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The meridian line traced by Egnazio Danti in the Torre dei Venti in Vatican demostrated the need of the Gregorian Reformation of the Calendar. A review on this instrument is presented, along with the astrometric recognition. This meridian line, dated 1580, is deviated of 72 arcminutes Westward from the true North.
The third column of the left row in the Basilica of Santa Maria in Aracoeli in Rome, has a hole carved in it, of probable astronomical use. The tube aims at a point a 116 degrees of azimut, East-South-East and 17.3 degrees of altitude, the Sun could be aimed in that direction at 07:00 UTC of 12 october and 7:25 UT of march 2, but the view is obstructed by the church's building. Same situation for the 3.9 magnitude alpha Monocerotis, visible 2000 years ago, taking into account the precession. Other hypotheses on the meridian astronomical use of this hole are here reviewed. In the case of solar observations it cannot be for meridian transits in Rome, since the lower transits occurs now at 24.5 degrees at winter solstice; we investigate the case of stellar transits, of declination 30.8 degrees South. Many alignments are possible leaving the azimut as free parameter, being the columun not in its original collocation, but here we investigate only the meridian transits, and no bright stars could have been seen through that hole, taking also into account the precession 2000 years ago. We conclude that this hole was probably not used for meridian observations.
The main claim of the paper is that one can be 'realist' (in some sense) about quantum mechanics without requiring any form of realism about the wave function. We begin by discussing various forms of realism about the wave function, namely Albert's configuration-space realism, Duerr Zanghi and Goldstein's nomological realism about the wave function, Esfeld's dispositional reading of the wave function and Pusey Barrett and Rudolph's realism about the quantum state. By discussing the articulation of these four positions, and their interrelation, we conclude that instrumentalism about the wave function is by itself not sufficient to choose one over the other interpretations of quantum mechanics, thereby confirming in a different way the indetermination of the metaphysical interpretations of quantum mechanics.
In this short note we discuss the case of the thought experiments on water-filled telescopes and their realizations during 18th and 19th century. The story of those instruments shows that the scientific progress occurs in a curious way, since there was no stringent reason for the construction of a water-filled telescope.
It is proposed that the recent controversy over "time-symmetric quantum counterfactuals" (TSQCs), based on the Aharonov-Bergmann-Lebowitz Rule for measurements of pre- and post-selected systems, can be clarified by taking TSQCs to be counterfactuals with a specific type of compound antecedent. In that case, inconsistency proofs such as that of Sharp and Shanks (1993) are not applicable, and the main issue becomes not whether such statements are true, but whether they are nontrivial. The latter question is addressed and answered in the negative. Thus it is concluded that TSQCs, understood as counterfactuals with a compound antecedent, are true but only trivially so, and provide no new contingent information about specific quantum systems (except in special cases already identified in the literature).
In the physics literature "ergodicity" is taken to mean that a system, including a macroscopic one, visits all microscopic states in a relatively short time. We show that this is an impossibility even if that time is billions of years. We also suggest that this feature does not contradict most physical considerations since those considerations deal with correlations of only a few particles.
Studies in thermodynamics often require the reduction of some first or second order partial derivatives in terms of a smaller basic set. A simple algorithm to perform such a reduction is presented here, together with a review of earlier related works. The algorithm uses Jacobians and is written in Maple language, but it is easily translated in terms of any other computer algebra language.
In 1839 Ebenezer Porter Mason (1819-1840) produced detailed drawings of the Omega Nebula (M17), the Trifid Nebula (M20) and the eastern part of the Veil Nebula (NGC 6992 and 6995). He used a 12-inch (30 cm) reflector that he and his friends had built at Yale College, which at the time was the largest telescope in the USA. The drawings were remarkable for their accuracy and for his adoption of a new technique for delineating gradients in nebulosity using isophotes, or lines of equal brightness. This paper reviews his life and his observations, comparing his results with those of the modern amateur astronomer.
This note is devoted to a detail concerning the work of Albert Einstein and Peter Bergmann on unified theories of electromagnetism and gravitation in five dimensions. In their paper of 1938, Einstein and Bergmann were among the first to introduce the modern viewpoint in which a four-dimensional theory that coincides with Einstein-Maxwell theory at long distances is derived from a five-dimensional theory with complete symmetry among all five dimensions. But then they drew back, modifying the theory in a way that spoiled the five-dimensional symmetry and looks contrived to modern readers. Why? According to correspondence of Peter Bergmann with the author, the reason was that the more symmetric version of the theory predicts the existence of a new long range field (a massless scalar field). In 1938, Einstein and Bergmann did not wish to make this prediction. (Based on a lecture at the Einstein Centennial Celebration at the Library of Alexandria, June, 2005.
This paper deals with the Berry phase, and the ontology of the electromagnetic vector potential. When the state of the system is gauge symmetric, the vector potential may be interpreted as a convenient tool of a mathematical formulation, with no ontological meaning. I argue that this interpretation is in difficulty because the vector potential depends linearly on the supercurrent in the superfluid state, which is a spontaneously broken gauge symmetry state, where particle number is not conserved. I suggest that when gauge symmetry is spontaneously broken, the vector potential becomes an emergent material object of nature. The revised version includes sections on scientific realism, and emergence, and new references on Noether's theorem, among others.
What can we discover? As the discussion in this paper is limited to ontological considerations, it does not deal with the discovery of new concepts. It raises the following question: What are the entities or existents that we can discover? There are two kinds of such entities: (1) actual entities, and (2) possible entities, which are pure possibilities. The paper explains why the first kind of discovery depends primarily on the second kind. The paper illustrates the discoveries of individual pure possibilities by presenting examples such as the Higgs particle, Dirac's positron, and Pauli-Fermi's neutrino.
