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Stories from the Sky: Astronomy in Indigenous Knowledge

Indigenous Australian practices, developed and honed over thousands of years, weave science with storytelling. In this Indigenous science series, we'll look at different aspects of First Australians' traditional life and uncover the knowledge behind them - starting today with astronomy.

physics.hist-ph↗

Towards an Informational Pragmatic Realism

I discuss the design of the method of entropic inference as a general framework for reasoning under conditions of uncertainty. The main contribution of this discussion is to emphasize the pragmatic elements in the derivation. More specifically: (1) Probability theory is designed as the uniquely natural tool for representing states of incomplete information. (2) An epistemic notion of information is defined in terms of its relation to the Bayesian beliefs of ideally rational agents. (3) The method of updating from a prior to a posterior probability distribution is designed through an eliminative induction process that singles out the logarithmic relative entropy as the unique tool for inference. The resulting framework includes as special cases both MaxEnt and Bayes' rule. It therefore unifies entropic and Bayesian methods into a single general inference scheme. I find that similar pragmatic elements are an integral part of Putnam's internal realism, of Floridi's informational structural realism, and also of van Fraasen's empiricist structuralism. I conclude with the conjecture that their valuable insights can be incorporated into a single coherent doctrine - an informational pragmatic realism.

physics.hist-ph↗

Measures of the Earth Obliquity during the 1701 Winter Solstice at the Clementine Meridian Line in Rome

The great meridian line in the Basilica of Santa Maria degli Angeli in Rome was built in 1701/1702 with the scope of measuring the obliquity of the Earth's orbit in the following eight centuries, upon the will of Pope Clement XI. During the winter solstice of 1701 the first measurements of the obliquity were taken by Francesco Bianchini. He was the astronomer who designed the meridian line, upgrading the similar instrument realized by Giandomenico Cassini in San Petronio, Bononia. The accuracy of the data is discussed from the point of view of the use of the pinhole.

physics.hist-ph↗

Epistemological and Ontological Paraconsistency in Quantum Mechanics: For and Against Bohrian Philosophy

We interpret the philosophy of Niels Bohr as related to the so called "linguistic turn" and consider paraconsistency in the light of the Bohrian notion of complementarity. Following [16], Jean-Yves Beziau has discussed the seemingly contradictory perspectives found in the quantum mechanical double slit experiment in terms of paraconsistent view-points [7, 8]. This interpretation goes in line with the well known Bohrian Neo-Kantian epistemological account of quantum mechanics. In the present paper, we put forward the idea that one can also consider, within quantum mechanics and departing from the philosophy of the danish physicist, a more radical paraconsistency found within one of the main formal elements of the theory, namely, quantum superpositions. We will argue that, rather than epistemological, the contradictions found within quantum superpositions could be interpreted as ontological contradictions.

quant-ph↗

Einstein and Besso: from Zürich to Milano

The 1896-1901 Milanese period is a key one to understand Einstein's training background. When he was a student at the ETH in Zürich (the Swiss Federal Polytechnic in Zürich) from 1896 to 1900, he would make regular trips back to Milan to stay with his family who was involved in the development of the electricity industry in northern Italy. Between 1899 and 1901, he would meet his faithful friend and collaborator, Michele Besso in Milan on a regular basis. Given their relationship, the 1899-1901 Milanese period therefore foreshadowed the Bern period later in 1904. In order to specify the circumstances under which Einstein and Besso got the chance to meet, we will show that their respective families did have interconnected social networks, especially through the electricity sector and the polytechnic engineering Universities of Zürich and Milan. The branch of the Cantoni family, on Michele's mother's side, rather ignored by now, played a crucial role: with Vittorio Cantoni, a renowned electrical engineer who had not been previously identified as being Michele's uncle, and Giuseppe Jung, professor at the Milan Politecnico. We will also show that when staying in Milan, Einstein, who lived in a well-known Milanese palace in the heart of the city, worked in the nearby rich library of the Istituto Lombardo, Accademia di Scienze e Lettere in Brera. The linkage between the scientific observations which can be found in Einstein's correspondence and this library collection sheds new light on his scientific work, in particular on his original thesis.

