Helge Kragh

A comprehensive account of highly ambitious attempts to understand nature in its totality, this book covers little known 'theories of everything' from the past as well as modern developments such as the theory of superstrings, the anthropic principle and ideas of many universes. These theories are presented in their historical contexts and used to problematize the limits of scientific knowledge. Do claims of theories of everything belong to science at all? Whichare the epistemic standards on which an alleged scientific theory of the universe - or the multiverse - is to be judged? Such questions are currently being discussed by physicists and cosmologists, butrarely within a historical perspective.

Grand Theories and Failed Revolutions in Physics and Cosmology

Higher Speculations

Scientific And Religious Preludes To Modern Cosmology (History of Modern Physical Sciences)

Matter And Spirit In The Universe

This first full-length biography of Paul Adrien Maurice Dirac offers a comprehensive account of his physics in its historical context, including less known areas such as cosmology and classical electron theory. It is based extensively on unpublished sources, including Dirac's correspondence with Bohr, Heisenberg, Pauli, Schrödinger, Gamow and others. Dirac was undoubtedly one of the most brilliant and influential physicists of the twentieth century. Between 1925 and 1934, the Nobel Prize laureate revolutionized physics with his brilliant contributions to quantum theory. This work examines Dirac's successes and failures, and pays particular attention to his opposition to modern quantum electrodynamics; an opposition based on aesthetic objections.

A Scientific Biography

Dirac

"Consisting of separate cases organized by chapter and divided into independent sections, this is no ordinary history of science book. Between the Earth and the Heavens is an episodic history of modern physical sciences covering the chronological development of physics, chemistry and astronomy since about 1860. Integrating historical authenticity and modern scientific knowledge, the cases within deal with the often surprising connections between science done in the laboratory (physics, chemistry) and science based on observation (astronomy, cosmology). Between the Earth and the Heavens presupposes an interest in and a certain knowledge of the physical sciences, but it is written for non-specialists and includes only a limited number of equations which are all clearly explained in simple terms. For readers who wish to delve further, the book is fully documented and ends with a bibliography of cited quotations and other relevant sources"--

Historical Studies in the Physical Sciences

Between the Earth and the Heavens

The main focus of this book is on the interconnection of two unorthodox scientific ideas, the varying-gravity hypothesis and the expanding-earth hypothesis. As such, it provides a fascinating insight into a nearly forgotten chapter in both the history of cosmology and the history of the earth sciences. The hypothesis that the force of gravity decreases over cosmic time was first proposed by Paul Dirac in 1937. In this book the author examines in detail the historical development of Dirac’s hypothesis and its consequences for the structure and history of the earth, the most important of which was that the earth must have been smaller in the past.

Dirac’s Legacy in Cosmology and Geophysics

Varying Gravity

“What a fantastic entrée into the life of Paul Dirac and the exotic world of Quantum Mechanics, of which he was one of the great pioneers. With its cast of some of the most important scientists of the modern age, this is both an entertaining and an enlightening read.” —Michael White, Bestselling author of 39 books including Isaac Newton: The Last Sorcerer Paul Dirac (1902–1984) was a brilliant mathematician and a 1933 Nobel laureate whose work ranks alongside that of Albert Einstein and Sir Isaac Newton. Although not as well known as his famous contemporaries Werner Heisenberg and Richard Feynman, his influence on the course of physics was immense. His landmark book, The Principles of Quantum Mechanics, introduced that new science to the world and his “Dirac equation” was the first theory to reconcile special relativity and quantum mechanics. Dirac held the Lucasian Chair of Mathematics at Cambridge University, a position also occupied by such luminaries as Isaac Newton and Stephen Hawking. Yet, during his 40-year career as a professor, he had only a few doctoral students due to his peculiar personality, which bordered on the bizarre. Taciturn and introverted, with virtually no social skills, he once turned down a knighthood because he didn’t want to be addressed by his first name. Einstein described him as “balancing on the dizzying path between genius and madness.” In Simply Dirac, author Helge Kragh blends the scientific and the personal and invites the reader to get to know both Dirac the quantum genius and Dirac the social misfit. Featuring cameo appearances by some of the greatest scientists of the 20th century and highlighting the dramatic changes that occurred in the field of physics during Dirac’s lifetime, this fascinating biography is an invaluable introduction to a truly singular man.

