Einstein's theory of relativity

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Einstein's Theory of Relativity is the title of a book by the later Nobel laureate in physics , Max Born . In it he presents the basic ideas of the special relativity theory and the general relativity theory . It is aimed at a wide audience and therefore uses little math. The book deals mainly with the historical overcoming of the ether theory .

classification

The work stands between scientific introductions to the theory of relativity, written for physicists, and numerous popular science books that dispense entirely with mathematics and can therefore only convey a superficial knowledge of the theory of relativity, as Max Born himself explains in the foreword.

Max Born does not use any analysis , but instead deviates in some places to considerations of difference quotients , the convergence of which is made plausible. This is even possible with complex topics such as the elasticity of the ether or the basic equations of electrodynamics , which require partial differential equations in common representations . Only the simplest manipulations of equations, as they are usually taught in schools, are used.

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The first German edition appeared in 1920, two more in the two following years, an English translation followed in 1924. In 1962, Dover Publications Inc. published a revised fifth edition, which was published in German by Springer-Verlag. A sixth edition was published in 2001 by Springer Verlag, commented and supplemented by Jürgen Ehlers and Markus Pössel . The seventh edition appeared in 2003.

content

Geometry and cosmology

The introductory chapter introduces length and time measurement. The background is Euclidean geometry , as well as the cosmological models from ancient times to Copernicus .

The basic laws of classical mechanics

The free fall and the vibrations serve as examples of classical mechanics , which goes back to Galileo Galilei and Isaac Newton . This includes the law of inertia , the concept of force and the law of conservation of energy . The equality of inert and heavy mass is discussed, this equality is " not firmly anchored in the foundations of the mechanics, but sticks loosely to the structure of the other sentences like a kind of curiosity ".

The Newtonian world system

This chapter offers an introduction to Newton's celestial mechanics (law of gravitation , planetary orbits , Kepler's laws ) and leads to a critical examination of the concepts of absolute time and absolute space introduced by Newton .

The basic laws of optics

In order to get to the bottom of the problems raised, in addition to mechanics, other sub-areas of physics that are directly related to space must be considered, such as the propagation of light. Therefore the historical development of optics up to the discovery of the wave nature of light is traced.

The transversality of light waves classically leads to the concept of aether, the physical properties of which are discussed. Optical effects are differentiated into such first order and second order, difficulties of the ether concept are illuminated and it is worked out that only optical effects of the second order can clarify the questions raised.

Fundamental laws of electrodynamics

Here Max Born gives an introduction to electrodynamics without assuming any previous knowledge of the reader. The use of the Gaussian system of units corresponds to the time the book was written, but has the advantage that very early on, when discussing the Biot-Savart law , a proportionality factor of the dimension of speed appears, which then turns out to be the speed of light . Faraday's lines of force and Maxwell's equations give rise to a discussion of theories of near and far action in electrodynamics. The worked out knowledge that light is an electromagnetic wave leads back to optics and thus to the ether.

New theoretical difficulties with the ether, especially in the electrodynamics of moving bodies, led Lorentz to electron theory , which in the light of the described Michelson-Morley experiment , an optical effect of the second order, forces further modifications up to the contraction hypothesis and the introduction of other time scales for bodies that are moved relative to the aether, which can now be identified with Newton's absolute space. This concludes the presentation of pre-relativistic physics.

Einstein's special principle of relativity

After the unmasking of simultaneity as an observer-dependent and thus relative quantity, the Lorentz transformation is derived from the special relativity principle in both a geometric and an algebraic way , which then leads to relativistic kinematics . By means of the relativistic addition theorems for velocities and the analysis of the inelastic collision , the velocity dependency of the mass is first shown and, based on this, the inertia of the mass, i.e. the equivalence of mass and energy, is derived, the latter is also derived from a thought experiment going back to Einstein (see also here ) justified. After discussing experimental confirmations, it is demonstrated how the problems presented above can be freely explained in the theory of relativity. The chapter ends with an introduction to the geometry of Minkowski space .

Einstein's general theory of relativity

The renunciation of higher mathematics only allows to convey a critique of the Euclidean geometry assumed a priori with Kant and an idea of ​​the curvature of space . The cause of the inertial forces is discussed. Due to the general relativity principle and the structure of the metric , the slower rate of clocks in strong gravitational fields is made plausible. The perihelion of Mercury , the deflection of light rays in the sun's gravitational field and optical effects are cited as experimental evidence of the general theory of relativity. Cosmological theories based on the general theory of relativity, Einstein's introduction of the lambda term and Einstein's efforts towards a unified field theory conclude the book.

Recent developments in relativistic physics

This chapter does not originally exist in Max Born's book. From the sixth edition onwards, it can be found as a supplement added by Jürgen Ehlers and Markus Pössel and deals with newer experimental findings, gravitational waves and black holes , takes up the topic of cosmology again and closes with the treatment of quantum gravity .

literature

  • Max Born: Einstein's Theory of Relativity. 5th edition. Springer Verlag, 1969, ISBN 3-540-04540-6 .
  • Max Born: Einstein's Theory of Relativity. 7th edition. Springer Verlag, 2003, ISBN 3-540-00470-X .