REVOLUCIÓN CIENTÍFICA
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La Revolución Científica
El año 1543 se puede tomar como el principio de la Revolución Científica, momento en que Nicholas Copernicus (1473-1543) estableció la teoría de un cosmos heliocéntrico (el sol como centro) y termina con Sir Isaac Newton (1642-1727)que propuso las Leyes Universales y un Universo mecánico.
I. Copernicus
Nicholas Copernicus nació en la ciudad polaca de Torun en 1473. Su padre, comerciante de origen aleman, murió cuando él tenía diez, fue adoptado por su tío, el obispo de Ermland. El obispo lo designó para un cargo eclesiástico y lo envió a estudiar a Italia entre 1496 y 1506. En Italia, Copernicus aprendió el sistema astronómico generalmente aceptado de Ptolemeo.
Este sistema representó el universo compuesto por la Tierra y diez esferas: la Luna, Mercurio, Venus, el Sol, Marte, Júpiter, Saturno, el Firmamento (estrellas fijas), el cielo cristalino que impartía el movimiento a las esferas alrededor de la Tierra, y finalmente el cielo empíreo inmóvil en donde Dios había elegido vivir. Estas esferas eran sólidas y transparentes, y los planetas estaban compuesto de una sustancia ingrávida no-terrenal dentro de las esferas y giraban con ellos alrededor de la tierra inmóvil. Más allá del cielo empíreo no había nada. Así, el universo era considerado ser una entidad finita con la tierra inmóvil como su centro.
La dificultad del sistema ptolemaico era que los planetas y las estrellas no giraban exactamente según lo imaginado. Cuanto más observaciones hacían los astrónomos medievales, más se evidenciaba que era incorrecta. Para solucionar estas discrepancias, los astrónomos modificaron el sistema sugiriendo que había esferas secundarias y excéntricas. Finalmente, el número de los tipos de esferas alcanzó ochenta, pero todavía los cálculos matemáticos no coincidían con los datos observados. Los astrólogos culpaban a la astronomía de los errores. Se sabía que el calendario tenía errores pero no se sabía cómo solucionarlas.
Copernicus se interesó en estos problemas. Él sabía que un astrónomo antiguo, Aristarco, había discutido que la tierra y los otros planetas giraban alrededor del sol y que la tierra también giraba diariamente en su eje. Él se dedicó a realizar los cálculos matemáticos basados en estas teorías, para ver si obtenía mejores resultados. Evitó la idea de las esferas secundarias y excéntricas y nunca dudó que las trayectorias de los planetas alrededor del sol eran circulares porque su conocimiento de Platón lo condujo a creer que el círculo era la más perfecta de las figuras geométricas. Por lo tanto, sus cálculos fueron más exactos que el sistema modificado de Ptolemeo. Sus cálculos eran más simples, y el número de esferas secundarias y excéntricas se reducía a treinta y cuatro.
Como se había previsto, los pocos teólogos que tomaron nota del sistema de Copérnico estaban inclinados rechazarla. Lutero desdeñosamente comentó que "este tonto desea invertir la ciencia entera de la astronomía". la actitud crítica de otros científicos era más seria. Copérnico había anticipado algunas de sus objeciones. La tierra podría rotar en su eje del oeste al este precisó, sin causar un viento de alta velocidad constante. También, la tierra podría moverse en una órbita alrededor del sol sin hacer que las estrellas pareciesen cambiar su localización, dijo que la distancia de la tierra al sol era una fracción minúscula comparada con la distancia de la tierra a las estrellas y que el cambio real en la posición no podría ser medido. Su teoría de las distancias extensas entre los planetas no condujo a Copérnico a creer que el universo era infinito, aunque sus partidarios pronto avanzarían en esa visión.
Al Aristotelians, la gravedad era la tendencia natural de cuerpos pesados a moverse hacia el centro del universo. En las situaciones en las cuales la gravedad no era un factor, seguía habiendo un objeto en el resto a menos que una fuerza fuera aplicada contra ella. Si una fuerza fue aplicada constantemente, el objeto se movió en una constante, no haber acelerado, velocidad. Si la fuerza fue quitada, el objeto paró. Mientras estas teorías fueron aceptadas, el sistema de Ptolemaic causó pocas dificultades que el Copernican. Si, como Aristotle dicho, una roca cayó naturalmente hacia el centro del universo, el astrónomo de Copernican tuvo que explicar porqué se movió realmente hacia la tierra más bien que el sol. También, a Aristotle, una fuerza constante tuvo que ser aplicada a la tierra para guardarla el moverse alrededor del sol o al sol y a los planetas para guardarlos el moverse alrededor de la tierra. El anterior era el más difícil de creer porque la tierra era sabida para ser muy grande y pesada mientras que el sol y los planetas fueron pensados para ser compuestos de unearthly, la sustancia ingrávida que se podría mover fácilmente por los ángeles o una cierta otra cierta otra fuerza supernatural. Así, una nueva teoría de la gravedad y del movimiento tuvo que ser desarrollada antes de que el sistema de Copernican podría ganar la aceptación. Esto era doble verdad porque el Aristotelians seguía siendo firmemente atrincherado en las sillas de la universidad de la ciencia y de la filosofía.
Además, el sistema de Copernican exigió que un hombre niegue sus sentidos, que fácilmente le dijeron que el sol circundara la tierra, en la vuelta para algunos cálculos matemáticos cuál no hizo posible ninguna predicción astronómica mejor que el método de Ptolemaic. No está sorprendiendo eso para más que un siglo allí era los científicos que negaron la validez del sistema de Copernican.
El discusión condujo a una pelea tres-echada a un lado referente al método científico apropiado. El Aristotelians prefirió analizar la naturaleza de cosas. Utilizaron pocos matemáticas y pocos experimentos pero los intentaron de construir su sistema por las discusiones lógicas que conducían de algunas premisas básicas. Su meta era más para explicar porqué suceden las cosas que describir cómo suceden. Una segunda escuela, conducida por los hombres tales que el astrónomo danés Tycho Brahe (1546-1601) y el filósofo inglés Francis Bacon (1561-1626) favoreció a método inductivo. Discutieron que el científico amontonara todo el experimento directo posible de la fecha y observación. Una vez que estén montada, éstos fechen señalaran a la conclusión correcta. Tycho Brahe, por ejemplo, hizo observaciones en el movimiento de los planetas que eran tan numerosos y tan exactos como habrían podido estar antes de la invención del telescopio. Su diagrama de los cambios periódicos en la localización de los cuerpos divinos lo condujo a creer que el mercurio y Venus giraron alrededor del sol, pero que el sol y los otros planetas giraron alternadamente alrededor de la tierra. Él nunca redujo su sistema a una declaración matemática, pero siguió hecho observado más de cerca que el sistema de Copernicus.
El acercamiento matemático, deductivo era el tercer sistema abogado en este tiempo. Había recibido ayuda inintencional de los humanistas del renacimiento que habían preferido Platón a Aristotle, porque Platón mismo había sido influenciado profundamente por un matemático griego del sexto siglo B.C. nombrado Pythagoras. Pythagoras había observado que el sonido produjo desplumando un variado fuerte estirada con su longitud. Esta relación entre la echada y la longitud del fuerte, que estaba conforme a la representación geométrica y a la medida matemática, conducidas le para creer que todos los elementos importantes en el universo estaban conforme a la demostración matemática y que ciertos números tenían una significación mystical peculiar. Platón aceptó este punto de vista y representó la naturaleza en términos de líneas rectas, de círculos, de triángulos, y de otras figuras geométricas que eran más perfectas que los objetos observados realmente. Bajo su influencia, la ciencia griega llegó a ser más matemática que experimental, y el énfasis renovado en su pensamiento tenía un efecto similar en el último renacimiento. Entre los principales partidarios del acercamiento deductivo-matema'tico de Platón y de Pythagoras estaban Copernicus mismo y Johannes Kepler. Galileo galilei, el tercero del gran trío de matemáticos, eligió Archimedes como su modelo porque ese científico antiguo había aplicado matemáticas a los problemas prácticos en la física y había sugerido el método que Galileo debiera hacer sus el propios.
Kepler (1571-1630) era un Platonist ardiente que creyó que los leyes matemáticos simples eran la base de todos los fenómenos naturales. Usando los datos recogidos por su amo, Brahe, él demostró que los planetas siguen órbitas elípticas alrededor del sol que él también encontró que se movieron más rápidamente mientras que acercaron al sol y que una ley matemática podría expresar la relación entre el tamaño de sus órbitas y del tiempo a que los tomó para ir toda la manera alrededor de ellos. Sus descubrimientos quitaron una de las objeciones a una Sistema Solar sol-centrada, porque sus tablas planetarias eran más exactas que ésas proporcionadas por los abogados de cualquier otro sistema.
Kepler no ofreció ninguna respuesta satisfactoria al problema de la gravedad, y la mejor explicación que él podría ofrecer para la fuerza que movió los planetas era sugerir que vino del sol. Otros progresos, sin embargo, minaban gradualmente el concepto aristotélico del movimiento y de la gravedad. Una estrella nueva que era tan brillante que podría ser visto en luz del día aparecía en 1572 desaparecer solamente otra vez en 1574. Obviamente, la región de las estrellas fijas no era permanente y unchanging pues el Aristotelians enseñó. Algunos años más adelante, un cometa nuevo era el pasar visto con la región en el lado lejano de la luna que Aristotelians dicho fue compuesto de las esferas impenetrables, transparentes en las cuales los planetas que giraban fueron situados. ¿El Aristotelians eran claramente incorrectos, pero si los planetas no consiguieron su capacidad de moverse en órbitas fijas de las esferas, dónde consiguieron su energía del movimiento y qué fuerza las sostuvo a una trayectoria prescrita? La gran contribución siguiente hacia el abastecimiento de una respuesta a estas preguntas y ganar la aceptación para la teoría de Copernican fue hecha por galileo galilei (1564-1642).
