Beatrice Hill Tinsley was an English-born, New Zealand-educated, theoretical astrophysicist and cosmologist. Through her research in the United States in the 1960s and 1970s, she proved that the universe was infinite and would expand forever. She also synthesised research by theoretical and observational astronomers to show that galaxies evolve and interact with each other, pioneering a new field of research. As well as being a scholar who published more than 100 papers, she was an excellent teacher, mother to two children, and a violinist.
Beatrice Muriel Hill was born on 27 January 1941 at Chester, in the north-west of England. She was the middle of three daughters born to Jean O’Hagan Morton and her husband Edward Owen Eustace Hill. Jean and Edward were from privileged upper-class families, and met through their involvement in Moral Re-Armament, a charismatic religious movement whose members lived by the Four Absolutes: Absolute Love, Absolute Purity, Absolute Honesty and Absolute Unselfishness. Edward, who had an MA in history from Oxford, and had also studied theology and law, served in England during the Second World War.
After the war, Edward and Jean began to consider moving overseas to escape post-war scarcity and rationing, bouts of whooping cough and chickenpox, and dissatisfaction with their extended families. Following a chance meeting with a New Zealand expatriate, in 1946 the family emigrated to Christchurch where Edward had a job as an Anglican curate. The family spent four years in the South Island, where Beatrice – called ‘Beetle’ by her family – first attended St Margaret’s College, the diocesan school for girls. From 1948, when Edward became vicar in the small country town of Southbridge, the girls went to Southbridge Primary School.
In 1950 the family moved to New Plymouth, where Edward worked first as a clergyman then as mayor of New Plymouth (1953–6), followed by a further term on the New Plymouth Borough Council (1956–9). The Hills were seen as glamorous, wealthy and upper-class.
The girls attended New Plymouth Central Primary School and New Plymouth Girls’ High School, where Beatrice excelled in all academic subjects as well as music; she gained the form prize each year, along with prizes in piano and violin. She was an intense and intelligent student and, as a teenager, began asking the big questions, seeking answers from science rather than her parents’ religion. She joined her school’s astronomy club and was inspired by reading Fred Hoyle’s book The nature of the universe. In 1957, her final year at school, Beatrice studied mathematics, chemistry, physics and English. She was dux of her school and won a Junior University Scholarship, one of 10 on offer for the whole country.
In 1958, Beatrice began studying maths, physics, and chemistry at Canterbury University College. As well as excelling in her studies she took part in cultural and social activities, joining the university’s Socratic Society, going to balls and rock and roll dances, taking winter journeys to a university lodge at Arthur’s Pass and playing in both a local chamber music group and the National Youth Orchestra.
Beatrice met Brian Alfred Tinsley, a postgraduate student in physics, at the Socratic Society; by that time she had already decided she wanted to be a cosmologist. She graduated in 1961 with a BSc in physics and was awarded a Senior Scholarship. She wanted to do a Master’s thesis on a topic in cosmology, but with no appropriately qualified supervisors she settled for a solid-state physics project.
On 13 May 1961, Beatrice and Brian were married at St Aidan’s Church in Miramar, Wellington; Beatrice was 20 years old, Brian 23. They set up house in central Christchurch. Although they were both postgraduate students, Beatrice took on the traditional wife’s role, taking responsibility for shopping, cooking and cleaning. She also earned money teaching science at Christchurch Girls’ High School, doing some short-term work in the university’s physics department, and private tutoring. As friends and colleagues noted throughout her life, she was never idle, and she also made time for volunteer work at the New Zealand Family Planning Association.
Beatrice completed her MSc in 1962. She got straight A’s in her exams and won all the prizes available in her year: the Haydon Prize for Physics, the Cook Memorial Prize, the Warwick House Prize, the Memorial Scholarship and a Postgraduate Scholarship. She was outraged to discover that an anti-nepotism rule meant that because Brian had a position at the University of Canterbury, she would never be offered anything other than short-term contracts there.
