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arXiv2015

Is E=mc^2 an exclusively relativistic result?

The mass-energy formula E=mc^2 is thought to be derived by Einstein from special relativity. The present study shows that since the formula has also been derived from classical physics by Einstein, it is not an exclusively relativistic result. The formula is implied by the classical electromagnetic momentum P=E/c and the Newtonian definition of momentum P=mv. Like momentum P=mv, E=mc^2 applies to both classical physics and special relativity, if relativistic mass is used in the equation. The derivation by Einstein in 1905 is logically flawed as a relativistic proof and the truly relativistic formula should be E=(E0)/(1-v^2/c^2)^(1/2) derived by Laue in 1911 and Klein in 1918. If the energy measured in one reference frame is E0, it is E=(E0)/(1-v^2/c^2)^(1/2) in a reference frame moving at velocity v relative to the first frame.

physics.gen-ph↗

arXiv2016

Weyl's search for a difference between `physical' and `mathematical' automorphisms

During his whole scientific life Hermann Weyl was fascinated by the interrelation of physical and mathematical theories. From the mid 1920s onward he reflected also on the typical difference between the two epistemic fields and tried to identify it by comparing their respective automorphism structures. In a talk given at the end of the 1940s (ETH, Hs 91a:31) he gave the most detailed and coherent discussion of his thoughts on this topic. This paper presents his arguments in the talk and puts it in the context of the later development of gauge theories.

physics.hist-ph↗

arXiv2016

Über die Beziehung der begrifflichen Grundlagen der Quantentheorie und der Allgemeinen Relativitätstheorie

In this dissertation the question of the unification of quantum theory and general relativity is treated. Based on the conceptual structure of these theories and under incorporation of certain ideas from classical philosophy there are formulated arguments for the assertion that these two fundamental theories of nature can only be led to a unification in the framework of a description, in which space-time is not presupposed but constituted by a more fundamental physical reality. Under this precondition an own model to derive the mathematical structure of general relativity from a unified quantum field theory of spinors is developed. In addition the quantum theory of fundamental binary logical alternatives, which has been conceived by Carl Friedrich von Weizsäcker in the second half of the twentieth century and in which the existence of physical space and his properties is a consequence of quantum theory, is treated elaborately and considered with respect to the question of the unification of quantum theory and general relativity.

physics.hist-ph↗

arXiv2015

A Note on Fourier and the Greenhouse Effect

Joseph Fourier's discovery of the greenhouse effect is discussed and is compared to the modern conception of the greenhouse effect. It is confirmed that what Fourier discovered is analogous to the modern concept of the greenhouse effect. However, the modern concept of the greenhouse effect is found to be based on a paradoxical analogy to Fourier's greenhouse work and so either Fourier's greenhouse work, the modern conception of the greenhouse effect, or the modern definition of heat is incorrect. The solution to this problem is not feigned to be given here.

physics.hist-ph↗

arXiv2016

The Metaphysics of D-CTCs: On the Underlying Assumptions of Deutsch's Quantum Solution to the Paradoxes of Time Travel

I argue that Deutsch's model for the behavior of systems traveling around closed timelike curves (CTCs) relies implicitly on a substantive metaphysical assumption. Deutsch is employing a version of quantum theory with a significantly supplemented ontology of parallel existent worlds, which differ in kind from the many worlds of the Everett interpretation. Standard Everett does not support the existence of multiple identical copies of the world, which the D-CTC model requires. This has been obscured because he often refers to the branching structure of Everett as a "multiverse", and describes quantum interference by reference to parallel interacting definite worlds. But he admits that this is only an approximation to Everett. The D-CTC model, however, relies crucially on the existence of a multiverse of parallel interacting worlds. Since his model is supplemented by structures that go significantly beyond quantum theory, and play an ineliminable role in its predictions and explanations, it does not represent a quantum solution to the paradoxes of time travel.

quant-ph↗

arXiv2021

Dirac canonical idea as an alternative to the approach of Bohr. A toy model

Classical objects have been excluded as subjects of the observed quantum properties, and the related problem of quantum objects nature has been suspended since the early days of Quantum Theory. Recent experiments show that the problem could be reasonably revisited. The outlined model indicates new issues, which could result from following and exploring the canonical idea of Dirac. Topological defects in solids are considered as an example. The aim is helping to grasp the underlying pre-theoretical new intuitions, which should replace the old ones attached to the background of classical physics.

quant-ph↗

arXiv2015

A Live Alternative to Quantum Spooks

Quantum weirdness has been in the news recently, thanks to an ingenious new experiment by a team led by Roland Hanson, at the Delft University of Technology. Much of the coverage presents the experiment as good (even conclusive) news for spooky action-at-a-distance, and bad news for local realism. We point out that this interpretation ignores an alternative, namely that the quantum world is retrocausal. We conjecture that this loophole is missed because it is confused for superdeterminism on one side, or action-at-a-distance itself on the other. We explain why it is different from these options, and why it has clear advantages, in both cases.