II. Galileo
Galileo nació en Pisa de una familia florentina noble. Él sirvió como profesor de las matemáticas en Pisa y Padua y llevó a cabo más adelante un poste en la corte del duque magnífico de Toscana. Sus éxitos científicos eran debido a su capacidad de hacer lo que han llamado algunos historiadores "pensaron experimentos." Tomando un problema particular, tal como la ley que gobierna cuerpos que caen, él lo pelaría de todos los factores de complicación, tales como el efecto de la resistencia del aire, y después especula en qué sucedería. ¿una caída pesada del objeto más rápidamente en un vacío que más ligero como el Aristotelians discutió, o caerían juntos a la misma velocidad? Galileo dibujó líneas para representar las varias fuerzas implicadas y por el uso de la geometría redúzcalas a un fórmula matemático. De este modo él demostró eso
s = gt2 where s is the distance of the fall, t is the time of fall, and g is a 2
constant. This discovery undermined the Aristotelians in two respects. it showed that there was no relation between the weight of a body and the speed at which it fell, and that if a uniform force (g) was applied to an object, it would move at an accelerated speed rather than at a constant speed as the Aristotelians had argued. this meant that if angels were constantly pushing the planets along their orbits, the planets would rotate faster and faster, Since this was obviously not the case, the force which had originally set the planets in motion was no longer being applied. Neither the angels nor any other supernatural power was needed to keep the planets in motion, for as our modern law of inertia states, a body in motion continues to move in a straight line until something tops it or alters its course. Galileo, himself, did not fully state the law of inertia, and its implication that the universe could function without the active interference of a God was not generally accepted by scientists until the eighteenth century, but Aristotelian science had received a mortal blow.
Galileo also contributed to the development of the scientific method. He had not needed to perform any experiments to arrive at the law of falling bodies, and, contrary to legend, he probably never dropped a light and heavy object from the Leaning Tower of Pisa. Mathematical proof was preferred because with mathematics alone could he remove the extraneous parts of the problem and express his law simply. Bacon and the advocates of induction insisted that such factors as air resistance be considered at the same time, and the problem was thereby made too complex to find a formula readily. An 'Aristotelian did drop two weights from the tower at Pisa and went away claiming that Aristotle had been right, that the heavier object had landed first. Other factors must have intervened to cause the experiment to go awry. With mathematics, Galileo thought, there could be no mistakes.
Therefore, he confidently reduced the universe to mass and motion. Both could be expressed in geometric terms.
"Philosophy," he wrote, "is written in the great book which never lies before our eyes - I mean the universe - but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written. The book is written in the mathematical language, and the symbols are triangles, circles, and other geometric figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth."
He was drawn to the system of Copernicus and Kepler because they made use of geometric reasoning.
"I cannot sufficiently admire," he wrote, "the eminence of those men's wits, that have received and held it to be true, and with the sprightliness of their judgments offered such violence to their own senses, as that they have been able to prefer that with their reason dictated to them, to that which sensible experiments represented most manifestly to the contrary. . . . I cannot find any bounds for my admiration, how that reason was able in Aristarchus and Copernicus, to commit such a rape on their senses, as in spite thereof to make herself mistress of their credulity."
Galileo's preference for mathematical calculations to knowledge derived only from his senses does not mean that he never made us of observation. Indeed, he was the first to use a telescope in astronomical work. He studied the moon and found that it was composed of the same substances as the earth and that it produced no light of its own, but only reflected rays from the sun. He turned his telescope on the sun itself and saw that it had spots. The sun was not a perfect substance, then, and since the spots moved, the sun rotated on its axis in the same direction as the planets moved in their orbits. He found the four satellites of Jupiter and saw that they revolved around the planet. These discoveries conformed his belief in the heliocentric system and suggested that other heavenly bodies had the same properties as the earth.
In 1632, he published his Dialogue Concerning the Two Chief Systems of World. He wrote in Italian to reach a wide audience and doubtless hoped to defeat forever the defenders of Ptolemy. He showed how the rotation of the earth on its axis produced the apparent rotation of the heavens, why an object dropped from a tower will land directly below because it moved eastward with the rotation of the earth at the same speed as the tower, how gravitation prevented objects from being thrown off the whirling earth, and how the stars' great distance from the earth prevented man from being able to see their changed, position as the earth moved around the sun. One by one, Galileo answered the objections that had been offered to the Copernican system; at the same time he pointed out problems that made the continued acceptance of the Ptolemaic system absurd. His work was a success, but he was summoned before the Inquisition at Rome for teaching a doctrine "contrary to Holy Scripture" and was compelled to recant. His book was placed on the Index where it remained until 1822, but it was too late to halt the new astronomy and physics.
The Copernican system with its new theory of motion and its mathematical, deductive method was now enthusiastically accepted by most scientists, although the problem of gravity was not fully solved. As early as 1600, William Gilbert (1540-1603) had published a study in which he argued that gravity was a universal magnetic attraction. The earth, he believed, was a gigantic magnet that attracted the moon, and the moon in turn was a magnet that attracted the earth. When he discovered that a spherical magnet revolved on its axis when placed in a magnetic field, he offered this as an explanation of why the earth and other heavenly bodies rotated on their axes. Kepler accepted many of Gilbert's ideas, and the view that gravity was a universal property became widely accepted. Christian Huygens (1629-1695) explained how the force of gravity, which pulled the planets towards the sun, was counterbalanced by a centrifugal force tending to cause them to leave their orbits on a tangent. It remained, however, for Sir Isaac Newton to discover the law of gravitation. With this discovery, eh provided the capstone tot eh scientific revolution in astronomy and physics that ushered in a new era.
The triumphs achieved by the mathematical method redoubled efforts in the field of mathematics itself, and during the seventeenth century, analytic geometry and calculus were discovered, logarithms and the slide rule were invented, and arithmetical and algebraic symbols were improved and came into common use. The need for accurate measuring instruments led to the invention of the barometer, thermometer, pendulum clock, microscope, telescope, and air pump. These and other discoveries had a profound effect. They influenced philosophy, religion, art, and political thought. As a contemporary wrote, the "geometric spirit is not so exclusively bound to geometry that it could not be separated from it and applied to other fields. A work on ethics, politics, criticism, or even eloquence, other things being equal, is merely so much more beautiful and perfect if it is written in the geometric spirit."
The year 1543 may be taken as the beginning of the scientific revolution, for it was then that Copernicus published The Revolution of the Heavenly Bodies and Vesalius, On the Structure of the Human Body. Within a century and a half, man's conception of himself and the universe he inhabited was altered, and the scholastic method of reasoning was replace by new scientific methods.
I. Copernicus
Nicholas Copernicus was born in the Polish city of Torun in 1473. Since his father, who was a merchant of German extraction, died when he was ten, he was raised by his uncle, the Bishop of Ermland. The bishop found an ecclesiastical position for his nephew and arranged for him to be educated in Italy between 1496 and 1506. While in Italy, Copernicus studied the generally accepted astronomical system of Ptolemy.
This system depicted the universe as consisting of the earth and ten spheres: the moon, Mercury, Venus, the sun, Mars, Jupiter, Saturn, the Firmament (fixed stars), the Crystalline Heaven which imparted motion to the spheres around the earth, and finally the motionless Empyrean Heaven where God dwelt with the elect. These spheres were generally believed to be solid and transparent, and the planets to be of a non-earthly weightless substance fitted into the spheres and revolving with them around the motionless earth. Beyond the Empyrean Heaven there was nothing. Thus, the universe was considered to be a finite entity with the stationary earth as its center.
The difficulty with the Ptolemaic system was that the planets and stars did not revolve exactly as predicted. The more observations the medieval astronomers made, the more it became apparent that something was wrong. To accommodate these discrepancies, the astronomers modified the system by suggesting that there were sub- and off-center spheres. Finally, the number of the various types of spheres reached eighty, but still mathematical calculations did not coincide with observed data. Astrologers could blame their errors on faulty astronomy and thereby repel the inference that no relation existed between the planets and fate. The calendar was known to be in error, but it was difficult to decide what corrections to make.
Copernicus became interested in these problems. He knew that an ancient astronomer, Aristarchus, had argued that the earth and the other planets revolved around the sun and that the earth also revolved daily on its axis. He determined to make mathematical calculations based on these theories, to see if they would bring better results. He kept the idea of the sub- and off-center spheres and never doubted that the planets' paths around the sun were circular because his Platonic background led him to believe that the circle was the most perfect of geometric figures. Consequently, his calculations yielded predictions that were no more accurate than the modified Ptolemaic system. His calculations were simpler, however, and the number of sub- and off-center spheres could now be reduced to thirty-four.
As might be expected, the few theologians who took note of Copernicus' system were inclined to reject it. Luther scornfully remarked that "this fool wishes to reverse the entire science of astronomy; but sacred Scripture tells us that Joshua commanded the sun to stand still, and not the earth." More serious was the critical attitude of other scientists. Copernicus had anticipated some of their objections. The earth could rotate on its axis from west to east, he pointed out, without causing a constant high-velocity wind from eats to west if the air revolved at the same speed and in the same direction. Also, the earth could move in an orbit around the sun without causing the stars to seem to change their location provided distance traveled by the earth was such a tiny fraction of the distance to the stars that the actual change in position could not be measured. His theory that vast distances separated the planets did not lead Copernicus to believe that the universe was infinite, although his supporters would soon advance that view. Only where his theory ran counter to the Aristotelian conception of gravity and motion was Copernicus unable to provide his critics with satisfactory answers.
To the Aristotelians, gravity was the natural tendency of heavy bodies to move towards the center of the universe. In situations in which gravity was not a factor, an object remained at rest unless a force was applied against it. If a force were constantly applied, the object moved at a constant, not an accelerated, speed. If the force were removed, the object stopped. As long as these theories were accepted, the Ptolemaic system caused fewer difficulties than the Copernican. If, as Aristotle said, a rock naturally fell towards the center of the universe, the Copernican astronomer had to explain why it actually moved towards the earth rather than the sun. Also, to Aristotle, a constant force had to be applied either to the earth to keep it moving around the sun or to the sun and planets to keep them moving around the earth. The former was the more difficult to believe because the earth was known to be very large and heavy while the sun and planets were thought to be composed of an unearthly, weightless substance that could be easily moved by the angels or some other some other supernatural force. Thus, a new theory of gravity and of motion had to be developed before the Copernican system could win acceptance. This was doubly true because the Aristotelians were still firmly entrenched in the university chairs of science and philosophy.
