Lecture 2 Scientific Knowledge: Announcements What does it mean? • Homework 1 Example: Description of Motion Due Monday, September 8 : What is knowledge? e • Today: r u t What is Science? What do we know? c i w p e g i i v • World views b How can you tell if a theory is “scientific”? d e r l h o T w • Purpose of creation of knowledge r u o ? ” s n • Role of physics (and mathematics) o i ? n t e v n o • Aristotelian view vs. Galilean view c “ y l e r e m • Example in Physics: Description of motion e c n e i c Is the knowledge guaranteed s s I • position, velocity, acceleration by the method? • Example of motion: Falling Bodies • Demonstrations • Which view is better? How do new scientific concepts arise? Case Study of Motion. Central Concepts for Today The Big Picture: World Views • World View: • How we make sense of the world • How do we make sense of the world? • Epistemology: • It is important to look at ancient times • What do we know? • What were world views? • How do we know what we know is true? • We will not spend much time on them, but it is • What questions do we ask? important to see that they made sense • Methodology: • Help us understand our own times • How do we learn? • In the last 1000 years there have been a complete revolution • How do we answer questions? in our world views - article by Powers • Science: In the last 100 years there have been complete revolutions in • • What distinguishes scientific knowledge? physics • How does science evolve? How has science evolved? • Major adjustments in our views of what • Motion: constitutes the basic laws of nature • Space, Time • Laws that describe Nature often do not jive with our intuitive everyday experiences Why is this the “Big Picture”? The Role of Physics in the Big Picture A brief taste Physics is the study of the basic phenomena • “ ‘It struck me that the more we learn about the changes in human life after the 16 th century’ – of of the natural world when most scholars mark the onset of the modern world – ‘the clearer it becomes that [the • Of all the sciences: change] was unprecedented and radical’ ” • It is the one most amenable to formulation of simple, • “People began to value institutions such as direct questions private property, to question religion’s public • that can be answered by careful study of nature role, and to adapt a Newtonian, scientific world • For example, only very recently has view” biology begun to reach such a point • Viewed as regression by some - a spiritual loss (Nietsche) – unleashing of unstainable • Example in Physics capitalism (Marx) … • Description of motion of bodies in space and time • Unquestionably an enormous effect on our lives Robert Pipin, The University of Chicago Magazine, August, 2003 1
Lecture 2 Timeline The ancient world Middle “Modern” Asia, Egypt • Mesopotamia (now Iraq) Greece, Rome Ages Renaissance Physics Mesopotamia • “Fertile crescent” Al-Khawarizmi Copernicus • Birthplace of civilization • Settled agriculture 0 -1000 1000 2000 • From at least 10,000 BC Ptolomy Aristotle • First written language ~3,000 BC Newton Galileo Euclid Kepler • Well-developed mathematics & • The ideas of classical Greece dominated Western Astronomy thought for centuries • Weights and measures • Aristotle defined physics! standardized in Babylon in 2500 BC • Measured positions of planets & • Islamic Culture preserved Greek hertitage --- Stars Babylon originated “Hindu-Arabic numerals”, Algebra, ... • Great civilization until it was • The Renaissance of intellectual thought in Europe: conquered by Alexander the • Fibanacci, Copernicus, Galileo, …. Great around 330 BC. • (See Timeline descriptions on WWW pages) The ancient world Aristotle (384-322 BC) • Student of Plato (427 - 347) • Egypt • Aristotle was noted for his works on Logic, Metaphysics, Ethics, Politics, …. • Alexander the Great was his student! • Webster’s Dictionary • Aristotelian: A person characterized by empirical or practical thinking • Platonist: A person characterized by • One of the greatest civilizations idealistic or visionary thinking • Rather static for thousands of years • Aristotle’s Physics • From at least 5,000 BC • Characterized by observation and empirical reasoning • Well-developed mathematics & Astronomy • But more deeply Aristotle believed in “Metaphysics” as the • Used for practical purposes ultimate cause for everything observed • Great feats of engineering • “Teleology” - Belief in “ultimate cause” at a deeper level than • Predicting the floods of the Nile River what one perceives (see March p 6) Teleology Aristotle’s description of motion • The idea that everything has a purpose – • Motion belongs in the heavens a “final cause” • Stars keep circling in assigned routes. • “ Stasis” belongs on Earth I eat; therefore, • Things on Earth come to rest. I walk, hunt, • Motion is an imperfection, or a path to Obvious kill, removing an imperfect placement. .... • Aristotle’s views held sway for more than 1000 years I open & close that is my “natural” potential • Until the Renaissance & Galileo 2
Lecture 2 Stassis on Earth – The Motion Problem Motion in the heavens • Aristotle’ description of motion: A contest between propulsion and resistance • What could be more natural! • Why does an arrow keep moving? At least for a while. My purpose is to rest My purpose is to move • Aristotle: There must be a cause for the motion - some propulsion - the air! Is Aristotle right? Is Aristotle right? • How does one define “right”? • Observations • Are observations “right”? • The earth appears to be at rest • Do you know anything on earth that keeps going indefinitely without some • Obvious “cause”? Demos: Examples of motion. • “ Stasis” belongs on Earth • Evidence that the earth is not at rest? • Things on Earth come to rest. • Do you know a heavenly bodies that is not in “eternal motion”? • Motion belongs in the heavens • Are the methology, epistemology “right”? • Heavenly bodies appear to be in eternal motion • Teleology? Is it essential to the observations? Mathematics and Physics (Science) The Big Picture: World Views • Euclid (Alexandria, c. 300 BC) • The “Renaissance” was a rebirth • Laws of Geometry • Rediscovery of ideas from ancient Greece • Preserved by the Moslem world • Euclidian Space - 3 dimensions - obeys laws such as: sum of angles in triangle = 180° • Introduction of Arabic Numerals, Algebra • Introduced to Europe in the Renaissance • Al Khawarizmi (Bagdad, 780-850 AD) • Essential for the next steps in science • Arabic numerals, Algebra • Revolutions in Science • Built upon older Hindu-Arabic work • Way of understanding the world • Physics has a central role • Fibanacci (Pisa, c. 1170-1240) • Galileo was one of the key players • Important in introducing Arabic numerals in • Development of the new ideas of experimental science Europe (which was then very backward!) • Active study of nature to discover the underlying laws • Many advances in “pure” mathematics 3
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