Post Galilean Astronomy Post Galilean Astronomy

Kicking and Screaming into the Kicking and Screaming into the Modern AgeModern Age

This logo denotes A102 appropriate

Old ideas die hardOld ideas die hard

Giambattista Riccioli Giambattista Riccioli (1598-1671) in 1651 (1598-1671) in 1651 publishes publishes Almagestum Almagestum NovumNovum ( (The New The New AlmagestAlmagest)) Mercury, Venus, Mars orbit Mercury, Venus, Mars orbit

the Sunthe Sun Sun, Jupiter, Saturn orbit Sun, Jupiter, Saturn orbit

EarthEarth 20 arguments for, 77 20 arguments for, 77

against heliocentismagainst heliocentism GeocentricGeocentric TychoneanTychonean Heliocentric Heliocentric

Copernicanism prompts questions:Copernicanism prompts questions:

If Earth is not the center, then If Earth is not the center, then what?what?

How can natural motion be How can natural motion be explained? explained?

If the Earth is a celestial body, If the Earth is a celestial body, is there really a difference is there really a difference between terrestrial motion and between terrestrial motion and celestial Physics?celestial Physics?

What is really true?What is really true? By 1700, the old scholasticism By 1700, the old scholasticism

gives way to more modern gives way to more modern epistemologies, and away epistemologies, and away from southern to northern from southern to northern EuropeEurope

Astronomy begins to look familiarAstronomy begins to look familiar

Galileo’s telescopeGalileo’s telescope Seeing things as they Seeing things as they

really arereally are Seeing more than ever Seeing more than ever

imaginedimagined

Kepler’s LawsKepler’s Laws Application of Application of

protocalculusprotocalculus

Slow abandonment of Slow abandonment of old ideasold ideas

The known planets in the 17The known planets in the 17thth CenturyCentury

And What Is This?And What Is This?

Giovanni Battista Giovanni Battista HodiernaHodierna 16541654 Noted in his “Noted in his “De De

Admirandis Coeli Admirandis Coeli CharacteribusCharacteribus””

His sketchHis sketch

CHANGES IN THINKING FROM CHANGES IN THINKING FROM 1600-17001600-1700

The evidence of the new technologies leads toThe evidence of the new technologies leads to

Aristotelian ScholastismAristotelian Scholastism

A mixture of ancient Greek and medieval A mixture of ancient Greek and medieval scholasticism, dominant in 1600 scholasticism, dominant in 1600 universitiesuniversities

Four components of causalityFour components of causality Material cause: stuff has to exist in the first Material cause: stuff has to exist in the first

placeplace Formal cause: what the stuff becomesFormal cause: what the stuff becomes Efficient cause: somebody/something has to Efficient cause: somebody/something has to

do the formingdo the forming Final cause: the reason for the actionFinal cause: the reason for the action

Aristotelian physics:Aristotelian physics: Distinction between terrestrial and celestial physicsDistinction between terrestrial and celestial physics

This has now changed to coupling Earth and skyThis has now changed to coupling Earth and sky Every body has a rightful place and must move naturally Every body has a rightful place and must move naturally

(up or down) toward it(up or down) toward it Newton finally buries this conceptNewton finally buries this concept

Material composition determines where that rightful Material composition determines where that rightful place isplace is Earth -- center of universe Earth -- center of universe Water -- above earth; below air Water -- above earth; below air Air -- above water; below fire Air -- above water; below fire Fire -- boundary of terrestrial and celestial realm Fire -- boundary of terrestrial and celestial realm Quintessence -- natural motion is at a constant speed in perfect Quintessence -- natural motion is at a constant speed in perfect

circles circles

The The DisputatioDisputatio

A hierarchy of belief or acceptance of A hierarchy of belief or acceptance of ideas; ideas; Authority: supernatural (God) first, then Authority: supernatural (God) first, then

natural, usually ancient Greeknatural, usually ancient GreekReason: Aristotelian causalityReason: Aristotelian causalityExperienceExperience

These are the intellectual descendants of These are the intellectual descendants of medieval scholasticism and the influence medieval scholasticism and the influence of Thomas Aquinasof Thomas Aquinas

Francis BaconFrancis Bacon

Contemporary of Galileo, KeplerContemporary of Galileo, Kepler Not an astronomerNot an astronomer

Sets the tone for 17Sets the tone for 17thth C inquiry in his C inquiry in his New New OrganonOrganon (new way to organize thinking) (new way to organize thinking) Knowledge is human powerKnowledge is human power Science is separate from theologyScience is separate from theology Science should always be tested through Science should always be tested through

experimentationexperimentation Science is an ongoing, cumulative activityScience is an ongoing, cumulative activity

Galileo echoed this sentiment in this quote:Galileo echoed this sentiment in this quote: ““The Bible tells how to go to Heaven, not how The Bible tells how to go to Heaven, not how

the heavens go”the heavens go”

