Einstein, Albert (1879–1955)

2018 ◽  
Author(s):  
Arthur Fine ◽  
Don Howard ◽  
John D. Norton
Keyword(s):  
Quantum Theory ◽  
Albert Einstein ◽  
Later Life ◽  
Special Theory ◽  
Theoretical Concepts ◽  
Gravitational Fields ◽  
Prominent Scientist ◽  
Dimensional Spacetime ◽  
Theory Of Gravitation ◽  
Geometric Formulation

Albert Einstein was a German-born Swiss and American naturalized physicist and the twentieth century’s most prominent scientist. He produced the special and general theories of relativity, which overturned the classical understanding of space, time and gravitation. According to the special theory (1905), uniformly moving observers with different velocities measure the same speed for light. From this he deduced that the length of a system shrinks and its clocks slow at speeds approaching that of light. The general theory (completed 1915) proceeds from Hermann Minkowski’s geometric formulation of special relativity as a four-dimensional spacetime. Einstein’s theory allows, however, that the geometry of spacetime may vary from place to place. This variable geometry or curvature is associated with the presence of gravitational fields. Acting through geometrical curvature, these fields can slow clocks and bend light rays. Einstein made many fundamental contributions to statistical mechanics and quantum theory, including the demonstration of the atomic character of matter and the proposal that light energy is organized in spatially discrete light quanta. In later life, he searched for a unified theory of gravitation and electromagnetism as an alternative to the quantum theory developed in the 1920s. He complained resolutely that this new quantum theory was not complete. Einstein’s writings in philosophy of science developed a conventionalist position, stressing our freedom to construct theoretical concepts; his later writings emphasized his realist tendencies and the heuristic value of the search for mathematically simple laws.

Book Reviews: Unveiling the atom

1993 ◽  
Vol 47 (1) ◽  
pp. 152-154
Keyword(s):  
Twentieth Century ◽  
Quantum Theory ◽  
Statistical Physics ◽  
Albert Einstein ◽  
Later Life ◽  
Niels Bohr ◽  
Major Research ◽  
Niels Bohr Institute ◽  
Research School

Abraham Pais, Niels Bohr’s Times, in Physics, Philosophy and Polity . Clarendon Press, Oxford, 1991. Pp. xvii + 565, £25.00. ISBN 019-85204-92 In 1982 Abraham Pais produced his much-acclaimed biography of Albert Einstein, entitled Subtle is the Lord .... Pais has now produced what is in effect a companion volume on Niels Bohr. The new book is planned on similar lines to the Einstein volume. Meticulously researched, biographical detail is interleaved with very clear and accurate presentations of the relevant physics, and interspersed with Pais’s own personal recollections and assessments. As with Einstein, Pais knew Bohr well in later life and so is ideally qualified to undertake both these biographies. In one of the most interesting sections of the new book, Pais compares and contrasts these two dominant figures in twentieth- century physics. Both were ‘possessed if not obsessed’ by physics, as Pais puts it. Einstein’s spectrum of scientific activities was the broader, comprehending, of course, statistical physics and quantum theory as well as relativity, while Bohr concentrated almost entirely on quantum theory and its ramifications. But there were two striking differences. Bohr identified very strongly with his native Denmark, and created a major research school in Copenhagen, the famous Niels Bohr Institute. Although he never supervised PhD students as such, he did his best work in endless discussion with the stream of visitors and research workers at the Institute. By contrast, Einstein never identified with any particular country, living and working in many different places, and although he had quite a number of collaborators on an individual basis, he never in any sense created a research school.

scholarly journals Post-Newtonian limit: second-order Jefimenko equations

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
David Pérez Carlos ◽  
Augusto Espinoza ◽  
Andrew Chubykalo
Keyword(s):  
Linear Equations ◽  
Space Time ◽  
Second Order ◽  
Field Equations ◽  
Gravitational Fields ◽  
Mass Distributions ◽  
Minkowski Space Time ◽  
Theory Of Gravitation ◽  
Gravity Probe ◽  
Gravitational Equations

Abstract The purpose of this paper is to get second-order gravitational equations, a correction made to Jefimenko’s linear gravitational equations. These linear equations were first proposed by Oliver Heaviside in [1], making an analogy between the laws of electromagnetism and gravitation. To achieve our goal, we will use perturbation methods on Einstein field equations. It should be emphasized that the resulting system of equations can also be derived from Logunov’s non-linear gravitational equations, but with different physical interpretation, for while in the former gravitation is considered as a deformation of space-time as we can see in [2–5], in the latter gravitation is considered as a physical tensor field in the Minkowski space-time (as in [6–8]). In Jefimenko’s theory of gravitation, exposed in [9, 10], there are two kinds of gravitational fields, the ordinary gravitational field, due to the presence of masses, at rest, or in motion and other field called Heaviside field due to and acts only on moving masses. The Heaviside field is known in general relativity as Lense-Thirring effect or gravitomagnetism (The Heaviside field is the gravitational analogous of the magnetic field in the electromagnetic theory, its existence was proved employing the Gravity Probe B launched by NASA (See, for example, [11, 12]). It is a type of gravitational induction), interpreted as a distortion of space-time due to the motion of mass distributions, (see, for example [13, 14]). Here, we will present our second-order Jefimenko equations for gravitation and its solutions.