Simply Dirac

The first full length biography of Dirac, one of the most brilliant physicists of the twentieth century.

Masanori Kaji

Gábor Palló

The reception of the periodic system of elements has received little attention. Many historians have studied Mendeleev's discovery of the periodic system, but few have analyzed how the scientific community perceived and employed it. American historian of science Stephen G. Brush concluded that the periodic law had been generally accepted in the United States and Britain and suggested the need to extend this study to other countries. Early Responses to the Periodic System is the first collection of comparative studies on the reception, response, and appropriation of the periodic system of elements. This book examines the history of pedagogy and popularization in scientific communities, educational sectors, and popular culture from the 1870s to the 1920s. Fifteen historians of science explore eleven countries (and one region) central to chemical research, including Russia, Germany, the Czech lands, and Japan, one of the few nation-states outside the Western world to participate in nineteenth century scientific research. The collection, organized by nation-state, explores how local actors regarded the new discovery as law, classification, or theoretical interpretation. The section on France discusses how a small but significant group of authors, including Adolphe Wurtz and Édouard Grimaux, introduced the periodic system as support for the atomic theory--not as the final solution to the longstanding quest for a natural classification of elements. The chapter on Germany discusses the role of Lothar Meyer, also awarded The Davy Medal for the discovery of the periodic system. Meyer's role was considered less important, and he was forgotten in his home country, where educational tradition was well established, and the periodic system was not used as a novel didactic approach. In addition to discussing the appropriation of the periodic system, the collection examines metaphysical reflections of nature based on the periodic system outside of chemistry and considers how far we can push the categories of "response" and "reception."

Early Responses to the Periodic System

The planet Venus is the closest neighbour to the Earth and in several respects similar to our globe. It revolves around the Sun at an average distance of 0. 72 astronomical units, in an elliptical orbit of eccentricity 0. 007. The corresponding 3 numbers for the Earth are 1 and 0. 017. The mean density of Venus is 5. 2 g/cm , 3 that of the Earth 5. 5 g/cm . Venus’ acceleration of gravity at its equator is 8. 9 2 2 m/s , compared with 9. 8 m/s at the Earth. The escape velocity is 10. 4 km/s, while the corresponding ?gure of the Earth is 11. 2 km/s. Although the mass of Venus is somewhat smaller than that of the Earth – the ratio is M /M =0. 815 V E – the diameters of the two planets are almost the same. In other words, Venus is indeed a sister planet of the Earth. In earlier times, when almost nothing was known about the physical con- tions of Venus, the similarity appeared even stronger than today. Not only was Venus’ period of rotation thought to be close to that of the Earth, it was also p- sible (and indeed common) to imagine intelligent life on Venus.

The Saga of Venus' Spurious Satellite

The Moon that Wasn't

At the end of the nineteenth century, some physicists believed that the basic principles underlying their subject were already known, and that physics in the future would only consist of filling in the details. They could hardly have been more wrong. The past century has seen the rise of quantum mechanics, relativity, cosmology, particle physics, and solid-state physics, among other fields. These subjects have fundamentally changed our understanding of space, time, and matter. They have also transformed daily life, inspiring a technological revolution that has included the development of radio, television, lasers, nuclear power, and computers. In Quantum Generations, Helge Kragh, one of the world's leading historians of physics, presents a sweeping account of these extraordinary achievements of the past one hundred years. The first comprehensive one-volume history of twentieth-century physics, the book takes us from the discovery of X rays in the mid-1890s to superstring theory in the 1990s. Unlike most previous histories of physics, written either from a scientific perspective or from a social and institutional perspective, Quantum Generations combines both approaches. Kragh writes about pure science with the expertise of a trained physicist, while keeping the content accessible to nonspecialists and paying careful attention to practical uses of science, ranging from compact disks to bombs. As a historian, Kragh skillfully outlines the social and economic contexts that have shaped the field in the twentieth century. He writes, for example, about the impact of the two world wars, the fate of physics under Hitler, Mussolini, and Stalin, the role of military research, the emerging leadership of the United States, and the backlash against science that began in the 1960s. He also shows how the revolutionary discoveries of scientists ranging from Einstein, Planck, and Bohr to Stephen Hawking have been built on the great traditions of earlier centuries. Combining a mastery of detail with a sure sense of the broad contours of historical change, Kragh has written a fitting tribute to the scientists who have played such a decisive role in the making of the modern world.

