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arXiv2011

Philosophical problems of space-time theories

I present a discussion of some open issues in the philosophy of space-time theories. Emphasis is put on the ontological nature of space and time, the relation between determinism and predictability, the origin of irreversible processes in an expanding Universe, and the compatibility of relativity and quantum mechanics. In particular, I argue for a Parmenidean view of time and change, I make clear the difference between ontological determinism and predictability, propose that the origin of the asymmetry observed in physical processes is related to the existence of cosmological horizons, and present a non-local concept of causality that can accommodate both special relativity and quantum entanglement.

physics.hist-ph↗

arXiv2011

Lo Gnomone Clementino: Astronomia Meridiana in Chiesa dal '700 ad oggi

The Clementine Gnomon is a giant pinhole dark camera dedicated to meridian solar astrometry operating in the Basilica of Santa Maria degli Angeli in Rome. Pope Clement XI ordered Francesco Bianchini (1662-1729) to build this instrument in 1701-1702. It renders solar images distortion-free, because the pinhole is optics-less. The azimut of the Clementine Gnomon has been referenced with respect to the celestial North pole, and it is 4'28.8"\pm0.6" Eastward. Also the local deviations from a perfect line are known with an accuracy better than 0.5 mm. Therefore the transit's times are systematically in delay with respect to the ephemerides. It is emphasized the opportunity of considering the Clementine Gnomon as introductory in modern astrometry besides its key role in the history of astronomy. Seeing effects on the solar image are studied using video. The need of a definitive solution in restoring the original pinhole is also shown.

astro-ph.IM↗

arXiv2011

Did Edwin Hubble plagiarize?

Recently Block published an astro-ph{http://arxiv.org/abs/1106.3928 (2011).} insinuating that Lemaitre discovery paper of the Expanding Universe was censored prior to its translation into English and publication in the Monthly Notices of the Royal Astronomical Society. Consequently, Lemaitre's credit for the discovery of the velocity-distance correlation was not recognized. We examine here the chain of events leading to the discovery of the 'Hubble law'. Our summary: (a) Lemaitre found a theoretical linear correlation between velocity and distance. (b) Lemaitre assumed the existence of a linear relation between velocity and distance and calculated the coefficient. (c) Hubble took the data plotted it and demonstrated that a linear relation represents the observed data. (d) Hubble never believed in Lemaitre's solution, namely in an expanding universe. Consequently, Hubble never cited Lemaitre. We conclude that the charge that Lemaitre's paper was censored or ignored let alone plagiarized by Hubble, is not founded, and explain why Lemaitre's earlier theoretical discovery and derived 'Hubble constant' was not cited or recognized, by Hubble as well as by many other leading researchers.

physics.hist-ph↗

arXiv2012

Who discovered the expanding universe?

Who discovered the expanding universe? Was it Hubble, or Lemaître, or was it just the end result of a long series of investigations? In this article we summarise the main steps and contributions that led to one of the most exciting discoveries ever made, of which Lemaître was the principal architect. In 1927 he combined his dynamical solutions of the Einstein equations with astronomical observations to conclude that the universe is expanding. He derived the linear velocity-distance relationship and calculated the first numerical value of what later was called the "Hubble constant". His discovery paper of 1927 was written in French and in 1931 it was translated into English and published in Monthly Notices. However, the translation omits the section where Lemaître computed the "Hubble constant". Why was that done, and who was responsible? We do not speculate on this question, but present in a very condensed way the facts along the path of discovery. The documented details from primary sources can be found in our book "Discovering the Expanding Universe".

physics.hist-ph↗

arXiv2012

S. Chandrasekhar: White Dwarfs, $H^-$ ion,.., Black holes, Gravitational waves

This is a concise review, addressed to undergraduate students, of S. Chandrasekhar's oeuvre in astrophysics, ranging from his early studies on white dwarfs using relativistic quantum statistics to topics as diverse as dynamical friction, negative hydrogen ion, fluid dynamical instabilities, black holes and gravitational waves. The exposition is based on simple physical explanations in the context of observational astronomy. Black holes and their role as central engines of active, compact, high energy sources have been discussed.

physics.hist-ph↗

arXiv2011

Quantum magic: A skeptical perspective

Quantum mechanics (QM) has attracted a considerable amount of mysticism, in public opinion and even among academic researches, due to some of its conceptually puzzling features, such as the modification of reality by the observer and entanglement. We argue that many popular "quantum paradoxes" stem from a confusion between mathematical formalism and physics; We demonstrate this by explaining how the paradoxes go away once a different formalism, usually inconvenient to perform calculations, is used. we argue that some modern developments, well-studied in the research literature but generally overlooked by both popular science and teaching-level literature, make quantum mechanics (that is, "canonical" QM, not extensions of it) less conceptually problematic than it looks at first sight. When all this is looked at together, most "conceptual puzzles" of QM are not much different from the well-known paradoxes from probability theory. Consequently, "explanations of QM" involving physical action of consciouses or an infinity of universes are conceptually unnecessary

