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At least 379 records · Page 21Linked to original sources
arXiv2014

Schwinger's Quantum Action Principle. I. From Dirac's Formulation through Feynman's Path Integrals to the Schwinger-Keldysh Method

Starting from the earlier notions of stationary action principles, we show how Schwinger's Quantum Action Principle descended from Dirac's formulation, which independently led Feynman to his path-integral formulation of quantum mechanics. The connection between the two is brought out, and applications are discussed. The Keldysh-Schwinger time-cycle method of extracting matrix elements is described. Part II will discuss the variational formulation of quantum electrodynamics and the development of source theory.

physics.hist-ph↗
arXiv2014

Einstein's aborted attempt at a dynamic steady-state universe

In June 1930 Einstein visited Cambridge where he stayed with Eddington who had just shown that Einstein's supposedly static universe of 1917 was not stable. This forced Einstein to rethink his cosmology. He spent January and February 1931 at Pasadena. There, he discussed cosmology intensely with Tolman, conscious that he had to replace his original model of 1917. However, at the end of February he still had not made up his mind about an alternative. The Albert Einstein Archives of Jerusalem (AEA) hold an undated draft, handwritten by Einstein, which I date to the beginning of January 1931. In this draft Einstein hopes to have found a solution to the cosmological problem: a stationary, dynamic universe in expansion. His model was stationary because particles leaving a given volume were replaced by particles created out of the vacuum, anticipating an idea of Bondi, Gold and Hoyle published in 1948. He saw the cosmological term as energy reservoir. However, he realised that his calculations contained a numerical error. When the error was corrected his steady-state-model collapsed.

physics.hist-ph↗
arXiv2014

On the origins and the historical roots of the Higgs boson research from a bibliometric perspective

Subject of our present paper is the analysis of the origins or historical roots of the Higgs boson research from a bibliometric perspective, using a segmented regression analysis in a reference publication year spectroscopy (RPYS). Our analysis is based on the references cited in the Higgs boson publications published since 1974. The objective of our analysis consists of identifying concrete individual publications in the Higgs boson research context to which the scientific community frequently had referred to. As a consequence, we are interested in seminal works which contributed to a high extent to the discovery of the Higgs boson. Our results show that researchers in the Higgs boson field preferably refer to more recently published papers - particular papers published since the beginning of the sixties. For example, our analysis reveals seven major contributions which appeared within the sixties: Englert and Brout (1964), Higgs (1964, 2 papers), and Guralnik et al. (1964) on the Higgs mechanism as well as Glashow (1961), Weinberg (1967), and Salam (1968) on the unification of weak and electromagnetic interaction. Even if the Nobel Prize award highlights the outstanding importance of the work of Peter Higgs and Francois Englert, bibliometrics offer the additional possibility of getting hints to other publications in this research field (especially to historical publications), which are of vital importance from the expert point of view.

physics.hist-ph↗
arXiv2014

A Kepler's note on secular inequalities

I discuss the problem of secular inequalities in Kepler by giving account of a manuscript note that has not been published until 1860. In his note Kepler points out the need for a model, clearly inspired by the method of epicycles, that describes the secular inequalities as periodic ones. I bring attention to this point, that seems to have been underestimated, since the references to Kepler's work usually report only that he observed a decreasing mean motion for Saturn and an increasing one for Jupiter.

physics.hist-ph↗
arXiv2014

Pathways of History of Elementary Particle Physics

In this first paper, we briefly retrace some historical pathways of modern physics of 20th Century. In particular, we have considered some moments of cosmic ray physics and, above all, the early theoretical and experimental bases which will lead to the first exact measurements of the anomalous magnetic moment of the muon, one of the main high precision tests of QED.

physics.hist-ph↗
arXiv2014

Bhavnagar Telescope: the most widely travelled telescope in the country

In the last decade of the 19th century Maharaja Takhtasingji Observatory was built at Poona (1888-1912) under the supervision of K.D.Naegamavala, with the grant from Maharaja of Bhavnagar (from where the name Bhavnagar Telescope must have originated. The story of this telescope from its inception to the current status is traced. IIA Archives has been extensively used to resource information for this note.