scholarly journals Relativity and the quantum theory

1928 ◽  
Vol 117 (778) ◽  
pp. 630-637 ◽  
Keyword(s):  
Quantum Theory ◽  
Space Time ◽  
Theory Of Gravitation ◽  
The Law

In Einstein’s theory of gravitation it is assumed that the geometry of space- time is characterised by the following equation for the measurement of displacement:— ds 2 = g mn dx m dx n { m n = 1, 2, 3, 4, the sign of summation being omitted for convenience. It is supposed that the coefficients, of which g mn is the type, are dependent upon the content of space, and the relation existing between them is the law of gravitation.

scholarly journals A contribution to modern ideas on the quantum theory

1927 ◽  
Vol 115 (770) ◽  
pp. 208-214
Keyword(s):  
Quantum Theory ◽  
Kinetic Energy ◽  
Line Element ◽  
Natural Extension ◽  
Space Time ◽  
Relativity Theory ◽  
Unit Mass ◽  
The World ◽  
Free Particles ◽  
Theory Of Gravitation

The relativity theory of gravitation indicates that space-time is a four dimensional continuum in which the line element is measured by the equation ( ds ) 2 = g mn dx m dx n , (1) the notation being that generally adopted. The world-lines or natural tracks of free particles in this space are geodesics. From (1) we have g mn dx m /ds . dx n /ds = 1, (2) the quantity on the left being an expression corresponding to the kinetic energy of ordinary dynamics for a particle of unit mass. This correspondence is readily appreciated if it be noted that dx m /ds is the natural extension of the velocity, dx m /dt .

scholarly journals Renormalizable and Unitary Lorentz Invariant Model of Quantum Gravity

2021 ◽  
Author(s):  
S. A. Larin
Keyword(s):  
General Relativity ◽  
Quantum Theory ◽  
Quantum Gravity ◽  
Curvature Tensor ◽  
Quantum Theory Of Gravitation ◽  
Proper Choice ◽  
Invariant Model ◽  
Self Consistent ◽  
Theory Of Gravitation

We analyze the R + R2 model of quantum gravity where terms quadratic in the curvature tensor are added to the General Relativity action. This model was recently proved to be a self-consistent quantum theory of gravitation, being both renormalizable and unitary. The model can be made practically indistinguishable from General Relativity at astrophysical and cosmological scales by the proper choice of parameters.

scholarly journals MATHEMATICAL EXPANSION OF SPECIAL THEORY OF RELATIVITY ONTO ACCELERATIONS

2021 ◽  
Vol 4 (1) ◽  
pp. 69-89
Author(s):  
Jakub Czajko
Keyword(s):  
Proper Time ◽  
Special Theory ◽  
Lorentz Factor ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Special Theory Of Relativity ◽  
Accelerator Pedal ◽  
Earth Gravity ◽  
Time Differential ◽  
Theory Of Gravitation

The special theory of relativity (STR) is operationally expanded onto orthogonal accelerations: normal  and binormal  that complement the instantaneous tangential speed  and thus can be structurally extended into operationally complete 4D spacetime without defying the STR. Thus the former classic Lorentz factor, which defines proper time differential  can be expanded onto  within a trihedron moving in the Frenet frame (T,N,B). Since the tangential speed  which was formerly assumed as being always constant, expands onto effective normal and binormal speeds ensuing from the normal and binormal accelerations, the expanded formula conforms to the former Lorentz factor. The obvious though previously overlooked fact that in order to change an initial speed one must apply accelerations (or decelerations, which are reverse accelerations), made the Einstein’s STR incomplete for it did not apply to nongravitational selfpropelled motion. Like a toy car lacking accelerator pedal, the STR could drive nowhere. Yet some scientists were teaching for over 115 years that the incomplete STR is just fine by pretending that gravity should take care of the absent accelerator. But gravity could not drive cars along even surface of earth. Gravity could only pull the car down along with the physics that peddled the nonsense while suppressing attempts at its rectification. The expanded formula neither defies the STR nor the general theory of relativity (GTR) which is just radial theory of gravitation. In fact, the expanded formula complements the STR and thus it supplements the GTR too. The famous Hafele-Keating experiments virtually confirmed the validity of the expanded formula proposed here.

Matvei Bronstein 1936, quantum theory of weak gravitational fields.

2012 ◽  
pp. 325-345
Author(s):  
Andrzej Krasiński ◽  
George F. R. Ellis ◽  
Malcolm A. H. MacCallum
Keyword(s):  
Quantum Theory ◽  
Gravitational Fields
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