physics.hist-ph↗

arXiv2012

Gauge symmetry breaking in gauge theories---In search of clarification

The paper investigates the spontaneous breaking of gauge symmetries in gauge theories from a philosophical angle, taking into account the fact that the notion of a spontaneously broken local gauge symmetry, though widely employed in textbook expositions of the Higgs mechanism, is not supported by our leading theoretical frameworks of gauge quantum theories. In the context of lattice gauge theory, the statement that local gauge symmetry cannot be spontaneously broken can even be made rigorous in the form of Elitzur's theorem. Nevertheless, gauge symmetry breaking does occur in gauge quantum field theories in the form of the breaking of remnant subgroups of the original local gauge group under which the theories typically remain invariant after gauge fixing. The paper discusses the relation between these instances of symmetry breaking and phase transitions and draws some more general conclusions for the philosophical interpretation of gauge symmetries and their breaking.

physics.hist-ph↗

arXiv2011

Discovery of the Expansion of the Universe

The myth that the expansion of the Universe was discovered by Hubble was first propagated by Humason (1931). The true nature of this discovery turns out to have been both more complex and more interesting.

physics.hist-ph↗

arXiv2011

Many Worlds Model resolving the Einstein Podolsky Rosen paradox via a Direct Realism to Modal Realism Transition that preserves Einstein Locality

The violation of Bell inequalities by quantum physical experiments disproves all relativistic micro causal, classically real models, short Local Realistic Models (LRM). Non-locality, the infamous "spooky interaction at a distance" (A. Einstein), is already sufficiently 'unreal' to motivate modifying the "realistic" in "local realistic". This has led to many worlds and finally many minds interpretations. We introduce a simple many world model that resolves the Einstein Podolsky Rosen paradox. The model starts out as a classical LRM, thus clarifying that the many worlds concept alone does not imply quantum physics. Some of the desired non-locality, e.g. anti-correlation at equal measurement angles, is already present, but Bell's inequality can of course not be violated. A single and natural step turns this LRM into a quantum model predicting the correct probabilities. Intriguingly, the crucial step does obviously not modify locality but instead reality: What before could have still been a direct realism turns into modal realism. This supports the trend away from the focus on non-locality in quantum mechanics towards a mature structural realism that preserves micro causality.

quant-ph↗

arXiv2011

Superconductivity - the first 100 years

On the occasion of centenary of superconductivity discovery I remind some facts from the first period and attempts to understand the phenomenon. It turns out that most famous physicists of the first half of XX century have tried to solve the puzzle. Bardeen, Cooper and Schrieffer succeeded in 1957. BCS theory successfully described all known facts and offered new predictions, which soon have been confirmed experimentally contributing to the widespread acceptance of the theory. New discoveries of the last quarter of the century put new requirements for the theory. It turns out that simple BCS model is not enough to understand new unconventional or exotic superconductors. Even though the superconductors have found many important applications in various branches they have not yet fulfilled the hopes. In spite of that the scientific studies of superconductors develop vividly and fascinate new generations of physicists.

physics.hist-ph↗

arXiv2011

Stato evolutivo delle stelle della Cintura di Orione ed implicazioni archeoastronomiche

In the present work it is evaluated the evolutionary state of the Orion Belt stars, an asterism very important for the ancient Egyptians, finding that, when the pyramids were built, the brightness of the three stars of the Belt was practically the same as today. This not trivial result has important implications in the framework of the so-called Orion Correlation Theory, a controversial theory proposed by Bauval and Gilbert (1994), according to which a perfect coincidence would exist between the disposition of the three stars of the Orion Belt and that of the main Giza pyramids, so that the latter would represent the monumental reproduction on the ground of that important asterism. ---- Nel presente lavoro viene determinato lo stato evolutivo delle stelle della Cintura di Orione, ricavando che, all'epoca della costruzione delle piramidi, la luminosita' delle tre stelle della Cintura era di fatto uguale a quella odierna. Tale non banale risultato riveste una importanza fondamentale nell'ambito della verifica della controversa Teoria della Correlazione di Orione proposta da Bauval e Gilbert nel 1994, secondo la quale esisterebbe una perfetta coincidenza tra la disposizione delle tre stelle della Cintura e quella delle tre piramidi nella piana di Giza.

physics.hist-ph↗

arXiv2014

How to Move an Electromagnetic Field?

The special relativity principle presupposes that the states of the physical system concerned can be meaningfully characterized, at least locally, as such in which the system is at rest or in motion with some velocity relative to an arbitrary frame of reference. In the first part of the paper we show that electrodynamic systems, in general, do not satisfy this condition. In the second part of the paper we argue that exatly the same condition serves as a necessary condition for the persistence of an extended physical object. As a consequence, we argue, electromagnetic field strengths cannot be the individuating properties of electromagnetic field---contrary to the standard realistic interpretation of CED. In other words, CED is ontologically incomplete.

physics.hist-ph↗

arXiv2011

The Never Ending Gale: its Role in Captain Robert F. Scott and his Companions' Deaths

