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Natural Science
NATS 1760
Vera Pavri

NATS 1760: The Scientific Revolution, Part I I. Science in the Renaissance - Renaissance means “rebirth”; interest in newly recovered classical texts that have been lost, including Plato - During the “SR” there is a growing critique of Aristotelian ideas and more support for cosmos and platonic view a) Attitudes towards science and technology b) Relationship between science and technology These ideas are key in the process of change during the scientific revolution - Travel, adventure and navigation - Technical arts: Engineers were sponsored by royal elites; in turn engineers would engage in military, civil projects, toys for royal families - Rise in the status of engineering, which is connected to the relationship between engineers and European royal courts during this time, allowing engineer’s to obtain fame, power, status, and wealth. - Many texts recovered after fall of Constantinople to Turkish army in 1453; transferred to Italy and retranslated - Catholic church challenged with Protestant Reformation; increased role of patronage and royal courts - Change in values: knowledge for wealth, power and status over standard theological considerations and attaining salvation - Changing attitude towards natural philosophy, movement away from “obtaining knowledge for knowledge sake” - Science is seen as a discipline to get status, wealth, fame and fortune - Natural philosophers: justify search for knowledge on utilitarian (usefulness and practical value, power wealth status and fame) and not just theological reasoning - Aristotle as research program in 15 and 16 centuries: study of all subjects he touched upon (i.e. physics, astronomy, biology, medicine, ethics, politics, etc… - Changes in the relationship between science and technology and highlighted in the Hong article Sungook Hong - Growing connection between science (industrial philosophy) and technology Factors accounting for relationship b/w science and technology 1. Instruments in scientific practice: more experiments require more tools 2. Social spaces: “Coffee Houses, Salons, Pubs” these places consists of people like engineers and philosophers 3. Hybrid humans: People with an interest in science and technology; they represent the shift b/w science and technology Transition from Natural Philosophy to modern science (MID TERM) 1. Practical uses of knowledge: Movement away from “knowledge for knowledge sake” towards practical purpose 2. Mathematization of nature: Increased emphasis on mathematics as a way of understanding nature; the growing influence of Plato (his view that mathematics key to understanding universe) 3. Increase Experimentation: Rise in Experimentation; experiments will be seen as valuable in practice of science 4. Rise in Mechanical Philosophy: Increased popularity of “MP”, viewing nature and humans as machines, this will be evident when analyzing the work of Descartes * For a long time Greeks believed the world was an earth-centered universe with circular motion (uniform speed, no beginning or end) II. Ptolemy (c. 87-150 A.D.) 1 - For almost 14 centuries, his planetary model used by all astronomers - Work on astronomy collected in Almagest; had prolong impact in astronomy - Created quality solutions in “saving the phenomena” - Fit in well with Aristotelian cosmology and astronomical observations - Accurate observations are possible with his tables (Handy Tables) and directions - Model explains retrograde orbit (planets appear to speed up, slow down, move forwards, backwards) which had contradicted idea of perfect circular motion - This made making calculations for astrological, navigational purposes - Ptolemy’s model resolves many of these problems - Important to understand it was considered a mathematical device rather than a true picture of the universe - Since system works and fits with established philosophy and theology, starts to be considered as an actual structure of the universe 1. His system WORKED for centuries!!!! - Devices allow Ptolemy to account for problematic planetary motions and allows for predicting future motions - Not mathematically complex; based on geometry of circle - His system regarded as the most complete and accurate of explaining heavens and widely accepted III. Ptolemy’s “Fixes” - These were solutions to the “saving the phenomena” - 4 tools used to explain these solutions A. EPICYCLE: circle centered on point going around deferent B. DEFERENT: circle centered on earth C. ECCENTRIC: planets rotate about a point removed from the earth. By placing the earth off- centre, astronomers can account for planetary variations in speed and brightness and distance from earth - Useful tool for understanding why plants appear to speed up and slow down D. EQUANT: rate of rotation of a deferent becomes uniform not with respect to its own geometric center, but with respect to equant point displaced from center - Could account for uniform circular motion 2 IV. Nicholas Copernicus (c. 1473-1543 (REFER TO RECORDING FOR THIS SECTION) - Born in Torun, Royal Prussia (now Poland); cannon in Catholic church - Benefited from humanist movement and rediscovery of texts - In late 15 century no complete copies of Ptolemy’s Almagest available in his homeland; by mid th 16 century work is