quant-ph↗

arXiv2015

The Necessity of Quantizing Gravity

The Eppley Hannah thought experiment is often cited as justification for attempts by theorists to develop a complete, consistent theory of quantum gravity. A modification of the earlier "Heisenberg microscope" argument for the necessity of quantized light, the Eppley-Hannah thought experiment purports to show that purely classical gravitational waves would either not conserve energy or else allow for violations of the uncertainty principle. However, several subsequent papers have cast doubt as to the validity of the Eppley-Hannah argument. In this paper, we attempt to resurrect the Eppley-Hannah thought experiment by modifying the original argument in such a manner as to render it immune to the present criticisms levied against it.

gr-qc↗

arXiv2015

Presenting Nonreflexive Quantum Mechanics: Formalism and Metaphysics

Nonreflexive quantum mechanics is a formulation of quantum theory based on a non-classical logic termed \ita{nonreflexive logic} (a.k.a. `non-reflexive'). In these logics, the standard notion of identity, as encapsulated in classical logic and set theories, does not hold in full. The basic aim of this kind of approach to quantum mechanics is to take seriously the claim made by some authors according to whom quantum particles are \ita{non-individuals} in some sense, and also to take into account the fact that they may be absolutely indistinguishable (or indiscernible). The nonreflexive formulation of quantum theory assumes these features of the objects already at the level of the underlying logic, so that no use is required of symmetrization postulates or other mathematical devices that serve to pretend that the objects are indiscernible (when they are not: all objects that obey classical logic are \ita{individuals} in a sense). Here, we present the ideas of the development of nonreflexive quantum mechanics and discuss some philosophical (mainly metaphysical) motivations and consequences of it.

quant-ph↗

arXiv2016

The battle of High Temperature Superconductivity

The early development of conflicting theories about the microscopic mechanism of High Temperature Superconductivity is described. The biographical roots of this diversity are stressed, as well as its subjective/objective roots. This study of a specific case of knowledge about a specific fact of nature allows to discuss the subjective and objective roots of scientific pluralism. Relativism, the Duhem-Quine thesis on the underdetermination of theory by facts, are discussed from the stand point of the materialist view on the dialectics of knowledge and nature. Developments of dialectic materialism seem to be suggested by this study.

physics.hist-ph↗

arXiv2015

General Relativity in Post Independence India

The most outstanding contribution to general relativity in this era came in 1953 (published in 1955 \cite{akr}) in the form of the Raychaudhri equation. It is in 1960s that the observations began to confront the eupherial theory and thus began exploration of GR as a legitimate physical theory in right earnest. The remarkable discoveries of cosmic microwave background radiation, quasars, rotating Kerr black hole and the powerful singularity theorems heralded a new canvas of relativistic astrophysics and cosmology. I would attempt to give a brief account of Indian participation in these exciting times.

physics.hist-ph↗

arXiv2015

Understanding the meaning of Greek temples' orientations. Akragas Valley of the Temples as a case study

The issue of the orientation of Greek Temples has been the subject of several debates since the end of the 19 century. In fact, although a general tendency to orientation within the arc of the rising sun is undeniable, specific patterns and true meaning remain obscure. With the aim of shedding light on this problem we present here a new complete, high precision survey of the temples of Akragas, the so called Valley of the Temples UNESCO site. Our results include a important temple which was essentially yet unpublished, and most of all show that very different reasons influenced the orientation choices, some symbolical, but others by far more practical, besides the general rule of orienting to the rising sun. In particular, the existence of temples orientated in accordance with the towns grid, as well as to the cardinal points irrespectively from the sun's declination associated to true east at the uneven horizon, is evidenced. Finally, for two temples having anomalous orientations a stellar and a lunar proposal are made respectively

physics.hist-ph↗

arXiv2016

A Comparative Study of Interdisciplinarity in Sciences in Brazil, South Korea, Turkey, and USA

A comparative study is done of interdisciplinary citations in 2013 between physics, chemistry, and molecular biology, in Brazil, South Korea, Turkey, and USA. Several surprising conclusions emerge from our tabular and graphical analysis: The cross-science citation rates are in general strikingly similar, between Brazil, South Korea, Turkey, and USA. One apparent exception is the comparatively more tenuous relation between molecular biology and physics in Brazil and USA. Other slight exceptions are the higher amount of citing of physicists by chemists in South Korea, of chemists by molecular biologists in Turkey, and of molecular biologists by chemists in Brazil and USA. Chemists are, by a sizable margin, the most cross-science citing scientists in this group of three sciences. Physicist are, again by a sizable margin, the least cross-science citing scientists in this group of three sciences. In all four countries, the strongest cross-science citation is from chemistry to physics and the weakest cross-science citation is from physics to molecular biology. Our findings are consistent with a V-shaped backbone connectivity, as opposed to a Delta connectivity, as also found in a previous study of earlier citation years.

