Renowned Nobel laureate and co-discoverer of 'echo of Big Bang' passes away at 90. Arno Penzias, the renowned cosmologist who was credited with the discovery of the cosmic microwave background (CMB) alongside Robert Wilson, died on January 22. In 1978, he was jointly awarded the Nobel Prize in Physics, sharing half of the prize with Wilson, while the other half went to Pyotr Kapitsa for his contributions to low-temperature physics.
Born on April 26, 1933, in Munich, Germany, Penzias and his family fled Nazi Germany when he was six years old, finding refuge first in England and eventually settling in New York in 1940. After graduating in physics from the City College of New York in 1954, Penzias served as a radar officer in the US Army Signal Corps until 1956.
Following his time at Columbia University's radiation laboratory, where he focused on microwave physics and earned his Ph.D. in 1962 under the guidance of maser inventor Charles Townes, Arno Penzias joined Bell Labs in New Jersey. At Bell Labs, he contributed to the development of microwave receivers for radio astronomy. Collaborating with Robert Wilson, they worked on a 6 m-diameter horn-reflector antenna equipped with a 7 cm ultra-noise receiver.
In 1964, the duo encountered an unexpected source of radiation at 3 K that proved challenging to eliminate. Initially suspecting a terrestrial origin for the hiss of radio waves at a wavelength of 7.35 cm, given its uniform distribution across the sky, they even humorously considered the possibility of pigeon excrement on the antenna.
Unknown to them, Arno Penzias and Robert Wilson had discovered cosmic microwave background radiation, a phenomenon initially predicted by cosmologists Ralph Alpher and Robert Herman in the late 1940s. Their accidental find was later confirmed as the afterglow of the Big Bang.
Penzias and Wilson detailed their experimental resultsin the Astrophysical Journal, coinciding with a paper by Robert Dicke. Dicke, who had previously calculated that the universe should contain residual blackbody radiation with a minimum temperature of 10 K, interpreted the noise measured by Penzias and Wilson as a distinct signature of the cosmic microwave background.
During that era, two primary theories about the universe competed for prominence. The "steady-state theory" posited that the universe continually expands but maintains a constant density. In contrast, the "Big Bang" theory suggested a universe originating from a single point, expanding and stretching as it grows.
The groundbreaking discovery of the cosmic microwave background (CMB) served as the inaugural direct evidence supporting the idea of a hot Big Bang as the origin of the universe. Subsequent examinations revealed the CMB's temperature to be approximately 2.7K, closely resembling a blackbody, leading theorists to understand that this low temperature is a consequence of the universe's expansion.
Arno Penzias and Robert Wilson were jointly awarded the 1978 Nobel Prize in Physics for their pivotal role in this discovery. Since then, the CMB has become a rich source of information about the universe. In the 1970s, researchers found that the CMB, rather than being purely isotropic, exhibits minute anisotropies, adding further depth to our understanding of the cosmos.
The cosmic microwave background (CMB) has undergone meticulous scrutiny through groundbreaking ground and space probes. Among these, NASA's Cosmic Background Explorer, launched in 1989, and the Wilkinson Microwave Anisotropy Probe, which took flight in 2001, have played pivotal roles in measuring the CMB with unprecedented detail.
Arno Penzias concluded his illustrious 37-year career at Bell Labs in 1998, where he held positions such as research director and chief scientist. Following his retirement, he delved into the realms of technology and business authorship, having penned two books on the subjects. Later, he ventured into the world of venture capital by joining the firm New Enterprise Associates.
In addition to the Nobel Prize, Penzias received the Henry Draper Medal in 1977 from the US National Academy of Sciences and the George Pake Prize from the American Physical Society in 1990, further acknowledging his significant contributions to the field of physics.
In a statement, Thierry Klein and Peter Vetter from Bell Labs say that Penzias will be "sorely missed". "Arno represented far more than his many accomplishments. He embodied the Bell Labs approach to innovation," they write. "Arno, like all his colleagues at Bell Labs, was an applied scientist, seeking answers to the technical challenges of communications. But in the course of his research, he uncovered bigger challenges and learned bigger truths."