Antony Hewish was a radio astronomer with an engineer's instinct and a patient eye for cosmic noise. His most celebrated achievement came not from a single brilliant insight but from the careful design of an instrument—the Interplanetary Scintillation Array at Cambridge—and the rigorous oversight of a team that knew how to use it. The pulsar's discovery would make history, win a Nobel Prize, and raise a persistent question about how science shares credit.
Hewish was born in 1924 in Fowey, Cornwall, and studied physics at Cambridge before the Second World War redirected his career. He spent the war years working in radar—experience that shaped his approach to radio astronomy. Radar taught him to listen carefully to noise, to build instruments that could hear faint signals against a background roar. After the war, he returned to Cambridge and spent decades developing techniques for detecting and measuring subtle variations in radio signals from distant sources.
The Work
In the 1960s, Hewish set out to build an instrument that could measure the scintillation—the twinkling—of distant radio sources. The idea was simple: as radio waves from distant galaxies and stars passed through the solar wind, they scattered slightly, causing their intensity to fluctuate. By measuring these fluctuations, astronomers could learn about the state of the interplanetary medium itself. It was a clever observational strategy, and it required precision engineering.
The Interplanetary Scintillation Array consisted of 2,048 dipole antennas spread across a 4.5-acre field at the Mullard Radio Astronomy Observatory near Cambridge. The design was elegant in its simplicity: simple antennas, arranged with geometric precision, each connected to a central receiver. When Hewish recruited Jocelyn Bell, a doctoral student joining his team in 1965, she helped not only build parts of the array but also learned to read and interpret the data it produced—data that came in the form of paper printouts covered in squiggly traces and numbers.
The array was not designed to discover pulsars. It was designed to measure scintillation. But it was exquisitely sensitive to any source that produced regular, narrowband radio emissions. This sensitivity, combined with careful calibration and a watchful eye—Bell's careful eye—led directly to the pulsar discovery in August 1967.
After the first pulsar was identified, Hewish's team used the same array to find three more within months. The technique proved robust, and other astronomers, using similar methods, discovered dozens of additional pulsars in the years that followed. Hewish co-authored the landmark 1968 Nature paper announcing the discovery, establishing the pulsar as a new class of astrophysical objects and paving the way for the subsequent explanation—that pulsars were rapidly rotating neutron stars.
Legacy and Recognition
In 1974, the Nobel Committee in Physics recognised Hewish and Martin Ryle "for their pioneering research in radio astrophysics: Ryle for his observations and inventions, in particular of the aperture synthesis technique; Hewish for his discovery of pulsars." Ryle's technique of aperture synthesis—combining signals from multiple antennas to simulate a single large antenna—was foundational to modern radio astronomy. Hewish's recognition for pulsar discovery was well-deserved.
Yet the absence of Jocelyn Bell's name in the citation remains contentious. Hewish was the senior researcher, the instrument's designer, and the team leader. In institutional terms, the credit followed the chain of command. But Bell was the person who recognised the anomaly in the data, who pursued it, and whose analysis helped establish the pulsar interpretation. The Nobel Prize, however, goes to senior researchers, and at that time, the practice was even more restrictive than it is today. Whether one views this as the inevitable hierarchy of scientific credit or as a missed opportunity to recognise an extraordinary junior researcher's contribution remains a matter of perspective.
For Hewish, the Nobel Prize crowned a distinguished career. He spent decades at Cambridge, eventually becoming a Fellow of the Royal Society. His work on radio scintillation and on pulsars themselves continued to influence radio astronomy for generations.
Connection to the Signal
Pulsars, through Hewish's discovery, became one of radio astronomy's most important tools. They are, paradoxically, both natural and artificial-seeming. Their signals are reliable, almost mechanical in their precision—exactly the kind of signal SETI researchers often imagine a technological civilisation might transmit. Yet they arise from purely natural processes: the rotation of a neutron star, collimated by its magnetic field, sweeping a beam of radiation across space.
The pulsar story illustrates a principle that sits at the heart of SETI: the universe is capable of producing signals that are indistinguishable from the products of intention. Distinguishing genuine technosignatures from natural phenomena requires rigorous methodology, multiple independent observations, and careful elimination of alternative hypotheses. It was Hewish's instrument, his team's vigilance, and his willingness to publish surprising results that created the pathway to understanding. That lesson—rigorous observation over speculation—remains essential to the search for signals from space.
On This Site
Antony Hewish's role in the pulsar discovery features in our story of how cosmic signals are identified and interpreted. Read about the discovery in The First Pulsar, and explore how pulsars were ultimately understood in Pulsars Explained: Cosmic Lighthouses. His work with Jocelyn Bell Burnell remains a cornerstone of radio astronomy and a model of careful, patient observation.