PREFACE - BY his theory of relativity Albert Einstein has provoked a revolution of thought in physical science. The achievement consists essentially in this Einstein has succeeded in separating far more completely than hitherto the share of the observer and the share of external nature in the things we see happen. The perception of an object by an observer depends on his own situation and circumstances for example, distance will make it appear smaller and dimmer. We make allowance for this almost unconsciously in interpreting what we see. But it now appears that the allowance made for the motion of the observer has hitherto been too crude a fact overlooked because in practice all observers share nearly the same motion, that of the earth. Physical space and time are found to be closely bound up with this motion of the observer and only an amorphous combination of the two is left inherent in the external world. When space and time are relegated to their proper source the observer the world of nature which remains appears strangely unfamiliar but it is in reality simplified, and the underlying unity of the principal phenomena is now clearly revealed. The deductions from this new outlook have, with one doubtful exception, been confirmed when tested by experiment. It is my aim to give an account of this work without intro ducing anything very technical in the way of mathematics, physics, or philosophy. The new view of space and time, so opposed to our habits of thought, must in any case demand unusual mental exercise. The results appear strange and the incongruity is not without a humorous side. For the first nine chapters the task is one of interpreting a clear-cut theory, accepted in allits essentials by a large and growing school of physicists although perhaps not everyone would accept the authors views of its meaning. Chapters x and xi deal with very recent advances, with regard to which opinion is more fluid. As for the last chapter, containing the authors specula tions on the meaning of nature, since it touches on the rudiments of a philosophical system, it is perhaps too sanguine to hope that it can ever be other than controversial. vi PREFACE A non-mathematical presentation has necessary limitations and the reader who wishes to learn how certain exact result follow from Einsteins, or even Newtons, law of gravitation m bound to seek the reasons in a mathematical treatise. But thj limitation of range is perhaps less serious than the limitation of intrinsic truth. There is a relativity of truth, as there is a relativity of space. For is and IS-NOT though with Rule and Line And UP-AND-DOWK without, I could define, Alas It is not so simple. We abstract from the phenomena that which is peculiar to the position and motion of the observer but can we abstract that which is peculiar to the limited imagina tion of the human brain We think we can, but only in the symbolism of mathematics. As the language of a poet rings with a truth that eludes the clumsy explanations of his commentators, so the geometry of relativity in its perfect harmony expresses a truth of form and type in nature, which my bowdlerised version misses. But the mind is not content to leave scientific Truth in a dry husk of mathematical symbols, and demands that it shall be alloyed with familiar images. The mathematician, who handles x so lightly, may fairly be asked to state, not indeed the in scrutablemeaning of a in nature, but the meaning which x conveys to him. Although primarily designed for readers without technical knowledge of the subject, it is hoped that the book may also appeal to those who have gone into the subject more deeply. A few notes have been added in the Appendix mainly to bridge the gap between this and more mathematical treatises, and to indicate the points of contact between the argument in the text and the parallel analytical investigation. It is impossible adequately to express my debt to con temporary literature and discussion...

Sir Arthur Eddington here formulates mathematically his conception of the world of physics derived from the theory of relativity. The argument is developed in a form which throws light on the origin and significance of the great laws of physics; its consequences are followed to the full extent in the consideration of gravitation, relativity, mechanics, space-time, electromagnetic phenomena and world geometry.

This is a new release of the original 1929 edition.

1929. The course of Gifford Lectures that Eddington delivered in the University of Edinburgh in January to March 1927. It treats of the philosophical outcome of the great changes of scientific thought which have recently come about. The theory of relativity and the quantum theory have led to strange new conceptions of the physical world; the progress of the principles of thermodynamics has wrought more gradual but no less profound change. The first eleven chapters are for the most part occupied with the new physical theories, with the reasons which have led to their adoption, and especially with the conceptions which seem to underlie them. The aim is to make clear the scientific view of the world as it stands at the present day, and, where it is incomplete, to judge the direction in which modern ideas appear to be tending. In the last four chapters I consider the position which this scientific view should occupy in relation to the wider aspects of human experience, including religion. Contents: The Downfall of Classical Physics; Relativity; Time; The Running-Down of the Universe; Becoming; Gravitation-the Law; Gravitation-the Explanation; Man's Place in the Universe; The Quantum Theory; The New Quantum Theory; World Building; Pointer Readings; Reality; Causation; and Science and Mysticism.

