This volume tells the untold story of how observations of the cosmic microwave background radiation were interpreted in the decades following its serendipitous discovery, before the Hot Big Bang model became the accepted orthodoxy. The authors guide the reader through this history, including the many false trails and blind alleys that occurred along the way. Readers will discover how the Big Bang theory was shaped by alternative theories that exposed its weaknesses – including some that persist even today. By looking carefully at what it takes to reject an incorrect theory and the assumptions and processes at each stage, the authors examine the epistemological factors at play between an emerging scientific orthodoxy and since discarded alternatives. Their analysis of the cosmic microwave background provides a uniquely well-documented case study of theory building for a wide readership spanning cosmology, the history of physics and astronomy, and the philosophy of science more broadly.

‘The Cosmic Microwave Background by Slobodan Perovic and Milan M. Cirkovic is a very welcome addition to the recent literature on the history and philosophy of experiment. The central focus is on the role that the discovery of the Cosmic Microwave Background (CMB) played in the establishment of the currently accepted ‘hot big bang’ theory of the origin of the universe. The authors also devote considerable discussion to the explanations of the CMB provided by alternative models of the origin, illustrating the complex relation between evidence and theory in cosmology. The discussion of the historical and philosophical issues is clear and well-written and will be understandable and valuable to those who are not expert in physics and cosmology. I strongly recommend it.’

Allan Franklin - University of Colorado, Boulder

‘Perović and Ćirković weave a fascinating and nuanced tapestry of history and epistemology. Not only is the historical narrative valuable in its own right, but the book really shines because of the pay-offs for both philosophers and physicists that arise from its rich historical analysis. The real story of the cosmic microwave background, in all its gritty detail, ultimately provides an even stronger methodological underpinning than the pristine textbook version that the authors set out to rectify.’

Niels Martens - Utrecht University