physics.soc-ph↗

arXiv2017

Young astronomer in Denmark 1946 to 1958

This is a personal account of how I became an astronomer. Fascinated by the stars and planets in the dark sky over Lolland, an island 100 km south of Copenhagen, the interest in astronomy was growing. Encouraged by my teachers, I polished mirrors and built telescopes with generous help from the local blacksmith and I observed light curves of variable stars. Studies at the Copenhagen University from 1950 gradually led me deeper into astronomy, especially astrometry (the astronomy of positions), guided by professor Bengt Strömgren and my mentor dr. phil. Peter Naur. I was lucky to take part in the buildup of the new observatory at Brorfelde during the first difficult years and the ideas I gathered there have contributed to the two astrometry satellites Hipparcos and Gaia launched by the European Space Agency (ESA) in respectively 1989 and 2013.

physics.hist-ph↗

arXiv2017

The Baltic Meetings 1957 to 1967

The Baltic meetings of astronomers from Northern Germany and Scandinavia began in 1957 and gathered up to 70 participants. Reports of the presentations are available from all meetings, providing an overview of the interests of astronomers in this part of the world 50 years ago. Most interesting to see for a young astronomer in our days, I think, is that a large part of the time was about astrometry. This focus on astrometry was the basis for the scientific knowhow which made the idea of space astrometry realistic, resulting in the approval by ESA of the first astrometry satellite Hipparcos in 1980 which brought a revolution of high-precision astrometry of positions, motions and distances of stars. The correspondence with ten observatories shows that only one of them has any archive of letters at all from the 1950s, that is in Copenhagen where about 7000 letters on scientific and administrative matters are extant. - These letters have now been stored in the Rigsarkivet.

physics.hist-ph↗

arXiv2015

String theory to the rescue

The search for a theory of quantum gravity faces two great challenges: the incredibly small scales of the Planck length and time, and the possibility that the observed constants of nature are in part the result of random processes. A priori, one might have expected these to be insuperable obstacles. However, clues from observed physics, and the discovery of string theory, raise the hope that the unification of quantum mechanics and general relativity is within reach.

hep-th↗

arXiv2015

Petrus Peregrinus of Maricourt and the Medieval Magnetism

Petrus Peregrinus of Maricourt, a 13th-century French scholar and engineer, wrote what we can consider as the first extant treatise on magnetism of Europe. This treatise is in the form of a letter, probably composed during the siege of Lucera in Italy, in 1269, where Peregrinus worked to fortify the camp and built engines for projecting stones and fireballs into the besieged town. Peregrinus' letter consists of two parts. The first is discussing the properties of magnets, describing also the methods for determining their north and south poles. The second part of the letter describes some instruments that utilize the properties of magnets, ending with the Peregrinus' art of making a wheel of perpetual motion. In this paper, we discuss the first part of the letter and the related medieval knowledge of magnetism.

physics.hist-ph↗

arXiv2015

In Appreciation of Abner Shimony

Abner Shimony was an exceptional human being and a remarkably lucid and penetrating thinker whose work centered on some of the most significant physical and philosophical questions of his era at their nexus. He approached these questions with an open, agile and critical mind, something quickly evident to anyone who had the privilege of conversing with him. His choice of problems to pursue, which for the most part involved epistemology and the relationships between mind, matter and space-time, was visionary. Undoubtedly, most of the discussions of Abner Shimony's work in future will center on his enormous contribution to the investigation of the significance to physics, both theoretical and experimental, of quantum entanglement, the characteristic of physical entities on which his work came to concentrate, well represented in the Clauser--Horne--Shimony--Holt inequality. Also significant for physics is his pioneering development of the quantification of entanglement in the early-to-mid 1990s. Shimony focused largely on the question of the relationship between knowledge and the world, as he did not view these two philosophical concerns as distinct from study of the implications of entanglement per se. Indeed, the most well known phrase he coined is "experimental metaphysics." He is also known for the reapplication of the expression "peaceful coexistence" as pertaining to the relationship between quantum mechanics and special relativity. Shimony's less well known intellectual engagement was with the question of the relationship between mind and matter, which only a few physicists of our time have engaged seriously, likely because of its more philosophical and less mathematically tractable character. This appreciation reflects all these aspects of Abner Shimony's long and successful intellectual career, in addition to details of his education, including mention of some of his teachers.

physics.hist-ph↗