physics.hist-ph↗
arXiv2014

The Inquisition's Semicolon: Punctuation, Translation, and Science in the 1616 Condemnation of the Copernican System

This paper presents high-resolution images of the original document of the 24 February 1616 condemnation of the Copernican system, as being "foolish and absurd in philosophy", by a team of consultants for the Roman Inquisition. Secondary sources have disagreed as to the punctuation of the document. The paper includes a brief analysis of the punctuation and the possible effects of that punctuation on meaning. The original document and its punctuation may also have relevance to public perception of science and to science education.

physics.hist-ph↗
arXiv2014

Charles Michie Smith - founder of the Kodaikanal (Solar Physics) Observatory and beginnings of physical astronomy in India

It has been about 115 years since the establishment of Kodaikanal Observatory as an extension of the original Madras Observatory, which has evolved into the present Indian Institute of Astrophysics at Bangalore. It is also the first mountain observatory in India. Charles Michie Smith was the man who selected the site, established the observatory and directed it for the first 12 years. He was also the man who recruited John Evershed, discoverer of the famous Evershed effect and established Kodaikanal Observatory as a major centre for solar physics. Michie Smith, the person and the establishment of Kodaikanal Observatory are discussed here in the context of the early studies in physical astronomy (observational astrophysics) in India.

physics.hist-ph↗
arXiv2014

Callisto III e la Cometa di Halley: la ricerca di Johan Stein SJ tra leggenda e storia

The Dutch Jesuit astronomer Johan Stein published in 1909 a text about the legend on a papal bull of Pope Callixtus III against the comet of 1456. This comet happened to be the Halley's one. The original documents, either chronicles and observations, and coeval testimonies are deeply investigated by Stein and the falsity of that legend is clearly demonstrated. In the occasion of the 200 years of the restoration of the Societas Jesu made in 1814 by Pope Pius VII an Italian edition of the full text of Johan Stein is here presented.

physics.hist-ph↗
arXiv2014

The True (?) Story of Hilbert's Infinite Hotel

What is known as "Hilbert's hotel" is a story of an imaginary hotel with infinitely many rooms that illustrates the bizarre consequences of assuming an actual infinity of objects or events. Since the 1970s it has been used in a variety of arguments, some of them relating to cosmology and others to philosophy and theology. For a long time it has remained unknown whether David Hilbert actually proposed the thought experiment named after him, or whether it was merely a piece of mathematical folklore. It turns out that Hilbert introduced his hotel in a lecture of January 1924, but without publishing it. The counter-intuitive hotel only became better known in 1947, when George Gamow described it in a book, and it took nearly three more decades until it attracted wide interest in scientific, philosophical, and theological contexts. The paper outlines the origin and early history of Hilbert's hotel paradox. At the same time it retracts the author's earlier conclusion that the paradox was originally due to Gamow.

physics.hist-ph↗
arXiv2014

The Emu Sky Knowledge of the Kamilaroi and Euahlayi Peoples

This paper presents a detailed study of the knowledge of the Kamilaroi and Euahlayi peoples about the Emu in the Sky. This study was done with ethnographic data that was not previously reported in detail. We surveyed the literature to find that there are widespread reports of an Emu in the Sky across Australian Aboriginal language groups, but little detailed knowledge available in the literature. This paper reports and describes a comprehensive Kamilaroi and Euahlayi knowledge of the Emu in the Sky and its cultural context.

physics.hist-ph↗
arXiv2014

Les inégalités de Bell et l'article Einstein, Podolsky, Rosen, une relecture

The relationship between the Bell article in 1964 and its well known inequalities with the Einstein Podolsky Rosen article in 1935 is revisited. Einstein views on quantum mechanics as stated in many circumstances up to his death in 1955 are recalled. The role of David Bohm is shown to be essential to understand the link between Bell and Einstein's views. This link appears not to be as usually recounted.

