Galileo Galilei, the great astronomer and physicist whose researches played so crucial a role in the history of science, also occupies an important place in the history of philosophy for his part in overthrowing the predominant Aristotelian concept of the nature of the universe. Galileo considered himself a philosopher and referred to himself as such on the title pages of his most influential works. Much recent research has been devoted to examining both the philosophical background of Galileo's scientific achievements and the philosophical implications of his scientific method. Born in Pisa, the eldest son of a famous music theorist, Galileo entered on the study of medicine at the University of Pisa but quickly shifted his interest to mathematics. From 1589 to 1592, he taught mathematics at Pisa while studying independently with Jacopo Mazzoni, a distinguished professor of philosophy. His earliest scientific works, directed against Aristotle's account of freely falling bodies, date from this period. In 1592 he moved to Padua, where he lectured on mathematics and astronomy, and by 1597 he was defending the Copernican helicocentric theory of the universe in a letter to his friend Mazzoni. When in 1609, he learned of the invention of the telescope in Holland, Galileo quickly designed an improved version of the instrument for his own astronomical observations. His startling discoveries---including the satellites of Jupiter---were revealed in 1610 in his Starry Messenger (Sidereus nuncius), which led to his appointment as mathematician and philosopher to the Grand Duke of Tuscany. On a visit to Rome in 1611, he demonstrated the power of his instrument and defended the Copernican worldview in learned circles. Church authorities were divided on the question of whether the Copernican theory was consistent with scriptural accounts of the cosmos, and Galileo's position was attacked on theological grounds. He defended himself eloquently in his famous Letter to the Grand Duchess Christina (1615), arguing for the independence of scientific inquiry from theological constraints. Nevertheless, in the following year, he was forbidden to hold or teach the Copernican view. Retiring to Florence to pursue his scientific researches, Galileo let the Copernican question lie until a new pope, Urban VIII, seemed to offer a more favorable reception to his views. In 1632 he brought out his great Dialogue Concerning the Two Chief World Systems, a presentation of the Ptolemaic-Aristotelian and Copernican systems heavily weighted in favor of the scientific superiority of the latter. In spite of the support of his Florentine and Roman friends, Galileo was tried and forced to recant his defense of helicocentrism under the threat of torture; the Dialogue was placed on the Index of Prohibited Books and its author sentenced to house arrest for life. Galileo's last years were spent in scientific investigations that culminated in the publication of his Discourses on Two New Sciences (1638). Galileo's legacy as a philosopher lies in his outspoken defense of the autonomy of scientific investigation from philosophical and theological authority, and his conviction that mathematical proofs can and should be sought in physical science, that celestial and terrestrial phenomena can be accounted for by a single set of scientific laws, and that scientific explanations cannot be divorced from direct empirical observation of phenomena.
Albert Einstein, March 14, 1879 - April 18, 1955 Albert Einstein was born on March 14, 1879 in Ulm. He spent his childhood in Munich where his family owned a small machine shop. By the age of twelve, Einstein had taught himself Euclidean geometry. His family moved to Milan, where he stayed for a year, and he used it as an excuse to drop out of school, which bored him. He finished secondary school in Aarau, Switzerland and entered the Swiss Federal Institute of Technology in Zurich. Einstein graduated in 1900, by studying the notes of a classmate since he did not attend his classes out of boredom, again. His teachers did not like him and would not recomend him for a position in the University. For two years, Einstein worked as a substitute teacher and a tutor before getting a job, in 1902, as an examiner for a Swiss patent office in Bern. In 1905, he received his doctorate from the University of Zurich for a theoretical dissertation on the dimension of molecules. Einstein also published three theoretical papers of central importance to the development of 20th Century physics. The first was entitled "Brownian Motion," and the second "Photoelectric Effort," which was a revolutionary way of thinking and contradicted tradition. No one accepted the proposals of the first two papers. Then the third one was published in 1905 and called "On the Electrodynamics of Moving Bodies." Einstein's words became what is known today as the special theory of relativity and said that the physical laws are the same in all inertial reference systems and that the speed of light in a vacuum is a universal constant. Virtually no one understood or supported Einstein's argument. Einstein left the patent office in 1907 and received his first academic appointment at the University of Zurich in 1909. In 1911, he moved to a German speaking University in Prague, but returned to Swiss National Polytechnic in Zurich in 1912. By 1914, Einstein was appointed director of the Kaiser Wilhelm Institute of Physics in Berlin. His chief patron in those early days was German physicist Max Planck and lent much credibility to Einstein's work. Einstein began working on generalizing and extending his theory of relativity, but the full general theory was not published until 1916. In 1919, he predicted that starlight would bend in the vicinity of a massive body, such as the sun. This theory was confirmed during a solar eclipse and cause Einstein to become world renowned after the phenomenon. Einstein received be Nobel Prize in Physics in 1921. With his new fame, Einstein attempted to further his own political and social views. He supported pacifism and Zionism and opposed Germany's involvement in World War I. His support of Zionism earned him attacks from both Anti-Semitic and right wing groups in Germany. Einstein left Germany for the United States when Hitler came into power, taking a position at the Institute for Advanced Study in Princeton, New Jersey. Once there, he renounced his stand on pacifism in the face of Nazi rising power. In 1939 he collaborated with other physicists in writing a letter to President Franklin D. Roosevelt informing him of the possibility that the Nazis may in fact be attempting to create an atomic bomb. The letter bore only Einstein's signature but lent credence to the letter and spurred the U.S. race to create the bomb first. After the war, Einstein was active in international disarmament as well as world government. He was offered the position of President of Israel but turned the honor down. Albert Einstein died on April 18, 1955 in Princeton, New Jersey.
J. L. Heilbron is a professor of history and Vice Chancellor Emeritus, University of California at Berkeley, and currently Senior Research Fellow, Worcester College, Oxford. He is the author of numerous books on the history of science, including most recentlyThe Sun in the Church: Cathedrals as Solar ObservatoriesandGeometry Civilized: History, Culture, and Technique. Stephen Jay Gould is the Alexander Agassiz professor of zoology and professor of geology at Harvard and the Vincent Astor visiting professor of biology at New York University. Recent books includeFull House,Dinosaur in a Haystack, andQuestioning the Millennium. He lives in Cambridge, Massachusetts, and New York City.