Dieser Buchtitel ist Teil des Digitalisierungsprojekts Springer Book Archives mit Publikationen, die seit den Anfangen des Verlags von 1842 erschienen sind. Der Verlag stellt mit diesem Archiv Quellen fur die historische wie auch die disziplingeschichtliche Forschung zur Verfugung, die jeweils im historischen Kontext betrachtet werden mussen. Dieser Titel erschien in der Zeit vor 1945 und wird daher in seiner zeittypischen politisch-ideologischen Ausrichtung vom Verlag nicht beworben.

This is a new release of the original 1929 edition.

This is a new release of the original 1929 edition.

THIS 58 PAGE ARTICLE WAS EXTRACTED FROM THE BOOK: The Nature of the Physical World, by A. S. Eddington. To purchase the entire book, please order ISBN 1417907185.

THIS 56 PAGE ARTICLE WAS EXTRACTED FROM THE BOOK: The Nature of the Physical World, by A. S. Eddington. To purchase the entire book, please order ISBN 1417907185.

THIS 58 PAGE ARTICLE WAS EXTRACTED FROM THE BOOK: The Nature of the Physical World, by A. S. Eddington. To purchase the entire book, please order ISBN 1417907185.

1929. The course of Gifford Lectures that Eddington delivered in the University of Edinburgh in January to March 1927. It treats of the philosophical outcome of the great changes of scientific thought which have recently come about. The theory of relativity and the quantum theory have led to strange new conceptions of the physical world; the progress of the principles of thermodynamics has wrought more gradual but no less profound change. The first eleven chapters are for the most part occupied with the new physical theories, with the reasons which have led to their adoption, and especially with the conceptions which seem to underlie them. The aim is to make clear the scientific view of the world as it stands at the present day, and, where it is incomplete, to judge the direction in which modern ideas appear to be tending. In the last four chapters I consider the position which this scientific view should occupy in relation to the wider aspects of human experience, including religion. Contents: The Downfall of Classical Physics; Relativity; Time; The Running-Down of the Universe; Becoming; Gravitation-the Law; Gravitation-the Explanation; Man's Place in the Universe; The Quantum Theory; The New Quantum Theory; World Building; Pointer Readings; Reality; Causation; and Science and Mysticism.

1929. Swarthmore Lecture. Contents: Outline of evolution leading to the advent of Man in the physical world; The questioning voice, What doest thou here?; Changing views of the scope of physical theory and the ideal of physical explanation; Both a scientific and a mystical outlook are involved in the problem of experience; The irrelevancy of natural law to some aspects of mind and consciousness; The importance of significances and the consequences of ruling them outside the scope of inquiry; and Assurance of the revelation of God rather than of the existence of God is demanded. See other titles by this author available from Kessinger Publishing.

1929. Swarthmore Lecture. Contents: Outline of evolution leading to the advent of Man in the physical world; The questioning voice, What doest thou here?; Changing views of the scope of physical theory and the ideal of physical explanation; Both a scientific and a mystical outlook are involved in the problem of experience; The irrelevancy of natural law to some aspects of mind and consciousness; The importance of significances and the consequences of ruling them outside the scope of inquiry; and Assurance of the revelation of God rather than of the existence of God is demanded. See other titles by this author available from Kessinger Publishing.

THIS 40 PAGE ARTICLE WAS EXTRACTED FROM THE BOOK: The Nature of the Physical World, by A. S. Eddington. To purchase the entire book, please order ISBN 1417907185.

