Texas symposium Astronomy: relativity's relative? from Virginia Trimble The uneasy marriage between general relativity and astronomy, solemnized by the biennial series of Texas Symposia on Relativistic Astrophysics, has endured another two years*, although the parties concerned continue to regard many of each others' concerns with tolerant puzzlement. The relativists, who were rather badly outnumbered on the programme, have been worrying about such issues as the logical structure of general relativity, ways of improving numerical calculations within it and possible approaches to a quantum theory of gravity that might, someday, be unified with gauge theories of the other forces. S. Deser (Brandeis University) reported progress towards demonstrating that energy, properly defined, is always positive within general relativity, so that real systems are guaranteed to have ground states and stability. The proof is essentially complete both locally and globally for cases with zero cosmological constant, A , and for global-positive A solutions. The case with negative A is still not quite fully understood, but the speaker expressed confidence that it would all turn out all right. T. Nakamura (Kyoto University) dis- cussed results of numerical solutions for the collapse (in two dimensions) of a rapid- ly rotating star, in which the matter is pro- perly included but gravitational radiation neglected. Considering the small number of grid points used, the results come impressively close to what we think should be the 'right ' answer. Thus, for several different patterns of angular momentum distribution, most of the material collapses only when the ratio of angular momentum to mass is small enough for a stable Kerr black hole eventually to result. Larger ratios always lead to much of the matter be- ing ejected, although the detailed ejection pattern is probably an artefact of the grid pattern, numerical viscosity and so on. Finally, P. Van Nieuwenhuizen (SUNY, Stony Brook) pointed out some of the pros and cons of supergravity, the extension of general relativity which adds to its gravitational field carried by gravitons a second field, carred by fermions (spin = 3/2) called gravitinos. On the plus side, it has now been demonstrated that supergravity (unlike general relativity) is renormalizable at least for all Feynman diagrams with one or two loops, though there are still some uncertainties at higher levels. A negative aspect is that it is not clear that even the largest (N = 8) supersymmetry has enough freedom to include both non-zero cosmological constant (vacuum energy) and all the kinds of fermion field we know exist. The speaker expressed guarded optimism that further significant progress could be expected, perhaps along the lines of multi- dimensional space. The astronomers, meanwhile, remain enamoured of telescopes and the objects they reveal. A half-day session addressed large ground-based optical telescopes for the late 1980s and beyond. The University of Texas 300-inch (7.6 m) project, dis- cussed by H. Smith (University of Texas), is the furthest along in funding. It will probably be a thin