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At least 253 records · Page 14Linked to original sources
arXiv2013

Wavefunction reality, indeterminate properties and degrees of presence

The degree-of-presence (of the quantum system) concept, accompanying that of the wavefunction-reality postulate, is introduced and studied in two ways. To begin with, an incomplete exposition of the present author's views is given. Subsequently, a short historical and philosophical review of answers to the question about the meaning of indeterminate individual-system probabilities is presented from the literature. It is done in the form of a carefully selected collage of quotations mostly with polemic comments by the present author and with further elaboration of his point of view. The advocated notion of 'degree of presence' generalizes the intuitively most easily acceptable idea of 'delocalization' in (roughly called)wavelike behavior of a quantum system.

physics.hist-ph↗
arXiv2013

Die weltweit erste Messung einer Lotabweichung in der Länge

During the summer of 1837 Christian Ludwig Gerling, a former student of Carl Friedrich Gauss, organized the world wide first determination of a vertical deflection in longitude. From a mobile observatory at the Frauenberg close to Marburg (Hessen) he measured the astronomical longitude difference between the observatory of C.F. Gauss at Göttingen and the observatory of F.G.B. Nicolai at Mannheim. By comparing these astronomical results with the geodetic determined longitude differences, which he just had measured as a part of the triangulation of Kurhessen, he was able to extract a combined value of the vertical deflection of Göttingen and Mannheim. His results are in very good agreement with modern vertical deflection data.

physics.hist-ph↗
arXiv2013

Astronomical orientations in sanctuaries of Daunia

Prehistoric sanctuaries of Daunia date back several thousand years. During the Neolithic and Bronze Age the farmers in that region dug hypogea and holes whose characteristics suggest a ritual use. In the present note we summarize the results of the astronomical analysis of the orientation of the row holes in three different sites, and we point out the possible use of the setting of the stars of Centaurus. An interesting archaeological confirmation of an archaeoastronomical prediction is also reported.

physics.hist-ph↗
arXiv2013

On the Eclipse of Thales, Cycles and Probabilities

According to classical tradition, Thales of Miletus predicted the total solar eclipse that took place on 28 May 585 BCE. Even if some authors have flatly denied the possibility of such a prediction, others have struggled to find cycles which would justify the achievement of the philosopher. Some of the proposed cycles have already been refuted, but two of them, namely those of Willy Hartner and Dirk Couprie, remain unchallenged. This paper presents some important objections to these two possibilities, based on the fact that these authors do not list all the eclipses potentially visible by their criteria. In addition, any explanation based on cycles will need to face the complex problem of visibility (smallest observable eclipse, weather...). The present article also includes a statistical study on the predictability of solar eclipses for a variety of periods, similar to that performed by Willy Hartner for lunar eclipses, resulting in lower probabilities in the solar case (and percentages depend on the chosen magnitude limit). The conclusion is that none of the cycles proposed so far provides a satisfactory explanation of the prediction, and, on statistical grounds, none of the periods studied leads to a significant probability of success with solar eclipse cycles.

physics.hist-ph↗
arXiv2013

The 1905 Relativity Paper and the "Light Quantum"

In 1905 the well-known physicist Max Planck was coeditor of the Annalen der Physik, and he accepted Einstein's paper on light quanta for publication, even though he disliked the idea of "light quanta". Einstein's relativity paper was received by the Annalen der Physik at the end of June 1905 and Planck was the first scientist to notice Einstein's relativity theory and to report favorably on it. In the 1905 relativity paper Einstein used a seemingly conventional notion, "light complex", and he did not invoke his novel quanta of light heuristic with respect to the principle of relativity. He chose the language "light complex" for which no clear definition could be given. But with hindsight, in 1905 Einstein made exactly the right choice not to mix concepts from his quantum paper with those from his relativity paper. He focused on the solution of his relativity problem, whose far-reaching perspectives Planck already sensed.

physics.hist-ph↗
arXiv2013

Anybody but Hubble!

The recent literature of astronomy and cosmology has included a good many suggestions for "who first recognized the expansion of the universe?" with cases having been made for Lemaitre, Lundmark, de Sitter, Slipher, Shapley, Friedmann, Wirtz, and perhaps others. I touch on these but also mention others (some of whose names have not come down to us) who might reasonably be credited with some part of the basic idea, but conclude that "Hubble's Law" is the right choice ("because it was discovered by Lundmark" in accordance with Stigler's Law). Of course there are a couple of previously unsung heroes (Dose and Zoellner), and the discussion bears some traces of its origin as an after-dinner talk. The full context goes back to ideas from China and forward to the struggle to correct Hubble's erroneous value of his constant.

physics.hist-ph↗
arXiv2014

Galileo knowledge of optics and the functioning of the telescope revised

What are the historical evidence concerning the turning of the spyglass into an astronomical instrument, the telescope? In Sidereus Nuncius and in his private correspondence Galileo tells the reader what he did with the telescope, but he did not disclose the existence of a theory of the instrument. Still, the instruments which Galileo produced are extant and can be studied. With replicas of Galileo's telescopes that magnify 14 and 21 times, we have simulated and analyzed Galileos practices as he reported them in Sidereus Nuncius. On this ground, we propose a new solution to this old problem. We establish the knowledge of optics that Galileo had as it can be read off from the telescopes he constructed and the way he put them to use. Galileo addressed optical difficulties associated with illumination, resolution, field of view, and magnification. His optical knowledge was well thought through, originated as it did in a radically new optical framework.

physics.hist-ph↗
arXiv2019

"We Think That We Think Clearly, But That's Only Because We Don't Think Clearly": Mathematics, Mind, and the Human World

This paper is concerned with a dialogue between Rabindranath Tagore and Albert Einstein, where Tagore argued that our knowledge is essentially human, while Einstein maintained that some kinds of knowledge are more objective. Arguments by Davis and Hersh concerning the nature of mathematics support the idea of mathematical truth being a human construct. It may further be argued that the scientific theories we arrive at are very much a result of the particular mathematical and experimental tools that we use. There may however be a deeper kind of knowledge that science has yet to understand.

physics.gen-ph↗
arXiv2013

Dispelling the Quantum Spooks -- a Clue that Einstein Missed?

