E. Elizalde - The true story of modern cosmology : origins, main actors and breakthroughs

Based on a translation of the book Cosmologa moderna desde sus orgenes (c) Los Libros de la Catarata, Madrid (2020)

Cover Image Credit:

Front Cover: Westerlund 2. Credit. NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team

Back Cover: A Deep Look into a Dark Sky. Credit ESO

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Having left behind a substantial part of my scientific life, initiated my emeritus period, and feeling an imminent need to respond without further delay to the insistent requests of an ever-growing number of colleaguesto write down those nice talks of yoursI eventually found in the COVID-19 pandemic the golden opportunity I was looking for. Since the middle of March 2020, I have been able to use most of my time to compile and bring together what I have learned in those many years of work at the frontier of knowledge, to compose an all-inclusive story, to find its deepest meanings, and to finally set everything in the plainest, most intelligible way I can. During this time, I could not stop writing, correcting, and rewriting again, night and day. The result is this book, which is not very thick, actually.

And it is at that point, when you feel trapped in the middle of a project like the presenthaving committed yourself to the search for the origins of everythingthat you soon realize the necessity to explain, along the way, a number of not-so-simple concepts. Some are particularly difficult to graspand this with almost no equations, as required for a popular book. Certainly, everybody can find all these definitionsalthough not necessarily very well explained, in factin the abundant outreach bibliography, which grows endlessly day by day. And very soon, it becomes clear that what we are trying to do here would best be left to specialists, the really competent fellows in such complex matters. But those who really know all the intricacies of the subject rarely have time to devote to such a commendable purpose, since they spend all the time they have on their everyday work at the forefront of knowledge.

Achieving wisdom, in whatever subject, is a noble goal and one that can often lead to addiction. Particularly in the case at hand, in the study of the Universe, our extended home as intelligent beings. We want to know exactly how it is, how it was in the past, and what it will become of it. How did everything start and how will it eventually end, even though we shall never actually see this to happen. These are indeed very profound queries, which arise from the innermost part of our being, from our soul, in fact. We have learned a lot since humanity came into existence. And the truth is, the more we learn, the more we find we need to know. This is an indisputable and unavoidable certainty; a dilemma, if you like, which is going to re-appear in various situations throughout the book, but which in no way should hinder or condition our search for knowledge.

Here, I will restrict myself mainly to a quite specific issue: to identify the moment when cosmologywhich is probably the oldest discipline of knowledge, the first to come into being at the dawn of human consciousnessfinally became a true science. This did not happen overnight through the enactment of some definitive laws of nature or due to some amazing astronomical discovery. It actually occurred through a long, slow process, which took up much of the twentieth century and involved a great many astronomical researchers, serious (but also sometimes bombastic) cosmologists, and theorists of fundamental physicswith their great breakthroughs and their gross (and, with hindsight, quite incomprehensible) errors, as we will soon discover.

In writing the book, I could only mention a few of those who contributed to this extraordinary feat. I have tried to stick to a chronological account, whenever possible; the unavoidable deviations I will always justify and try to keep to a minimum. And I have highlighted in various places the small but very important lessons that we can learn from this story. It is now easier for us to identify them clearly, from the standpoint of our present understanding, given the very broad perspective we now have of the exceptional discoveries made over the last hundred years. These lessons can be of enormous use to us in understanding the present and in trying to determine the possible future of our beloved universe.

Having written this book is already a way of showing my gratitude to all those colleagues and friends who, during my scientific career, have shared with me, with much patience and generosity, their precious knowledge, acquired after many years of hard work. It was precisely these colleagues (some of them quite prestigious) who, after listening to my lectures, urged me to write this story in detail. I do not give their names here, as they will be cited throughout the book, although I feel I should mention Enrique Gaztaaga, for a careful reading of the manuscript and important observations, my Springer Nature editor, Angela Lahee, for wonderful words of praise upon receiving my first draft, and for her constant encouragement and dedication, Rdiger Vaas for a very careful review, important comments, and numerous relevant suggestions, and Stephen Lyle, for such a professional improvement of my primitive English in the last version of the book. I also thank the Spanish Royal Physics Society and, in special, his president and friend Prof. Adolfo Azcrraga who asked me to write the first version of this book, in Spanish, and helped me to get it published. To finish, I appreciate the interchange of ideas with a number of loyal friends and the love and understanding of my wonderful family.