In the history of physics 1905 can be considered as the year of Einstein's proclamation of independence of events. Indeed the concept of independent events occupies a essential place in the three main 1905 Einstein's papers (quanta of light, brownian motion and special relativity). We show that the independent events and the independent points of light are inseparable not only in Einstein's 1905 paper on quanta of light but also in Einstein's 1905 paper on special relativity. Einstein's special relativity without ether is therefore based on a quantum conception of the light. We show also that there exists another special relativity with ether: Poincare's special relativity (based on the principle of relativity and the principle of real contraction of the lengths)without the concept of event and with a purely classical wavy conception of the light.
The most outstanding contribution to general relativity in this era came in 1953 (published in 1955 \cite{akr}) in the form of the Raychaudhri equation. It is in 1960s that the observations began to confront the eupherial theory and thus began exploration of GR as a legitimate physical theory in right earnest. The remarkable discoveries of cosmic microwave background radiation, quasars, rotating Kerr black hole and the powerful singularity theorems heralded a new canvas of relativistic astrophysics and cosmology. I would attempt to give a brief account of Indian participation in these exciting…
Relativity was Einstein's main research program and scientific project. It was an open-ended program that developed throughout Einstein's scientific career, giving rise to special relativity, general relativity and unified field theory. In this paper, we want to uncover the methodological logic of the Einsteinian program, which animated the whole program and its development, and as it was revealed in SR, GR, and unified field theory. We aver that the same methodological logic animated all these theories as Einstein's work progressed. Each of these theories contributed towards constructing Eins…
The paper considers the "GR-desideratum", that is, the way general relativity implements general covariance, diffeomorphism invariance, and background independence. Two cases are discussed where $5$-dimensional generalizations of general relativity run into interpretational troubles when the GR-desideratum is forced upon them. It is shown how the conceptual problems dissolve when such a desideratum is relaxed. In the end, it is suggested that a similar strategy might mitigate some major issues such as the problem of time or the embedding of quantum non-locality into relativistic spacetimes.
Between 1935 and 1936, Einstein was occupied with the Schwarzschild solution and the singularity within it while working in Princeton on the unified field theory and with his assistant Nathan Rosen, on the theory of the Einstein-Rosen bridges. He was also occupied with quantum theory. He believed that quantum theory was an incomplete representation of real things. Together with Rosen and Boris Podolsky he invented the EPR paradox. I demonstrate that the two-body problem in general relativity was a heuristic guide in Einstein's and collaborators' 1935 work on the Einstein-Rosen bridge and EPR p…
1905年，著名的物理学家马克斯·普朗克（Max Planck）是《物理学年鉴》（Annalen der Physik）的共同编辑，他接受了爱因斯坦关于光量子的论文，尽管他不喜欢“光量子”的概念。1905年6月底，爱因斯坦的相对论论文被《物理学年鉴》（Annalen der Physik）收录，普朗克是第一个注意到爱因斯坦相对论并对其进行正面报道的科学家。在1905年的相对论论文中，爱因斯坦使用了一个看似传统的概念，即“光复合体”，但他并没有引用他的关于相对论原理的新颖的光量子启发式。他选择了“轻度复合体”这一措辞，因为无法对这一措辞给出明确的定义。但事后看来，爱因斯坦在1905年做出了正确的选择，没有把量子论文中的概念和相对论论文中的概念混为一谈。他专注于解决他的相对论问题，普朗克已经意识到了这个问题的深远前景。
On the basis of his `Zürich Notebook' I shall describe a particularly fruitful phase in Einstein's struggle on the way to general relativity. These research notes are an extremely illuminating source for understanding Einstein's main physical arguments and conceptual difficulties that delayed his discovery of general relativity by about three years. Together with the `Ent\-wurf' theory in collaboration with Marcel Grossmann, these notes also show that the final theory was missed late in 1912 within a hair's breadth. The Einstein-Grossmann theory, published almost exactly hundred years ago, con…
There is a myth that Einstein's discovery of general relativity was due to his following beautiful mathematics to discover new insights about nature. I argue that this is an incorrect reading of the history and that what Einstein did was to follow physical insights which arose from asking that the story we tell of how nature works be coherent.
