Langevin's influence on relativity theories

2020 ◽  
Vol 33 (4) ◽  
pp. 380-386
Author(s):  
Douglas A. Staley

A century ago, Paul Langevin [C. R. 173, 831 (1921)], through his influence, convinced the scientific community that Einstein's theories of relativity were correct and could explain the Sagnac effect. A simple note in Comptes Rendus was all it took to silence many prominent skeptical scientists. The relativity skeptics had pointed to Sagnac's experiment [C. R. 157, 1410 (1913)] with the interference of counter rotating light beams as proof that the speed of light was not the same in both directions, contrary to the key postulate in Einstein's theory. Langevin showed that the result was also explained by relativity. The rest is history, and relativity has remained a center piece of theoretical physics ever since. Langevin had been captivated by solar eclipse observations of a shifted star pattern near the sun as reported by Eddington [Report on the Relativity Theory of Gravitation (Fleetway Press, Ltd., London, 1920)]. This was taken as proof positive for Einstein's General Theory of Relativity. The case of a light beam split into two beams, which propagate in opposite directions around a circuit, has an analog in a simple thought experiment—a speed test for runners. Two runners can be timed on a running track with the runners going around the track in opposite directions. Two stop watches will display the time for each runner's return to the starting position. The arithmetic difference in time shown on each stop watch will provide the differences in speed between the two runners. If the two speeds are the same, the time difference will be zero. It would not make any sense for one of the stop watches to measure a negative time, that is, time moving into the past. In fact, the idea is absurd! However, Langevin did just that, assigned the time for light to travel in one direction as positive while the time for the light to traverse in the opposite direction as negative, moving into the past! By so doing, Langevin reproduced Sagnac's expression and declared that relativity explains Sagnac's experiment. Langevin was wrong!

Lightspeed ◽  
2019 ◽  
pp. 144-158
Author(s):  
John C. H. Spence

The confused state of theoretical physics in 1900 and the great unresolved issues are summarized, one of which led to the birth of quantum mechanics, and the other to relativity. How it seemed impossible to reconcile Bradley’s measurements of the speed of light with Fresnel’s Aether drag hypothesis, which was well supported by Fizeau’s measurements in Paris of the speed of light in a moving medium (flowing water). Maxwell’s equations predicted a constant speed of light, suggesting an absolute frame of reference in the universe, but did not “transform” in the same way as Newton’s equations from one moving observer to another. How Einstein made sense of all these rival theories and experimental results with his unifying theory of relativity, based on two assumptions. His life and work is discussed, and a simple explanation given of his relativity theory. How the failure of this search for an absolute frame of reference in our universe led him inexorably to perhaps the most famous equation in physics E = mc2, giving the energy release from nuclear explosions and the stars.


2019 ◽  
Vol 950 (8) ◽  
pp. 2-11
Author(s):  
S.A. Tolchelnikova ◽  
K.N. Naumov

The Euclidean geometry was developed as a mathematical system due to generalizing thousands years of measurements on the plane and spherical surfaces. The development of celestial mechanics and stellar astronomy confirmed its validity as mathematical principles of natural philosophy, in particular for studying the Solar System bodies’ and Galaxy stars motions. In the non-Euclidean geometries by Lobachevsky and Riemann, the third axiom of modern geometry manuals is substituted. We show that the third axiom of these manuals is a corollary of the Fifth Euclidean postulate. The idea of spherical, Riemannian space of the Universe and local curvatures of space, depending on body mass, was inculcated into celestial mechanics, astronomy and geodesy along with the theory of relativity. The mathematical apparatus of the relativity theory was created from immeasurable quantities


This volume contains lectures delivered at the Les Houches Summer School ‘Integrability: from statistical systems to gauge theory’ held in June 2016. The School was focussed on applications of integrability to supersymmetric gauge and string theory, a subject of high and increasing interest in the mathematical and theoretical physics communities over the past decade. Relevant background material was also covered, with lecture series introducing the main concepts and techniques relevant to modern approaches to integrability, conformal field theory, scattering amplitudes, and gauge/string duality. The book will be useful not only to those working directly on integrablility in string and guage theories, but also to researchers in related areas of condensed matter physics and statistical mechanics.