The figure of the Sun reflects its inner structure and dynamics, influencing also the perihelion precession of close orbiting bodies, like Mercury. To study the solar figure from ground, the deformation on the solar image induced by the atmosphere has to be known up to one part over a million, and this is done through differential refraction models: a historical review of them is drafted. The solar oblateness has been investigated in order to validate alternative theories to General Relativity and to understand the internal dynamics of our star. The solar figure should possess only micro departures from sphericity according to the standard stellar structure theory and helioseismology data, though variations along the cycle has been observed. Ground-based and satellite data show contrasting observational results. The oblateness measured onboard RHESSI satellite, the one of SDS onboard a stratospheric ballon and that one of the Astrolabe of Rio de Janeiro are presented with their implications in classical and relativistic gravitation. The perspectives offered by the reflecting heliometer in the future measurement of the oblateness are depicted.
Our interpretive conjecture is inspired by the epistemology due to Ferdinand Gonseth (1890-1975) who interpreted complementarity as the relationship between profound and apparent reality horizons. It consists, on the one hand, on enlarging the scope of quantum theory to the most profound reality horizon, namely a triply quantum theory of gravitation that would be able to take into account simultaneously as elementary quanta the Planck's constant, the Planck's space-time area and the Boltzmann constant, and, on the other hand, on interpreting in terms of generalized complementarity three doubly quantum schemata taking into account by pairs, these three elementary quanta and form the apparent reality horizon.
By c. 3000 BC, in the late Neolithic, there had been a significant change in the way people materialized their cosmology across Scotland with the introduction of free-standing stones. These were erected almost until the end of the Bronze Age (Burl 2000, 1993). Significantly, a series of astronomical patternings have been empirically verified for many Bronze Age monuments that were erected between 1400-900 BC (Higginbottom et 14 al. 2013, 2003, 2001, 2000). Further, two series of complex landscape patternings associated with the same monuments and their orientations have been identified (Higginbottom et al. 2013 & Higginbottom 'in preparation' - Bronze Age megalithic monuments on the isle of Mull). However, when and where these patterns were first associated with standing-stone structures was unknown. Through innovative statistics and software we show that visible astronomical-landscape variables found at Bronze Age sites on the inner isles and mainland of western Scotland were actually first established nearly two millennia earlier, with the erection of the first 'great circles' in Britain: Callanish on the Isle of Lewis and Stenness on the Isle of Orkney. In particular, we introduce our new statistical test that enables the quantitative determination of astronomical connections of stone circles. It is seen that, whilst different standing-stone monuments were created over time (Burl 2000, 1993; 22 Higginbottom et al. 2013; Sheridan & Brophy 2012) with a mixture of landscape variables (Higginbottom et al. 2013), there are nevertheless highly relevant aspects that remained unchanged through these years. This suggests that there is some continuity of this cosmological system through time, despite the various radical material and social changes that occurred from the late Neolithic to the Late Bronze Age (Lynch 2000; Mullin 26 2001; Owoc 2001).
Quantum correlations and other phenomena characteristic to a quantum world can be understood as simply consequences of a principle derived from the postulates of Quantum Mechanics. This explanatory principle states that these phenomena specific to the quantum world are caused by the tension between the constraints, or initial conditions, imposed by incompatible observations. This tension is found to be at the root of Bohr's complementarity, Heisenberg's uncertainty, results concerning nonlocality, contextuality, quantum correlations in time and space. This tension requires the presence of noncommuting observables, but noncommutativity doesn't always lead to the tension, and the two concepts are not exactly the same, as it will be explained and exemplified.
Using a very simple Gedankenexperiment, I remind the reader that (contrary to what happens in classical mechanics) the energy of a quantum system is inevitably increased just by performing (some) textbook measurements on it. As a direct conclusion, this means that some measurements require the expenditure of a finite amount of energy to be carried out. I also argue that this makes it very difficult to regard measurements as disembodied, immaterial, informational operations, and it forces us to look at them as physical processes just like any other one.
The objective of this paper is not simply to present an historical overview of Einstein's cosmological considerations, but to discuss the central role they played in shaping the paradigm of relativistic cosmology. This, we'll show, was a result of both his actions and, perhaps more importantly, his inactions. Accordingly, discussion won't simply be restricted to Einstein's considerations, as we'll analyse relevant contributions to the relativistic expansion paradigm during the approximately twenty years following Slipher's first redshift measurements in 1912. Our aim is to shed some light on why we think some of the things we do, with the idea that a better understanding of the reasoning that fundamentally influenced the common idea of our expanding universe might help to resolve some of the significant problems that modern cosmology now faces; and we eventually use this knowledge to probe the foundations of the standard model. Much of the information we present, including many of the historical details, we expect will be news to modern practitioners.
No matter how counterintuitive they are, quantum phenomena are all simple consequences of the laws of Quantum Mechanics. It is not needed to extend the theory with hidden mechanisms or additional principles to explain what Quantum Mechanics already predicts. This indubitable fact is often taken as supporting the view that all we can know about the universe comes from the outcomes of the quantum observations. According to this view, we can even learn the physical laws, in particular the properties of the space, particles, fields, and interactions, solely from the outcomes of the quantum observations. In this article it is shown that the unitary symmetry of the laws of Quantum Mechanics imposes severe restrictions in learning the physical laws of the universe, if we know only the observables and their outcomes.