Furthermore, the Copernican system demanded that a man deny his senses, which easily told him that the sun went around the earth, in return for some mathematical calculations which made possible no better astronomical predictions than the Ptolemaic method. It is not surprising that for more than a century there were scientists who denied the validity of the Copernican system.
The debate led to a three-sided quarrel concerning the proper scientific method. The Aristotelians preferred to analyze the nature of things. They used little mathematics and few experiments but sought to construct their system by logical arguments leading from a few basic premises. Their goal was more to explain why things happen than to describe how they happen. A second school, led by such men as the Danish astronomer Tycho Brahe (1546-1601) and the English philosopher Francis Bacon (1561-1626) favored the inductive method. They argued that the scientist should amass all the date possible through experiment and observation. Once assembled, these date would point to the correct conclusion. Tycho Brahe, for example, made observations on the motion of the planets that were as numerous and as accurate as they could have been before the invention of the telescope. His plot of the periodic changes in the location of the heavenly bodies led him to believe that Mercury and Venus revolved around the sun, but that the sun and the other planets revolved in turn around the earth. He never reduced his system to a mathematical statement, but it did follow observed fact more closely than Copernicus's system.
The mathematical, deductive approach was the third system advocated at this time. It had received unintentional assistance from the Renaissance humanists who had preferred Plato to Aristotle, for Plato himself had been deeply influenced by a Greek mathematician of the sixth century B.C. named Pythagoras. Pythagoras had noted that the sound produced by plucking a stretched strong varied with its length. This relationship between the pitch and the length of the strong, which was subject to geometrical representation and mathematical measurement, led him to believe that all the important elements in the universe were subject to mathematical demonstration and that certain numbers had a peculiar mystical significance. Plato accepted this point of view and depicted nature in terms of straight lines, circles, triangles, and other geometric figures that were more perfect than the objects actually observed. Under his influence, Greek science became more mathematical than experimental, and the renewed emphasis on his thought had a similar effect in the late Renaissance. Among the chief supporters of the deductive-mathematical approach of Plato and Pythagoras were Copernicus himself and Johannes Kepler. Galileo Galilei, the third of the great trio of mathematicians, chose Archimedes as his model because that ancient scientist had applied mathematics to practical problems in physics and suggested the method that Galileo was to make his own.
Kepler (1571-1630) was an ardent Platonist who believed that simple mathematical laws were the basis of all natural phenomena. Using the data collected by his master, Brahe, he showed that planets follow elliptical orbits around the sun. he also found that they moved more rapidly as they neared the sun and that a mathematical law could express the relationship between the size of their orbits and the time that it took them to go all the way around them. His discoveries removed one of the objections to a sun-centered solar system, for his planetary tables were more accurate than those provided by the advocates of any other system.
Kepler offered no satisfactory answer to the problem of gravity, and the best explanation that he could offer for the force that moved the planets was to suggest that it came from the sun. Other developments, however, were gradually undermining the Aristotelian conception of motion and gravity. A new star that was so bright that it could be seen in daylight appeared in 1572 only to disappear again in 1574. Obviously, the region of the fixed stars was not permanent and unchanging as the Aristotelians taught. A few years later, a new comet was seen passing through the region on the far side of the moon that Aristotelians said was composed of the impenetrable, transparent spheres in which the revolving planets were located. Clearly the Aristotelians were wrong, but if the planets did not get their capacity to move in fixed orbits from the spheres, where did they get their power of motion and what force held them to a prescribed path? The next great contribution towards providing an answer to these questions and winning acceptance for the Copernican theory was made by Galileo Galilei (1564-1642).
II. Galileo
Galileo was born in Pisa of a noble Florentine family. He served as professor of mathematics at both Pisa and Padua and later held a post in the court of the Grand Duke of Tuscany. His scientific successes were due to his ability to make what some historians have called "thought experiments." Taking a particular problem, such as the law that governs falling bodies, he would strip it of all complicating factors, such as the effect of air resistance, and then speculate on what would happen. Would a heavy object fall faster in a vacuum than a lighter one as the Aristotelians argued, or would they fall together at the same speed? Galileo drew lines to represent the various forces involved and by the use of geometry reduce them to a mathematical formula. In this manner he showed that
s = gt2 where s is the distance of the fall, t is the time of fall, and g is a 2
constant. This discovery undermined the Aristotelians in two respects. it showed that there was no relation between the weight of a body and the speed at which it fell, and that if a uniform force (g) was applied to an object, it would move at an accelerated speed rather than at a constant speed as the Aristotelians had argued. this meant that if angels were constantly pushing the planets along their orbits, the planets would rotate faster and faster, Since this was obviously not the case, the force which had originally set the planets in motion was no longer being applied. Neither the angels nor any other supernatural power was needed to keep the planets in motion, for as our modern law of inertia states, a body in motion continues to move in a straight line until something tops it or alters its course. Galileo, himself, did not fully state the law of inertia, and its implication that the universe could function without the active interference of a God was not generally accepted by scientists until the eighteenth century, but Aristotelian science had received a mortal blow.
Galileo also contributed to the development of the scientific method. He had not needed to perform any experiments to arrive at the law of falling bodies, and, contrary to legend, he probably never dropped a light and heavy object from the Leaning Tower of Pisa. Mathematical proof was preferred because with mathematics alone could he remove the extraneous parts of the problem and express his law simply. Bacon and the advocates of induction insisted that such factors as air resistance be considered at the same time, and the problem was thereby made too complex to find a formula readily. An 'Aristotelian did drop two weights from the tower at Pisa and went away claiming that Aristotle had been right, that the heavier object had landed first. Other factors must have intervened to cause the experiment to go awry. With mathematics, Galileo thought, there could be no mistakes.
Therefore, he confidently reduced the universe to mass and motion. Both could be expressed in geometric terms.
"Philosophy," he wrote, "is written in the great book which never lies before our eyes - I mean the universe - but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written. The book is written in the mathematical language, and the symbols are triangles, circles, and other geometric figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth."
He was drawn to the system of Copernicus and Kepler because they made use of geometric reasoning.
"I cannot sufficiently admire," he wrote, "the eminence of those men's wits, that have received and held it to be true, and with the sprightliness of their judgments offered such violence to their own senses, as that they have been able to prefer that with their reason dictated to them, to that which sensible experiments represented most manifestly to the contrary. . . . I cannot find any bounds for my admiration, how that reason was able in Aristarchus and Copernicus, to commit such a rape on their senses, as in spite thereof to make herself mistress of their credulity."
Galileo's preference for mathematical calculations to knowledge derived only from his senses does not mean that he never made us of observation. Indeed, he was the first to use a telescope in astronomical work. He studied the moon and found that it was composed of the same substances as the earth and that it produced no light of its own, but only reflected rays from the sun. He turned his telescope on the sun itself and saw that it had spots. The sun was not a perfect substance, then, and since the spots moved, the sun rotated on its axis in the same direction as the planets moved in their orbits. He found the four satellites of Jupiter and saw that they revolved around the planet. These discoveries conformed his belief in the heliocentric system and suggested that other heavenly bodies had the same properties as the earth.
In 1632, he published his Dialogue Concerning the Two Chief Systems of World. He wrote in Italian to reach a wide audience and doubtless hoped to defeat forever the defenders of Ptolemy. He showed how the rotation of the earth on its axis produced the apparent rotation of the heavens, why an object dropped from a tower will land directly below because it moved eastward with the rotation of the earth at the same speed as the tower, how gravitation prevented objects from being thrown off the whirling earth, and how the stars' great distance from the earth prevented man from being able to see their changed, position as the earth moved around the sun. One by one, Galileo answered the objections that had been offered to the Copernican system; at the same time he pointed out problems that made the continued acceptance of the Ptolemaic system absurd. His work was a success, but he was summoned before the Inquisition at Rome for teaching a doctrine "contrary to Holy Scripture" and was compelled to recant. His book was placed on the Index where it remained until 1822, but it was too late to halt the new astronomy and physics.
The Copernican system with its new theory of motion and its mathematical, deductive method was now enthusiastically accepted by most scientists, although the problem of gravity was not fully solved. As early as 1600, William Gilbert (1540-1603) had published a study in which he argued that gravity was a universal magnetic attraction. The earth, he believed, was a gigantic magnet that attracted the moon, and the moon in turn was a magnet that attracted the earth. When he discovered that a spherical magnet revolved on its axis when placed in a magnetic field, he offered this as an explanation of why the earth and other heavenly bodies rotated on their axes. Kepler accepted many of Gilbert's ideas, and the view that gravity was a universal property became widely accepted. Christian Huygens (1629-1695) explained how the force of gravity, which pulled the planets towards the sun, was counterbalanced by a centrifugal force tending to cause them to leave their orbits on a tangent. It remained, however, for Sir Isaac Newton to discover the law of gravitation. With this discovery, eh provided the capstone tot eh scientific revolution in astronomy and physics that ushered in a new era.
The triumphs achieved by the mathematical method redoubled efforts in the field of mathematics itself, and during the seventeenth century, analytic geometry and calculus were discovered, logarithms and the slide rule were invented, and arithmetical and algebraic symbols were improved and came into common use. The need for accurate measuring instruments led to the invention of the barometer, thermometer, pendulum clock, microscope, telescope, and air pump. These and other discoveries had a profound effect. They influenced philosophy, religion, art, and political thought. As a contemporary wrote, the "geometric spirit is not so exclusively bound to geometry that it could not be separated from it and applied to other fields. A work on ethics, politics, criticism, or even eloquence, other things being equal, is merely so much more beautiful and perfect if it is written in the geometric spirit."
Scientific Revolution, Information, Resources, Web Links - Scientific Revolution Home Page - Dr Robert A. Hatch
T H E S C I E N T I FI C R E V O L U T I O N
DEFINITION - CONCEPT - HISTORY
Professor Robert A. Hatch - University of Florida
Working Definition: By tradition, the "Scientific Revolution" refers to historical changes in thought & belief, to changes in social & institutional organization, that unfolded in Europe between roughly 1550-1700; beginning with Nicholas Copernicus (1473-1543), who asserted a heliocentric (sun-centered) cosmos, it ended with Isaac Newton (1642-1727), who proposed universal laws and a Mechanical Universe.