Author(s):  
Moataz H. Emam

This book is an introduction to the modern methods of the general theory of relativity, tensor calculus, space time geometry, the classical theory of fields, and a variety of theoretical physics oriented topics rarely discussed at the level of the intended reader (mid-college physics major). It does so from the point of view of the so-called principle of covariance; a symmetry that underlies most of physics, including such familiar branches as Newtonian mechanics and electricity and magnetism. The book is written from a minimalist perspective, providing the reader with only the most basic of notions; just enough to be able to read, and hopefully comprehend, modern research papers on these subjects. In addition, it provides a (hopefully short) preparation for the student to be able to conduct research in a variety of topics in theoretical physics; with particular emphasis on physics in curved spacetime backgrounds. The hope is that students with a minimal mathematical background in calculus and only some introductory courses in physics may be able to study this book and benefit from it.


2021 ◽  
Vol 11 (3) ◽  
pp. 43-49
Author(s):  
Hamdoon A. Khan ◽  

With the consideration of the light which carries the photon particles, the Lorentz transformation was constructed with an impressive mathematical approach. But the generalization of that equation for all the velocities of the universe is direct enforcement on other things not to travel faster than light. It has created serious issues in every scientific research that was done in the last century based on the special theory of relativity. This paper replaces the velocity of light with some other velocities and shows us the possible consequences and highlights the issues of special relativity. If I travel through my past or future and was able to see another me there, who would be the real Hamdoon I or the one I see there in the past or future! If the real one is only me, the one I saw, is not me, so, I could not travel through my or someone else's past or future. Therefore, no one can travel through time. If both of us are the same, can the key of personal identity be duplicated or be separated into two or more parts? These are some of the fundamental philosophical arguments that annihilate the concept of time travel which is one of the sequels of special relativity.


2020 ◽  
Author(s):  
Douglas Michael Snyder

Though Einstein and other physicists recognized the importance of an observer being at rest in an inertial reference frame for the special theory of relativity, the supporting psychological structures were not discussed much by physicists. On the other hand, Rock wrote of the factors involved in the perception of motion, including one’s own motion. Rock thus came to discuss issues of significance to relativity theory, apparently without any significant understanding of how his theory might be related to relativity theory. In this paper, connections between Rock’s theory on the perception of one’s own motion, as well as empirical work supporting it, and relativity theory are explored. Paper available at: https://arxiv.org/abs/physics/9908025v1 .


Metaphysics ◽  
2020 ◽  
pp. 64-68
Author(s):  
M. L Fil’chenkov ◽  
Yu. P Laptev

Quantum theory and relativity theory as well as possible reconciliation have been analyzed from the viewpoint of mathematical models being used in them, experimental affirmation, interpretations and their association with dualistic paradigms.


2021 ◽  
Vol 9 ◽  
Author(s):  
Jian Wang ◽  
Yize Liang

Structured light beams have rapidly advanced over the past few years, from specific spatial-transverse/longitudinal structure to tailored spatiotemporal structure. Such beams with diverse spatial structures or spatiotemporal structures have brought various breakthroughs to many fields, including optical communications, optical sensing, micromanipulation, quantum information processing, and super-resolution imaging. Thus, plenty of methods have been proposed, and lots of devices have been manufactured to generate structured light beams by tailoring the structures of beams in the space domain and the space–time domain. In this paper, we firstly give a brief introduction of different types of structured light. Then, we review the recent research progress in the generation and detection of structured light on different platforms, such as free space, optical fiber, and integrated devices. Finally, challenges and perspectives are also discussed.


Author(s):  
David J. Stump

Although primarily a mathematician, Henri Poincaré wrote and lectured extensively on astronomy, theoretical physics, philosophy of science and philosophy of mathematics at the turn of the century. In philosophy, Poincaré is famous for the conventionalist thesis that we may choose either Euclidean or non-Euclidean geometry in physics, claiming that space is neither Euclidean nor non-Euclidean and that geometry is neither true nor false. However, Poincaré’s conventionalism was not global, as some have claimed. Poincaré held that only geometry and perhaps a few principles of mechanics are conventional, and argued that science does discover truth, despite a conventional element. Poincaré followed new developments in mathematics and physics closely and was involved in discussion of the foundations of mathematics and in the development of the theory of relativity. He was an important transitional figure in both of these areas, sometimes seeming ahead of his time and sometimes seeming very traditional. Perhaps because of the breadth of his views or because of the way in which philosophers focused on issues or small pieces of his work rather than on accurate history, interpretations of Poincaré vary greatly. Frequently cited by the logical positivists as a precursor, and widely discussed in the philosophy of science and the philosophy of mathematics, Poincaré’s writings have had a strong impact on English-language philosophy.


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