Eddington and Uncertainty

Arthur Stanley Eddington (1882-1944) is acknowledged to be one of the greatest astrophysicists of the twentieth century, yet his reputation suffered in the 1930s when he embarked on a quest to develop a unified theory of gravity and quantum mechanics. His attempt ultimately proved to be fruitless and was regarded by many physicists as misguided. I will show, however, that Eddingtons work was not so outlandish. His theory applied quantum-mechanical uncertainty to the reference frames of relativity and actually foreshadowed several later results. His philosophy regarding determinism and uncertainty also was quite orthodox at the time. I first review Eddingtons life and philosophy and then discuss his work within the context of his search for a theory of quantum gravity.     

Quirino Majorana’s Experiments on the Speed of Light and Gravitational Absorption

Quirino Majorana (1871–1957) was an outstanding Italian experimental physicist who investigated a wide range of phenomena during his long career in Rome,Turin, and Bologna. We focus on his experiments in Turin during 1916–1921 and in Bologna during 1921–1934 to test the validity of Albert Einstein’s postulate on the constancy of the speed of light and to detect gravitational absorption. These experiments required extraordinary skill, patience, and dedication, and all of them confirmed Einstein’s postulate and Isaac Newton’s law of universal gravitation to high precision. Had they not done so, Majorana’s fame among historians and physicists no doubt would be much greater than it is today. Giorgio Dragoni is Professor of History of Physics at the University of Bologna. Giulio Maltese is a Roman member of the Italian Society for the History of Physics and Astronomy. Luisa Atti is a Bolognese member of the Association for the Teaching of Physics.     

Astrophysically significant solutions of the Einstein and Einstein-Maxwell equations from the Laplace’s seed

The stationary solutions given by Amenedo and Manko generated from known solutions of Laplace’s equation as seed have been generalised to include the electromagnetic field. Further, the exterior solution of an axially symmetric rotating body with higher multipole moments and a solution corresponding to a Kerr object embedded in a gravitational field are given. We also give a method for constructing stationary vacuum solutions from static magnetovac solutions and vice versa and discuss a specific application of this method.     

Peter Bergmann:The Education of a Physicist

I explore the early life and contributions of Peter Bergmann (1915–2002), focusing on his family background, education, and ideas. I examine how Bergmann’s formative years were shaped by the outspoken influence of his mother, a leading educational reformer; the distinguished reputation of his father, a renowned materials chemist; and his cherished hope of working with Albert Einstein (1879–1955), to whom he eventually became an assistant. Inspired by these and other notable thinkers, Bergmann became an exemplary organizer, educator, and mentor in the fields of general relativity and quantum gravity.     

想象力比知识更重要——从相对论的起源谈起

文章介绍了爱因斯坦相对论的起源,并对学校教育进行了思考.相对论起源于爱因斯坦对光速问题与相对性问题的研究,从相对论的起源与建立不难发现,其中最具关键性作用的并非人们的既有知识,而是爱因斯坦超乎寻常的想象力.相对论的起源充分证明,在推动科学发展的知识创新活动中,想象力与创新精神比知识更重要.人的知识是有限的,然而想象力是无限的,想象力与创新精神是知识进化的源泉.学校教育的目的不仅在于传授知识,更重要的在于激发人的想象力与培养人的创新精神.     

利用爱因斯坦转盘推求中心引力场中的光频红移--在普通物理教学中讲解等效原理的一种尝试

通过球对称引力场与爱因斯坦转盘上的惯性离心力场的对比，利用强等效原理导出光频的引力红移。     

The Calculations that Gave Einstein “Heart Palpitations”

In what follows, I reply to the preceding article by Michel Janssen and Robert Schulmann, which itself was a response to my article on One month in the history of the discovery of general relativity theory, published in the February 1998 issue of this journal. I stand by the historical analysis and conclusions presented in my original article.     

Lanczos Potential for the Gödel Cosmological Model

Using a Lovelock's theorem we obtain the Lanczos spintensor for the Gödel's metric.     

Einstein,de Sitter and the beginning of relativistic cosmology in 1917

In 1917, both Einstein and de Sitter proposed a new interpretation of the universe as a whole: the structure of the universe could be described in terms of relativistic field equations. Their contributions marked the beginning of the modern scientific comprehension of the origin and evolution of the universe. Our aim is to propose a critical review paper, based on references in primary sources, on the formulation in 1917 of Einstein’s and de Sitter’s models of the universe, which represents a fundamental chapter in the history of relativistic Cosmology.     

Algebraically special hypersurface-homogeneous Einstein spaces in general relativity

This paper illustrates the value of the Newman—Penrose complex null tetrad formalism by using it to obtain all algebraically special Einstein spaces admitting three-parameter groups of motions acting on timelike surfaces containing the repeated principal null direction. Taken together with earlier work, this enables us to give a complete list of Einstein spaces which are both algebraically special and hypersurface-homogeneous or homogeneous.     

Letter: Cerenkov Radiation from a Charged Particle in a Weyl–Dirac Theory

A thin shell can separate an interior region of Riemannian geometry from an exterior spherically symmetric Weyl space. We explore the possibility that a charged particle propagating in the gravitational field outside this thin shell could emit Cerenkov radiation. Some astrophysical scenarios in which such effect could arise are discussed.     

