J O H N PA U L W I L D 17 may 1923 . 10 may 2008 PROCEEDINGS OF THE AMERICAN PHILOSOPHICAL SOCIETY VOL. 155, NO. 3, SEPTEMBER 2011
biographical memoirs J ohn Paul Wild was born in Sheffield, England, the son of a cutlery manufacturer who lost everything in the Great Depression. Paul’s father went to the U.S. when Paul was three months old and, al- though he was able to provide support after selling some patents, Paul did not see him for the next thirty-three years. Paul had an early love of mathematics that he attributed to the enthusiasm and encour- agement of his school mathematics teachers. He went to Cambridge University in 1942 and studied mathematics and physics before joining the navy in July 1943. This two years was to be his only period of uni- versity study. Paul served as a radar officer on the flagship HMS King George V in the British Pacific Fleet for two and a half years. On one of the many visits the fleet made to Sydney, Australia, Paul met Elaine Hull, and their friendship grew with subsequent visits. Paul returned to England after the war and taught radar to naval officers, corresponding fre- quently with Elaine. In 1947, he obtained a job at the Radiophysics Laboratory of Australia’s Council for Scientific and Industrial Research (CSIR) and moved to Sydney, his proposal of marriage by mail having already been accepted. Paul’s first role was the relatively mundane main- tenance and development of test equipment, but after a year he was able to join Joe Pawsey’s radioastronomy group. Paul was a great admirer of Pawsey, who provided “an ideal environment to allow everyone to use their own initiative.” CSIR became the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in 1949. Paul worked with Lindsay McCready to build, at Pawsey’s sugges- tion, the first spectrograph to study the frequency dependence of solar bursts. This instrument provided a display of frequency versus time covering a swept frequency range from 40 to 70 MHz. Paul travelled to Penrith, 50 km west of Sydney, by train each day with a technician and a hand-cranked movie camera to record the cathode ray screen show- ing the variation of intensity with frequency of the solar radio emission. Paul recalled, “Every now and then a great burst would come from the sun and we were very excited and we photographed everything that went on. . . . After four months we got so much data that we just closed everything down and came back and I analysed the data at very great length; the results were spectacular.” Three types of bursts were identified—which they named Types I, II, and III—distinguished by the way the frequency changed with time. In a series of papers published in 1950, they presented their data and the conclusion that Type II bursts were associated with shock waves coming out through the solar atmosphere at 1,000 km/sec that were associated, about a day later, with aurorae visible near the earth’s poles. The more frequent Type III bursts were associated with streams [ 378 ]
john paul wild 379 of electrons being ejected one hundred times faster—at a third the speed of light—and taking only an hour to reach the earth. This was one of the first realisations that astrophysical phenomena could result in the production of particles travelling at relativistic speeds. The interpreta- tions proved to be correct, and their naming of the burst types became the standard. The success of these observations led to the construction of three rhombic spectrograph antennas at Dapto, 100 km south of Sydney, to conduct further studies of the sun at frequencies between 40 and 240 MHz, which confirmed and extended the Penrith work. Paul likened this research to the study of taxonomy that preceded Darwin’s Origin of Species. His analysis of the anatomy of the solar flares and his devel- opment of the physical interpretation culminated in a unified model that integrated the apparently complex radio flare phenomena in the solar chromosphere, in the solar corona, and in the interplanetary space. In the course of this solar work, Paul became interested in the radio spectrum of hydrogen and wrote up an internal report related to the potential for spectral lines in the solar bursts. When Ewen and Purcell in the USA first observed the 1420 MHz hyperfine transition of hydro- gen in 1951, Paul went back to his report, generalized it to include the interstellar medium, and six months later published the first detailed theoretical paper on the microwave spectral lines from the hydrogen atom—a classic in the field. After ten years of research, Paul’s collected papers gained him a doctor of science degree from Cambridge. The group was the pre-eminent group in the world for solar radioastron- omy and would continue its work for three decades. All these results had been inferred from spectral observations, and there was a growing desire to be able to image the sun at the same range of frequencies with an angular resolution comparable to the hu- man eye. This dictated the need for an instrument more than a million times the size of the aperture of the human eye. With Pawsey’s help, a grant of US$500,000 (later increased to $630,000) was received from the U.S. Ford Foundation to build a radio-heliograph at Culgoora, near the town of Narrabri, in northern New South Wales. Paul acknowl- edged his friend Kevin Sheridan, chief electronics engineer, as the key figure in this development. The radio-heliograph consisted of 96 steerable parabolic antennas, each 13.7 m in diameter, and spaced at 100 m intervals around a circle of diameter 3 km. More than 320 km of copper wire was used to form open transmission lines to transport the signals to the central control building. Operating initially at 80 MHz (a wavelength of 3.75 m), the radio-heliograph was able to produce a detailed image of the sun each second, and to record both senses of polarization of the radio waves.