In 1963, Brian and Beatrice moved to Dallas, Texas, for Brian to take up a research position at the Southwest Center for Advanced Studies – later known as the University of Texas, Dallas (UTD). Beatrice decided it was time to have children, but their attempts to conceive were unsuccessful. With no career opportunities in Dallas, Beatrice enrolled for a PhD in a small astronomy department at the University of Texas at Austin (UTA), under Dr Rainer Sachs. She commuted, more than 300 kilometres each way.
A gynaecologist had told Beatrice she was unlikely to ever get pregnant, and she and Brian decided to adopt. An opportunity arose earlier than they had planned: a relative of Brian’s was pregnant. The boy, who they named Alan Roger, was born on 28 August 1966. Beatrice and Brian adopted him in New Zealand and returned with him to Dallas.
Beatrice had completed most of the research for her thesis before Alan’s arrival, but now had to juggle parenting with writing. She submitted in late 1966 and passed her oral exam in December. Her thesis, ‘Evolution of galaxies and its significance for cosmology’, aptly displayed Beatrice’s talent for synthesising information to draw new conclusions about the nature of the universe.
In 1967, now as Dr Beatrice Tinsley, she presented her research on the evolution of galaxies at a major cosmology conference in New York. Here she met James Gunn, a young astronomer from California Institute of Technology who was to become a key collaborator, friend, and later lover. When leading Caltech cosmologist Allan Sandage gave a talk at the UTA, Beatrice questioned his assertion that the universe was a closed system and would eventually collapse. The confrontation started an ongoing scientific feud between the two scholars, ultimately settled in Beatrice’s favour, which would help define her career. Beatrice demonstrated in a 1968 paper that galaxy evolution was an observable phenomenon, spawning a whole new subfield in extragalactic astronomy.
Beatrice and Brian adopted a baby girl, whom they named Teresa Jean, in 1968. Now juggling her scientific work – reading and writing papers, going to conferences when she could, some teaching – and childcare, Beatrice continued her interest and involvement in music and community work. She joined the Richardson Symphony Orchestra, volunteered with Planned Parenthood (a non-profit organisation providing reproductive healthcare), and became secretary of the Dallas chapter of Zero Population Growth, a political movement aimed at stabilising the world population. With her commitment to Zero Population Growth, and two children already, she travelled to New York to have an abortion when she unexpectedly became pregnant (with Brian’s permission, which was legally required).
Once the children started school and preschool, Beatrice could devote her mornings to work. She read the latest astronomy and cosmology books and articles, wrote papers and attended conferences. In 1970 Brian was promoted to associate professor (a tenured position) at the UTD, where nepotism rules still prohibited Beatrice from being eligible for a permanent position so long as her husband worked there. She came to rely on grants and temporary and part-time contracts.
Beatrice’s reputation was growing and she was soon being offered opportunities outside Dallas. In 1972 she and the children moved temporarily to California, where she took a three-month appointment at Caltech. In 1973 she took a six-month position in the astronomy department at the University of Maryland and travelled there with the children (Brian had refused to let her accept their offer of an 18-month position). Later that year she started a half-time position as assistant professor of astronomy at UTA, with a weekly commute by air from Dallas. In 1974 Beatrice was awarded the Annie Jump Cannon Award, a prize for female astronomers working in the United States.
There were no career opportunities for Beatrice in Dallas, and she was cut off from other people working in her field. Her proposals to develop and lead an astronomy department at UTD were unsuccessful. Her relationship with Brian, who was often away, had been strained for years, and the couple divorced in 1974. It was clear to Beatrice that to continue her research she would have to leave Dallas. She wanted custody of the children, but rather than fight Brian in court, she agreed to leave them with him.
In late 1974 she accepted an associate professorship in the astronomy department at Yale University, in Connecticut, where she could work with an existing collaborator, Richard Larson. She left her family on Christmas Day for a 2300-kilometre drive to Pasadena, California, to collaborate with Gunn. She then took up a six-month position as assistant research astronomer and lecturer at Lick Observatory in Santa Cruz before making her way to Yale.