Many of the earliest books, particularly those dating back to the 1900s and before, are now extremely scarce and increasingly expensive. We are republishing these classic works in affordable, high quality, modern editions, using the original text and artwork.

Stars and Atoms Stars and Atoms A. S. EDDINGTON M. A., D. Sc., LL. D., F. R S., Flumian Professor of Astronomy in the University of Cambridge OXFORD AT THE CLARENDON PRESS 1927 PREFACE STARS and Atoms was the title of an Evening Dis course given at the meeting of the British Association in Oxford in August 1926. In adapting it for publication the restrictions of a time limit are removed and accord ingly it appears in this book as three lectures. Earlier in the year I had given a course of three lectures in Kings College, London, on the same topics these have been combined with the Oxford lecture and are the origin of most of the additions. A full account of the subject, including the mathe matical theory, is given in my larger book, The Internal Constitution of the Stars Camb. Univ. Press, 1926. Here I only aim at exposition of some of the leading ideas and results. The advance in our knowledge of atoms and radiation has led to many interesting developments in astronomy and reciprocally the study of matter in the extreme con ditions prevailing in stars and nebulae has played no mean part in the progress of atomic physics. This is the general theme of the lectures. Selection has been made of the advances and discoveries which admit of comparatively elementary exposition but it is often necessary to detnand from the reader a concentration of thought which, it is hoped, will be repaid by the fascination of the subject. The treatment was meant to be discursive rather than systematic but habits of mind refuse to be suppressed entirely and a certain amount of system has crept in. In these problems where our thought fluctuates continually from the excessively great to the excessively small, from the star to the atom and back to the star, the story of 6 Preface progress is rich in variety if it has not lost too much in the telling, it should convey in full measure the delights and the troubles of scientific investigation in all its phases. Temperatures are expressed throughout in degrees Centigrade. The English billion, trillion, c. io l8, c. are used. A. S. E. CONTENTS LECTURE I. THE INTERIOR OF A STAR . 9 Temperature in the Interior . .11 lonization of Atoms, 17 Radiation Pressure and Mass . . 24 The Interior of a Star . . 26 Opacity of Stellar Matter . . 28 The Relation of Brightness to Mass . 31 Dense Stars . . 36 LECTURE II. SOME RECENT INVESTIGATIONS 42 The Story of Algol ., 42 The Story of the Companion of Sirius . . 48 Unknown Atoms and Interpretation of Spectra . 53 Spectral Series . . 59 The Cloud in Space . . 63 The Suns Chromosphere . . 70 The Story of Betelgeuse . .76 LECTURE III. THE AGE OF THE STARS . 85 Pulsating Stars, . 85 The Cepheid as a Standard Candle .90 The Contraction Hypothesis . . 94. Subatomic Energy . t oo Evolution of the Stars . .106 Radiation of Mass . - in APPENDIX Further Remarks on the Companion of Sirius . 122 LIST OF ILLUSTRATIONS FIG. 1. The Sun. Hydrogen Spectroheliogram. J. Evershed . . Frontispiece 2. Solar Vortices. Hydrogen Spectroheliogram. Mount Wilson Observatory . To face page 10 3. Tracks of Alpha Particles helium atoms. C. T. R. Wilson . . 18 4. Tracks of Beta Particles electrons. C. T. R. Wilson . . 18 5. lonization by X-rays. C. T. R. Wilson, 24 6. Ions produced by Collision of a Beta particle C. T. R Wilson . . 24 7. The Mass-luminosity Curve . . page 33 8. The Ring Nebula in Lyra. Slitless Spectro gram. W. H. Wright . .To face page 4 9. Flash Spectrum of Chromosphere showing Head of the Balmer Series British Eclipse Expedition, 14 Jan. 1926 . 54 10. Solar Prominence. British Eclipse Expedi tion, 29 May 1919 . . 70 11. Star Cluster a Centauri. Cape Observatory 70 LECTURE I THE INTERIOR OF A STAR sun belongs to a system containing some 3,000 JL million stars. The stars are globes comparable in size with the sun, that is to say, of the order of a million miles in diameter. The space for their accommodation is on the most lavish scale...

