Antony Hewish (1924–2021): Architect of the Pulsating Universe
Antony Hewish was a pioneer of British radio astronomy whose work fundamentally altered our understanding of the extreme states of matter and the scale of the universe. While his name is inextricably linked to the discovery of pulsars—a breakthrough that earned him the Nobel Prize—his broader career at the University of Cambridge helped transform radio astronomy from a niche offshoot of radar technology into a cornerstone of modern astrophysics.
1. Biography: From Radar to the Stars
Early Life and Education
Antony Hewish was born on May 11, 1924, in Fowey, Cornwall. The son of a banker, he grew up with a natural affinity for the coast, which sparked a lifelong passion for sailing. He began his undergraduate studies at Gonville and Caius College, Cambridge, in 1942, but his education was interrupted by the exigencies of World War II.
The War Years
From 1943 to 1946, Hewish contributed to the war effort at the Royal Aircraft Establishment in Farnborough and the Telecommunications Research Establishment at Malvern. Here, he worked on radar countermeasures. Crucially, this was where he met Martin Ryle, the man who would become his long-term collaborator and the visionary behind Cambridge’s radio astronomy program.
Academic Trajectory
Returning to Cambridge in 1946, Hewish completed his degree and joined Ryle’s research team at the Cavendish Laboratory. He earned his PhD in 1952. Hewish spent his entire professional life at Cambridge, serving as a Fellow of Churchill College and eventually succeeding Ryle as the Professor of Radio Astronomy (1971) and Director of the Mullard Radio Astronomy Observatory (1982–1988).
2. Major Contributions: Scintillation and Pulsars
Hewish’s primary intellectual contribution was the development of techniques to observe the "invisible" universe through radio waves.
Interplanetary Scintillation (IPS)
In the early 1960s, Hewish realized that the "twinkling" of distant, compact radio sources was caused by plasma clouds in the solar wind. He developed the theory of Interplanetary Scintillation (IPS), which allowed astronomers to measure the size of distant radio sources and study the solar wind itself. To exploit this, he designed and secured funding for the Interplanetary Scintillation Array, a massive radio telescope covering four acres at Lord’s Bridge, consisting of over 2,000 dipole antennas.
The Discovery of Pulsars (1967)
In 1967, while using this array to study quasars, Hewish’s PhD student, Jocelyn Bell Burnell, noticed a "bit of scruff" on the chart recordings. Hewish initially dismissed it as man-made interference, but Bell Burnell’s persistence showed it was a celestial signal pulsing with incredible regularity (every 1.33 seconds).
Hewish led the subsequent investigation, ruling out terrestrial interference and even briefly considering the "Little Green Men" (LGM-1) hypothesis—the idea that the signals were extraterrestrial beacons. He eventually concluded these were natural phenomena. These sources were named pulsars (pulsating radio stars), later identified as rapidly rotating neutron stars. This discovery provided the first observational evidence that neutron stars—objects so dense that a teaspoon of their material would weigh billions of tons—actually existed.
3. Notable Publications
Hewish authored hundreds of papers, but several stand as landmarks in the history of physics:
- "The diffraction of radio waves in passing through a phase-changing ionosphere" (1951): An early foundational paper on how radio waves interact with the Earth's atmosphere.
- "Observation of a Rapidly Pulsating Radio Source" (Nature, 1968): Co-authored with Bell, Pilkington, Scott, and Collins. This paper announced the discovery of pulsars to the world and is considered one of the most significant physics papers of the 20th century.
- "Pulsars and High Density Physics" (1975): His Nobel lecture, which synthesized the discovery with the broader implications for nuclear physics and general relativity.
4. Awards & Recognition
Antony Hewish received the highest honors available to a scientist:
- Nobel Prize in Physics (1974): Shared with Martin Ryle "for their pioneering research in radio astrophysics... and for his decisive role in the discovery of pulsars." This was the first Nobel Prize ever awarded for observational astronomy.
- Eddington Medal (1969): Awarded by the Royal Astronomical Society.
- Hughes Medal (1977): Awarded by the Royal Society.
- Fellow of the Royal Society (FRS): Elected in 1968.
- Honorary Degrees: Received from several universities, including Manchester, Exeter, and Leicester.
5. Impact & Legacy
The "Pulsar Era"
The discovery of pulsars opened a new window into the universe. Pulsars have since been used as "cosmic clocks" to test Einstein's Theory of General Relativity, detect gravitational waves, and even find the first exoplanets.
The Nobel Controversy
Hewish’s legacy is often discussed in the context of the "Bell Burnell controversy." Many astronomers, including the famed Fred Hoyle, argued that Jocelyn Bell Burnell should have shared the Nobel Prize, as she was the one who first spotted the signal. While Hewish maintained that he was responsible for the telescope's design and the overall research program, the debate fundamentally changed how the Nobel Committee views the contributions of students and collaborators, leading to a more inclusive approach in later decades.
6. Collaborations
- Martin Ryle: Together, they built the Cambridge radio astronomy group into a world leader. Ryle provided the interferometry techniques, while Hewish focused on the physics of the medium and the sources.
- Jocelyn Bell Burnell: As his graduate student, her meticulous data analysis was the catalyst for the pulsar discovery.
- The Mullard Group: Hewish mentored a generation of radio astronomers who went on to map the cosmic microwave background and study galaxy evolution.
7. Lesser-Known Facts
- LGM-1: Before the term "pulsar" was coined, Hewish and Bell Burnell referred to the signal as "LGM-1" (Little Green Men). Hewish was genuinely concerned about the ethical implications of announcing a signal from an alien civilization.
- Science and Faith: Hewish was a person of faith. He often spoke about the compatibility of science and religion, stating,
"The ghost in the machine is the most important part of the machine."
He was a member of the International Society for Science and Religion. - Sailing: An expert sailor, Hewish often compared the "noise" of the ocean to the "noise" of the radio sky, finding a poetic symmetry between his hobby and his research.
- Persistence of Paper: At the time of the pulsar discovery, the data was recorded on miles of paper charts. Hewish and his team had to analyze these by eye, a task that would be handled by AI today.
Antony Hewish passed away on September 13, 2021, at the age of 97. He remains a towering figure who bridged the gap between the radar technology of WWII and the high-energy astrophysics of the 21st century.