physics.hist-ph↗

Cosmological Ontology and Epistemology

In cosmology, we would like to explain our observations and predict future observations from theories of the entire universe. Such cosmological theories make ontological assumptions of what entities exist and what their properties and relationships are. One must also make epistemological assumptions or metatheories of how one can test cosmological theories. Here I shall propose a Bayesian analysis in which the likelihood of a complete theory is given by the normalized measure it assigns to the observation used to test the theory. In this context, a discussion is given of the trade-off between prior probabilities and likelihoods, of the measure problem of cosmology, of the death of Born's rule, of the Boltzmann brain problem, of whether there is a better principle for prior probabilities than mathematical simplicity, and of an Optimal Argument for the Existence of God.

physics.hist-ph↗

Applying Popper's Probability

Professor Sir Karl Popper (1902-1994) was one of the most influential philosophers of science of the twentieth century, best known for his doctrine of falsifiability. His axiomatic formulation of probability, however, is unknown to current scientists, though it is championed by several current philosophers of science as superior to the familiar version. Applying his system to problems identified by himself and his supporters, it is shown that it does not have some features he intended and does not solve the problems they have identified.

physics.hist-ph↗

The first winter solstice observed at the meridian line of Santa Maria degli Angeli in Rome

The page written by the astronomer Francesco Bianchini (1662-1729) and containing the data of the 1701 winter solstice observed at Santa Maria degli Angeli is presented for the first time in figure 2 and widely discussed along this paper. The great meridian line in the Basilica of Santa Maria degli Angeli in Rome was built in 1701/1702 with the scope to measure the Obliquity of the Earth's orbit in the following eight centuries, upon the will of pope Clement XI. During the winter solstice of 1701 the first measurements of the obliquity have been realized by Francesco Bianchini, the astronomer who designed the meridian line, upgrading the similar instrument realized by Giandomenico Cassini in San Petronio, Bononia. In this paper the accuracy of the data observed by Francesco Bianchini is discussed and compared with up-to-date ephemerides. The modern situation of this historical instrument is also presented.

physics.hist-ph↗

Tower bells and time zones, a history of synchronization

The Astrarium made by Jacopo Dondi dell'Orologio in Padua in 1344 is one of the first public horologia in the World, their public utility is also shown through the history of the tower bell of Our Lady of Suffragio in Turin, made by the mathematician Francesco Faà di Bruno in 1866. The tower bell of St. Anthony in Lanciano made by Antonio Cibotti was inaugurated by the Pope Paul VI in 1973 through a radio impulse, and now many tower bells are radio synchronized to the Central European Time within a single second of accuracy.

physics.hist-ph↗

Understand assumptions and know uncertainties: Boscovich and the motion of the Earth

The general prohibition of books advocating heliocentric theory put many progressive Jesuits in a difficult position. One of the most prominent Jesuit scientists of the 18th century, Rogerius Boscovich, was in particularly affected by conflicts between a beautifully simple theory of gravity by Newton, his Jesuit peripatetic education, Church doctrine and the lack of crucial experimental evidence for the motion of the Earth. I present the development of Boscovich's ideas prior to the lifting of the ban, and his retrospective considerations in later writings. These show that Boscovich's acceptance of the motion of the Earth was primarily driven by the existence of a working physical theory that also explained the motion of the Earth, and the lack of a consistent theory that supported any variation of a geocentric system.

physics.hist-ph↗

Maxwell-Huygens, Newton-Cartan, and Saunders-Knox Spacetimes

I address a question recently raised by Simon Saunders [Phil. Sci. 80(2): 22-48 (2013)] concerning the relationship between the spacetime structure of Newton-Cartan theory and that of what I will call "Maxwell-Huygens spacetime". This discussion will also clarify a connection between Saunders' work and a recent paper by Eleanor Knox [Brit. J. Phil. Sci. 65(4): 863-880 (2014)].

physics.hist-ph↗

The Paradigm of Projectile Motion and its Consequences for Special Relativity. Making Sense of Physics

