300811 – Scientific Literacy | My Assignment Tutor

300811 – Scientific LiteracyDr Luke BarnesLuke Barnes 01Lecture 7: Science isNon-Linear1Luke BarnesLast Time …• Deductive Logic• Deriving Predictions• Categorising Data• Writing and Speaking• Spotting fallacies2Luke BarnesThe Problem of Induction3Good BadThis inductionmachine worksGood BadLuke BarnesThe History of Science• Previously: 2,500 BC to 100 BC.• Egypt• Babylon• Greece• China• In the tutorial (100 BC to 1500 AD)• Rome• Medieval Europe• Middle East4Luke BarnesThe Scientific Revolution• Not the beginning of science• A warning …5Scientists SuckAt HistoryLuke BarnesThe Eve of the Revolution• Collapse of Rome →Fragmented Region• Higher Learning• Monasteries, Madrassasand the University• Evidence is mountingagainst Aristotle6Luke BarnesThe Protestant Revolution7Martin Luther (1509 – 1564) John Calvin (1483 – 1546)Luke BarnesNicolaus Copernicus (1473–1543)8Luke BarnesClaudius Ptolemy (100 – 170 AD)9Aristotle’s Universe Ptolemy’s UniverseLuke BarnesNicolaus Copernicus (1473–1543)10Aristotle’s Universe Copernicus’s UniverseLuke BarnesNicolaus Copernicus (1473–1543)11Retrograde MotionLuke BarnesCopernican Model• 1514: Copernicus has a working model• Word is spreading• 1533: Johann Albrecht Widmannstetter (secretary toPope Clement VII) lectures on Copernican Theory• 1536: cardinal Nikolaus von Schönberg urgesCopernicus to publish• 1539: Georg Rheticus (German mathematician) andAndreas Osiander (Lutheran theologian) convinceCopernicus to publish12Luke BarnesDe Revolutionibus Orbium CoelestiumDe Revolutionibus Orbium Coelestium(On the Revolutions of theHeavenly Spheres) is publishedin 1543.Copernicus has a severe strokein 1542, and dies 24 May 154313Luke BarnesDe Revolutionibus Orbium CoelestiumMathematics: interesting anduseful, though not a decisiveimprovement on Ptolemy.Current physics could make nosense of Copernicus’s model.14Luke BarnesTycho Brahe (1546-1601)15Luke BarnesTycho Brahe (1546-1601)16Luke BarnesJohannes Kepler (1571-1630)1. The orbit of a planet is an ellipse with theSun at one of the two foci.2. A line joining a planet and the Sun sweepsout equal areas during equal intervals of time.3. The square of a planet’s orbital period isproportional to the cube of the length of thesemi-major axis of its orbit.17Luke BarnesGalileo Galilei (1564-1642)• 1580: Enrols at University ofPisa, first in medicine thenmathematics• 1591: professor of mathematicsat Pisa• 1592: professor of mathematicsat Padua18Luke BarnesGalileo Galilei (1564-1642)• 1609: Galileo builds his firsttelescope19Luke BarnesGalileo’s Telescope20Luke BarnesGalileo’s Telescope21Luke BarnesSidereus NunciusMarch 1610: Galileo publishesSidereus Nuncius (Starry Messenger),outlining his observations anddefending CopernicusJune 1610: Galileo leaves Padua tobecome the “court mathematician”of Cosimo II de’ Medici, GrandDuke of Tuscany22Luke BarnesLetter to the Grand Duchess Christina1615: In response to controversy,Galileo circulates his Letter to the GrandDuchess Christina.The issue is theological: is the motionof the Earth contrary to the Bible?23Luke BarnesLetter to the Grand Duchess ChristinaSome years ago, as Your SereneHighness well knows, I discoveredin the heavens many things thathad not been seen before our ownage. The novelty of these things, aswell as some consequences whichfollowed from them incontradiction to the physicalnotions commonly held amongacademic philosophers, stirred upagainst me no small number ofprofessors — as if I had placedthese things in the sky with myown hands in order to upset natureand overturn the sciences. …Showing a greater fondness fortheir own opinions than for truth,they sought to deny and disprovethe new things which, if they hadcared to look for themselves, theirown senses would havedemonstrated to them. To this endthey hurled various charges andpublished numerous writings filledwith vain arguments, and theymade the grave mistake ofsprinkling these with passagestaken from places in the Biblewhich they had failed tounderstand properly, and whichwere ill suited to their purposes. …24Luke BarnesLetter to the Grand Duchess ChristinaWell, the passage of time has revealedto everyone the truths that Ipreviously set forth. … Men who werewell grounded in astronomical andphysical science were persuaded assoon as they received my firstmessage. …[Those who disagree with me] knowthat as to the arrangement of the partsof the universe, I hold the sun to besituated motionless in the center ofthe revolution of the celestial orbswhile the earth rotates on its axis andrevolves about the sun. They knowalso that I support this position notonly by refuting the arguments ofPtolemy and Aristotle, but byproducing many counter-arguments;in particular, some which relate tophysical effects whose causes canperhaps be assigned in no other way.In addition there are astronomicalarguments derived from many thingsin my new celestial discoveries thatplainly confute the Ptolemaic systemwhile admirably agreeing with andconfirming the contrary hypothesis.