Magnetized cylindrically symmetric universe in general relativity

A magnetized cylindrically symmetric universe with two degrees of freedom in which the free gravitational field is Petrov type I degenerate, is obtained. The magnetic field is due to an electric current produced along the x-axis. The distribution consists of an electrically neutral perfect fluid with an infinite electrical conductivity. The behaviour of the model when magnetic field tends to zero and other physical aspects of the model are also discussed.     

About neutrino signals from SN 1987A

Summary The properties of neutrino signals from SN 1987A are unexpected, namely, two pulses occurred with a 4 h 43 min interval and the total energy carried away by neutrinos is too high (E ₅₄≥3) for either of the pulses,i.e. an order as high as the maximum value ensuing from the neutron star mass defect. If the function of neutrino energy distribution is assumed to be equilibrium and of Fermi form, the data obtained from different equipments are in a poor agreement with each other. The general relativity and the geometry as a whole were used earlier to demonstrate that, in case of a sufficiently high mass when any equilibrium static solution is absent, there exists a dynamic oscillatory solution, namely, matter moves periodically to under the gravitational radius and emerges from under the latter to enter the same physical space. The mass defect for the dynamic configuration is 60%, thereby eliminating all the troubles involved by energy considerations. A feasible scenario of the SN 1987A explosion is discussed considering the function of neutrino energy distribution to differ from an equilibrium function.

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Riassunto Le proprietà dei segnali neutrinici dalla SN 1987A sono impreviste, cioè due impulsi si sono verificati con un intervallo di 4 h 43 min e l'energia totale portata via dai neutrini è troppo elevata (E ₅₄≥3) per ciascuno degli impulsi, cioè è dello stesso ordine del valore massimo che deriva dal difetto di massa della stella di neutroni. Se la funzione della distribuzione dell'energia dei neutrini è ipotizzata in equilibrio e della forma di Fermi, i dati ottenuti con diverse apparecchiature sono in scarso accordo tra loro. La relatività generale e la geometria nel complesso sono state usate precedentemente per dimostrare che, nel caso di una massa sufficientemente grande, quando manca una soluzione di equilibrio statico, esiste una soluzione oscillatoria dinamica, cioè la materia si muove periodicamente fino a sotto il raggio gravitazionale e emerge da sotto quest'ultimo per entrare nello stesso spazio fisico. Il diffetto di massa per la configurazione dinamica è il 60%, eliminando perciò tutti i problemi che le considerazioni sull'energia implicano. Si discute uno scenario fattibile dell'esplosione della SN 1987A assumendo che la funzione di distribuzione dell'energia neutrinica differisca dalla funzione di equilibrio.

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Резюме Свойства нейтринных сигналов от SN 1987A неожиданны: были два имульса с интервалом 4 h 43 min: полная энергия, унесенная нейтрино, слишком велика (E ₅₄>3 для каждого из импульсов, что на порядок превышает максимальное значение, вытекающее из дефекта массы нейтронной звезды. Если предположить, что функция распределения нейтрино по энергии равновесная фермиевская, то данные установок плохо согласуются между собой. Ранее, строго в рамках общей теории относительности и геометрии в целом, было показано, что при достаточно большой массе, когда не существует равновесного статического решения, есть динамическое колебательное решение-материя периодически заходит под гравиатционный радиус и выходит из под него в тоже самое физическое пространство. Дефект массы для динамической конфигурации равен 60%, что снимает все трудности с энергетикой. Обсуждается возможный сценарий взрыва SN 1987A, при этои функция распределения нейтрино по энергии отличается от равновесной.

     

Recognition of gravitation impulses on a correlated non-Gaussian noise background

We consider the problem of gravitation-wave impulse recognition against the background of correlated noise produced by resonance gravitational antennas. A new algorithm for the joint processing of data recorded by spatially separated gravitational detectors is obtained. The algorithm is an alternative to the coincidence scheme, which is traditionally used in gravitation-wave experiments. It is based on the principles, well known in statistical radiophysics, of joint detection and parameter estimation in quasi-deterministic signals.     

爱丁顿与广义相对论的验证

简单介绍了在广义相对论诞生之初,验证其理论正确性的三个天文实验,并详细介绍了爱丁顿为验证广义相对论,发起并组织的观测1919年5月29日的日全食考察队的具体情况.这是爱丁顿认为他在天文学研究中最激动人心的事件.     

The Mathematical Basis for Physical Laws

Laws of mechanics, quantum mechanics, electromagnetism, gravitation and relativity are derived as “related mathematical identities” based solely on the existence of a joint probability distribution for the position and velocity of a particle moving on a Riemannian manifold. This probability formalism is necessary because continuous variables are not precisely observable. These demonstrations explain why these laws must have the forms previously discovered through experiment and empirical deduction. Indeed, the very existence of electric, magnetic and gravitational fields is predicted by these purely mathematical constructions. Furthermore these constructions incorporate gravitation into special relativity theory and provide corrected definitions for coordinate time and proper time. These constructions then provide new insight into the relationship between manifold geometry and gravitation and present an alternative to Einstein’s general relativity theory.