A new explanation for space contraction and time dilation in special relativity is offered based on kinetic energy differences between observers rather than velocity differences. The classical (Newtonian) concept of projectile motion underwent a series of seemingly minor changes and adjustments between the discovery of the quantum (Planck, 1900) and the early codification of quantum theory (Dirac, 1928). The goal of physicists in this period was to keep change to a minimum and preserve as much as possible of the traditional projectile paradigm (TPP). These adjustments were successful in masking an all-out projectile paradigm crisis, but they have left us with a conceptual muddle. This has been especially deleterious for special relativity and our understanding of space contraction and time dilation. A reinterpretation of projectile motion focusing on kinetic energy permits a new understanding of relativistic space contraction and time dilation.

physics.hist-ph↗

The search for longitude: Preliminary insights from a 17th Century Dutch perspective

In the 17th Century, the Dutch Republic played an important role in the scientific revolution. Much of the correspondence among contemporary scientists and their associates is now digitally available through the ePistolarium webtool, allowing current scientists and historians unfettered access to transcriptions of some 20,000 letters from the Dutch Golden Age. This wealth of information offers unprecedented insights in the involvement of 17th Century thinkers in the scientific issues of the day, including descriptions of their efforts in developing methods to accurately determine longitude at sea. Unsurprisingly, the body of correspondence referring to this latter aspect is largely dominated by letters involving Christiaan Huygens. However, in addition to the scientific achievements reported on, we also get an unparalleled and fascinating view of the personalities involved.

physics.hist-ph↗

Was Lepenski Vir an ancient Sun or Pleiades observatory?

In this work we consider some old hypotheses according to which remarkable mesolithic village Lepenski Vir (9500 -- 5500 BC) at the right (nearly west) Danube riverside in the Iron gate in Serbia was an ancient (one of the oldest) Sun observatory. We use method recently suggested by A. C. Sparavigna, concretely we use "freely available software" or local Sun radiation direction simulation computer programs. In this way we obtain and discuss pictures of the sunrise in the Lepenski Vir during winter and summer solstice and spring and autumn equinox in relation to position of the mountains, especially Treskavac (Trescovat) and Kukuvija at left (nearly east) Danube riverside (in Romania). While mountain Kukuvija represents really the marker for the Sun in date of the winter solstice, mountain Treskavac, in despite to usual opinions, does not represent a real marker for the Sun in date of the summer solstice. Sun rises behind Treskavac, roughly speaking, between 22.April and 1. May. It corresponds to year period when heliacal rising of the Pleiades constellation occurs, which by many ancient cultures, e.g. Celts of northern Europe, denotes very beginning of the year. All this, in common with some archeological facts (house-shrine No.47 in the Lepenski Vir holds seven signs beside hearth which would correspond to the seven Pleiades stars), opens a possibility that Lepenski Vir was an ancient Pleiades constellation observatory.

physics.hist-ph↗

ERBU, Expanding Rubber Band Universe

I put forward a simple unidimensional mechanical analogue of the three-dimensional universe models of modern relativistic cosmology. The main goal of the proposal is the appropriate appreciation of the intrinsic relationship between Hubble's law and the homogeneity of expanding relativistic models.

physics.hist-ph↗

Monadic Dynamics

We develop a monadic framework formalising an operational notion of dynamics, seen as the setting and evolution of initial value problems, in general physical theories. We identify in the Eilenberg-Moore category the natural environment for dynamical systems and characterise Cauchy surfaces abstractly as automorphisms in the Kleisli category. Our main results formally vindicates the Aristotelian view that time and change are defined by one another. We show that dynamics which respect the compositional structure of physical systems always define a canonical notion of time, and give the conditions under which they can be faithfully seen as actions of time on physical systems. Finally, we construct state spaces and path spaces, and show that our framework to be equivalent to the path space approaches to dynamics. The monadic standpoint is thus as strong as the established paradigms, but the shift from histories to dynamics helps shed new light on the nature of time in physics. In the appendix we present some additional structures of wide applicability, introduce prop- agators and draft applications to quantum theory, classical mechanics and network theory.

physics.hist-ph↗