A History of Physics in the Twentieth Century

Quantum Generations

Niels Bohr's atomic theory of 1913 is one of the absolute highlights in the history of modern science. It was only with this work that physicists realized that quantum theory is an essential ingredient in atomic physics, and it was also only with this work that Rutherford's nuclear model dating from 1911 was transformed into a proper theory of atomic structure. In a longer perspective, Bohr's quantum atom of 1913 gave rise to the later Heisenberg-Schrödinger quantum mechanics and all its marvellous consequences. This book is a detailed account of the origin of the Bohr atom centred around his original scientific articles of 1913 which are here reproduced and provided with the necessary historical background. In addition to the so-called trilogy -- the three papers published in Philosophical Magazine -- also two other and less well-known yet important papers are included. The present work starts with a condensed biographical account of Bohr's life and scientific career, from his birth in Copenhagen in 1885 to his death in the same city 77 years later. It then proceeds with a chapter outlining earlier ideas of atomic structure and tracing Bohr's route from his doctoral dissertation in 1911 over his stays in Cambridge and Manchester to the submission in April 1913 of the first part of the trilogy. The reproduction of Bohr's five articles is followed by notes and comments directly related to the texts, with the aim of clarifying some of the textual passages and to explicate names and subjects that may not be clear or well known. The reception of Bohr's radically new theory by contemporary physicists and chemists is discussed in a final chapter, which deals with the immediate reactions to Bohr's theory 1913-1915 mostly among British, German and American scientists. Historians of science have long been occupied with Bohr's atomic theory, which was the subject of careful studies in connection with its centenary in 2013. The present work offers an extensive source-based account of the original theory aimed at a non-specialist audience with an interest in the history of physics and the origin of the quantum world. In 1922 Bohr was awarded the Nobel Prize for his theory. The coming centenary will undoubtedly cause an increased interest in how he arrived at his revolutionary picture of the constitution of atoms and molecules.

On the Constitution of Atoms and Molecules

Niels Bohr

Niels Bohr and the Quantum Atom gives a comprehensive account of the birth, development, and decline of Bohr's atomic theory. It presents the theory in a broad context which includes not only its technical aspects, but also its reception, dissemination, and applications in both physics and chemistry.

The Bohr Model of Atomic Structure 1913-1925

Niels Bohr and the Quantum Atom

Niels Bohr and the Quantum Atom is the first book that focuses in detail on the birth and development of Bohr's atomic theory and gives a comprehensive picture of it. At the same time it offers new insight into Bohr's peculiar way of thinking, what Einstein once called his 'unique instinct and tact'. Contrary to most other accounts of the Bohr atom, the book presents it in a broader perspective which includes the reception among other scientists and the criticism launched against it by scientists of a more conservative inclination. Moreover, it discusses the theory as Bohr originally conceived it, namely, as an ambitious theory covering the structure of atoms as well as molecules. By discussing the theory in its entirety it becomes possible to understand why it developed as it did and thereby to use it as an example of the dynamics of scientific theories.

astronomi og fysik mod det nye årtusinde

Kvantespring i det 20. århundrede

La primera historia exhaustiva de la física del siglo XX en un solo volumen es un libro que nos lleva desde el descubrimiento de los rayos X a mediados de la década de 1890 hasta la teoría de las supercuerdas de los años noventa. A diferencia de las historias de la física narradas sólo desde una perspectiva científica, o desde una perspectiva social e institucional, Generaciones cuánticas combina ambas aproximaciones: Kragh escribe sobre la ciencia pura con la experiencia de un físico competente, pero con un estilo ameno y accesible para los no especialistas, prestando atención a los aplicaciones prácticas de la ciencia, desde los discos compactos hasta las centrales nucleares.

Generaciones cuánticas

Jeg vil vide, hvordan Gud skabte verden. Jeg onsker at kende hans tanker - resten er detaljer. Sadan sagde Albert Einstein (1879-1955), og han stod ved sit ord. Mere end nogen anden var Einstein arkitekten bag det 20. arhundredes nye verdensbillede, hvor begreber som tid og rum fik en radikalt anden betydning end tidligere.I Einsteins univers redegores for den beromte fysikers placering i videnskabshistorien, og hovedtrAekkene i hans vigtige bidrag til relativitetsteori, kvantefysik og kosmologi forklares. Bogen gennemgar ogsa Einsteins filosofiske og religiose standpunkter, ligesom den beskriver hans samfundsmAessige engagement og politiske holdninger. For selv om fysikken var det vigtigste i Einsteins liv, sa folte han en stAerk moralsk pligt til at engagere sig i verden uden for videnskaben.