… Mistrusting their defense so long asthey confine themselves to the field ofphilosophy, these men have resolvedto fabricate a shield for their fallaciesout of the mantle of pretendedreligion and the authority of theBible.25Luke BarnesGalileo and BellarmineFebruary 1616: heliocentrismis declared “foolish and absurdin philosophy, and formallyheretical since it explicitlycontradicts in many places thesense of Holy Scripture”.26Cardinal Robert Bellarmine:I say that if there were a truedemonstration that the Sun is at thecenter of the world and the Earth inthe third heaven, and that the Sundoes not circle the Earth but theEarth circles the Sun, then onewould have to proceed with greatcare in explaining the Scripturesthat appear contrary, and say ratherthat we do not understand themthan what is demonstrated is false.But I will not believe that there issuch a demonstration, until it isshown to me.Luke BarnesMaffeo Barberini1620: Cardinal Maffeo Barberiniwrites a poem entitled AdulatioPerniciosa (Perilous Flattery) inGalileo’s honor.1623: Galileo dedicates his book TheAssayer to Barberini.1623: Barberini is elected PopeUrban VIII27Luke BarnesDialogue Concerning the Two Chief World Systems28Luke BarnesDialogue Concerning the Two Chief World Systems (1632)29• Ptolemy vs Copernicus, ignoring Kepler and Brahe.• Galileo (Salviati) acts as if he has undeniablearguments for Copernicus, but doesn’t. He has goodarguments against Ptolemy and Aristotle, butnothing against Brahe. That is, he could show thatthe other planets orbit the Sun, but not that theEarth moves. Some arguments for Copernicus areseriously flawed: e.g. tides.• “Neutral” layperson Segredo always ends up agreeingwith the Copernican, Salviati.• Defender of Ptolemy is Simplicio, an insult.• An argument from Barberini is put in the mouth ofSimplicio.Luke BarnesGalileo on Trial30• Galileo is summoned to Romeand stands trial in 1633.• Never imprisoned or tortured.• Tries to claim that his book doesnot defend Copernicanism.Everyone knows this is a lie.• Convicted of disobeying the 1616instruction to not defendCopernicanism as reality.Sentenced to house arrest. Diesin 1642.Luke BarnesAftermath31• Scientists in non-Catholic countries(England, Holland and Germany) turnedGalileo into a hero.• No one appeared before the Inquisitionfor their scientific work before or afterGalileo.• Italian science in particular, and Catholicscience in general, continued to flourish.• If you don’t tell theologians how to dotheology, and don’t personally insult yourfriend the Pope in print, you’ll be fine.Luke BarnesFrancis Bacon (1561 – 1626)• Throughout the Galileo affair,there is no complete theory ofmotion that can replace Aristotle• What was needed?• Empirical• Experimental• Mathematical32Luke BarnesIsaac Newton (1642-1727)1687: Philosophiæ Naturalis PrincipiaMathematica (MathematicalPrinciples of Natural Philosophy)33Luke BarnesNewton’s Laws of Motion1. An object at rest will stay at rest,and an object in motion will stay inmotion, unless acted on by anexternal force.2. An object changes its motionproportional to the imposed force(push or pull), and on the mass ofthe object.3. If object A pushes or pulls on objectB, then object B gives an equal andopposite push or pull to object A.34Luke BarnesIsaac Newton (1642-1727)Newton explains:• Kepler’s laws of planetary motion.• The tides: the Moon pulls on theoceans.• The trajectories of comets. EdmondHalley predicted in 1705 that aparticular comet would return in1758. And it did.• To do this, he invented calculus.35Luke BarnesScience is not Hero WorshipThe history of science is not“Aristotle got it wrong, then Newtongot it right.”You may read: “Galileo was the firstto perform real experiments in howthings move.”Jordanus de Nemore wasexperimenting on gravity, forces,equilibrium and levers 400 yearsbefore Galileo.36Luke BarnesScientific RevolutionsScience is not simple and steady:observe facts, accumulate data, anddraw generalisations from them.General pattern:• Normal science under a paradigm• Anomalies• Crisis• New paradigm proposed• Paradigm shift37Luke BarnesEvaluating KuhnParadigms are incommensurable:“When one paradigm competes with another,there is no logically compelling argument thatdictates that a rational scientist shouldabandon one for the other. There is no singlecriterion by which a scientist must judge themerit or promise of a paradigm, and, further,proponents of competing programs willsubscribe to different sets of standards and willeven view the world in different ways anddescribe it in different languages. The aim ofarguments and discussions between supportersof rival paradigms should be persuasion ratherthan compulsion.”Chalmers38Luke BarnesEvaluating KuhnProblem solving in a paradigm: do weactually learn anything about the realworld?Of principle of Newton, Kuhn asks is it“a mere fact that [scientists] have alwayssought, or is it rather the answer to aquestion that first arose only withinNewtonian theory?”Two examples:• Comets in Aristotle• Neptune39Luke BarnesKuhn and ProgressOn the one hand:“… later scientific theories are better thanearlier ones for solving puzzles in the oftenquite different environments to which theyare applied. … I am a convinced believer inscientific progress.”On the other hand,“[In] a debate about paradigm choice, theirrole is necessarily circular. Each group usesits own paradigm to argue in that paradigm’sdefence … [Paradigm choice] cannot bemade logically or even probabilisticallycompelling. … There is no standard higherthan the assent of the relevant community.”40Luke BarnesScience is Non-LinearKuhn’s history is good, but hisphilosophy of science – his accountof how science is supposed to work– has largely been abandoned orignored by philosophers andscientists.Science is non-linear, but it canmake progress.We still need to work out: how?41


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