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Gathering the Team
Published in Volker Knecht, AI for Physics, 2023
In the 20th century, the physical view of the world was turned upside down by two revolutionary theories supported by a wealth of experimental data. The first one is Albert Einstein's theory of relativity transforming our perception of space, time, and matter. Special relativity says the velocity of light in vacuum is the ultimate speed limit in nature and a fundamental constant connecting space and time to a four-dimensional spacetime. General relativity (often termed the most beautiful of all existing physical theories) declares gravity as curvature of spacetime. The second theory is quantum mechanics; it says energy (like light) is transmitted in quanta and microscopic objects have both particle and wave character, with often incredibly bizarre consequences.
Celestial Mechanics and Astrodynamics
Published in K.T. Chau, Applications of Differential Equations in Engineering and Mechanics, 2019
Einstein’s general theory of relativity speculated that the space-time around a massive body is distorted and curved, and such curved space-time can be described mathematically by Riemann geometry, as illustrated in Figure 12.18. In 1915, Einstein published his celebrated paper on the advance of perihelion precession of Mercury using general relativity based on the approximate gravitational field around a spherically symmetric, non-rotating, non-charged mass. On December 22, 1915, while still serving a war stationed on the Russia front of World War I, Karl Schwarzschild sent a letter to Einstein and presented his exact solution of Einstein’s field equation in polar form. In 1916, Einstein replied:
Geochemistry tools, statistical geochemistry, equilibrium thermodynamics: phase diagrams, nonequilibrium thermodynamics, thermodynamic principles of evolution, laws of self-development
Published in Aleksey B. Ptitsyn, Lectures in Geochemistry, 2018
Later it was determined that Earth rotates around the Sun, being “tied” to it by the force of gravity. It should be noted that the physical nature of gravity is mysterious and has not yet been fully understood. The gravitational field and gravitational waves (lately much spoken and written about) are thought to spread almost as rapidly as light and never to be screened. Gravity is not a force acting in the passive background of space and time; according to Einstein’s theory, it is a distortion of space-time itself (Dubnischeva, 1997). In other words, the gravitational field is the curvature of space-time. The gravitational interaction must be described by a quantum theory of gravity, which has not yet been developed. So, gravity is energy, and therefore it contributes to the overall energy balance of any system, including the system of planet Earth. The gravitational impact on Earth is determined by its position relative to other celestial bodies, which varies cyclically, because the cosmic orbits are elliptical. Consequently, some cyclic processes inside Earth may be associated with fluctuations in the intensity of gravitational energy in the near cosmos, rather than with some internal cyclic mechanism. This reveals a connection between geology (and geochemistry) and astronomy.
Magnetic dipolar modes in magnon-polariton condensates
Published in Journal of Modern Optics, 2021
It is important to note here that Figure 17(b) indicates a relativistic effect that imprints the orbital angular momentum on the EM wave of the waveguide. This is similar to the effects of twisting of light around rotating black holes. In curved spacetime geometries, the direction of a vector is generally not preserved when parallel-transported from one event to another, and light beams are deflected because of gravitational lensing. If the source of the gravitational field also rotates, it drags spacetime with it, causing linearly polarized EM radiation in vacuum to undergo polarization rotation similar to the Faraday rotation of light in a magnetized medium [86].