Was there such a thing as the 'Scientific Revolution' -- and if the question makes sense, what is it, or what was it? Better still, what do historians mean when they speak of the 'Scientific Revolution'?
What follows is a modest attempt to clarify basic issues and suggest others that are less obvious. As an introduction to the concept of the Scientific Revolution, the following narrative provides examples that make the story increasingly complex, arguably, it may seem to undermine the very notion of a Scientific Revolution. In any case, this short essay should be viewed as but one example of how historians more generally think about history.
Which is to say, the Scientific Revolution provides an excellent exercise for thinking about how historical periodizations emerge, develop, and mature. Arguably, periodizations serve as paradigms, for students and scholars alike. They also serve as a forum for debate. Good periodizations foster debate, and the best among them grow more richly problematic, they promote ever more focused research and ever more imaginative and satisfying interpretations of past events.
All students of history confront these kinds of issues. They are ever present in any historical periodization, whether it be the Renaissance, Reformation, Scientific Revolution, and Enlightenment, or the Colonial Period, Civil War, Gilded Age, 'Sixties', or Harlem Renaissance.
More About the Scientific Revolution
A traditional description of the Scientific Revolution would go much further than our opening mini-definition allowed. A good basic description would include some of the following information (and inevitably) interpretive claims. Most specialists would agree on the following basic interpretations traditionally associated with the 'Scientific Revolution' --:
As we have said, in European history the term 'Scientific Revolution' refers to the period between Copernicus and Newton. But the chronological period has varied dramatically over the last 50 years. The broadest period acknowledged usually runs from Nicholas Copernicus (1473-1543) and his De Revolutionibus to Isaac Newton (1642-1727). Some historians have cut this back, claiming that it properly extends only to the publication of Newton's Principia (1687) or to his Opticks (1704) or to Newton's death (1727). More radical proposals have suggested that the Scientific Revolution might apply to the so-called Enlightenment 'Newtonians' thus extending to roughly 1750. Further, as we shall see below, some historians have cut back the earlier period. Some have all but removed Copernicus from their chronological definition, claiming that the 'Copernican Revolution' virtually began and ended in 1610 with the work of Galileo and Kepler. Historians have consistently disputed the presumed beginning and ending dates of the much-disputed 'Scientific Revolution'.
Most historians agree, however, that the traditional interpretation (which has its own history) was based on belief in a core transformation which began in cosmology and astronomy and then shifted to physics (some historians have argued that there were parallel developments in anatomy and physiology, represented by Vesalius and Harvey).
Most profoundly, some historians have argued, these changes in "natural philosophy" (= science) brought important transformations in what came to held as "real" (ontology) and how Europeans justified their claims to knowledge (epistemology).
The learned view of things in 16th-century thought was that the world was composed of Four Qualities (Aristotle's Earth, Water, Air, Fire). By contrast, Newton's learned contemporaries believed that the world was made of atoms or corpuscles (small material bodies). By Newton's day most of learned Europe believed the earth moved, that there was no such thing as demonic possession, that claims to knowledge (so the story goes) should be based on the authority of our individual experience, that is, on argument and sensory evidence. The motto of the Royal Society of London was: Nullius in Verba, roughly, Accept nothing on the basis of words (or someone else's authority).
Further Complexity for the Scientific Revolution
As a periodization, the Scientific Revolution has grown increasingly complex. As it has attempted to take account of new research and alternative perspectives, new additions and alterations have been made. Among the most obvious additions over the last 50 years have been a number of sub-periodizations that have been spawned by more narrow research topics, usually from a more focused topical theme or from a more narrow chronological period. Among these sub-periodizations, the more widely accepted include: The Copernican Revolution; the Galilean Revolution; the Keplerian Revolution; the Cartesian Synthesis; and not least, the Newtonian Revolution and the Newtonian Synthesis.
Understood as an historical periodization (which inevitably place limits of 'space, time & theme' -- that is, periodizations are defined by geographical, chronological, topical elements) the Scientific Revolution refers to European developments or movements extending over periods of at least 75 to 185 years. These developments involve changing conceptual, cultural, social, and institutional relationships involving nature, knowledge and belief.
As mentioned, specialist do not agree on the exact dates of the Scientific Revolution. Generally speaking, most scholars have reduced or entirely denied the earliest years of the Scientific Revolution, usually associated with what has been long known as the 'Copernican Revolution'. One noted historian, for example, has argued that if there was a Copernican Revolution, then it began and ended in 1610 with the work of Galileo and Kepler. Other specialists, emphasizing the development of key conceptual elements, have suggested that the key period of the Scientific Revolution was 1610-1660. Other scholars, specializing in social and institutional elements, have suggested that the period after 1660 was critical, as it was then that scientific periodicals and state-sponsored science emerged.
Additional Details - The Scientific Revolution
As we have said, a strong traditional claim is that the Scientific Revolution stands for a series of changes that stemmed from Copernicus' bold claim that the earth moves. This claim clearly ran contrary to tradition, to the authority of the Ancients and to established views in the universities and most church officials. Copernicus claimed that the earth is not fixed and stationary in the center of the cosmos (geocentric and geostatic) but instead argued that it rotates on its axis each day and revolves around the sun each year.
From Copernicus' bold but simple claim, so the story goes, a complex series of new developments were necessary to support his view and, at the same time, to replace earlier beliefs. What was needed, at least in retrospect, were new astronomical observations, these now associated with Tycho Brahe (1546-1601); new theoretical modifications concerning planetary orbits and their motions, now associated with Johannes Kepler (1571-1630); and not least, new theories of motion that would accommodate a moving earth, these theories now associated with Galileo Galilei (1564-1642), René Descartes (1596-1650), Christiaan Huygens (1629-1695), and of course, Isaac Newton (1642-1727). The latter, by acclaim, joined heaven and earth by uniting terrestrial and celestial bodies under one set of universal laws of motion. Newton invented the universe. It displaced the traditional Aristotelian cosmos. This widely held view was due largely to the work of the historian Alexandre Koyré.
In this view, the 'Newtonian Synthesis' marked the shift from a closed, finite, hierarchical, qualitative cosmos to an infinite, homogeneous, quantitative universe. This change signaled that all things were one. There is one kind of matter, one set of laws, one kind of space, one kind of time. Everything is always and everywhere the same: Space, Time, Matter, Cause. Hence the very word: Universe.
This shift from Cosmos to Universe also marked a transformation from an Organic Worldview to a Mechanical World Picture. That is, the Modern World Machine. All of this, according to traditional definitions, would have been rather important in itself, given the importance of science to 20th-century civilization.
But in the bargain, so the argument goes, not only was the world of Nature entirely re-conceptualized, so was the nature of Human Knowledge. This in turn raised questions about the traditional Human Eternal Verities -- how humans understood themselves in relation to 'God, Nature, and Man'.
From these concerns came the 'Clockwork Universe' debates about God's relationship to Nature and whether God was rational or willful. One historian suggested that God, in effect, had been excommunicated from the world of humans -- not to the edge of Space (as with Aristotle and Aquinas) but left there at the beginning of Time. From such debates (according to this narrative) came new distinctions that walked the line from Theism to Deism to Agnosticism and Atheism. Koyré, among others, was concerned about alienation.
In sum, as a simple overview, the traditional definition of the Scientific Revolution with which we began focused on a wholesale redefinition of nature and the categories of human knowing. The result was a deep and enduring shift that led some historians to make the first appearances of Science synonymous with Modern and Western. These historians found it difficult to talk meaningfully about their world without 'Science' -- the defining characteristics of Modern and Western, they seemed to suggest, were inconceivable without 'Science'. Further, they saw Science as the defining element of the early modern period, more important than the wars or forgotten treaties.
Why has the Scientific Revolution persisted as a periodization? In the end, there are several reasons. Not least is the simple utility of the phrase. However unfortunate and potentially misleading, it continues to serve as a convenient division for textbooks and curricula. Second, some historians believe there is fair evidence that something very dramatic unfolded during this complex and disputed period, call it the New Science or the New Philosophy (they argue) the name hardly impinges on the thing that happened. Third, and perhaps not least, the periodization called the 'Scientific Revolution' has been useful in drawing together very disparate disciplines. New historical, philosophical, psychological, and sociological problems have emerged from the same basic set of beliefs, fruitful questions have been defined, extended, articulated, and often enough, accommodated. Overall, the 'Scientific Revolution' have been a resilient -- albeit problematic -- periodization.
For further information about the history of this periodization, consult sections at this WebSite, note especially: The sections on 'Scientific Revolution Historians' and 'Scientific Revolution - Major Interpretive Theses' -- most notably: The 'Koyré Thesis' - 'Merton Thesis' - 'Hessen Thesis' - 'Yates Thesis' - and 'Zilsel Thesis'.
The Scientific Revolution - Table of Contents
. Nicolas Copernicus (1473-1543)
A. Astronomical Background.
1. Ptolemaic astronomy, within the general framework of Aristotelian physics, dominated contemporary astronomical thought--a mathematical, nonobservational approach concerned with 'saving the phenomena'.
2. Basic premises of ancient astronomy:
a. Geostatic and geocentric cosmos.
b. Celestial bodies possess uniform, circular motion around a central point.
c. Celestial bodies are composed of a fifth element, the quintessence.
d. The cosmos is finite.
3. Difficulty developed concerning the Ptolemaic use of the equant, which violated the aesthetic concept of uniform motion, and the use of epicycles, which put the center of motion on a geometric point other than a center of a deferent.
4. Primary weakness of the existing Ptolemaic schema: it did not entirely "save the phenomena," that is, observational-theoretical discrepancies had become apparent.
B. The Copernican System.
1. Introduced three celestial motions.
a. Diurnal rotation of the earth on its axis.
b. The earth, and the planets, revolve around the sun.
c. A conical axial motion of earth to explain the fixed orientation of earth in space.
