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. 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 the
Einstein field equation 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. 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" 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 (1968),
Thomas Ranken Lyle Medal (1972), Member of the
American Optical Society (1974), Overseas Fellow of
Churchill College, 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==