widely circulated because of printing press - Printing Press: Accessibility of different kinds of texts like Ptolemy, Islamic Scholars, etc. - Copernicus studies Ptolemy’s work and compares it to other medieval planetary charts; sees many astronomical discrepancies that can no longer be blamed on poor translations - Differences in prediction of planetary locations make it hard to obtain accurate information for calendar (for the church) and navigational purposes - Major criticism Copernicus had of Ptolemy’s idea that Ptolemy did not really adhere to notion of perfect circular motion by using equant and epicycles - Copernicus believer in perfect circular motion, has noted many planetary discrepancies and wants to create a more accurate calendar and so creates a solution (redraw the heaven’s) - He Redraws cosmos by placing sun at center with earth revolving around it; earth given daily motion, motion about its own axis - Earth’s orbit not sun, but an eccentric point from sun “mean sun” (Earth was revolving around the mean sun) Why did Copernicus come up with these ideas but never publish them? - His idea even then was something that was very controversial and radical theory and in his lifetime he was very reluctant to publish findings, fear with churches concern with sun centered rather then earth centered - Publication of De Revolutionibus Orbium Coelestium in 1543 on his deathbed - Andres Osiander (Copernicus’ apprentice): Adds preface to book stating it is only mathematical hypothesis ALTHOUGH Copernicus believed his system to be true; this had huge impact on people’s viewing of this work; work was a mathematical device and was not necessarily real, however Copernicus believed his work to be true and real - This is a misleading preface because it did not represent Copernicus’ views upon his work - Osiander did this to protect the status of Copernicus; churches perspectives 3 V. Advantages and Disadvantages of System - Copernicus’ work was highly mathematical and in large part was done so that his work could be used to better things, his desire to come up with this new found look of universe was for practical reasons. - Does account for two major problems plaguing astronomers: cold account for brightness of Mars and could account for why two planets, Mercury and Venus never appear more than 45 degrees away from Sun - Solves problem of retrograde motion in aesthetically pleasing manner in comparison to Ptolemy’s work - Mathematically complex system; while he does away with equant point, he still uses as many (if not more) epicycles and deferents to account for variable velocity of planets (although not used to explain retrograde motion) - This makes him look like he’s trying to account for PERFECT CIRCULAR MOTION - Cannot account for phases of Venus and Mercury which should be observed; stellar parallax: The idea of observing the stars (with Copernican system dimensions of earth should grow; we should be able to observe whether stars are near to us or farther; but we couldn’t have account for it) - Violates Aristotelian traditions: if earth just another planet, what does this say about status of human species? - Idea of sun centered universe clashes with some biblical passages - The notion of earth at it center; the notion that the earth had movement; two ideas of church that Copernicus’ system contradicted - Traditional arguments regarding motion of earth: If the earth moves why don’t we feel earth moving, why do objects appear to fall straight down; why don’t we fly off earth if there is movement; what do you mean objects have more than one kind of motion: This is a concern for natural philosophers influenced by Aristotle because their focus was things moving to its natural place/one kind of motion. - No real geometric differences between system: same types of observations and accounts for them VI. Who Read Copernicus’ Book? Who believed it and how significant? - Not a lot of people read the book; very mathematically complex and hard to understand; astronomers found his work tedious and boring - Between 1543-1600; only ten “Copernicans” who believed his work to be true - What does this tell us about initial revolutionary impact of ideas? : This shows that his work was not really revolutionary at all. - Other Philosophers and mathematicians study it for different reasons - Astronomers who used calculations to create better tables but did not consider the reality of system - Protestants: Luther, Calvin don’t initially pay much attention to findings - Catholics: varied responses; harden views with counter reformation - System only fully adopted with modifications of Kepler and Newton - NO ONE CARED ABOUT COPERNICUS’ WORK; over time after the work of Galileo it will be criticized - The full acceptance of Copernicus’ work will only occur with the rise of Isaac Newton. VII. Alternatives to the Copernican system - Tycho Brahe (1546-1601); Danish nobleman; filthy rich - Self taught astronomer and consider the best expert naked-eye observer; builds his own observatory as well as number of large astronomical instruments on his own island - His observations of planetary motion will be “second to none” - Example of precision: while astronomical error was on average fifteen minutes, Brahe’s observations were merely two minutes - Creates his own planetary system that