Ralph Asher Alpher, who first predicted the microwave-background signature of a hot early universe, died on 12 August 2007 in Austin, Texas, after a long illness.
Our understanding of the origins of the universe rests on three fundamental observations. The first is that the universe is expanding; the second is that thermal radiation at 3 K pervades all space. The third observation involves the makeup of the universe: three-quarters of all visible matter is hydrogen; most of the remaining one-quarter is helium-4; the other light elements, deuterium and 3He, are found at levels of merely 10 parts per million, with lithium-7 at a few parts in 10 billion; heavier elements account for roughly 1% of the mass density. These data are the firmest now in hand.
Edwin Hubble documented the cosmic expansion in the 1920s. During five inspired years, between 1948 and 1953, Alpher and his long-time friend and colleague Robert Herman showed that the chemical abundances observed today implied that the temperature of the universe was once in the billion-degree range for a few minutes after the birth of the cosmos. They also predicted that a faint remnant of the intense radiation permeating the early universe must still persist today at a temperature “of order 5°K … to be interpreted as the background temperature from the universal expansion alone.” In 1965 Arno Penzias and Robert Wilson discovered that radiation. Its temperature was a remarkably close 3 K.
Alpher was born in Washington, DC, on 3 February 1921, the youngest of four children. His father, a building contractor, had immigrated from Russia; his mother, from Latvia. Starting at age 14, during the Depression, Alpher was always working—as a typist, secretary, or theater stagehand—at times contributing as much as his father did to the family’s support. At 16 he began working his way through night school at George Washington University, where Edward Teller was his freshman physics professor. During the day Alpher was a full-time secretary in the Department of Terrestrial Magnetism at the Carnegie Institution of Washington. In free moments he worked analyzing cosmic-ray data as an apprentice to Carnegie’s Scott Forbush.
During World War II, Alpher worked in the Navy Department under John Bardeen to protect ships against magnetic mines. In 1944 he joined the Johns Hopkins Applied Physics Laboratory; he also applied for a navy commission but was rejected because of poor eye-sight. He stayed at Hopkins and worked on supersonic aerodynamics.
At George Washington, Alpher took a course in relativity from George Gamow, was captivated by Gamow’s enthusiasm, and wrote a master’s thesis under his direction. Gamow had suggested that all chemical elements could have been formed in an early, hot relativistically expanding universe, and he recommended that Alpher do the actual calculations as a PhD project to see whether the idea made physical sense. Today we know that only the light chemical elements formed at those early times.
At Hopkins, Alpher met Herman, who was also working on wartime projects. Herman, who had studied relativity with H. P. Robertson at Princeton University, became intrigued in the spring of 1948 with Alpher’s thesis work. New cosmological questions were arising, and the two agreed to pursue them jointly. They soon solved the thermal cosmic background problem and communicated their findings to Gamow, who was at the Los Alamos laboratory at the time.
Gamow apparently was unenthusiastic, but Alpher and Herman published a note in Nature in 1948 and a more detailed paper in the Physical Review in 1949. Those articles led to invitations to give talks at technical laboratories. Most experts at the time felt that an isotropic 5-K flux was undetectable. Cooled detectors unavailable until much later eventually did enable the background detection in 1965. But over the intervening 17 years, Alpher and Herman’s striking prediction was forgotten.
The calculations they had started on the chemical abundances culminated in their now-classic Physical Review paper published in 1953 with Johns Hopkins colleague James Follin Jr. That effort also fared badly, coming under immediate attack by supporters of the steady-state theory of cosmology, who claimed that the abundances of all elements could be explained by nucleosynthesis in stars; they considered the “Big Bang” a fiction.
The year 1953 marked the end of Alpher and Herman’s most creative period. Alpher moved to the General Electric Research Laboratory in 1955. There he worked on high-speed aerodynamics, theoretical problems involving the physics of television projection systems, magnetohydrodynamic methods, and eventually strategic planning and technology forecasting. After retiring from GE in 1986, Alpher taught at Union College in Schenectady, New York, until 2004. Colleagues remember Alpher as a warm, thoughtful man with a strong social conscience, who often took a lead in addressing community issues.
Following the discovery of the background radiation in 1965 and the consequent demise of the steady-state theory, Alpher and Herman expected their contributions of 1948 and 1953 to be recognized. But their papers apparently were not read, and their work was often misattributed to Gamow, who certainly had first proposed a hot early universe but had not identified or quantitatively predicted the critical observations that would later confirm the hypothesis.
Recognition came late and in puzzling patterns. Alpher and Herman received many high honors from leading scientific societies before Herman’s death in 1997, all the more emphasizing two remarkable anomalies. The Nobel Prize has twice been awarded for work on the background radiation, but neither Alpher nor Herman was included. The Gruber Foundation, which inaugurated a munificent annual prize for cosmology in 2000, never recognized Alpher’s contributions during any of the eight years he was eligible.
Such statistics, however, should not mislead us. Alpher and Herman answered questions raised since antiquity. We still have far to search, but they showed us where and how to look. History will remember their contributions.
Two weeks before his death, Alpher’s son Victor represented him at the White House, where President Bush awarded Ralph Alpher the National Medal of Science, the highest scientific honor the US bestows.
