The death of Dr John Stewart

Dr John Stewart 1 July 1943–14 November 2016

 

John’s funeral took place on Wednesday 30 November 3 p.m. Crematorium West Chapel

We are saddened to report the death of Dr John Stewart, Fellow of King’s and an Emeritus Reader in Gravitational Physics.

Born in Pinner, John was educated at Latymer Upper School and studied at Jesus College Cambridge, receiving his BA in 1965. From 1968–71 he was a Junior Research Fellow at Sidney Sussex College, subsequently moving to Munich where he was Research Associate at the Max Planck Institute. On his return to Cambridge in 1975, John was appointed Senior Research Fellow, then subsequently Fellow and College Lecturer in 1978, two years after his appointment as University Lecturer in Applied Mathematics.

Professor Michael Proctor, Provost of King’s, writes:

‘John retired as Reader in Gravitational Physics in 2010, but continued to be active in the College and Department until the week before his death. His work on numerical relativity was much admired, but he will be best known to generations of Mathematics students at King’s and elsewhere as a patient, careful and meticulous teacher, able to bring illumination to the most difficult of subjects. He took a keen and thoughtful interest in the College’s finances and served on the Investment and Finance Committees and as Inspector of Accounts.  He was also very fond of the musical life of the College and was a regular attender at concerts. His expertise will be much missed. He leaves a widow, Mary, a Fellow of Robinson College.’

Professor Paul Shellard, Department of Applied Mathematics and Theoretical Physics, reflects on John’s career and his achievements:

‘John Stewart was a student of Dennis Sciama and then George Ellis,
graduating with his PhD from the Department of Applied Mathematics and Theoretical Physics (DAMTP) in 1969. He was appointed as a DAMTP Lecturer in 1976. He was universally admired as a superb teacher by successive generations of students throughout his career, mainly because of his careful and systematic style, as well as his good sense of humour. John pioneered research in numerical relativity in Cambridge over many years, with a number of students continuing to pursue these interests in academic posts around the world, including Ian Hawke (Southampton), Oliver Rinne (AEI) and Luke Drury (Dublin IAS). One of his most influential students is the relativist Ruth Gregory (Durham).

Research activity in numerical relativity remains vibrant in DAMTP and, of course, John was very interested in the LIGO announcement early this year of the discovery of gravitational waves. He made many contributions to relativistic hydrodynamics, including his 1971 book, Non-equilibrium relativistic kinetic theory (in the Lecture Notes in Physics series). For example, in 1967 with Dennis Sciama, he studied the detailed form of temperature variations expected in the CMB due to our motion relative to its isotropic frame. In 1967, with George Ellis, he found a family of perfect fluid and magnetic LRS exact anisotropic cosmological solutions of Einstein's equations that have been important in the study and classification of spatially homogeneous universes.

From 1969–1971 John studied the role of collisionless particles and non-equilibrium behaviours in anisotropic universes and the differences between the behaviour of collisionless particles and that of simple fluid viscosities. This was needed for a detailed analysis of Misner's chaotic cosmology programme. In particular, he showed that a bouncing universe would increase its entropy with each cycle, so could not be eternal to the past.  John also pioneered the use of phase plane methods in studying the qualitative dynamics of homogeneous cosmologies.

In 1979 with Werner Israel, John developed a comprehensive theory of causal thermodynamics to handle close to equilibrium behaviour in general relativity, including bulk and shear viscosities, heat conduction and shock wave formation. He also made substantial advances in relativistic perturbation theory, both for cosmology and around black hole spacetimes. He was one of the first to point out the scalar-vector-tensor decomposition of linear perturbations. He studied gravitational waves, gravitational shock waves, and initial value problems, as well as numerically solving gravitational collapse problems in spherically and axisymmetric contexts.  He also studied bubble collisions in an inflationary universe, the measure problem and related problems in quantum cosmology. In 1991 he published Advanced General Relativity in the Monographs in Mathematical Physics series published by Cambridge University Press.

Following retirement, John wrote a book on computing, Python for Scientists, and he was nearing completion of a much larger and extended version about scientific applications using Python.’

15 November 2016