blends both Ptolemic and Copernican ideas - The system states that the Sun and moon revolve around earth; but all other planets revolve around sun 4 - This model however did not really fix anything and only came up with the “best of both worlds” - Allows earth to continue at center of universe and also explains planetary irregularities like motion of Mercury and Venus and stellar parallax - Gives no explanation why planets move - Two major contributions: include sighting of comet in 1577 and sighting of new star in 1572 - Significance: think physical reality of celestial and terrestrial worlds; perfection and imperfection; changing and unchanging realms - According to Aristotle the celestial world was considered perfect and unchanging, but observing comets suggest that the heaven are not perfect and changing and represent a place of imperfection, the downfall of Aristotelian view - This represents a transition away from Aristotle ideas and the increase in platonic ideas (CRUCIAL FOR MIDTERM EXAM) VIII. Johannes Kepler (1571-1630) - Very unhappy childhood; because mother branded and tried as witch; spent a lot of time moving because persecuted - Studied astronomy, mathematics, astrology and theology - Fully embraces Copernican system; was a “COPERNICAN” - After finishing studies at University of Tubingen, become mathematics teacher and practices astrology - Asks questions about planetary spacing, questioned the regularity of planetary movement and number of planets - Answer comes to him in “revelation”: planetary orbits can be explained through three dimensional geometrical solids - Therefore he believed each planet (6) fits between each (5) geometrical solids: Mysterium Cosmograhicum (1596); in later works he suggests that sun’s “magnetic force” plays role in planetary motion - Becomes assistant to Tycho Brahe who soon dies after Kepler gets his job - Before death, asks Kepler to work on motion of Mars [Very Significant] - After eight years he was able to calculate to within 8 minutes of arc which would be considered by most at time as sufficient, but because he trusts Brahe’s observations so much, he does not quit to improve the 8 minutes - Significance: theory must adhere to facts and fact adhering to theory, as was tradition; THEREFORE CHANGED THEORY because facts were right! - Comes up with idea of elliptical orbit with sun as one focus; planetary motion happens in ellipses and not circular motion - Ironic, considering Copernicus such strong believer of circular motion - Eventually becomes Imperial Mathematician to Rudolph II in court of Holy Roman Emperor in 1601 - Contemporary of Galileo who used him when needed but more often than not ignored him - Extremely influential to newton down the road IX. Kepler’s Three Laws a. Planets move in elliptical orbits b. Planets sweep out equal areas in equal times c. Period law: the square of period “T” (the time to complete one orbit around sun) of two planets is proportional to square of distance “R” to sun - In 1627 publishes Rudolphine Tables - very accurate astronomical table since Ptolemy ; for the first time made Copernican system more accurate and more precise/accurate than Ptolemy’s - Final thought: Kepler represents prime example of individual whose work we tend to categorize as being valid or invalid depending on how it fits with our modern conceptions of science X. Galileo Galilei (1564-1642) • Attitude towards science and technology • Shows the growth in technology 5 - Professor of mathematics at Padua university (this profession was the last thing he wanted to be) , had wide range of interests and “burning ambition” - Relied heavily on court patronage of Medici family - Skilled rhetorician; done in pursuit of ambitious roles; wanted to influence public opinion - Gains knowledge for himself and extends this to others also; he published in the common language of Italy (vernacular), extending his work to a greater audience - Contemporary of Kepler and advocate of Copernican system; Galileo was one of those who continued to believe in perfect circular motion - Still thought planetary motion was circular - Interest in experiment, observation, measurement and design; use Experiments to disprove someone like Aristotle - Focus on theories of motion and force, telescope, conflict with the Church - Understand cosmos through mathematical perspective XI. Galileo on Aristotle - Considered first true experimenters; - Contrary to popular belief, did not throw objects from Leaning Tower of Pisa; lots of theoretical experiments - Criticized Aristotelian ideas of motion Recall that Aristotle beliefs: a. Bodies of different weights move in one and the same medium with different speeds which stand in the same ratio as their weights (In other words body 10x as heavy as another will move 10x as rapidly) b. The speed of a body moving in two different media (i.e. air and water) are an inverse ratio according to the density of these media (i.e. if water is 10x more dense than air, the speed of a body in air would be 10x greater than it would in water) Criticism of Aristotle - Galileo questions whether Aristotle has done experiments to prove these points; for example, if two stones are dropped and one is 10x heavier than another, when it falls to the ground the other
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