2. Copernicus was a mathematical, not an observational, astronomer, and the mathematical apparatus of his system was as complex as Ptolemy's, employing the same geometrical devices (except the equant).
3. Copernicus sought to purify ancient astronomy, not to overthrow Ptolemy; not a 'revolution' in the technical sense, in that either system would 'save the phenomena' to some degree; the Copernican system only altered the geostatic and geocentric premise of ancient astronomy.
4. Copernican advantages were limited to a somewhat simpler computational technique and the introduction of a more intelligible order in the heavens, for example, removal of the ad hoc constructions needed to describe retrograde motion and the ordering of planets.
5. The main disadvantage of the Copernican system was its violation of Aristotelian physics--the physical problems involved with the heliocentric system called for a new, as yet nonexistent, physics.
C. Motivation for the Copernican System.
1. Copernicus was educated at Cracow and Bologna in a critical atmosphere that called for the reform of Ptolemaic astronomy and cosmology.
2. Renaissance Platonic-Pythagorean influences stressed unity, coherence, and harmony in the cosmos in addition to accounting for observed phenomena.
D. The Copernican 'Revolution'
1. A 'revolution' inadvertently, in that Copernicus was a conservative who sought to purify, not destroy, ancient astronomy.
2. Its revolutionary aspect lay in its violation of Aristotelian physics and the implicit requirement of a 'new' physics which caused natural philosophers to think, and look, in a new astronomical frame of reference.
II. Johannes Kepler (1571-1630)
A. Background of Keplerian Astronomy.
1. Platonic and Pythagorean elements, especially a mystical sense of mathematical harmony in the cosmos, for example, the use of the five regular polyhedra to account for the planetary orbits, The Cosmographic Mystery (1596).
2. The heliocentric Copernican cosmos with uniform circular motion.
3. The mechanical ideas of the Renaissance, particularly "clockwork" as a suggestive conceptual model for celestial physics.
4. Existence of 'powers' such as magnetism and light which could be used to account for the physical force necessary to drive the celestial machine.
5. Kepler was a highly competent mathematician.
B. Kepler and the Tychonic System.
1. Brahe provided Kepler with the best collection of observational (empirical) data in existence.
2. He set Kepler to work on the problem of the orbit of Mars, that is, the planet's nonuniform motion with respect to the center of its orbit:
a. Disregarded the use of equants and epicycles as a solution.
b. Formulated the Area Law: in equal time intervals a planet will sweep out equal areas (Second Law).
c. Kepler settled on the ellipse as an orbital path, that is, planetary orbits are elliptical (First Law).
C. Synopsis of Keplerian Astronomy.
1. A nonempirical, mathematical commitment to the area law and the geometrical cosmos of elliptical orbits--the data were observational but the commitment was philosophical.
2. Introduced a type of 'physical' unity, that is, a solar 'power' or 'virtue' moves the planets in their orbits.
3. The account of elliptical orbits was based on the assumption that the sun and the planets were magnets, an action between "animate souls" which served to attract, or be attracted by, the sun thus drawing the planets into elliptical paths.
4. No quantitative elements have been introduced--a qualitative analysis expressed in terms of mathematical harmonies, for example, the square of a planetary period is proportional to the planet's mean distance from the sun, T [squared] is proportional R [cubed] (Kepler's Third Law ).
5. Kepler thought he had penetrated the structural reality of the cosmos and in so doing, was forced to seek a 'new' celestial physics.
III. Galileo Galilei (1564-1642)
A. Intellectual Roots of Galileo's Science.
1. Copernican astronomy and the implicit necessity of a 'new' physics to replace Aristotelian mechanics.
2. A long tradition in mechanics extending from the ancient world and middle ages through the Renaissance (for example, Aristotle, Philoponus, Avempace, the Merton and Parisian schools, Padua), and especially the works of Archimedes.
B. Galileo and Astronomy.
1. Galileo was a confirmed Copernican and given to the concept of circular motion.
2. Galileo wrote for a literate but nontechnical reader in his defense of Copernicus, and not as a professional astronomer--his arguments and evidence were polemical and perhaps propagandistic.
3. Galileo's 'facts' differed from the traditional data of astronomy in that they were derived from qualitative telescopic observations.
4. Observational data obtained with the telescope:
a. Stellar 'population explosion' implying an expanded cosmos.
b. The topography of the moon was similar to, or more pronounced than, that of the earth; the earth-like moon moves around the earth--why can't the earth move around the sun?
c. The phases of Venus were inexplicable in terms of Ptolemaic cosmology; Ptolemaic scheme no longer viable.
d. The satellites of Jupiter, moving with, and approximately in the same plane as the planet, suggested more than one center of rotation in the solar system and, by analogy, the earth's rotation around the sun.
e. Sun spots implied that the heavens are not perfect (to reinforce the argument of the moon's topography); these data were obviously unknown to Aristotle or Ptolemy.
C. The Problem of Falling Bodies.
1. His early work in the 1 590s dealt with falling bodies as a problem in dynamics approached in terms of the self-expending impetus theory of Oresme and Avempace, V is proportional to W-R.
2. Inspired by Archimedes and Benedetti, Galileo used hydrostatics as a model for his science.
3. In his later work, Galileo abandoned the dynamical approach in favor of kinematics.
4. He proceeded to clarify, restate, and systematize medieval problems in kinematics while giving them a more complete mathematical expression, for example, problems suggested by the Odd Numbers Law relating distance to time (S proportional to t squared) and velocity to distance (V proportional to S), out of which he came to relate velocity to time (V proportional to T), and eventually, S = 1/2at [squared].
5. After 1609, Galileo's kinematic treatment of an idealized model identified falling bodies as a case of uniformly accelerated motion and thereafter demonstrated it with his inclined plane experiment.
D. Projectile Motion.
1. Galileo's work developed out of the impetus theories of contemporary physics, especially those of Tartaglia and Benedetti.
2. In his later theory (1632), no force is necessary to keep a body moving on a level (frictionless) plane; a body, as such, has no inclination to move or remain at rest, it is indifferent.
3. Thus, if a body is indifferent to motion, no mover is required to sustain movement once a body is in motion.
4. Motion is now a state rather than a process, and rest is motion of zero speed in a continuum.
5. Galileo's conception of inertia as circular motion was an attempt to save Copernican circularity, particularly in the absence of any known force which could 'bend' rectilinear motion into an orbit.
E. Galileo's Method.
1. Galileo argued that theoretical conclusions required experimental verification even if the experimentation was mental rather than empirical.
2. He was a thinker about nature and thought in terms of ideal situations rather than the complexities of the sensate world.
3. Expressed confidence in deductive, reasoned conclusions: Archimedean mathematics applied to physical problems rather than extensive experimental programs.
IV. René Descartes (1596-1650) and the Mechanical Philosophy
A. Background of the Mechanical Philosophy.
1. Derived from ancient atomism but reworked by 17th century thinkers such as Descartes, Gassendi, Huygens, Hooke, and Boyle.
2. Reaction against the animistic philosophies of the Renaissance, notably Hermetism.
3. Conceived as an alternative to existing Aristotelian metaphysics.
B. Basic Tenets of the Mechanical Philosophy.
1. Viewed nature as composed of inert (without quality) matter in motion.
2. All causality involved matter in contact with matter--no action at-a-distance.
C. Cartesian Mechanical Philosophy.
1. Descartes, reacting against Renaissance skepticism, sought to affirm the existence of certain knowledge.
2. The conclusions of mathematics, especially those of geometry, are demonstrable, that is, start with true premises (clear and distinct ideas) and proceed deductively to certain conclusions.
3. Mathematics accepted as a model, though not the essence, of knowledge.
4. Descartes' methodical doubt reduces existing substances to two types:
a. Res cogitans (thinking stuff): immaterial thought or mind.
b. Res extensa (extended stuff): geometrical extension or matter.
5. All that exists outside the mind is matter: only primary qualities exist, that is, motion, size, shape, number, location, place; secondary qualities are illusory (soft, hard, hot, cold, wet, dry, etc.).
6. The universe is a plenum, that is, it is 'full' with no void possible.
7. Matter is of three types, classified as to size: First matter, fine (chips); second matter, medium (spheres); and third matter, gross (chunks), that is, respectively, material light, aether, and ordinary, visible matter.
8. The interaction between the various forms of matter occur as the result of vortex action; the universe is composed of vortices or whirlpools of matter. Vortices explain the varying periods and uniform orbital directions and inclinations of the planets.
9. Formulated the concepts of rectilinear inertia and the conservation of motion.
V. Francis Bacon (1561-1626) and the Baconian Method
A. Opposition to Scholastic and Renaissance Philosophy: The Idols.
1. The Tribe: weaknesses of human nature, that is, prejudice, passions, limited mental and sensory faculties.
2. The Cave: weaknesses of environment, that is, education, habit, prejudice, predisposition of approach to philosophical-scientific questions.
3. The Market Place: semantic difficulties arising from confusing words with things.
4. The Theatre: philosophical systems or theories which direct the mind beyond the data of experience to unsupported generalities.
B. Basic Assumption: The Simplicity of Nature.
1. Scientific progress is a matter of finding the correct method, that is, the correct method is equivalent to truth:
a. If nature is approached in the appropriate manner, the truth can be found.
b. Error is the result of defective methods.
2. The ultimate goal of science is practical utility for the benefit of mankind.
3. The method is the 'tool' of the intellect: it enables the mind to overcome its weaknesses, and can compensate for disparity of mental ability.
4. The function of method is to collect data from the natural world and refashion it (the bee)--it is not just empirical cataloguing (the ant) and it is not a matter of pure speculation (the spider).
C. The Baconian Method.
1. The basic premise: observe nature with the senses--proceed inductively from observations (data) to generalities (axioms), and form deductive conclusions which can be tested by experimental evidence.
2. The method of exclusion:
a. Tabulate all possible causes of an observed effect.
b. Observe nature to see what causes actually exist in the given physical circumstances.
c. Exclude all but one, that is, the result of the crucial experiment.
VI. Isaac Newton (1642-1727) and the Newtonian Synthesis
A. Elements of the Synthetic, "New" Physics.
1. Galileo's idealized formulation of the law of freely falling bodies, d = 1 /2at [squared].
2. Galileo's analysis of terrestrial inertia: a body is indifferent to uniform rectilinear motion and is as 'natural' as rest.
