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Una controversia historica al servicio de una situacion de aprendizaje: una reconstruccion didactica basada en Dialogo sobre los dos maximos sistemas del mundo de Galileo

It is difficult for the common sense to admit that an object dropped from the top of the mast of a ship moving at a constant velocity falls down at the bottom of the mast because it keeps inside the horizontal movement of the ship. This difficulty is similar to the one faced by early scientists from the pre-classical science and staged by Galileo in his Dialogue concerning the two chief world systems. This proximity leads us to elaborate a learning pathway in which some elements of Galileo's dialogue are selected and reorganized according to specific educational constraints. The relevance of the teaching-learning sequence is asserted by the `didactical engineering' framework and leans on the identification of students with the characters staged by Galileo.

physics.hist-ph↗

The Weather and its Role in Captain Robert F. Scott and his Companions' Deaths

A long debate has ensued about the relationship of weather conditions and Antarctic exploration. In no place on Earth is exploration, human existence, and scientific research so weather dependent. By using an artificial neural network simulation, historical (Heroic Age) and modern weather data from manned and automated stations, placed at different locations of the Ross Ice Shelf, and the Ross Island, I have examined minimum near surface air temperatures. All modern meteorological data, as well as historical data of Cherry-Garrard, high correlations between temperatures at different locations, and artificial neural network retrodiction of modern and historical temperature data, point out the oddity of Captain Scott's temperature recordings from February 27 - March 19, 1912. I was able to show that in this period the actual minimum near surface air temperature was on the average about 13°F(7°C) above that reported by Captain Scott and his party. On the basis of the mentioned evidence I concluded that the real minimum near surface air temperature data was altered by Lt. Bowers and Captain Scott to inflate and dramatize the weather conditions.

physics.hist-ph↗

A cognitive approach to the topography of the 12th dynasty pyramids

The topography of the royal pyramids of the 12th dynasty is investigated in its historical and chronological context, in order to highlight connections between the architectural choices, the religious ideas and the traditions inspiring the reign of the corresponding pharaohs. A close, explicit connection with the double building projects carried out more than six centuries before by Snefru at Dahshur and at Meidum-Seila comes out. This connection involved geometry, perspective and astronomical alignments in the progressive planning of the pyramidal complexes. In such a context, the architectural choices of the last great king of the dynasty, Amenemhet III - who built two pyramids, one at Dahshur and the other at Hawara - appear to be due mostly to symbolic, as opposed to practical, reasons.

physics.hist-ph↗

Relativistic Constraints for a Naturalistic Metaphysics of Time

The traditional metaphysical debate between static and dynamic views in the philosophy of time is examined in light of considerations concerning the nature of time in physical theory. Adapting the formalism of Rovelli (1995, 2004), I set out a precise framework in which to characterise the formal structure of time that we find in physical theory. This framework is used to provide a new perspective on the relationship between the metaphysics of time and the special theory of relativity by emphasising the dual representations of time that we find in special relativity. I extend this analysis to the general theory of relativity with a view to prescribing the constraints that must be heeded for a metaphysical theory of time to remain within the bounds of a naturalistic metaphysics.

physics.hist-ph↗

Causal Symmetry and the Transactional Interpretation

Cramer's (1986) transactional interpretation of quantum mechanics posits retrocausal influences in quantum processes in an attempt to alleviate some of the interpretational difficulties of the Copenhagen interpretation. In response to Cramer's theory, Maudlin (2002) has levelled a significant objection against any retrocausal model of quantum mechanics. I present here an examination of the transactional interpretation of quantum mechanics and an analysis of Maudlin's critique. I claim that, although Maudlin correctly isolates the weaknesses of Cramer's theory, his justification for this weakness is off the mark. The cardinal vice of the transactional interpretation is its failure to provide a sufficient causal structure to constrain uniquely the behaviour of quantum systems and I contend that this is due to a lack of causal symmetry in the theory. In contrast, Maudlin attributes this shortcoming to retrocausality itself and emphasises an apparently fundamental incongruence between retrocausality and his own metaphysical picture of reality. I conclude by arguing that the problematic aspect of this incongruence is Maudlin's assumptions about what is appropriate for such a metaphysical picture.

quant-ph↗

Is the Quantum World Composed of Propensitons?

