Theodore R. Madden, lifelong professor of geophysics at the Massachusetts Institute of Technology (MIT), fascinated with all things electromagnetic, ingenious in bridging theory with experiment, AGU Fellow, and a geophysicist’s geophysicist, died on 11 November 2013 at age 88. A special symposium and memorial (http://eapsweb.mit.edu/news/2014/madden-memorial) was held at MIT on 14 March 2014 on the occasion of his birthday. At that time, Frank Press, former president of the U.S. National Academy of Sciences, said, “Ted Madden and his students put geophysics on the map at MIT.”
Ted’s early education was at the Dexter School in Brookline and at the Milton Academy in Milton, Mass. He entered MIT as a freshman in 1942 but, faced with the onset of World War II, volunteered for the U.S. Marine Corps and became a radar technician on Peleliu Island in the Pacific Ocean. Ted returned to MIT at the war’s end to complete a bachelor’s degree in physics in 1949.
Ted’s geophysical interests spanned the range of the natural environment. Together with his students, he pursued fluid motions in the Earth’s core, searched for metallic minerals with induced polarization methods, investigated the conductivity of the mantle and the moon, studied crustal resistivity with direct current and magnetotelluric methods that also found later application in earthquake prediction work, addressed the brittle failure of stressed rocks, explored atmospheric gravity waves and Schumann resonances (global electromagnetic resonances excited by lightning), and ventured into the plasma physics of the magnetosphere.
Learning with his students was his priority from beginning to end, with interest in publication and his own advancement being secondary. As just one example, a detailed survey of direct current (DC) resistivity carried out in the median strip along the Massachusetts Turnpike, with interpretation for geological features, was never published. His enjoyment lay in doing the work and interpreting the results.
Ted may best be remembered for his determined use of electrical networks for nearly every geophysical problem he chose to pursue. The collection of ideas on network analogies for both forward and inverse methods was drawn together in an MIT technical report (http://mtnet.dias.ie/papers/ClassicPapers/Madden_1972_TechRep72-3.pdf) but was also never published. In the introduction to this report, one finds these words: “All these matters are essentially well known and thus this report does not represent new ideas.” This quotation is but one small sample of Ted’s modesty. In reality, every application of an electrical circuit analogy to a geophysical problem in this report represented a new idea. This report acquired the name “the Grey Peril” among his students, not so much because of the color of its cover but because of its terseness and impenetrability. By the late 1980s, Ted had adopted the same name in referring to this report, to the great amusement of all of his students.
Evidence that these ideas were considerably ahead of their time can be found in literature by other scientists who later rediscovered Ted’s ideas. For example, the Russian scientist Kirillov  later applied the lumped circuit transmission line to electromagnetic problems and wrote the following:
In Madden and Thompson (1965) it is said that the propagation of ELF radio waves in a near-Earth waveguide channel can be interpreted as propagation in a 2-D transmission line. Because of its qualitative nature, this idea was not embraced for more than two decades.
Ted’s tenacity is exemplified in his interest in Archie’s law, an empirical power law relationship relating resistivity and porosity in rocks. He was long impressed with how well this purely empirical law fit the data over such a wide range of porosities and set out to understand this behavior. This law first caught his attention in geophysical field work, but decades later, he invented random networks, closely akin to the renormalization group in physics, to understand it theoretically. Still later, he used Archie’s law to interpret a spatially organized precursory change in DC resistivity prior to the great Tangshan earthquake in China [Qian, 1985].
Ted’s instant, back-of-the-envelope calculations in all realms of Earth sciences were legendary. Once when I accompanied Ted on one of his many field trips to the San Andreas fault in California for his earthquake-related studies with the U.S. Geological Survey, we hiked to the New Melones Dam and Reservoir in the drainage of the Sierras. In response to the question of how long it would take the reservoir to empty if the dam broke, Ted had calculations completed in less than 1 minute. His solution was as follows: (1) Apply the shallow-water wave equation, with wave speed equal to the square root of the acceleration of gravity (g) times the depth (D) of the reservoir. (2) Estimate the length of the reservoir to be about 10 kilometers. (3) Estimate D, comparable to dam height, to be about 50 meters. (4) Calculate the speed of the wave to be about 20 meters per second. The rough time to empty is length divided by speed, or 10,000/20. This equates to roughly 500 seconds, or about 8 minutes. There was no envelope this time. The calculations were all in his head.
The 1955 register for the MIT Department of Geology and Geophysics lists Ted as the only faculty member without a doctoral degree, but to many, Ted was the department’s superstar. Engrossed in teaching and geophysical field work with mining companies in Nova Scotia, Missouri, and New Mexico, Ted’s PhD thesis work on “The Induced Polarization of Metallic Minerals” was not completed for another 6 years, giving Ted special status as the longest-standing MIT professor with only a bachelor’s degree.
Mild mannered and soft-spoken, Ted was also intensely competitive. Anyone who doubted that fact needed only to go up against him in a hockey, lacrosse, or basketball game. By his own reckoning, his social life at MIT revolved around sports.
Ted’s receipt of the Fessenden Award in 1986 from the Society of Exploration Geophysics was particularly fitting. At one point, Reginald Fessenden, who transmitted the first sinusoidal very low frequency oscillations from Brant Rock, Mass., to a receiving station in Scotland, collaborated with Ted’s father, Richard Madden, on submarine communication and the detection of icebergs (in the wake of the Titanic disaster). As a child, Ted had played with the Fessenden oscillator equipment, and while in high school he worked on research projects in his father’s Submarine Signal Company.
Given this rich history, Ted’s early involvement with radar, his transition from physics to geophysics at MIT, his oceanographic expeditions with Maurice Ewing, his pioneering use of sine waves in induced polarization studies, and his major inroads in the Earth’s Schumann resonances—envisaged early on as a means for submarine communication—all come as little surprise.
Ted is survived by three of the four coauthors of this tribute, his wife and two daughters, and by a large cadre of former students who have forged successful careers in industry, government, and academia. His legacy has been and will continue to be deep and pervasive.