Professor Mark Birkinshaw
OP 1972
4 December 1954 - 23 July 2023

With our thanks to Clive Barrett, Tim Hollins and Chris Stanley (all from the Class of 1972)

With a love of physics nurtured by his time at PGS, Mark Birkinshaw was regarded by his academic peers as “a remarkable scientist, perhaps the leading British radio-astronomer of his generation.” Even more importantly, he was also described by colleagues and friends alike as “kind,” “happy,” “honest,” “refreshing,” and with a good sense of humour. He was not only academically brilliant, he was a warm and caring person, too. For those of us who have stayed close to Mark over 50 years, his tragically early death, at 68, from pancreatic cancer, has ended one of our longest friendships.

Mark’s parents moved to the south coast from London, where Mark had been born in December 1954. In 1966, in the Direct-Grant era, he obtained a Hampshire County Council place at PGS, the start of six years of long daily commuting, by bus and train, from Hayling Island to Old Portsmouth.

For those of us lucky enough to be his friends, he was a source of assurance; invariably he would grasp a subject before we did, and he had the skill to be able to explain it clearly so we could understand it better. Even at school he was nicknamed “Prof.” His Physics Master, Mr Hornby, recognized Mark as "the most outstanding and promising science scholar that I have ever taught in almost thirty years of science teaching." In PGS, Mark also played bridge, chess and Mah Jongg, and belonged to the British Association of Young Scientists. As Acting Headmaster, Mr Thorp, wrote in 1972, Mark had “a most pleasant and open personality; there is an air of easy confidence about him which enables him to mix well with his fellows but nothing ostentatious in his make up or manner to indicate his brilliance.”

From PGS, he won a scholarship to read Natural Sciences at St John’s College, Cambridge, where he thrived, following up a First in Theoretical Physics with a Ph.D. in the radio and X-ray properties of clusters of galaxies. He had the qualities needed for disciplined, patient, innovative research: curiosity, collegiality, dedication, and an encyclopedic knowledge of physics and mathematics. He held research and teaching posts at Berkeley, Cambridge (again), Harvard and the Smithsonian, before, in 1995, becoming Professor of Cosmology and Astrophysics at Bristol University, his principal base for the next 28 years. Concurrently, he also had a post at a research university in Gothenburg.

Colleagues recall not only the brilliance of his research, but also the qualities he brought to teaching: the clarity with which he taught 4th year undergraduates general relativity and cosmology; the care, respect and infectious enthusiasm he shared with his Ph.D. students; and the passion he showed to amateur local astronomy groups.

He produced over 250 refereed papers, of which the most cited concerned his observational verification of the Sunyaev-Zeldovich (SZ) effect. In the early 1980s, Mark and colleagues used the Owens Valley radio telescope in California to measure the cosmic microwave background (CMB) which is the remnant radiation of the big bang. According to two Soviet scientists, the CMB should be slightly cooler in the direction of rich clusters of galaxies. Mark’s results showed that the CMB was indeed one thousandth of a degree Kelvin colder than elsewhere. Mark further used the SZ effect to measure the size of the Universe to a new level of accuracy, developing an entirely independent method of measurement.

With a reputation for clear, forensic critique, Mark was held in high regard within the scientific field and was regularly called upon to be a senior reviewer of major projects. He chaired the UK Research Council’s oversight committees on future international facilities for gamma-ray and radio astronomy.

Mark married astrophysicist Diana Worrall in 1984.  Together over many years they researched radio-galaxies, black holes and the radio jets they produce that stretch thousands of light years from their source. They shared not only academic research but also travel and companionship, and for the last two decades the life of their community in Long Ashton, North Somerset.

For all his academic prowess, Mark was a gentle, modest, and kind man. He was quiet, humble, not one to crave the crowds or to push himself forward to become the focus of attention. His love of learning was lifelong and broad, his expertise ranging from bellringing at the local church to the Chinese language. His interests were broad, his travels wide, and he was a prolific reader. He would cook and play occasional golf.

With his distinctive tiny but elegant handwriting, he ensured he kept up to date with his friends over the years. In January 2023, Mark was in a group of four of us who dined in London to commemorate the 50th anniversary of our leaving PGS. We envisaged many more occasions to reminisce, but six months later Mark learned that he had contracted terminal pancreatic cancer, and he died very quickly at the Bristol Royal Infirmary. It was typical of him that as soon as he knew himself he wrote to let us know of his diagnosis.

The scientific community has lost an inspirational colleague, Diana a loving husband, and we a valued friend.