Solomon Franco on the Zero Point for Trepidation

In the Middle Ages theories of trepidation, or accession and recession, were proposed to account for variable precession of the equinoxes; the values for trepidation were sometimes positive and sometimes negative, depending on the date. Several dates when the value was 0º have been noted in the literature, and the Hebrew text of Solomon Franco (14th century) confirms two of them: about 18 years before the Hijra, and about 40 years before the Hijra

Maxwell’s Methodological Odyssey in Electromagnetism

In addition to his scientific achievements, James Clerk Maxwell was an innovator in methodologies in physics. In fact, in his hands methodology and theory mutually inform one another, an aspect of his work that has not been properly appreciated. We examine closely from a methodological perspective Maxwell’s contributions to electromagnetism and uncover a trajectory of great interest, which we call Maxwell’s methodological odyssey. There are four principal stations along the fifteen-year trajectory of Maxwell’s published writings devoted to electromagnetism. These contributions form a sequence of different methodologies which culminated in 1873 in his Treatise on Electricity and Magnetism. Tracing the path leading to his magnum opus yields novel insights into the various methodologies which Maxwell applied in the course of constructing his epoch-making electrodynamic theory. Indeed, we claim that the framework of the theory is just as important as the empirical facts in this physical domain. Thus, we are persuaded that Maxwell's formulation and application of novel scientific methodologies is no less a feat than proposing a fundamental theory

A Geographical List in Hebrew Previously Ascribed to Abraham Bar Ḥiyya

A geographical list in Hebrew was published in 1851 as an appendix to a treatise on the calendar by Abraham Bar Ḥiyya (d. ca. 1136). It is argued here that this list has nothing to with Bar Ḥiyya; rather, it was copied from the Tables of Barcelona (second half of the fourteenth century), and derives in part from the geographical list in the zij of Ibn al-Kammād (early twelfth century)

Astronomical Handbooks and Tables from the Islamic World (750-1900): an Interim Report

The purpose of this paper is to present an overview of the current state of research on the medieval Islamic astronomical handbook known as zijes in particular, and astronomical tables in general

Electromagnetic Polarizabilities and Charge Radii of the Nucleons in the Diquark-model

The diquark model is used to calculate the electromagnetic polarizabilities and charge radii of the nucleons for three different potentials. Making the scalar diquark lower in mass introduces a mixing angle $\theta$ between the $\left| 56\right\rangle$ and $\left| 70\right\rangle$ states ,which allows an improvement in value of all 6 properties. Generalizing the Gamov-Teller matrix and the magnetic moment operator to the diquark model gives constraints on this mixing. We obtain for the Richardson potential $\theta =23.2^{\circ },$ $\overline{\alpha }_p=7.9_{-0.9}^{+1.0}\times 10^{-4}fm^3,$ $\overline{\alpha }_n=7.7_{-0.6}^{+0.3}\times 10^{-4}fm^3,$ $\overline{\beta }_p=5.4_{-0.4}^{+1.6}\times 10^{-4}fm^3,$ $\overline{\beta }_n=6.7_{-0.7}^{+1.3}\times 10^{-4}fm^3,$ $\left\langle r^2\right\rangle _p=0.37_{-0.03}^{+0.02}fm^2,$ $\left\langle r^2\right\rangle _n=-0.07_{-0.02}^{+0.03}fm^2.$ Additional pion cloud contributions could improve on all six results.Comment: 15 Pages, Latex, Figs on request, to be published Phys.Lett.B. Minor errors corrected and eqn 5,6,8,9 correcte