Bücher von Helge Kragh

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-Schrodinger 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.

The main focus of this book is on the interconnection of two unorthodox scientific ideas, the varying-gravity hypothesis and the expanding-earth hypothesis.

The planet Venus is the closest neighbour to the Earth and in several respects similar to our globe. 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.

Presenting the history of twentieth-century physics, this book takes us from the discovery of X rays in the mid-1890s to superstring theory in the 1990s. It 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.

Presents the development of scientific cosmology as a historical event, one that embroiled many scientists in a controversy over the very notion of an evolving universe with a beginning in time. This work examines how the big-bang theory drew inspiration from and eventually triumphed over rival views.