The Royal SocietyThe Royal Society

Founded 1660 in LondonFounded 1660 in LondonA reaction to the continued Aristotelian A reaction to the continued Aristotelian

curriculum at Oxford and Cambridgecurriculum at Oxford and Cambridge Initially very much influenced by William Initially very much influenced by William

Gilbert’s ‘magnetic philosophy’, that Gilbert’s ‘magnetic philosophy’, that celestial motion is caused by magnetismcelestial motion is caused by magnetismNo theories of gravity are extantNo theories of gravity are extant

““When all you have is a hammer, everything looks When all you have is a hammer, everything looks like a nail”like a nail”

Rene Descartes 1596-1650Rene Descartes 1596-1650 French French

Mathematician/PhilosophMathematician/Philosopherer Cartesean coordinatesCartesean coordinates Cogito ergo sumCogito ergo sum Believed like Averroes that Believed like Averroes that

God (the Great God (the Great Clockmaker) created the Clockmaker) created the Universe and then just let it Universe and then just let it run without daily run without daily adjustments adjustments

Afraid in Catholic France Afraid in Catholic France to embrace to embrace Copernicanism publiclyCopernicanism publicly Remembered Bruno’s fateRemembered Bruno’s fate

Couched his ideas in a Couched his ideas in a hypothetical distant hypothetical distant planetplanet

HeliocentricHeliocentric The cosmos was filled The cosmos was filled

with unseen matter that with unseen matter that flowed like a river, flowed like a river, carrying the stars and carrying the stars and planets alongplanets along Emptiness is impossible Emptiness is impossible

– “nature abhors a – “nature abhors a vacuum”vacuum”

Motion occurs due to Motion occurs due to physical contactphysical contact

Orbits were vortices of Orbits were vortices of this celestial fluid, the this celestial fluid, the luminiferous aetherluminiferous aether

Stars at the center of Stars at the center of the ‘whirlpools’the ‘whirlpools’

Planets carried Planets carried aroundaround

Comets swoop Comets swoop through, unbound to through, unbound to any particular starany particular star

Not Gilbert’s Not Gilbert’s magnetic forces; magnetic forces; fluids!fluids! ““When all you have is When all you have is

a hammer, everything a hammer, everything looks like a nail”looks like a nail”

Even earthly motion fits the vortex Even earthly motion fits the vortex model, according to Descartesmodel, according to Descartes

Isaac NewtonIsaac Newton

Born in England the Born in England the year Galileo dies in year Galileo dies in Woolsthorpe-by-Woolsthorpe-by-Colsterworth Colsterworth 300 years before Steven 300 years before Steven

Hawking is born: 1642Hawking is born: 1642 Father dies before he is Father dies before he is

bornborn A sickly child, given up A sickly child, given up

by his mother by his mother (remarried) to her (remarried) to her parents at age 2parents at age 2

Early Years*Early Years* Newton began his schooling in the village schools Newton began his schooling in the village schools

and later was sent to Grantham Grammar Schooland later was sent to Grantham Grammar School Naturally he was the top student!Naturally he was the top student!

At Grantham he lodged with the local apothecary, At Grantham he lodged with the local apothecary, William ClarkeWilliam Clarke He became engaged to the apothecary's He became engaged to the apothecary's

stepdaughter, Anne Storey, before he went off to stepdaughter, Anne Storey, before he went off to Cambridge University at the age of 19Cambridge University at the age of 19

As Newton became engrossed in his studies, the As Newton became engrossed in his studies, the romance cooled and Miss Storey married someone romance cooled and Miss Storey married someone else. else.

It is said he kept a warm memory of this love, but It is said he kept a warm memory of this love, but Newton had no other recorded 'sweethearts' and Newton had no other recorded 'sweethearts' and never married.never married.

*Men of Mathematics E.T. Bell (1937, Simon and Schuster)

SchoolingSchooling

Entered Trinity College (Cambridge) in Entered Trinity College (Cambridge) in 16611661Still taught Aristotelian physicsStill taught Aristotelian physicsStudents discussed Galileo and Kepler, but Students discussed Galileo and Kepler, but

not in classnot in classBrilliant (geeky) studentBrilliant (geeky) student

Devoted to the Cartesian model of the Devoted to the Cartesian model of the universeuniverse

1665 school closes because of the plague1665 school closes because of the plagueNewton invents calculus (!) to solve a problemNewton invents calculus (!) to solve a problem

ProfessorshipProfessorship

School reopens 1667School reopens 1667 Newton elected Newton elected

fellow, then in 1669 fellow, then in 1669 becomes a professor becomes a professor of mathematicsof mathematics

Studies Descartes’ Studies Descartes’ theory of light as theory of light as motion in a mediummotion in a medium Shows white light is Shows white light is

made of all colorsmade of all colors

MotionMotion Newton's (Cartesian) ideas on falling bodies (ca. 1664): Newton's (Cartesian) ideas on falling bodies (ca. 1664):

...so may the gravitating attraction of the Earth be ...so may the gravitating attraction of the Earth be caused by the continuall condensation of some ... caused by the continuall condensation of some ... aethereall Spirit, not of the main body of flegmatic aethereall Spirit, not of the main body of flegmatic aether, but of something very thinly and subtily aether, but of something very thinly and subtily diffused through it .. diffused through it ..