physics.hist-ph↗
arXiv2014

Ya. B. Zeldovich (1914-1987): Chemist, Nuclear Physicist, Cosmologist

Ya.B. Zeldovich was a pre-eminent Soviet physicist whose seminal contributions spanned many fields ranging from physical chemistry to nuclear and particle physics, and finally astrophysics and cosmology. March 8, 2014 marks Zeldovich's birth centenary, and this article attempts to convey the zest with which Zeldovich did science, and the important role he played in fostering and mentoring a whole generation of talented Scientists.

physics.hist-ph↗
arXiv2014

The Early Years of Condensed Matter Physics at Illinois -- in Celebration of the 80th Birth Year of Charles P. Slichter -- Charlie Slichter & the gang at Urbana

The 1950s-- and perhaps also the 1960s-- were very special times for the development of solid-state/condensed-matter physics. The University of Illinois at Urbana was at the center of these activities. In areas like NMR and superconductivity, methods were developed which would form the basis for the next half century of science and technology. Experimentalists, including Charlie and John Wheatley, worked hand in hand with theorists, including the incomparable John Bardeen. They worked cooperatively to develop ideas, often born in Urbana, but with godparents at Harvard and Moscow and Paris. A characteristic style of broad collaboration and spirited exchange developed and spread from Illinois. This development was not an accident but the result of the vision of leaders like Wheeler Loomis, Fred Seitz, and later Gerald Almy1. The strong leadership saved the other scientists from expending their time on departmental decision-making. The style of the scientific activity was set by Fred, who strongly encouraged joint activities--especially the interaction between between theory and experiment and between physics and engineering. Fred encouraged comments from everyone, and helped everyone grow fast

physics.hist-ph↗
arXiv2014

Maudlin's Challenge Refuted: A Reply to Lewis

Lewis has recently argued that Maudlin's contingent absorber experiment remains a significant problem for the Transactional Interpretation (TI). He argues that the only straightforward way to resolve the challenge is by describing the absorbers as offer waves, and asserts that this is a previously unnoticed aspect of the challenge for TI. This argument is refuted in two basic ways: (i) it is noted that the Maudlin experiment cannot be meaningfully recast with absorbers described by quantum states; instead the author replaces it with an ordinary which-way experiment; and (ii) the extant rebuttals to the Maudlin challenge in its original form are not in fact subject to the alleged flaws that Lewis ascribes to them. This paper further seeks to clarify the issues raised in Lewis' presentation concerning the distinction between quantum systems and macroscopic objects in TI. It is noted that the latest, possibilist version of TI (PTI) has no ambiguity concerning macroscopic absorbers. In particular, macroscopic objects are not subject to indeterminate trajectories, since they are continually undergoing collapse. It is concluded that the Maudlin challenge poses no significant problem for the transactional interpretation.

quant-ph↗
arXiv2014

Laborexperimente zur Entstehung und Wirkung kosmischer Magnetfelder

Magnetic fields of cosmic bodies are generated by the hydromagnetic dynamo effect in moving electrically conducting fluids, such as liquid metals or plasmas. Once produced, cosmic magnetic fields are able to act back on moving fluids. This back-reaction may have dramatic consequences for cosmic structure formation, with the magnetorotational instability (MRI) in accretions disks as the most prominent example. Considerable theoretical and computational progress has been made in understanding both the dynamo effect as well as magnetically triggered flow instabilities. Complementary to this, the last fifteen years have seen much effort in studying both effects in liquid metal experiments. We summarize the history of these experiments, discuss their main results and their limitations, and give an outlook on future activities.

physics.hist-ph↗
arXiv2014

Presentism meets black holes

Presentism is, roughly, the metaphysical doctrine that maintains that whatever exists, exists in the present. The compatibility of presentism with the theories of special and general relativity was much debated in recent years. It has been argued that at least some versions of presentism are consistent with time-orientable models of general relativity. In this paper we confront the thesis of presentism with relativistic physics, in the strong gravitational limit where black holes are formed. We conclude that the presentist position is at odds with the existence of black holes and other compact objects in the universe. A revision of the thesis is necessary, if it is intended to be consistent with the current scientific view of the universe.

physics.gen-ph↗