THE PHYSICAL SOCIETY LONDON. REPORT OK THE RELATIVITY THEOEY OF GRAVITATION. A. S. EDDINOTON, M. A., M. Sc., F. E. S. M Plumtan Professor of Astronomy and Experimental Philosophy, Cambridge. Price to Non-Fellows, 6 8. net, post free 6s. 3d, Bound in doth, 8s. 6d., post ree 8s 9d LONDON. FLEET WAY PRESS, LTX, 1, 2 AND 3, SALISBURY COUBT, FLEET STBEET 1920. CONTENTS. CHAPTEE L PAGE THE KESTRICTED PRINCIPLE or EELATIVITY 1 1-3. The Michelson-Morley experiment and its significance. 4. The transformation of co-ordinates for a moving observer. 5. Reciprocity of the transformation. 6. Standpoint ot the Principle of Relativity. 7, Transformation of velocity, of den sity and of mass. 8. Scope of the Principle. CHAPTER II. THE KELATIONS OF SPACE, TIME, AND FORCE 14 9-10. Minkowskis transformation. 11. Invanance of 8. 12. Irrelevance of co-ordinate systems to the phenomena, 13-14. The Principle of Equivalence. 15-16. Definition of a field of force by g v . 17. Purpose of the theory of tensors. 18, Nature of space and time in the gravitational field. CHAPTEE III. THE THEORY OF TENSORS 30 19. Notation, definition and elementary properties of tensors. 20. The fundamental tensors associated tensors. 21. Auxili ary formula for the second derivatives of the co-ordinates. 22. Covariant differentiation. 23-24. The Riemann-Ghristoffel ten sor. 26. Summary. CHAPTEE IV. EINSTEINS LAW OF GRAVITATION 41 26. The contracted Eiemann-Christoffel tensor. 27. Limitation of the Principle of Equivalence. 28. The gravitational field of a Dartiole IV. CONTENTS. CHAPTER V. PAGB THE CRUCIAL PHENOMENA 48 29-30. The Equations of Motion. 31. Motion of the Perihelion of Mercury. 32-33. Deflection of a ray of hght 34. Displacement of spectra lines. CHAPTER VL THE GRAVITATION OF A CONTINUOUS DISTRIBUTION OF MATTER 59 35-36 Equations for a continuous medium. 37 The energy tensor T v, and the equations of hydrodynamics. 38. The Law of Conservation 39. Reaction of the gravitational field on matter. 40. Propagation of gravitation CHAPTER VII. THE PRINCIPLE OF LEAST ACTION 71 41. Expression ot the law of gravitation in the torm ot Lagranges Equations 42. Principle of Least Action. 43. Energy of the gravitational field 44 Method of Hilbert and Lorentz. 45-46. Electromagnetic equations. 47 The JEJther. 48. Summary of the last two chapters CHAPTER VIII. THE CURVATURE OF SPACE AND TIME 82 49. Absolute rotation and the limits ol generalised relativity. 50 Einsteins curved space 51. T e Sitters curved space-time. 52. Boundary Conditions. 53. Conclusion PREFACE TO FIRST EDITION. THE relativity theory of gravitation in its complete form was published by Einstein in November 1915. Whether the theory ultimately proves to be correct or not, it claims attention as one of the most beautiful examples of the power of general mathematical reasoning. The nearest parallel to it is found in the applications of the second law of thermo-dynamics, in which remarkable conclusions are deduced from a single principle without any inquiry into the mechanism of the phenomena similarly, if the principle of equivalence is accepted, it is possible to stride over the difficulties due to ignorance of the nature of gravita tion and arrive directly at physical results. Einsteins theory has been successful in explaining the celebrated astronomical discordance of the motion of the perihelion of Mercury, without introducing any arbitrary constantthere is no trace of forced agreement about this prediction. It further leads to interesting conclusions with regard to the deflection of light by a gravitational field, and the displacement of spectral lines on the sun, which may be tested by experiment. The arrangement of this Report is guided by the object of reaching the theory of these crucial phenomena as directly as possible. To make the treatment rather more elementarv, use of the principle of least action and Hamiltonian methods has been avoided and the brief account of these m Chapter VII...

