Obituary of Sir Antony Hewish | Astronomy


In 1967, a team led by radio astronomer Antony Hewish, who died at the age of 97, discovered pulsars, fast-pulsing radio sources that turned out to be due to spinning magnetized neutron stars, the remains ultra – Dense collapsed massive stars.

It was one of the most exciting astronomical events of the second half of the 20th century: the precise synchronization of the pulses of these objects is more precise than the best atomic clocks and has enabled tests of general relativity to be accurate.

The team assembled by Hewish – Jocelyn Bell, John Pilkington, Paul Scott and Robin Collins – all played a crucial role in the detection and confirmation of the first pulsar, with attention naturally focused on Bell, the student researcher who noticed unusual signals first.

Seven years later, Hewish and Martin Ryle jointly received the Nobel Prize in Physics, “for their pioneering work in radioastrophysics: Ryle for his observations and inventions, in particular of the aperture synthesis technique, and Hewish for his decisive role. in the discovery of pulsars ”.

The invention of aperture synthesis by Ryle and Hewish in 1960, where the rotation of the Earth is used to convert a row of telescopes into a single giant circular antenna, was crucial to the development of radio astronomy. The Very Large Array in New Mexico, the Atacama Large Millimeter / submillimeter Array (Alma), the European Low-Frequency Array (Loray) and the Event Horizon Telescope used to map black holes are modern examples of their innovation.

Hewish’s early research focused on the propagation of radio waves through lumpy transparent media, and he realized in 1952 that the scintillation or flicker of recently discovered radio “stars” (actually radiogalaxies or quasars) could be used to probe conditions in the ionosphere and the interplanetary medium.

Today, these techniques are used to map the large-scale structure of the solar wind. Hewish showed that interplanetary scintillations could be used to make very high resolution observations of distant objects, equivalent to a telescope with a 1000 km baseline.

Antony Hewish speaking at the Boston Astronomers’ Conference, Lincolnshire, 1987, with a slide of the M1 Crab Nebula. Photograph: Markives / Alamy

He conceived the idea of ​​a huge phased array antenna with which a major study of radio galaxies and quasars could be done, and secured funds to build one in 1965. Bell joined his team at that time. and was responsible for analyzing the paper tape recordings of the matrix. It took them all to build the 1.8 hectare (4.5 acre) array with its 1,024 dipole antennas.

Once it was commissioned, Hewish asked Bell to create sky maps of each day’s sightings. Actual astronomical sources would reproduce at the same position in the sky every day, while human-made interference would occur at random. On August 6, 1967, Bell noticed an unusual patch of “rust” on the charts, which occasionally recurred at the same position in the sky.

Hewish decided to improve the temporal resolution of the recording equipment, which showed that the source was pulsing every 1.33 seconds. Careful work by the team showed that the source was not an instrumental effect, or due to “little green men”, but came from a source 200 light years away. Bell also discovered three other pulsars. Hewish edited the results for publication in Nature, along with Bell and the other three authors.

His interpretation was that the source had to be either a rotating white dwarf star or a neutron star. The interpretation of the neutron star was soon confirmed by the discovery of a pulsar with a much shorter half-life in the Crab Nebula. In an interview, Hewish said that when Stephen Hawking heard the news, he called to say that if neutron stars did exist, black holes were almost certain to happen as well.

Born in Fowey, Cornwall, the youngest of three sons of Frances (née Pinch) and Ernest Hewish, bank manager, Antony grew up in Newquay, where he developed a passion for swimming and boating. The family lived above the bank where his father was the manager, and Antony was allowed to set up a laboratory there. One of his first experiments with electricity blew the fuse in the whole building. At the boarding school – King’s College, Taunton – he built a crystal radio because ordinary radio was not allowed in the dormitory.

In 1942, Antony went to the University of Cambridge to study the natural sciences. His studies were interrupted from 1943 to 1946 by war work on airborne radar countermeasures devices at the Royal Aircraft Establishment in Farnborough and the Telecommunications Research Establishment in Malvern, where he met Ryle.

Returning to Cambridge in 1946, he graduated two years later and immediately joined Ryle’s research group at the Cavendish Laboratory as a research student. After obtaining his doctorate in 1952 on fluctuations in galactic radio waves, Hewish became a researcher at Gonville and Caius College, then in 1961 transferred to Churchill College as director of physics studies.

Visualization of an artist of a neutron star.
Visualization of an artist of a neutron star. Photograph: Sam Barnes / Alamy

He became a lecturer in 1961, reader in 1969 and professor of radio astronomy in 1971, until his retirement in 1989, when he was appointed professor emeritus at Cambridge. When Ryle fell ill in 1977, Hewish took charge of the Cambridge Radio Astronomy Group and ran the Mullard Radio Astronomy Observatory from 1982 to 1988.

The attribution of the Nobel Prize to Hewish and Ryle was immediately controversial, criticized, among others, by Fred Hoyle and Thomas Gold, for the exclusion of Bell, later Dame Jocelyn Bell Burnell.

Hewish was undoubtedly a major player in the work leading up to the discovery, inventing the scintillation technique in 1952, leading the team that built the network and made the discovery, and providing the interpretation as due. to a white dwarf or a neutron star. Bell herself was gracious about it, stating, “I think it would demean the Nobel Prizes if they were awarded to student researchers, except in very exceptional cases, and I don’t think that’s the case. one of them.

After the discovery of pulsars, Hewish continued his work on interplanetary scintillations and the mapping of solar wind and “interplanetary time”, which can have a dramatic effect on terrestrial communications.

In addition to being an honorary member of many foreign academies, he was made a fellow of the Royal Society in 1968 and received the Eddington Medal from the Royal Astronomical Society in 1969 and the Hughes Medal from the Royal Society in 1977. A shy and modest man, Hewish declined offers to become a master at a Cambridge university.

He believed that science and religion were complementary and that: “We should be prepared to accept that the deepest aspects of our existence are beyond our understanding of common sense. “

Antoine married Marjorie Richards in 1950 and they had a son, Nicholas, and a daughter, Jennifer, who died in 2004.

Marjorie and Nicholas survive him, along with five grandchildren and three great grandchildren.

Antony Hewish, radio astronomer, born May 11, 1924; passed away on September 13, 2021

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