دانلود کتاب گالیله و ناوبری ماهواره‌ای

Soon after discovering Jupiter’s satellites, Galileo Galilei realized that their mutual positions provided an absolute clock that could be consulted from Earth, and the possible uses of this clock became an obsession that haunted him until he died. A navigator on the high seas would have been able to note the local time of an eclipse of one of Jupiter’s satellites (on average, there are two or three each night) and compare it with the time it was expected to occur at the European reference point; the difference would provide the ship’s longitude, which, combined with a well-known technique for calculating latitude, would allow geolocation. In 1612, Florentine diplomacy began negotiations with the Spanish Crown to provide Iberian navigators with tables (from which an instrument was also derived) of Galilean invention to calculate eclipses of Jupiter’s satellites and telescopes with which to make observations. It took the Spaniards six years to evaluate the idea, concluding that it was impossible to perform the observation from the deck of a ship on the high seas because of roll and pitch. Galileo took up the problem again after his conviction (which occurred in 1633), this time negotiating through intermediaries with the States General of the Netherlands. While Galileo was rewarded (pending the final evaluation of the project) with a valuable gold necklace, which the Inquisition forbade him to accept, the Dutch technical committee had doubts in line with the Spanish committee. Satellite navigation, technically impossible at the time of Galileo because of Jupiter’s satellites’ considerable distance and relative angular proximity and the difficulties of pointing telescopes, has become feasible in the space age. Of the four constellations of geolocating satellites in orbit today, the European constellation is named after Galileo himself. This book tells the story of the Galilean proposal for geolocation, framing it historically and astronomically between the “before” (the techniques attributed to the Greeks and perfected by medieval astronomers) and the “after” (the arrival on the scene of precision clocks; then, in the twentieth century, the wireless transmission of electromagnetic signals; and finally, space technology). The book is based primarily on the twenty volumes of the beautiful National Edition of the Works of Galileo, published between 1890 and 1909 by Antonio Favaro. Keeping with a widespread tradition among Galileo scholars, I will refer hereafter to this book simply as the Works. I also make use of the fourth volume of the updated edition of the Works, edited by Michele Camerota together with Patrizia Ruffo; this volume, published in 2019, presents some unpublished documents on the contacts between Galileo and the Spanish government for the sale of the Galilean method of determining longitude at sea. The documents cited, Galileo’s letters, and those otherwise relevant in the context of the book are mostly taken from the Works. I always make a clear reference to the original edition, giving in square brackets, where possible, the progressive letter number in the Works, preceded by the volume number (e.g., [11/757]), otherwise the volume and page (e.g., [A4/p79], where A4 indicates the fourth volume of the Update). I have translated the texts from Italian, Castilian, Latin, and French, but always with a clear reference to the original. In short, the reader who is particularly curious or interested in philology will easily find the necessary references to satisfy his curiosity. I have also relied, to a lesser extent, on some of the texts listed in the bibliography. The occasion for writing this book was the organization by the Italian Permanent Delegation to the International Organizations in Paris of the 2024 “Italian Research Day in the World”: the subject was geolocation. The event, organized in collaboration with the Museo Galileo in Firenze and Sorbonne Université Paris, comprised the exhibition “Galileo and satellite navigation” held at the “La Passerelle” gallery in the Pierre et Marie Curie Campus from June 13 to June 28, 2024. The exhibition was replicated in the Italian Institute of Culture in Prague from October 21 to 31, in the Italian Institute of Culture in Amsterdam from December 9 to 13, and is going to be replicated again in the Italian Institute of Culture in Stockholm, and at the Perimeter Institute in Waterloo (Canada).