Einstein's biographer Albrecht Fölsing explained: Einstein presented his field equations on November 25, 1915, but six days earlier, on November 20, Hilbert had derived the identical field equations for which Einstein had been searching such a long time. On November 18 Hilbert had sent Einstein a letter with a certain draft, and Fölsing asked about this possible draft: "Could Einstein, casting his eye over this paper, have discovered the term which was still lacking in his own equations, and thus 'nostrified' Hilbert?" Historical evidence support a scenario according to which Einstein discover…
This article is an overview of 100 years of testing general relativity, to be published in the book General Relativity and Gravitation: A Centennial Perspective, to commemorate the 100th anniversary of general relativity. It is effectively an abridged version of the recent update of the author's Living Review in Relativity.
Einstein's special theory of relativity starts with assumptions about how observations conducted in relatively moving inertial frames must compare. From these assumptions, conclusions can be drawn regarding the laws of physics in any one frame. Can we do the reverse, that is, build the correct physics entirely from considerations within a single frame and infer therefrom the results of measurements in moving frames? Can we, in this project, supply the "elementary foundations" that Einstein found lacking in his own theory, thereby converting special relativity from (in Einstein's terminology) a…
This paper discusses Maxwell's demon thought experiment. In recent years, there has been extensive research on Maxwell's demon. I first provide a detailed overview of important historical milestones of Maxwell's demon thought experiment. Einstein would often write about both relativity and thermodynamics. In this paper, I first argue that: 1. Einstein spoke of Perpetuum mobile of the second kind (a Maxwell's demon) in the context of the discovery of his relativity theory, the famous chasing a light beam thought experiment, and the contraction of lengths. 2. He would often compare relativity wi…
In this paper I describe the genesis of Einstein's early work on the problem of motion in general relativity (GR): the question of whether the motion of matter subject to gravity can be derived directly from the Einstein field equations. In addressing this question, Einstein himself always preferred the vacuum approach to the problem: the attempt to derive geodesic motion of matter from the vacuum Einstein equations. The paper first investigates why Einstein was so skeptical of the energy-momentum tensor and its role in GR. Drawing on hitherto unknown correspondence between Einstein and George…
For the celebrations of the 100 years of the observations undertaken by Eddington at the island of Principe and collaborators at Sobral during a total solar eclipse in May 29, 1919, which have confirmed Einstein's theory of general relativity through the deflection of the incoming light from distant stars due to the spacetime curvature caused by the Sun, we highlight the main aspects of the theory, its tests and applications, focusing on some of its outstanding consequences. These are black holes, the object par excellence of general relativity, and gravitational waves, the gravitational probe…
In 1922, Albert Einstein visited Paris and interacted extensively with an illustrious section of the French academia. In overfilled sessions at the Collége de France and the Sorbonne, Einstein explained his theories of relativity, and prominent physicists, mathematicians and philosophers listened, debated, questioned and explored facets of relativity. The 1922 visit had its echoes in the life and works of many who participated, particularly decisive for Einstein and the philosopher Henri Bergson. This essay examines that eventful visit, focusing on the physical and logical aspects of Bergson's…
The objective of this second part of the work is to present heuristic derivations of the three classical tests of general relativity. These derivations are based on the Einstein equivalence principle and use Newtonian physics as a theoretical framework. The results obtained are close to Einstein's original predictions. Historical and anecdotal aspects of the subject are also discussed.
This article presents hitherto unpublished correspondence of Struble in 1947 with Menger, Chandrasekhar, and eventually Einstein, about a possible observational test supporting Einstein's special relativity against Ritz's emission theory using binary stars. This `Struble effect,' an acceleration Doppler effect in emission theory, appears to have been overlooked, and the historical context, including de Sitter's binary star test of special relativity, is also discussed.
We present a historical review of Einstein's 1917 paper 'Cosmological Considerations in the General Theory of Relativity' to mark the centenary of a key work that set the foundations of modern cosmology. We find that the paper followed as a natural next step after Einstein's development of the general theory of relativity and that the work offers many insights into his thoughts on relativity, astronomy and cosmology. Our review includes a description of the observational and theoretical background to the paper; a paragraph-by-paragraph guided tour of the work; a discussion of Einstein's views …
The eclipse of the Sun of 1919 was fundamental in the development of physics and earns a high place in the history of science. Several players took part in this adventure. The most important are Einstein, Dyson, Eddington, the Sun, the Moon, Sobral, and Principe. Einstein's theory of gravitation, general relativity, had the prediction that the gravitational field of the Sun deflects an incoming light ray from a background star on its way to Earth. The calculation gave that the shift in the star's position was 1.75 arcseconds for light rays passing at the Sun's rim. So to test it definitely it …