In this paper I outline my propensiton version of quantum theory (PQT). PQT is a fully micro-realistic version of quantum theory that provides us with a very natural possible solution to the fundamental wave/particle problem, and is free of the severe defects of orthodox quantum theory (OQT) as a result. PQT makes sense of the quantum world. PQT recovers all the empirical success of OQT and is, furthermore, empirically testable (although not as yet tested). I argue that Einstein almost put forward this version of quantum theory in 1916/17 in his papers on spontaneous and induced radiative transitions, but retreated from doing so because he disliked the probabilistic character of the idea. Subsequently, the idea was overlooked because debates about quantum theory polarised into the Bohr/Heisenberg camp, which argued for the abandonment of realism and determinism, and the Einstein/Schrödinger camp, which argued for the retention of realism and determinism, no one, as a result, pursuing the most obvious option of retaining realism but abandoning determinism. It is this third, overlooked option that leads to PQT. PQT has implications for quantum field theory, the standard model, string theory, and cosmology. The really important point, however, is that it is experimentally testable. I indicate two experiments in principle capable of deciding between PQT and OQT.

physics.hist-ph↗

Felix de Roy: a life of variable stars

Felix de Roy (1883-1942), an internationality recognised amateur astronomer, made significant contributions to variable star research. As an active observer, he made some 91,000 visual estimates of a number of different variable stars. A Belgian national, he took refuge in England during World War 1. While there, de Roy became well enough known to later serve as Director of the BAA Variable Star Section for seventeen years. Through this office, and his connections with other organisations around the world, he encouraged others to pursue the observation of variable stars. Not merely content to accumulate observational data, de Roy also analysed the data and published numerous papers.

physics.hist-ph↗

50 Years of Neutrino Physics

Some important topics from history of neutrino physics over the last fifty years are discussed. History of neutrinos is older, at 4th December 2010 it will be eightieth anniversary of the "neutrino birth". In that day W. Pauli wrote the famous letter to participants of the physics conference at Tubingen with the suggestion that "there could exist in the nuclei electrically neutral particle". We will concentrate mostly on the 50 years of neutrino history just to show the long tradition of the Zakopane Theoretical School.

hep-ph↗

The Coriolis Effect Apparently Described in Giovanni Battista Riccioli's Arguments Against the Motion of the Earth: An English Rendition of Almagestum Novum Part II, Book 9, Section 4, Chapter 21, Pages 425, 426-7

In his encyclopedic work on astronomy, the 1651 Almagestum Novum, the Italian Jesuit Giovanni Battista Riccioli (1598-1671) argued against the movement of the Earth on the grounds that (among other things), if the Earth rotated, that rotation should produce a deflection in the trajectories of projectiles. This argument appears to be an early description of the Coriolis effect.

physics.hist-ph↗

Unitary theories in the work of Mira Fernandes (beyond general relativity and differential geometry)

An analysis of the work of Mira Fernandes on unitary theories is presented. First it is briefly mentioned the Portuguese scientific context of the 1920s. A short analysis of the extension of Riemann geometries to new generalized geometries with new affine connections, such as those of Weyl and Cartan, is given. Based on these new geometries, the unitary theories of the gravitational and electromagnetic fields, proposed by Weyl, Eddington, Einstein, and others are then explained. Finally, the book and one paper on connections and two papers on unitary theories, all written by Mira Fernandes, are analyzed and put in context.