380 biographical memoirs This unprecedented capability yielded its first surprise in its first days of operation: a series of bursts, previously assumed to all be originating from the same part of the sun, were found to be coming from two loca- tions separated by more than 800,000 km but connected, it was subse- quently realised, by solar magnetic field lines. The radio-heliograph, which was later extended to frequencies of 40, 160, and 327 MHz, stayed in operation for seventeen years from 1967, providing a tremendous amount of data and insight into the way the solar corona works and the relationship between solar and terres- trial phenomena. Paul published more than seventy papers in this area, and his achievements brought him the Balthasar van der Pol Gold Medal of the International Union of Radio Science for contributions to radioastronomy “including completion of a notable high-resolution radio-heliograph” in 1968; the Hendryck Arctowski Gold Medal of the U.S. National Academy of Sciences in 1969; the Herschel Medal of the Royal Astronomical Society in 1974; and the Hale Prize of the Ameri- can Astronomical Society for Solar Astronomy in 1980. In 1971, Paul took over from E. G. (“Taffy”) Bowen as chief of CSIRO’s Division of Radiophysics. While continuing his interest in solar studies, he also looked for opportunities to use the skills gained from the radioastronomy work and to provide a balance of pure and applied work in the division. Discussions with the Department of Civil Aviation identified a replacement for the existing commercial aircraft all-weather Instrument Landing System as a key opportunity, which was taken up with great enthusiasm by Paul. This work led to the Inter- scan microwave landing system, which was accepted as the new global standard in 1978, and was used until cheaper GPS-based systems be- came available. Paul was awarded the Royal Medal of the Royal Soci- ety in 1980, “[i]n recognition of his conception of the basic principles of the Interscan instrument landing system and the guidance of its de- velopment to a successful conclusion.” Paul was appointed chairman and chief executive of CSIRO in 1978. As chairman of CSIRO from 1978 to 1985, he was Australia’s national science leader. He led the Organisation through a restructuring to mod- ernise it and bring it closer to the industries and community it serves. Recognising that CSIRO needed to adapt and provide scientific and technological leadership in a changing world, he wrote in 1984, “Yet, whatever the changes, one characteristic must remain inviolate: a high standard of excellence and originality. Without excellence and original- ity, research achieves nothing.” During this period he was instrumental in securing funding for major national research facilities including Aus- tralia’s National Oceanographic Research Vessel, the Australian Animal Health Laboratory, and the Australia Telescope, and he established a
john paul wild 381 new Division of Information Technology. The Australia Telescope Com- pact Array was built on the site of the radio-heliograph. Another project that started in this era was his Very Fast Train (VFT) project. He envisaged a fast train linking Sydney, Canberra, and Melbourne, noting, “We’re trying to take Australian railways out of the 19th century and into the 21st in one leap.” He became chairman of the VFT consortium, but the project collapsed in 1991 when the government rejected proposals to provide tax benefits for infrastructure projects. Progress in science requires “big-picture” people who can see their way through the complexity to set the path forward. In this arena, as il- lustrated from his earliest work, Paul was absolutely first class. He clearly had an exceptional intellect, wide knowledge, appreciation of technical issues, and unquenchable interest in new projects and ideas. Paul’s work was recognized by many awards: he was made a fellow of the American Academy of Arts and Sciences in 1961, a foreign mem- ber of the American Philosophical Society in 1962, a fellow of the Aus- tralian Academy of Science in 1964, and a fellow of the Royal Society in 1970. He was made a Commander of the Order of the British Empire (CBE) in 1978 and a Companion of the Order of Australia in 1986. Paul died a week before his eighty-fifth birthday. At his funeral ser- vice the casket was covered in red, orange, yellow, green, blue, and in- digo flowers—the colours of the sun’s spectrum. Some of Paul’s ashes were sealed into a memorial sundial near the Visitor Centre at Cul- goora, which is now known as the Paul Wild Observatory. Paul outlived Elaine and his second wife, Margaret, and is survived by his children, Peter, Penny, and Tim. Elected 1962 Bob Frater Former Deputy Chief Executive CSIRO Vice President for Innovation ResMed Corporation Philip Edwards Head of Science Operations Australia Telescope National Facility CSIRO Astronomy and Space Science Ron Ekers CSIRO Fellow Australia Telescope National Facility