Hans Adolf Buchdahl (7 July 1919 – 7 January 2010) was a German-born Australian physicist. He contributed to

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

thermodynamics Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...

and

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultrav ...

. He is particularly known for developing

f(R) gravity () is a type of modified gravity theory which generalizes Einstein's general relativity. () gravity is actually a family of theories, each one defined by a different function, , of the Ricci scalar, . The simplest case is just the function bei ...

and Buchdahl's theorem on the Schwarzschild's solution for the inside of a spherical star.

Biography

Hans Adolf Buchdahl was born in

Mainz Mainz () is the capital and largest city of Rhineland-Palatinate, Germany. Mainz is on the left bank of the Rhine, opposite to the place that the Main joins the Rhine. Downstream of the confluence, the Rhine flows to the north-west, with Ma ...

, Germany, in a Jewish family (he used the spelling Adolph to dissociate himself from Hitler). His older brother Gerd Buchdahl was a well-known philosopher in science. In 1933, Gerd took Hans with him to England, to escape the Nazi government. At London, he completed a BSc and received the Associate of the Royal College of Science (ARCS) from Imperial College. When

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

began, the UK government, unable to determine individual allegiance, interned German nationals including many Jewish refugees already fully assimilated. In July 1940, Hans came to Australia together with Gerd on board the

HMT Dunera HMT (Hired Military Transport) ''Dunera'' was a British passenger ship which, in 1940, became involved in a controversial transportation of thousands of "enemy aliens" to Australia. The British India Steam Navigation Company had operated a pr ...

. He was detained initially at Hay in New South Wales, then at the Tatura centre in Victoria in May 1941. Once his mathematical abilities had been recognised there, he was released on a guarantor program and was transferred to the Physics Department of the

University of Tasmania The University of Tasmania (UTAS) is a public research university, primarily located in Tasmania, Australia. Founded in 1890, it is Australia's fourth oldest university. Christ College, one of the university's residential colleges, first prop ...

in Hobart. There he had to assist the overloaded teaching staff involved in wartime military research in optics. In 1949, he received his doctorate from University of Tasmania. In 1956, he was awarded a D.Sc. from Imperial College London. From 1963 he was professor and head of the Department of Theoretical Physics in the Faculty of Science at the

Australian National University The Australian National University (ANU) is a public research university located in Canberra, the capital of Australia. Its main campus in Acton encompasses seven teaching and research colleges, in addition to several national academies an ...

in Canberra until his retirement in 1984–1985. He married Pamela Wann in 1950 and they had three children. He died in Adelaide, Australia, on 7 January 2010.

Works

When working at the Waterworth Hobart Annexe, Buchdahl found the formulas for optical aberration coefficients taken to high orders that the Waterworth group used in designing imaging systems. These formulas were later applied worldwide, including in systems carried by satellites. At the same time, he also continued research in general relativity and classical thermodynamics. His first interest in thermodynamics focused on fitting Carathéodory's axiomatic formulation better to a physicist's intuition. Buchdahl's attempt at making the foundations of

more concise was far from advertising the use of the axiomatic method; instead it was an endeavour allowing "physical intuition to take precedence over mathematical niceties". Buchdahl's interest in

tensor In mathematics, a tensor is an algebraic object that describes a multilinear relationship between sets of algebraic objects related to a vector space. Tensors may map between different objects such as vectors, scalars, and even other tensor ...

and

spinor In geometry and physics, spinors are elements of a complex vector space that can be associated with Euclidean space. Like geometric vectors and more general tensors, spinors transform linearly when the Euclidean space is subjected to a sligh ...

analysis was related to dealing with formalisms and calculational procedures, be it spherical and spheroidal harmonics. While working with Weyl's theory and quadratic Lagrangians, he decided to present the Euler–Lagrange derivative of the most general Lagrangian built from the metric, the curvature tensor and its derivatives to arbitrary order. However, he did not use spinors as an important tool in general relativity, e.g., for the study of gravitational radiation and null infinity. In gravitational theory, Buchdahl's contribution on

Einstein field equation In the general theory of relativity, the Einstein field equations (EFE; also known as Einstein's equations) relate the geometry of spacetime to the distribution of matter within it. The equations were published by Einstein in 1915 in the form ...

or scalar-tensor theory are almost as well known as his spherically symmetric solutions describing the interior of stars. From his work on higher-order Lagrangians he concluded that theories with quadratic Lagrangians or f(R)-theories are unphysical.Buchdahl, H.: ''The Concepts of Classical Thermodynamics''. Cambridge University Press, Cambridge (1970); private communication, 15 July 1977 When Einstein was still alive, as with many other theorists Hans Buchdahl could not escape the lure of the famous scientist's "

unified field theory In physics, a unified field theory (UFT) is a type of field theory that allows all that is usually thought of as fundamental forces and elementary particles to be written in terms of a pair of physical and virtual fields. According to the modern ...

" of gravitation and electricity. However, as Buchdahl's papers in this field show, he was attracted by the enlarged constructive possibilities of the more general geometries, not by any hoped-for physics behind the theory. As shown in his "17 simple lectures", his understanding of general relativity made him clearly stay away from and criticise the parlance of the mainstream following J. A. Wheeler when speaking of "mass-energy curving space", " black hole" (in place of the physically more appealing "occluded star", or "frozen star") and, in the frame of quantum gravity, of "foamlike 3-geometry". He was honoured by grants, prizes, medals, and memberships, to list some of them:

Fellow of the Australian Academy of Science The Fellowship of the Australian Academy of Science is made up of about 500 Australian scientists. Scientists judged by their peers to have made an exceptional contribution to knowledge in their field may be elected to Fellowship of the Academy ...

(1968),

Thomas Ranken Lyle Medal The Thomas Ranken Lyle Medal is awarded at most every two years by the Australian Academy of Science to a mathematician or physicist for his or her outstanding research accomplishments.

(1972), Member of the American Optical Society (1974), Overseas Fellow of

Churchill College Churchill College is a constituent college of the University of Cambridge, England. It has a primary focus on science, engineering and technology, but still retains a strong interest in the arts and humanities. In 1958, a trust was establish ...

, Cambridge (1979), Walter Burfitt Medal (Roy. Soc. NSW) (1980), C. E. K. Mees Medal (Opt. Soc. Amer.) (1993), A. E. Conrady Award (Int. Soc. Opt. Eng.) (1997).

Publications

Books

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Selected papers

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References

{{DEFAULTSORT:Buchdahl, Hans Adolf 1919 births 2010 deaths 20th-century Australian physicists Fellows of the Australian Academy of Science Academic staff of the Australian National University Academic staff of the University of Tasmania Alumni of Imperial College London British emigrants to Australia Naturalised citizens of Australia Jewish emigrants from Nazi Germany to the United Kingdom People interned during World War II Prisoners and detainees of the United Kingdom