physics.hist-ph↗

Penetrating Radiation on the Sea

At the beginning of the twentieth century, two scientists, the Austrian Victor Hess and the Italian Domenico Pacini, developed two brilliant lines of research independently, leading to the determination of the origin of atmospheric radiation. Hess measured the rate of discharge of an electroscope that flew aboard an atmospheric balloon. Because the discharge rate increased as the balloon flew at higher altitude, he concluded in 1912 that the origin could not be terrestrial. For this discovery, Hess was awarded the Nobel Prize in 1936, and his experiment became legendary. At the same time, in 1911, Pacini, a professor at the University of Bari, made a series of measurements to determine the variation in the speed of discharge of an electroscope (and thus the intensity of the radiation) while the electroscope was immersed in a box in a sea near the Naval Academy in the Bay of Livorno (the Italian Navy supported the research). Pacini discovered that the discharge of the oscilloscope was significantly slower than at the surface. Before his conclusive measurements, Pacini performed a series of experiments between 1907 and 1910, in particular by comparing radioactivity on ground and on the sea surface a few kilometers off the coast. These experimennts gave marginal indications on the presence of a non-terrestrial component, encouraging Pacini to continue his research till the conclusive results. Such first experiments on the sea are presented in the article by D. Pacini in Le Radium VIII (1911) 307, which is essentially a translation into French of another article published in Italian in Ann. Uff. Centr. Meteor. XXXII, parte I (1910); this is a translation in English of the article by Pacini in "Le Radium", article which was quoted by Hess in his famous paper.

physics.hist-ph↗

Geometric Algebra: A natural representation of three-space

Historically, there have been many attempts to produce an appropriate mathematical formalism for modeling the nature of physical space, such as Euclid's geometry, Descartes' system of Cartesian coordinates, the Argand plane, Hamilton's quaternions and Gibbs' vector system using the dot and cross products. We illustrate however, that Clifford's geometric algebra (GA) provides the most elegant description of physical space. Supporting this conclusion, we firstly show how geometric algebra subsumes the key elements of the competing formalisms and secondly how it provides an intuitive representation of the basic concepts of points, lines, areas and volumes. We also provide two examples where GA has been found to provide an improved description of two key physical phenomena, electromagnetism and quantum theory, without using tensors or complex vector spaces. This paper also provides pedagogical tutorial-style coverage of the various basic applications of geometric algebra in physics.

physics.hist-ph↗

Consciousness: A Direct Link with Life's Origin?

Inspired by the Penrose-Hameroff thesis, we are intuitively led to examine an intriguing correspondence of 'induction' (by fields), with the complex phenomenon of (metabolism-sustained) consciousness: Did sequences of associated induction patterns in field-susceptible biomatter have simpler beginnings?

physics.hist-ph↗

Meteoritics and cosmology among the Aboriginal cultures of Central Australia

The night sky played an important role in the social structure, oral traditions, and cosmology of the Arrernte and Luritja Aboriginal cultures of Central Australia. A component of this cosmology relates to meteors, meteorites, and impact craters. This paper discusses the role of meteoritic phenomena in Arrernte and Luritja cosmology, showing not only that these groups incorporated this phenomenon in their cultural traditions, but that their oral traditions regarding the relationship between meteors, meteorites and impact structures suggests the Arrernte and Luritja understood that they are directly related.

physics.hist-ph↗

The astronomical orientation of the urban plan of Alexandria

Alexander the Great founded Alexandria in 331 BC. The newly founded town was conceived as an orthogonal grid based on a main longitudinal axis, later called Canopic Road. We analyse here the astronomical orientation of the project and propose that the main axis was deliberately oriented towards the rising sun on the day of birth of Alexander the Great. The argument is admittedly speculative as any Archaeoastronomy argument not backed up by written sources. However, it is nested accurately into the archaeological records and into what is known on the foundation of the town. Further, a topographical analysis is given to sustain the thesis.

physics.hist-ph↗

Charles Lewis Brook: third Director of the BAA Variable Star Section

Charles Lewis Brook, MA, FRAS, FRMetS (1855 - 1939) served as Director of the BAA Variable Star Section from 1910 to 1921. During this time he was not merely interested in collecting the observations of the members (to which he also contributed), but he also spent considerable amounts of time analysing the data and preparing numerous publications on the findings. This paper discusses Brook's life and work, with a particular focus on his contribution to variable star astronomy.

physics.hist-ph↗