Polar historians and enthusiasts are aware that toward the end of March 1912, Captain Robert F. Scott reported in his journal a meteorological event, which was extraordinary as far as its length and strength was concerned. This event was the gale which according to Captain Scott, lasted nine/ten days. Were the laws of physics suspended at the end of March 1912 in the Antarctic? I have shown that the near surface winds in the Antarctic are self-organized critically and that the winds over the continent form an ergodic system. I have presented an analysis of wind events in the proximity of Captain Scott's camp and at Ross Island. By comparing wind events at these locations, and performing an analysis of a gale's wind duration and strength at One Ton Depôt, I concluded that Captain Scott's wind record was highly inaccurate. I concluded that the nine/ten day gale described by Captain Scott, that lasted from March 21 to 29, did not take place. This result combined with my previous analysis of Captain Scott's temperature record, shows that two black swan meteorological events: February 27-March 19, 1912 - Extreme Cold Snap and March 21-29, 1912 - Never Ending Gale reported by Captain Scott, did not take place. Therefore, I conclude that the deaths of Scott, Wilson and Bowers were a matter of choice rather than chance.

physics.hist-ph↗

arXiv2013

On Max Born's "Vorlesungen ueber Atommechanik, Erster Band"

A little more than half a year before Matrix Mechanics was born, Max Born finished his book "Vorlesungen ueber Atommechanik, Erster Band", which is a state-of-the-art presentation of Bohr-Sommerfeld quantisation. This book, which today seems almost forgotten, is remarkable for its epistemological as well as technical aspects. Here I wish to highlight one aspect in each of these two categories, the first being concerned with the rôle of axiomatisation in the heuristics of physics, the second with the problem of quantisation proper before Heisenberg and Schrödinger. This paper is a contribution to the project "History and Foundations of Quantum Physics" of the Max Planck Institute for the History of Sciences in Berlin and will appear in the book "Research and Pedagogy. The History of Quantum Physics through its Textbooks", edited by M.Badino and J.Navarro.

physics.hist-ph↗

arXiv2014

A quantitative astronomical analysis of the Orion Correlation Theory

The link between the three major Giza pyramids and the stars of the Orion Belt has been since long time the subject of various qualitative speculations. In this framework an important role is played by a controversial theory, the so-called "Orion Correlation Theory" (OCT), according to which a perfect coincidence would exist between the mutual positions of the three stars of the Orion Belt and those of the main Giza pyramids. In the present paper the OCT has been subjected to some quantitative astronomical and astrophysical verifications, in order to assess its compatibility with the results of both naked-eye astrometry and photometry. In particular, a linear correlation is found between the height of such monuments and the present brightness of the Orion Belt stars. According to these analyses it is possible to conclude that the OCT is not incompatible with what expected for the stars of the Orion Belt on the basis of naked-eye astrometry and photometry, as well as of the stellar evolution theory.

physics.hist-ph↗

arXiv2011

Digging down the past

It is often stated that cosmology is an extreme form of archeology that deals with aeons of time extending back to thousands of millions of years. One talks, for instance, of relics of the early Universe, and phases in the history of the Universe that resemble the division of phases in human development used by archeologists to interpret the data they gather in the field. In this text we shall analyze these "linguistic" similarities, and the differences between these two scientific activities paying some attention on the role played by their theoretical guidelines.

physics.hist-ph↗

arXiv2011

Conceptual Problems in Cosmology

In this essay a critical review of present conceptual problems in current cosmology is provided from a more philosophical point of view. In essence, a digression on how could philosophy help cosmologists in what is strictly their fundamental endeavor is presented. We start by recalling some examples of enduring confrontations among philosophers and physicists on what could be contributed by the formers to the day-time striving of the second ones. Then, a short review of the standard model Friedmann-Lemaître-Robertson-Walter (FLRW) of cosmology is given. It seems apparent that cosmology is living a golden age with the advent of observations of high precision. Nonetheless, a critical revisiting of the direction in which it should go on appears also needed, for misconcepts like "quantum backgrounds for cosmological classical settings" and "quantum gravity unification" have not been properly constructed up-to-date. Thus, knowledge-building in cosmology, more than in any other field, should begin with visions of the reality, then taking technical form whenever concepts and relations inbetween are translated into a mathematical structure. It is mandatory, therefore, that the meaning of such concepts be the same for all cosmologists, and that any relationship among all them be tested both logically as well as mathematically. In other words, the notorius feature of improbability of our universe, as is well-known, assures to cosmologists a priviledged degree of freedom for formulating interpretations and theories. However, at the same time, it demands for their formulations and conclusions to be considered in the light of data taken from astrophysical observations.

physics.hist-ph↗

arXiv2011

Visualising Matter and Cosmologies: A Transhistorical Example

We propose a connection between the visualisation of cosmic matter and structure formation in the Cartesian tradition and that used by contemporary astrophysics. More precisely, we identify cosmological simulations of large scale structure in the Universe with the system of vortices in Descartes physics. This connection operates at different levels of the images: their representational purpose; the theoretical systems behind their use; and, finally, their function and materiality as visual productions. A skilled use of image analysis is necessary to stress the continuities and peculiarities between different epochs and disciplines.

physics.pop-ph↗