1679: Debate in the Royal Society on the elliptical 1679: Debate in the Royal Society on the elliptical motion of planetsmotion of planets Newton was still working with vorticesNewton was still working with vortices

Robert Hooke:Robert Hooke: ““...of compounding the celestiall motions of the ...of compounding the celestiall motions of the

planetts of a direct motion by the tangent (inertial planetts of a direct motion by the tangent (inertial motion) and an attractive motion towards the centrall motion) and an attractive motion towards the centrall body ... my supposition is that the Attraction always is body ... my supposition is that the Attraction always is in a duplicate proportion to the Distance from the in a duplicate proportion to the Distance from the Center Reciprocall... Center Reciprocall...

Newton to the RescueNewton to the Rescue 1684: Edmund Halley goes to Newton, asks 1684: Edmund Halley goes to Newton, asks

what orbital shape would an inverse square what orbital shape would an inverse square force yield?force yield? An ellipse!An ellipse!

Newton has already done the problemNewton has already done the problem The reason he invented calculus during his The reason he invented calculus during his

forced vacation in 1665forced vacation in 1665 Newton sends papers off to Halley who Newton sends papers off to Halley who

finances the projectfinances the project He goes into seclusion for 18 months and He goes into seclusion for 18 months and

writes the writes the Principia MathematicaPrincipia Mathematica (1687) (1687) THETHE book on Physics, even now book on Physics, even now

Three Laws of MotionThree Laws of Motion

1.1. An object moves in constant motion in a An object moves in constant motion in a straight line unless acted upon by an straight line unless acted upon by an external force (inertia)external force (inertia)

2.2. The acceleration of an object depends The acceleration of an object depends directly on the applied force and directly on the applied force and inversely upon its massinversely upon its mass

3.3. For every action there is an equal and For every action there is an equal and opposite reactionopposite reaction

And the answer is:And the answer is:

The solution to the ellipse question combines The solution to the ellipse question combines Kepler’s third law, calculus, and Newton’s laws of Kepler’s third law, calculus, and Newton’s laws of motionmotion

The Law of Universal Gravitation: every mass in The Law of Universal Gravitation: every mass in the universe attracts every other mass with a the universe attracts every other mass with a force equal to the product of their masses and force equal to the product of their masses and inversely proportional to the square of the inversely proportional to the square of the distance between themdistance between them

Newton had to abandon a matter-filled universe Newton had to abandon a matter-filled universe for one of forces across empty spacefor one of forces across empty space

ConsequencesConsequences

How gravity makes How gravity makes orbitsorbits The apple mythThe apple myth

Newton offered no Newton offered no explanation as to why explanation as to why gravity worked this gravity worked this wayway

100 years later 100 years later Coulomb would use Coulomb would use Newton’s ideas for Newton’s ideas for electric forceelectric force

Illustration of Newton’s LawsIllustration of Newton’s Laws

War with Leibniz over calculusWar with Leibniz over calculus

Newton’s infinite series Newton’s infinite series (not far from Kepler’s (not far from Kepler’s swept areas)swept areas) FluxionsFluxions Developed Developed beforebefore but but

published published afterafter Leibniz Leibniz Wilhelm Leibniz Wilhelm Leibniz

differentialsdifferentials Bitter disputeBitter dispute Delayed acceptance of Delayed acceptance of

Newtonian Physics into Newtonian Physics into continental Europecontinental Europe

Newton’s later lifeNewton’s later life Studies alchemy extensivelyStudies alchemy extensively

Looks for scientific revelations Looks for scientific revelations in scripturein scripture

Leibniz beat him up over thisLeibniz beat him up over this Pursues the corpuscular Pursues the corpuscular

theory of lighttheory of light OpticsOptics published in 1704 published in 1704

Lucasian Chair in Lucasian Chair in Mathematics at CambridgeMathematics at Cambridge Hawking’s position todayHawking’s position today

Warden of the Mint 1699Warden of the Mint 1699 Ceases to do much scienceCeases to do much science Concentrates on finding Concentrates on finding

counterfeiterscounterfeiters Dies in 1727Dies in 1727

1726 engraving

Edmund Halley (1656-1742)Edmund Halley (1656-1742) HALL ee, not Hail ee!HALL ee, not Hail ee! English AstronomerEnglish Astronomer