3. Descartes' conception of rectilinear inertia existing in Euclidean space and the implied rejection of privileged spatial position.
4. Kepler's 'discovery' of his three laws of celestial motion, especially the The Third Law, T squared is proportional to the mean Radius cubed.
5. Huygens' and Borelli's work on centrifugal forces, terrestrial and celestial respectively, suggested an inverse square relationship, as well as the analogy from light made explicit by Boulliau.
B. The Problem and the Test Case: Lunar Motion.
1. Lunar motion was essential to both Aristotle and Newton:
a. The lunar orbit was the demarcation line for the Aristotelian two-world system (sublunar/superlunar regions).
b. The connection of lunar-terrestrial motion under the same principle was the crux of the Newtonian argument.
2. Newtonian assumptions:
a. The Copernican hypothesis: the earth is a planet.
b. The hypothesis that inter-planetary space is empty, that is, free space.
3. The problem was to explain the configuration of planetary orbits, that is, what mechanism or force can account for the orbital alteration of a planet's rectilinear path.
C. The Moon's Orbit and the Unification of Terrestrial-Celestial Physics.
1. Problem of translating the moon's rectilinear acceleration into the centripetal acceleration necessary to account for the lunar orbit--assume circular Copernican orbits.
2. Problem of demonstrating that lunar acceleration represents a ratio equivalent to that of free fall on the earth, implying the same gravitational force: the inverse square law.
3. Problem of justifying the mathematical treatment of the earth's total mass as concentrated in a single mass point at the earth's center; Newton's solution rested upon his invention of the calculus, his "fluxions", which could be used to consider the intricacies of the problem.
4. The final stage was to transfer the concept of force for a planetary orbit in relation to the sun, based on the moon-earth test case to a universal, reciprocal gravitational relationship which applied to all matter
D. Components of Newtonian Physics.
1. Matter: an infinite number of separate, hard, and unchangeable particles which are not identical.
2. Motion: the relational state which moves particles from place to place in an infinite void of free space without affecting them.
3. Space: the infinite homogeneous void in which the particles, and the bodies they form, move.
4. Attraction: the undefined unifying force which is not a constructive element but rather a "hyperphysical" power or mathematical statement describing how the universal components are connected.
E. The Destruction of the Aristotelian Cosmos.
1. Considerations of such concepts as perfection, harmony, teleology, formal and final causality, and value are removed from scientific discussion.
2. The world was no longer viewed as finite and hierarchically ordered: quantitative considerations replace qualitative ones.
3. The celestial and terrestrial worlds are no longer philosophically and scientifically distinct; astronomy and physics have been geometrically unified.
F. The Mathematical Generation of Homogeneous, Abstract Euclidean Space.
1. The common sense world of the pre-Galilean cosmos is replaced by an idealized mathematical universe.
2. Newtonian science attempted to synthesize mathematics and experiment: the integration of theory and experience under the 'direction' of the inverse square law.
3. The Newtonian pattern of empirical-deductive knowledge provided both physical and intellectual unity for the 18th-century universe. Alexander Pope suggested:
Nature and nature's laws
Lay hid in night,
And God said
'Let Newton be'
And all was light.
The Enlightenment is sometimes called 'Newton's Century.'
Of all the changes that swept over Europe in the seventeenth and eighteenth centuries, the most widely influential was an epistemological transformation that we call the "scientific revolution." In the popular mind, we associate this revolution with natural science and technological change, but the scientific revolution was, in reality, a series of changes in the structure of European thought itself: systematic doubt, empirical and sensory verification, the abstraction of human knowledge into separate sciences, and the view that the world functions like a machine. These changes greatly changed the human experience of every other aspect of life, from individual life to the life of the group. This modification in world view can also be charted in painting, sculpture and architecture; you can see that people of the seventeenth and eighteenth centuries are looking at the world very differently.
Making the Universe Visible
The scientific revolution did not happen all at once, nor did it begin at any set date. Realistically speaking, the scientific revolution that we associate with Galileo, Francis Bacon, and Isaac Newton, began much earlier. You can push the date back to the work of Nicolaus Copernicus at the beginning of the sixteenth century, or Leonardo da Vinci in the middle of the fifteenth. Even then, you haven't gone back far enough and you haven't included all the factors that contributed to the set of epistemological transformations that we call the scientific revolution.
Ancient Greece
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Aristotle
Plato
You're safer to find the origins of the scientific revolution in the European re-discovery of Aristotle in the twelfth and thirteenth centuries. Aristotle entered the European Middle Ages by means of the Islamic world, which had preserved both Aristotelean and Platonic philosophy after Europe had completely forgotten it. Originally, Aristotle based knowledge on a kind of empiricism: he would investigate a question by a) examining what everyone else had said about the matter, b) making several observations, and finally, c) deriving either general or probable principles on the matter from both a and b. This method of thinking, which is the theoretical origin of empirical thought, formed the rudiments of a new revolution in human thinking in the twelfth and thirteenth centuries. The earliest Aristoteleans were burned as heretics (in a medieval university, when they fired you, they really fired you&emdash;have you ever wondered where the expression might come from?). Eventually, Aristoteleanism was combined with church doctrine to form a hybrid type of inquiry: Scholasticism. Unlike Aristoteleanism, Scholasticism did not have a strong empirical bent, but some Aristotelean thinkers took to Aristotle's empiricism like a duck to water. In the thirteenth and fourteenth century, empirical science began to take off. People such as Roger Bacon conducted empirical investigations on natural phenomena, such as optics.
The rage of all the medieval scientists, however, was alchemy . Now alchemy is a greatly misunderstood phenomenon&emdash;we associate it with mad monks trying to turn lead into gold. In the Middle Ages, however, it referred to a variety of questions; some of them were mystical and religious, but most were questions we would consider to be standard chemistry problems. The medievals had inherited the science from Islam, for chemistry was never a separate discipline in Greek or Roman thought. In fact, the words "chemistry" and "alchemy" are both Arabic words, as are many of the terms that you use in a chemistry course, such as "alkali," "alembic," and "alkane." Alchemy, or chemistry, is one of the most important scientific revolutions in the Middle Ages, for the people who worked on alchemical questions by and large invented most of the empirical methods that would form the cornerstone of empirical science in the seventeenth century. The most important of these scientists was Roger Bacon. Besides inventing gunpowder, Bacon devised the trial and error method of finding knowledge while cataloging very carefully all the circumstances of these trials. This is the germ of experimental science. The word "experiment" comes from the word "experience." An experiment, then, is an experience , but it is a controlled experience. What an experiment concludes is the following: if the experience of a natural phenomenon is controlled in a certain way, that experience will be identical to any repeated experience that is controlled in precisely the same way. Experimental science, then, requires that all factors that have gone into the experience of the natural phenomenon be cataloged in some way. This, by and large, is what Bacon invented in a rudimentary form.
There was a scientific revolution of sorts in the high Middle Ages that in many ways rivalled the later scientific revolution in its sweeping changes, but all the cultural components were not in place. So the scientific revolution of the thirteenth and fourteenth centuries did not produce a way of thinking about the world that closely resembles our own (this is why some people think that there was little scientific "progress" in the Middle Ages). You see, even in the high Middle Ages, Europeans believed that the center of all truth and experience was in God and that an overweaning concern with material phenomenon was a serious neglect of one's soul and one's dependence on God. The medievals also deeply distrusted human perception. Not only was human perception variable and untrustworthy, the material world itself was deceptive. Rather than a vehicle for truth, the material world was put in place to actively distract humans from the real task--living the sort of life that would get you into heaven.
It's hard to pinpoint the shift in these attitudes. The introduction of humanism in the fourteenth century was in large part based on the idea that human intellect and creativity were trustworthy, and human experience was, to some extent, a reliable base on which to hang knowledge. But the humanist revolution didn't happen all at once; the dichotomy between "experience" and "authority" was a vexed question throughout the fourteenth and fifteenth centuries. What should you believe? What your experience shows you? Or what authorities, including the church and the bible, tell you to believe?
While it's hard to pinpoint the shift in European attitudes, the first, unambiguous statement of this shift in values comes in Leonardo da Vinci's treatise on painting:
Renaissance Readings
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The Painter
Here, right here, in the eye, here forms, here colors, right here the character of every part and every thing of the universe, are concentrated to a single point. How marvelous that point is! . . . In this small space, the universe can be completely reproduced and rearranged in its entire vastness!
The argument Leonardo is making is that the entire universe can be made visible to human sight, and human vision can encompass the universe in the same way that God can encompass the universe. When Leonardo says that all the forms and colors of the universe are concentrated in the human eye as to a single point, he is reversing the medieval definition of God, which postulated that God was the single point in which all parts of the universe are gathered, as in Dante Alighieri's vision of God at the end of his poem, Paradise :
Within his depths I saw internalized, ingathered with love into his volume, all the scattered leaves of the universe: substances, accidents, and their characteristics, as if they were all combined, so that what I saw was a single point.
This new perspective expressed by Leonardo was a profound shift in the European world view. In a fundamental way, it postulated that human experience was and should be the central concern of human beings. It also postulated that human sensory experience, especially vision, was not only a valid way of understanding the universe, it also made it possible for humans to understand anything whatsoever about the universe. Making the universe visible, then, became a shared project among a number of Europeans; extending human vision with microscopes and telescopes seemed like a good idea. Europeans had the scientific knowledge to produce microscopes and telescopes since the time of Bacon; no one really thought to make them until making all parts of the universe visible became a viable and valuable project.
Making the Universe Move
It's hard for us to really understand, but the universe for most of human experience has been a small and very intimate place. We live in such a vast universe, both temporally and spatially, that the controversies surrounding the motions of the universe in the sixteenth and seventeenth century seem ludicrous. However, the universe for Europeans in the sixteenth century was very small. In its largest version, it could fit within the orbit of Pluto. When a Mesopotamian astrologer climbed his ziggurat, or a Renaissance astronomer climbed his tower, they weren't just getting a better view of the stars, they were literally getting closer.