En fysikers tanker om natur og erkendelse

Einsteins univers

Henry Nielsen

Naturvidenskabens historie i Danmark beskrives samlet, fyldigt og gennemillustreret og de naturvidenskabelige områders udvikling kortlægges og knyttes sammen med den almindelige danmarkshistorie.

Dansk naturvidenskabs historie: Viden uden grænser : 1920-1970

Tobias Wang

Morten A Skydsgaard

Naturvidenskabens storste erkendelser og opdagelser har vAeret med til at skabe vores moderne verdensbillede og forstaelse af naturen. Men hvilken betydning har fx Einsteins relativitetsteori, Daltons teori om atomet, den kopernikanske revolution og opdagelsen af radioaktiviteten faet? Hvad var den historiske baggrund for erkendelserne - og hvad gor dem egentlig sa unikke? I bogen 50 opdagelser. Hojdepunkter i naturvidenskaben prAesenteres de 50 mest markante gennembrud inden for naturvidenskaben - fra de gamle grAekeres erkendelse af Jordens form og storrelse, over den biologiske udviklingstanke i 1900-tallet og til opdagelsen i det 21. arhundrede af planeter i omlob omkring andre stjerner end Solen.De 50 fortAellinger dykker ned i de sma detaljer, men bibeholder det store perspektiv. Skrevet i et letforstaeligt sprog og rigt illustreret kan de lAeses efter lystprincippet enkeltvis eller i sammenhAeng. Tilsammen giver de lAeseren et enestaende indblik i videnskabens forunderlige verden.

Hojdepunkter i naturvidenskaben

50 opdagelser

For over three millennia, most people could understand the universe only in terms of myth, religion, and philosophy. Between 1920 and 1970, cosmology transformed into a branch of physics. With this remarkably rapid change came a theory that would finally lend empirical support to many long-held beliefs about the origins and development of the entire universe: the theory of the big bang. In this book, Helge Kragh presents the development of scientific cosmology for the first time as a historical event, one that embroiled many famous scientists in a controversy over the very notion of an evolving universe with a beginning in time. In rich detail he examines how the big-bang theory drew inspiration from and eventually triumphed over rival views, mainly the steady-state theory and its concept of a stationary universe of infinite age. In the 1920s, Alexander Friedmann and Georges Lemaître showed that Einstein's general relativity equations possessed solutions for a universe expanding in time. Kragh follows the story from here, showing how the big-bang theory evolved, from Edwin Hubble's observation that most galaxies are receding from us, to the discovery of the cosmic microwave background radiation. Sir Fred Hoyle proposed instead the steady-state theory, a model of dynamic equilibrium involving the continuous creation of matter throughout the universe. Although today it is generally accepted that the universe started some ten billion years ago in a big bang, many readers may not fully realize that this standard view owed much of its formation to the steady-state theory. By exploring the similarities and tensions between the theories, Kragh provides the reader with indispensable background for understanding much of today's commentary about our universe.

The Historical Development of Two Theories of the Universe

Cosmology and Controversy

How did our modern picture of the universe come into being? Masters of the Universe tells this fascinating story in an unusual format that blends factual and fictional elements. It is based on a series of interviews that a fictional person conducted with leading astronomers and physicists between 1913 and 1965. Among the interviewed scientists are giants such as Albert Einstein, Edwin Hubble, and George Gamow, but also scientists who are less well known today or not primarily known as cosmologists such as Karl Schwarzschild, Paul Dirac, and Svante Arrhenius. By following the interviews the reader gets a lively and "almost authentic" impression of the problems that faced this early generation of cosmologists. Although the interviews are purely fictional, a product of the author's imagination, they could have taken place in just the way that is described. They are solidly based on historical facts and, moreover, supplemented with careful annotations and references to the literature. In this way the book bridges the gap between scholarly and popular history of science.

Helge Kragh

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