PREFACE - BY his theory of relativity Albert Einstein has provoked a revolution of thought in physical science. The achievement consists essentially in this Einstein has succeeded in separating far more completely than hitherto the share of the observer and the share of external nature in the things we see happen. The perception of an object by an observer depends on his own situation and circumstances for example, distance will make it appear smaller and dimmer. We make allowance for this almost unconsciously in interpreting what we see. But it now appears that the allowance made for the motion of the observer has hitherto been too crude a fact overlooked because in practice all observers share nearly the same motion, that of the earth. Physical space and time are found to be closely bound up with this motion of the observer and only an amorphous combination of the two is left inherent in the external world. When space and time are relegated to their proper source the observer the world of nature which remains appears strangely unfamiliar but it is in reality simplified, and the underlying unity of the principal phenomena is now clearly revealed. The deductions from this new outlook have, with one doubtful exception, been confirmed when tested by experiment. It is my aim to give an account of this work without intro ducing anything very technical in the way of mathematics, physics, or philosophy. The new view of space and time, so opposed to our habits of thought, must in any case demand unusual mental exercise. The results appear strange and the incongruity is not without a humorous side. For the first nine chapters the task is one of interpreting a clear-cut theory, accepted in allits essentials by a large and growing school of physicists although perhaps not everyone would accept the authors views of its meaning. Chapters x and xi deal with very recent advances, with regard to which opinion is more fluid. As for the last chapter, containing the authors specula tions on the meaning of nature, since it touches on the rudiments of a philosophical system, it is perhaps too sanguine to hope that it can ever be other than controversial. vi PREFACE A non-mathematical presentation has necessary limitations and the reader who wishes to learn how certain exact result follow from Einsteins, or even Newtons, law of gravitation m bound to seek the reasons in a mathematical treatise. But thj limitation of range is perhaps less serious than the limitation of intrinsic truth. There is a relativity of truth, as there is a relativity of space. For is and IS-NOT though with Rule and Line And UP-AND-DOWK without, I could define, Alas It is not so simple. We abstract from the phenomena that which is peculiar to the position and motion of the observer but can we abstract that which is peculiar to the limited imagina tion of the human brain We think we can, but only in the symbolism of mathematics. As the language of a poet rings with a truth that eludes the clumsy explanations of his commentators, so the geometry of relativity in its perfect harmony expresses a truth of form and type in nature, which my bowdlerised version misses. But the mind is not content to leave scientific Truth in a dry husk of mathematical symbols, and demands that it shall be alloyed with familiar images. The mathematician, who handles x so lightly, may fairly be asked to state, not indeed the in scrutablemeaning of a in nature, but the meaning which x conveys to him. Although primarily designed for readers without technical knowledge of the subject, it is hoped that the book may also appeal to those who have gone into the subject more deeply. A few notes have been added in the Appendix mainly to bridge the gap between this and more mathematical treatises, and to indicate the points of contact between the argument in the text and the parallel analytical investigation. It is impossible adequately to express my debt to con temporary literature and discussion...

1929. Swarthmore Lecture. Contents: Outline of evolution leading to the advent of Man in the physical world; The questioning voice, What doest thou here?; Changing views of the scope of physical theory and the ideal of physical explanation; Both a scientific and a mystical outlook are involved in the problem of experience; The irrelevancy of natural law to some aspects of mind and consciousness; The importance of significances and the consequences of ruling them outside the scope of inquiry; and Assurance of the revelation of God rather than of the existence of God is demanded. See other titles by this author available from Kessinger Publishing.