A small universe made a great deal of sense. Everyone could see that the universe moved; this perhaps is one of the oldest pieces of human knowledge. Not only did it move, it moved in a circular fashion. So human beings got very good at describing this circular motion; in particular, if the universe moves in a circular fashion, it must be moving around a center point. When they thought about the size of the universe, it was obvious to them that if the universe were too big, then the parts of the universe at the outer edge would be travelling at speeds of billions of miles per hour. Nothing could survive speeds like this. So the universe was a small place; the outer edge was fairly close; in fact, both the Egyptians and the Mesopotamians lived in a universe that would fit within the orbit of the moon.
When it came time to define the central point of this circular motion, the answer was completely obvious. The stars moved in a circular motion around the earth. Look up in the sky and this becomes immediately evident. However, there were some astronomers in Greece who argued that the earth was not the center of the universe, but rather the sun. This was an elegant solution, for it explained all the quirky movements of the planets. While the stars moved in beautiful circles around the earth, the planets also moved in circles but sometimes they would move backwards; this is called precession. Even though placing the sun at the center of the universe solved the precession problem, it created a new one. This meant that the earth was moving in a circular orbit. It also meant that the earth was moving pretty darn fast. If the earth were moving at thousands of miles per hour then if you jumped straight up in the air, when you landed, you'd hit the ground ten or twelve miles away from the spot you started at. Everyone could see, however, that when you jumped straight up in the air, you landed on the spot you started from. (Until Isaac Newton, Europeans, Muslims, and Asians understood only one-half of the concept of inertia: things at rest stay at rest. They did not figure out that things in motion stay in motion).
The Ptolemaic Universe: The scientific revolution really begins in Europe when Nicolaus Copernicus challenges the dominant model of the motion of the universe: Ptolemy's Almagest . Ptolemy wrestled with the problem of the motion of the universe and all the problems associated with regression. Since common sense dictated that the earth can't be moving (see the "jump" experiment in the previous paragraph), then the motions of the planets had to be described in such a way as to explain why they regularly go backwards. The universe, however, had to still remain logical, for precession was logical. One could fairly accurately predict when a planet would start moving backwards in the sky.
Ptolemy solved the problem in two ways. First, he made the elliptical orbits eccentric, that is, while the planets still orbited around the sun, the center of the circle of their orbit was not the earth, but a point somewhere else. Each planetary orbit, then, had a different center of rotation. But this still didn't explain every instance of precession. So Ptolemy took the planets out of their orbital path and set them spinning around a moving point on the orbital path., like a tether-ball spinning around a moving pole. These extraorbital orbits Ptolemy called epicycles. The universe became a grand, nonsensical Rube Goldberg machine, with planets orbiting around points that orbited around the earth in uneven and unbalanced elliptical orbits. Even Ptolemy hated it. The great virtue of his scheme was that it fully accounted for all planetary precession; the downside is that it turned the universe into a messy room. So Ptolemey actually argued that the universe did not, in fact, move this way; he only argued that his system was a "mathematical fiction" that should be used only to predict the motions of the universe.
Somewhere along the line, though, the astrologers and astronomers of the Islamic world decided that the Ptolemaic universe was, in fact, an accurate physical description of the motion of the universe. When Arabic science entered the European world in the twelfth and thirteenth centuries, so did the Ptolemaic world view. This view would go largely unchallenged for hundreds of years while the universe squeaked and wobbled in its eccentrics and epicycles.
Nicolaus Copernicus: Copernicus (1473-1543) was the first major astronomer to challenge the Ptolemaic universe. Let's keep in mind, though, that Ptolemy had his critics&emdash;starting with Ptolemy himself. The Ptolemaic universe was, after all, a nonsensical affair; when King Alfonso of Spain was introduced to the system in the thirteenth century, he said, "If God had made the universe thus, he should have asked me for advice first." The result of this criticism was not one, but hundreds of versions of the Ptolemaic universe. Copernicus, in the year of his death, published On the Revolutions of the Heavenly Spheres . This book did not revise Ptolemy's system, as all previous criticisms had, but rather challenged the fundamental assumption of the Ptolemaic universe: that the earth was the center point of the revolution of the heavens. In many ways, Copernicus attempted to solve the problem of precession by coming up with the simplest possible explanation. By simply moving the sun to the center of the universe, almost all the problems with planetary precession disappeared (almost all). Copernicus was also a mystical philosopher; he believed that the sun not only symbolized but also contained God; putting the sun at the center of the universe was more than a mathematical solution, it also better explained the spiritual structure of the universe.
The Copernican universe, however, was still nothing like our own. It was still a small and intimate place; moving the orbits of the stars out too far meant that they'd travel at impossible speeds. Copernicus also kept the Ptolemaic epicycles and argued that the planets moved in circular orbits. His system, though, was a far more accurate predictor of planetary motion than any that had been previously put forth. That, argued Copernicus, was more than enough to justify its adoption.
Arabic numerals: We need, however, to step back and briefly discuss one other innovation of the middle ages: the adoption of Arabic numerals. For Arabic numerals made the Copernican revolution possible in a way that can't be overstressed. Before the adoption of Arabic science in the twelfth and thirteenth centuries, Europeans used the Roman numeral system. This is a subtractive number system: numbers are indicated by letters and the transition to higher letters is first preceded by subtraction:
I II III IV V
While people were fairly proficient at working with these numerals, calculation was not exactly a blazing fast process. Try multiplying MDMCXLVII by CCCLXXIII without converting them to Arabic numerals and see how fast you can do it.
The Arabs, on the other hand, used a place number system, which is the number system that you've been trained on. It consisted of ten numerals; when all ten numerals were used up, then another place was added and numbers would then consist of two sets, or places, of numerals. The immense advantage of a place system (only the Mayans and the Hindus also developed place systems) is that you can do calculations extremely rapidly. When this system was introduced into Europe, learned people began to calculate like mad. Books upon books piled up filled with calculations from the hands of busy monks and busy students and busy university teachers adding and subtracting and multiplying and dividing.
Books of astronomical calculations especially began to pile up: this was the beginning of mathematical astronomy. As astronomical observations and calculations piled up, the problems with the Ptolemaic universe also piled up. More than anything else, it was this pile of mathematical calculations that pushed Copernicus to radically revise the Ptolemaic universe.
Tycho Brahe: The man who most greatly influenced the adoption of the Ptolemaic system was Tycho Brahe (1546-1601), who was one of those fanatics doing all those mathematical calculations of the motion of the universe. Tables and tables and tables of calculations. For a man with a boring profession, however, he led a singularly interesting life: temperamental, he had lost his nose to syphilis, or, rather, to the cure for syphilis; he was a raucous heavy drinker and he died a particularly just death for a heavy drinker. At a dinner with a prince, he drank a bit too much, and, since you were not allowed to leave the table until the person outranking you left the table, he waited out his full bladder until it burst and sent him to the heavens he had so lovingly observed and calculated.
Brahe opposed the Copernican universe and vehemently argued that the earth was the center of the universe. In order to prove this, however, he cataloged a superhuman number of astronomical observations and calculations. These tables of calculations made up the best astronomical observations in any culture at any time up to that point and would become the basis for proving the Copernican system to be a more accurate model of the universe.
Johannes Kepler: Like Copernicus, Kepler (1571-1630) believed that the sun represented the spiritual essence and presence of God and should be placed at the center of the universe. He discovered Brahe's observations and calculations and set about using them to develop a new, sun-centered universe. He rejected two major aspects of the Copernican universe: epicycles and circular orbits. In the Keplerian universe, the planets orbited around the sun and remained in their orbital paths; these paths, however, were elliptical rather than circular. This was the big prize: by revising Copernicus's model through the use of Brahe's calculations, he produced a mathematical model of the universe that perfectly predicted planetary motions and accounted for every instance of planetary precession. This model he published in the book New Astronomy in 1609, and it instantly created a sensation. It would also inspire an Italian astronomer, Galileo Galilei, to fit his new observations into this Keplerian universe.
Even though the model was perfect in terms of its predictive power, it still had a number of problems. It still didn't explain why the earth didn't move out from under us when we jumped in the air. Also: why would the planets move elliptically? Circular orbits made sense, but elliptical orbits? Both of these questions would be answered by Newtonian physics a few decades later.
Galileo Galilei: Galileo (1564-1642) combined the two roles of observer and theorist and, more than anyone else, provided the empirical discoveries that cinched the Copernican-Keplerian universe. First, in 1609, he eagerly read Kepler's New Astronomy and bought into it completely. That same year he bought a curious new Dutch invention, the telescope. While the telescope had been around for a few years, he was the first to use it to systematically look at the heavens. What he saw amazed even him.
The first thing he saw was mountains on the moon. Until this time, the moon was regarded as more or less gaseous; the presence of mountains meant that the moon was terrestrial, just like earth. If it had mountains, it could also have plants and people. The second thing he saw were planets orbiting around the planet of Jupiter. Five, to be exact. This was the big banana. For if the planet of Jupiter was an independent orbital system orbiting around a larger system, that meant that the sun could also be an independent orbital system orbiting around a larger system. The universe, which until Galileo's time was a small and homey place, suddenly expanded infinitely outwards and became a vast and incomprehensible place.
Galileo announced his findings in The Starry Messenger , which he published in 1610, one year after the publication of Kepler's New Astronomy . The Starry Messenger was really only a pamphlet, and Galileo would not write a full exposition of his observations and his model for a much larger universe until his Dialogues on the Two Chief Systems of the World . It was this book that inspired the Roman Catholic church to closely examine his observations and models and compare them to church doctrine and the texts of the Old and New Testament. The Church concluded that his ideas were at variance with both doctrine and Scriptures and demanded, on pain of death, that he recant his views.
The one part of Galileo's system that most greatly influenced all subsequent European inquiry into the nature of the universe was his insistence that the universe operated according to mathematical principles. The circle, you might say, had been completed. The Ptolemaic universe was a mathematical model designed to assist predictions but was not designed to be a physical description of the universe. Both the Copernican and Keplerian systems were primarily proposed as mathematical rather than physical models. Galileo insisted that the two were coterminous, that all physical description of the universe would of necessity be a mathematical description. His revolutionary argument was this: if a physical model did not fit the mathematical properties of that phenomenon, the physical model was wrong. This would become the basis of a profound shift in European knowledge: classical mechanics.