It is well-known that Bell's Theorem and other No Hidden Variable theorems have a "retrocausal loophole", because they assume that the values of pre-existing hidden variables are independent of future measurement settings. (This is often referred to, misleadingly, as the assumption of "free will".) However, it seems to have gone unnoticed until recently that a violation of this assumption is a straightforward consequence of time-symmetry, given an understanding of the quantization of light that would have seemed natural to Einstein after 1905. The new argument shows precisely why quantization makes a difference, and why time-symmetry alone does not imply retrocausality, in the classical context. It is true that later developments in quantum theory provide a way to avoid retrocausality, without violating time-symmetry; but this escape route relies on the "ontic" conception of the wave function that Einstein rejected. Had this new argument been noticed much sooner, then, it seems likely that retrocausality would have been regarded as the default option for hidden variables theories (a fact that would then have seemed confirmed by Bell's Theorem and the No Hidden Variable theorems). This paper presents these ideas at a level intended to be accessible to general readers.

physics.hist-ph↗
arXiv2013

Sirius and the project of the megalithic enclosures at Gobekli Tepe

The megalithic enclosures of Gobekli Tepe (Urfa, Turkey) are the most ancient sacred structures of stone known so far, dating back to the 10 millennium BC. The possible presence of astronomical targets for these structures is analysed, and it turns out that they may have been oriented, or even originally constructed, to celebrate and successively follow the appearance of a new, extremely brilliant star in the southern skies: Sirius.

physics.hist-ph↗
arXiv2013

Cyclic models of the relativistic universe: the early history

Within the framework of relativistic cosmology oscillating or cyclic models of the universe were introduced by A. Friedmann in his seminal paper of 1922. With the recognition of evolutionary cosmology in the 1930s this class of closed models attracted considerable interest and was investigated by several physicists and astronomers. Whereas the Friedmann-Einstein model exhibited only a single maximum value, R. Tolman argued for an endless series of cycles. After World War II, cyclic or pulsating models were suggested by W. Bonnor and H. Zanstra, among others, but they remained peripheral to mainstream cosmology. The paper reviews the development from 1922 to the 1960s, paying particular attention to the works of Friedmann, Einstein, Tolman and Zanstra. It also points out the role played by bouncing models in the emergence of modern big-bang cosmology.

physics.hist-ph↗
arXiv2013

Evolution of quasi-history in a Physics Textbook

The primary aim, in teaching physics, is that the student should gain an understanding of the principles of physics and how to apply them to different problems. A secondary aim is to allow the students to appreciate the scientific approach and significance of it in the evolution of science and society. One approach for the second aim has been to include 'historical material' in physics textbooks. The quantity of the historical material included is quite diverse, from textbooks with a very strong historical approach to others without any historical material. The quality of the material included is also diverse. In this article we focus on the development of the historical material, i.e. a certain historical development, in a specific textbook (Sears & Zemansky's University Physics) over a number of editions. The aim is to see when and how the historical material is included and how well it describes the actual history. Will the physics adapt to history or vice-verse. The event of interest is the introduction of the Blackbody radiation formula or Planck's radiation formula. This is well known out of an historical perspective, but also a case where a quasi-historical is quite common in textbooks.

physics.ed-ph↗
arXiv2013

Institute for Molecular Physics at the University of Maryland

The Institute for Physical Science and Technology at the University of Maryland was founded in 1976 from a merger of the Institute for Fluid Dynamics and Applied Mathematics (IFDAM) and the Institute for Molecular Physics (IMP), which were established at the College Park Campus after World War II to enhance the expertise of the University of Maryland in some areas of science and technology of interest to the US Department of Defense. Here I try to reconstruct the history of the Institute for Molecular Physics at the University of Maryland.

physics.hist-ph↗
arXiv2013

What is a Singularity in Geometrized Newtonian Gravitation?

I discuss singular spacetimes in the context of the geometrized formulation of Newtonian gravitation. I argue first that geodesic incompleteness is a natural criterion for when a model of geometrized Newtonian gravitation is singular, and then I show that singularities in this sense arise naturally in classical physics by stating and proving a classical version of the Raychaudhuri-Komar singularity theorem.

physics.class-ph↗
arXiv2013

Econophysics Research in India in the last two Decades

We discuss here researches on econophysics done from India in the last two decades. The term `econophysics' was formally coined in India (Kolkata) in 1995. Since then many research papers, books, reviews, etc. have been written by scientists. Many institutions are now involved in this research field and many conferences are being organized there. In this article we give an account (of papers, books, reviews, papers in proceedings volumes etc.) of this research from India.

q-fin.GN↗
arXiv2014

Jacob's Ladder and Scientific Ontologies

The main goal of this article is to use the epistemological framework of a specific version of Cognitive Constructivism to address Piaget's central problem of knowledge construction, namely, the re-equilibration of cognitive structures. The distinctive objective character of this constructivist framework is based on Heinz von Foerster's fundamental metaphor of - objects as tokens for eigen-solutions, and is also supported by formal inference methods of Bayesian statistics. This epistemological perspective is illustrated using some episodes in the history of chemistry concerning the definition or identification of chemical elements. Some of von Foerster's epistemological imperatives provide general guidelines of development and argumentation.

physics.hist-ph↗