C. W. Kilmister

Can one explain the recently discovered quasars as objects thrown from exploding nebulae? Are pulsars rapidly rotating neutron stars, so dense that a thimbleful of their matter would weigh more than ten million tons? or could a star collapse into a 'black hole' in space, leaving no trace other than an intensely strong gravitational field? These are some of the perplexing questions now facing cosmologists. How such questions relate to modern theories of the universe is the main theme of this book. The author prepares the ground for his central discussion with a historical survey of relevant scientific developments from earliest times, and concludes with some thoughts on the intractable problem of reconciling the worlds of the astronomer and nuclear physicist in a single comprehensive theory.… (altro)

This book has two parts. The second part consisits of some reprints of papers that are relevant to general relativity theory. The first part is an introduction to general relativity and an explanation of how those papers reprinted in the second part fit in to the whole picture.

The first part reads more like a Scientific American article and is very easy to read, possibly because at the time the book was published (1973) most people were totally unacquainted with general relativity. The author gives a very good intuitive explanation of many points which are glossed over in later books. The basic ideas behind the Petrov classification is an example of one of these points.

Highlights of the reprint section include a paper by Riemann (translated by W. K. Clifford) which gives Riemann's orginal ideas on the possible physical significance of Riemannian geometry. Riemann points out that we can by experiment determine the geometry of space on the middle scale in which we live, but the geometry of space on the infinitely large scale and the infinitely small scale would be very challenging. Indeed, interest has now focused on the large (cosmology) and given up on the infinitely small. The latter is now given over to quantum theories which essentially hide the details. A reprinted part of a paper by Clfford provides an example what might be done in the latter context. He presents a view that all matter and its actions are describable in terms of extremely small variations in the geometry of space.

Another reprinted paper by Einstein presents elaborates on that theme. In this paper (summarizing work from the thirties and fourties) it is shown that the motion of particles (represented by singularities) in response to force fields can be accounted by the interaction of the fields. The mathematics of this interaction is accomplished by surface integrals over very small spherical surfaces surrounding (and thus isolating) the singularity. A similar idea was presented by Weyl about 1925 and is called the agens theory of matter. It would be interesting to know the interaction of Weyl and Einstein on this subject.

This book is an interesting sidelight on the development of general relativity.… (altro)