Making the Universe Move Mechanically
Francis Bacon: The grounds for a mechanical universe, that is, a universe that operated like a machine, was laid down by Galileo's insistence that the universe operated by predictable mathematical laws and models. In addition, Francis Bacon (1561-1626), added a key element to the genesis of the mechanical universe in his attacks on traditional knowledge. Bacon wasn't a scientist in our sense of the word, but he did take great joy in telling everybody why they were wrong. In particular, he argued that all the old systems of understanding should be abandoned: he called them idols. He believed that knowledge shouldn't be derived from books, but from experience itself. Europeans should move beyond their classics and observe all natural and human phenomena afresh. He proposed the Aristotelean model of induction and empiricism as the best model of human knowledge; in inductive thinking, one begins by observing the variety of phenomena and derives general principles to explain those observations. (In deductive thinking, one starts with general principles and uses these principles to account for the variety of phenomena). This model of systematic empirical induction was the piece that completed the puzzle in the European world view and made the scientific revolution possible.
Isaac Newton
Isaac Newton: The mechanical universe in all its glory would emerge from the work of Isaac Newton (1642-1727) in his compendious The Mathematical Principles of Natural Philosophy (1687), which is primarily known by the first two words of its Latin title: Principia Mathematica . The fundamental arguments of the book were the following:
The universe could be explained completely through the use of mathematics; mathematical models of the universe were accurate physical descriptions of the universe.
The universe operated in a completely rational and predictable way following the mathematics used to describe the universe; the universe, then, was mechanistic.
One need not appeal to revealed religion or theology to explain any aspect of the physical phenomena of the universe.
All the planets and other objects in the universe moved according to a physical attraction between them, which is called gravity; this mutual attraction explained the orderly and mechanistic motions of the universe.
Ancient Greece
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Aristotle
The Atomists
Newton's mechanistic view of the universe is an idea that derives from Greek atomism, but Newton's mechanistic universe would become the dominant model in European thought for the next several centuries ( and still is). According to Newton, the universe was like a massive clock built by a creating god and set into motion. Actually, even though Newton was a devout Christian, this argument has a philosophical basis. For Newton based his entire view of the universe on the concept of inertia: every object remains at rest until moved by another object; every object in motion stays in motion until redirected or stopped by another object. (This latter principle explains why we can jump in the air without the earth moving out from under us). According to the concept of inertia, no object has the ability to move or stop itself. The universe, then, becomes a vast billiard ball table, in which everything moves because something else has just knocked into it or caused it to move.
But this leads to a serious philosophical problem: who moved the first object? How did the universe get going if no object can move itself? The Greek atomists, who believed that the universe consisted of atoms (in Greek the word atoma means "indivisibles") that create all phenomena by colliding into and combining with each other, explained this with the concept of "swerve": somewhere at the beginning of time, one atom swerved all by itself and knocked into another and hence the universe came into being. Aristotle, on the other hand, who also based his thought more or less on a mechanistic view of the universe, solved the problem by positing an "Unmoved Mover": somewhere at the beginning of time, an "Unmoved Mover" (which he calls God), was able to set things in motion without having to be moved itself. This idea was appropriated in the Middle Ages by the Scholastics, who, like Aristotle, believed the universe functioned in a rational and mechanistic way and was set in motion and ruled over by a rational and unmoving mover, God. Newton adopts this idea whole-cloth: although the universe is a vast machine of objects moving and colliding into each other and functioning by its own laws, it still requires some original thing that set it all in motion in the first place. That thing, for Newton, was God.
But God did not interfere with the day to day workings of the universe (although Newton never denied that God couldn't, just that God didn't become involved). If the universe was a vast machine of interacting objects, that meant that it could be understood as a machine. Human reason and the simple observation of phenomena were sufficient to explain the universe; one need not drag religion or God into the explanation. If physical phenomena were mechanistic, that means that physical phenomena can be manipulated , that is, engineered. This mechanistic view of the universe, called classical mechanics, focuses entirely on the concept of motion, that is, at the base of Newton's thought is an attempt to explain why the universe moves. This is what physics is all about: why things change.
Enlightenment Glossary
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Deism
Newton's mechanistic view of the universe would soon be applied to other phenomena as well. If the universe was a machine and could be understood rationally, then so perhaps could economics, history, politics, and ethics (human character). It also followed that if economics, history, politics, and ethics were mechanical, they could be explained without recourse to religion or God and they could be manipulated as if they were machines, that is, they could be improved, engineered, and made to run better. As the Enlightenment developed, classical mechanics would give rise to a larger phenomenon, Deism, which is founded on the idea that all phenomena are fundamentally rational and mechanistic and can be explained in non-religious terms. All of modern Western knowledge and the majority of your experience is ultimately derived from this principle. Newton's separation of the mechanical universe from religious explanation and the Enlightenment concept of deism went further than this, however. If the universe was created by God and the universe was a rational place, that meant that God was rational. If one understood the workings of the universe, one understood the workings of the mind of God. So the separation of physical explanation from religious explanation was not as tightly enforced as it seems at first glance. The great innovation of this view for Western religion would be the Enlightenment insistence that religion itself be rational.
Western Science Moves
All the pieces were now in place, fused there by Newton's elaborate concept of a mechanical universe. Eighteenth century science saw an explosion of empirical knowledge about the physical world. A virtual flood of empirical observations and calculations inspired not only an increase in knowledge, but a massive effort to systematize that knowledge as Newton had done. The scientific revolution of the eighteenth century is, above everything else, characterized by fanatical conversion of knowledge into rational systems.
Biology: The greatest strides in systematizing an unsystematic science occurred in biology. While Galileo trained his new optical device on the stars and discovered new worlds, another optical device was being used to discover equally dramatic worlds in drops of water: the microscope. The earliest scientists to use the microscope, Robert Hooke in England, and Jan Swammerdam and Antony van Leeuwenhoek (1632-1723), found that plant and animal tissues were made out of rooms or cells, but they also discovered frightening and nonsensical monsters in mud puddles: hydras, ameobas, and equally baffling creatures.
Systematizing this vast new catalogue of knowledge fell to a Swedish botanist, Karl von Linné (1707-1778), also known as Carolus Linnaeus. In his Systema Naturae , published in 1767, he cataloged all the living creatures into a single system that defined their morphological relations to one another: the Linnean classification system. Morphologically distinct living creatures he called "species," which means "individuals." Morphologically related species were called a "genus," which means "kind." And so on up a scale of more abstract morphological relationships: family, class, order, phylum, kingdom. Each individual species was marked by both its species and its genus name; this classification system, with some modifications, still dominates our understanding of the living world.
There was no such concept as evolution in Linneaus's time. The morphological relationships between living creatures, then, were purely descriptive; they did not explain why living creatures seemed to have these morphological relationships nor why these relationships could be abstracted to such high levels. It was George Buffon (1707-1788) who tried to explain these relationships, but he couldn't really commit himself to an evolutionary theory. What troubled Buffon was the close morphological relationships between humans and primates; this implied that the account of creation in Christianity wasn't valid. Buffon was only willing to admit that it was possible that all the range of living creatures ultimately derived from a single species which had changed over time in the variety of its descent.
Chemistry: Chemistry, you'll remember, was originally an Islamic import into European culture and served as the foundational science in the development of European empirical and experimental science. While chemical knowledge advanced in leaps and bounds from the thirteenth century onwards, nobody could really explain how chemical systems worked. There were a pile of theories, but none of them fully explained the range of chemical phenomena. A new system of understanding chemicals and elements was precipitated by the discovery of gases by Henry Cavendish and Joseph Priestley in the latter half of the eighteenth century. In 1766, Cavendish discovered hydrogen (but he didn't know what it was at the time) and found that it would not burn all by itself; however, when it was exposed to air, whooosh!, it burned like crazy. In 1774, Priestley discovered oxygen; if a candle were put in a tube filled with oxygen, it, too, burned like crazy. This was a great breakthrough. Up until this point, Europeans believed that fire was a separate element and the properties of combustion were derived from the properties of fire. Cavendish and Priestley had proven, however, that fire was caused by the mixture of things with a gas. Finally, Cavendish discovered that water, which was also considered to be an element, was, in fact, made up of two gases: hydrogen and oxygen. A new chemical model of the universe was forming: the world was made up of "compounds" of basic elements.
The picture was put together by Antoine Lavoisier, who proved that burning was caused by oxidation, that is, the mixing of a substance with oxygen. He also proved that diamonds were made of carbon and, more importantly, argued that all living processes were at their heart chemical reactions. Finally, and most importantly, he forumulated the "law of conservation of mass," which argued that the amount of physical substance never changes in a chemical reaction. The only thing that changes is the nature of chemical combinations.
Electricity: The most exciting of the new sciences, however, was electricity. In 1672, Otto von Guericke, was the first human to knowingly generate electricity using a machine, and in 1729, Stephen Gray demonstrated that electricity could be "transmitted" through metal filaments. The first electrical storage device was invented in 1745, the so-called "Leyden jar," and in 1749, Benjamin Franklin demonstrated that lightning was electricity by firing up a Leyden jar in a thunderstorm (this discovery led to the invention of the lightning rod). However, throughout the eighteenth century, electricity was the most abstract of the physical sciences. It was a toy, a bric-a-brac, in the scientific community because nobody could think of any real practical use for it.
Medicine: Enormous amounts of knowledge were added to medical practice throughout the seventeenth and eighteenth centuries: anatomy, microscopic anatomy, the circulation of blood, inoculation (which Europeans learned from the Ottoman Muslims) and vaccination, and so on. Most important, however, was a new system of understanding human biological processes: pathology. Enlightenment medicine proposed that the body was a natural system that functioned in predictable and rational ways--that is, it operated like a machine. No surprise there. Disease was a malfunction, disease was the breaking down of this machine: this was pathology. All disease processes, then, could be understood as natural phenomena and the recovery of health was also a natural and rational phenomenon.
Richard Hooker
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