known for his groundbreaking work on the origin of Earth’s magnetic field. While his name may not be as widely recognized outside geophysics as some of his contemporaries, his theoretical contributions—particularly the "Rikitake dynamo model"—remain a cornerstone in the study of geomagnetism and chaotic systems. The Rikitake Dynamo Model In the mid-1950s, Rikitake sought to explain one of geology's greatest puzzles: why does the Earth's magnetic field reverse polarity irregularly? Building on the dynamo theory proposed by Walter Elsasser and Edward Bullard, Rikitake developed a simplified mathematical model of two coupled disk dynamos. This system demonstrated that even under perfectly symmetric, steady driving conditions, the magnetic field could spontaneously reverse direction at irregular intervals.