At Yale, Beatrice realised her life’s goal by becoming a cosmologist with a full-time and permanent position whose work was recognised and applauded. She was a theoretic astrophysicist rather than an observer, using a computer rather than a telescope. Her work bridged the gap between other theoreticians and observational astronomers by looking at the entire life cycle of galaxies from birth (usually the realm of theorists) to maturity (generally the focus of observers). Her research covered star formation, stellar evolution and galactic evolution. Her research collaborations with Gunn, which focused on the life history of stars forming in a galaxy, concluded that rather than having constant luminosity, galaxies become dimmer with age. This finding had implications for understanding the expansion rate of the universe, which was often computed by assuming that nearby and distant galaxies had the same intrinsic luminosity and their distance could be deduced from their apparent brightness.
In 1974 she was one of four authors of an important paper, ‘An unbound universe’, published in the Astrophysical Journal. The previous consensus, espoused by Allan Sandage among others, was that the universe was ‘closed’ and would only expand to a certain point before collapsing in on itself. Tinsley and her co-authors demonstrated that the data showed that the universe was ‘open’ and would expand indefinitely.
One of Beatrice’s many enthusiasms was interpreting science for a non-scientific audience. In 1976 she co-authored a Scientific American article, ‘Will the universe expand forever?’ While it had already been established that the universe was expanding, this article presented evidence from the age of stars, the mass of galaxies, the abundance of chemical elements and the observed rate of the expansion of the universe to support a cosmological model of ‘a universe that is infinite in extent and that will expand forever.’1
In 1978 she and Larson published ‘Star formation in normal and peculiar galaxies’ in the Astrophysical Journal. This paper showed that star formation was triggered by the merging of galaxies. Over time, Larson become Beatrice’s close friend, lover and partner. He shared her passion for both science and music, and they played chamber music together.
In early 1978, not long before she was promoted to full professor, Beatrice discovered a bleeding mole on the side of her leg. A biopsy revealed melanoma, a virulent form of skin cancer. In the three years that followed, Beatrice had further surgeries and chemotherapy. Teresa joined Beatrice at Yale and attended boarding school at the nearby Cheshire Academy.
Beatrice continued working even when bedridden in the Yale Infirmary, and when paralysis affected her right side she learned to write with her left hand. Her last year of life, 1980, was her most productive: she published 10 papers, including a 100-page review paper, ‘Evolution of the stars and gas in galaxies’. Published in Fundamentals of cosmic physics, this now has more than 1000 academic citations. Beatrice also supervised postgraduate students and, once she realised she had little time left, wrote references for her past students. She died on 23 March 1981, aged 40.
In an obituary published in the Quarterly Journal of the Royal Astronomical Society, Richard Larson and Linda Stryker, one of Beatrice’s PhD students and a close friend, described her ‘joy in the pursuit of knowledge, and the enthusiasm that she transmitted to others’ and praised her professional ‘vigour, astuteness and uncompromising standards.’2
In the decades after her death, Beatrice Tinsley was not well known outside astronomical circles. She did, however, write numerous letters, and these were used as a basis for two biographical accounts of her life – her father’s My daughter Beatrice, published in 1984, and Christine Cole Catley’s Bright star, published in 2006 – and for a 20-part Radio New Zealand radio series, ‘The stars are comforting’, and a play, also called Bright star.
She is remembered by the American Astronomical Society’s Beatrice M. Tinsley Prize for outstanding creative or innovative contributions to astronomy or astrophysics, and the Beatrice M. Tinsley Centennial Visiting Professorship in Astronomy at the University of Texas, Austin. In 2010 the New Zealand Geographic Board named a Fiordland mountain in her honour. Also named after her are an asteroid, a Royal Astronomical Society of New Zealand lecture series, a New Zealand Association of Scientists award and a building at the University of Canterbury.