Revealing the Universe: Prediction and Proof in Astronomy

I read this book first 20 years ago, and again about 10 year ago, and it still sits on my shelf as a useful reference with its double set of highlights. Despite being somewhat out of date, 'Revealing the Universe' is a useful text, set up in an interesting fashion. Astronomy, like all the sciences, is a tug-of-war between theoretical speculation and observational data. In astronomy, this tension is as old as the written word, if not older; how does one fit the retrograde motion of the planets in to a Ptolemaic system, for example? The tension between Tycho Brahe's observations and Copernicus' theories is a more modern example; even when personalities are not at issue (as was the case here), there is not always harmony between the theoretical and observational spheres.This book, edited by James Cornell and Alan Lightman, is a collection of essays that put together the theory and the 'facts', the observational data. As Owen Gingerich says in his essay, determining whether disagreements are due to data or theory is one of the most difficult tasks for any scientist. There are five major sections of the book, each with two essays - one from a theoretical scientist, and one from an observational scientist (leaving aside the fact there are no 'pure' theorists or observers). The five sections look at issues that are still of interest and concern in astronomy today: Einstein's space and time construct; solar system evolution; the puzzle of the Sun's corona temperature; quasars and black holes; and the age and structure of the universe. Progress has been made in each of these fields since this book was published in the early 1980s, but these essays still present for the interested layperson some of the latest information in readily accessible form, as well as background material (which largely does not change). It sets out the problems of both theory (how does one think about such things) as well as the observational issues (how does one appropriately observe and measure such things). The final chapter shows a snapshot of concerns of astronomy in the early 1980s, and shows how far we have progressed since then, with George Field's three unanswered questions: (1) are there more than nine planets in the universe? (2) are theories of stellar evolution correct? and (3) what form does invisible matter take in the universe? While each of these questions has been dealt with, sometimes in dramatic fashion (it seems rare for a week to go by of late when more extra-solar-system planets are not announced around nearby stars, for example), many of the key questions remain - how do we know what we know? A good book to have, even with its limitations.