Proposed using transits of Proposed using transits of Mercury and Venus to Mercury and Venus to determine the distance of the determine the distance of the Sun and therefore the scale of Sun and therefore the scale of the solar system using the solar system using Kepler's third lawKepler's third law

Suggested that Kepler’s 3Suggested that Kepler’s 3rdrd Law implied an inverse square Law implied an inverse square relationrelation

Predicted the return of the Predicted the return of the 1705 comet1705 comet 1305, 1380, 1456,1531, 1607, 1305, 1380, 1456,1531, 1607,

16821682 Period?Period?

Bill Bill HaleyHaley and the Comets and the Comets

Christian Huygens (Christian Huygens (1629 - 16951629 - 1695))

Dutch PhysicistDutch Physicist Proponent of wave Proponent of wave

theory of lighttheory of light Argued with Newton Argued with Newton

over thisover this Discoverer of TitanDiscoverer of Titan

Lander named after Lander named after himhim

Correctly identified Correctly identified Saturn’s ‘ears’ as Saturn’s ‘ears’ as ringsrings

Comparison of observations of Saturn by Galileo, Scheiner, Hevelius and others from 1616-1655,from Huygens' Saturnian System (1659)

Giovanni Giovanni CassiniCassini ( (1625 - 1712)1625 - 1712) Mathematician and Mathematician and

AstronomerAstronomer Astronomer at the Panzano Astronomer at the Panzano

ObservatoryObservatory Director of the Paris Director of the Paris

ObservatoryObservatory Viewed a ‘gap’ in Saturn’s Viewed a ‘gap’ in Saturn’s

ring systemring system correctly proposed that the correctly proposed that the

rings were composed of rings were composed of large numbers of tiny large numbers of tiny satellites each orbiting the satellites each orbiting the planet. planet.

But he was a geocentrist!But he was a geocentrist!

Other AccomplishmentsOther Accomplishments 1664: measured the period of rotation of 1664: measured the period of rotation of

Jupiter on its axis, discovered the bands and Jupiter on its axis, discovered the bands and spots on the planet, and saw that the planet spots on the planet, and saw that the planet was flattened at its poles was flattened at its poles

1666: measured the period of rotation of Mars 1666: measured the period of rotation of Mars on its axis, getting a value within three minutes on its axis, getting a value within three minutes of the correct one, and observed surface of the correct one, and observed surface featuresfeatures

He was the first to observe four of Saturn's He was the first to observe four of Saturn's moons: Iapetus (1671), Rhea (1672), Tethys moons: Iapetus (1671), Rhea (1672), Tethys (1684), and Dione (1684)(1684), and Dione (1684)

Made successful measurements of longitude Made successful measurements of longitude by the method suggested by Galileoby the method suggested by Galileo

The Longitude ProblemThe Longitude Problem Age of discovery: needed for navigationAge of discovery: needed for navigation Latitude easyLatitude easy

North StarNorth Star Equal spacingEqual spacing

Longitude more difficultLongitude more difficult The lines of longitude fan out from one pole to a maximum at the equator then The lines of longitude fan out from one pole to a maximum at the equator then

reconvergereconverge

A clock is neededA clock is needed

15301530 Gemma Frisius of Antwerp proposed use Gemma Frisius of Antwerp proposed use of portable mechanical clockof portable mechanical clock Won’t work on a rocking shipWon’t work on a rocking ship

16361636 Galileo proposes using mechanical clock Galileo proposes using mechanical clock and moons of Jupiter to determine longitudeand moons of Jupiter to determine longitude Off world clock versus local timeOff world clock versus local time

16761676 Greenwich Observatory foundedGreenwich Observatory founded 17141714 Queen Anne establishes the longitude Queen Anne establishes the longitude

prize -- £20,000!!prize -- £20,000!!

And the winner is:And the winner is:

John Harrison 1693-1776John Harrison 1693-1776 working class carpenterworking class carpenter

Build dual spring Build dual spring pendulum H1pendulum H1

H2 and H3H2 and H3

H4 1765H4 1765

Accurate to 40 Accurate to 40 seconds/day, 3X better seconds/day, 3X better than the prize requiredthan the prize required

Prize committee baulked Prize committee baulked at £20,000, offered at £20,000, offered £10,000 for H1-H4£10,000 for H1-H4

Both sides stubborn but Both sides stubborn but Harrison finally agreedHarrison finally agreed

Actually got £8750 in Actually got £8750 in 1773 for H1-H51773 for H1-H5

Prime Meridian Prime Meridian established through established through Greenwich Greenwich ObservatoryObservatory

GMTGMT As important to As important to

Astronomy as to Astronomy as to navigationnavigation

118W, 34N: home!118W, 34N: home!

Time ZonesTime Zones

Coincidence???Coincidence???

Capt. James Capt. James CookCook Capt. James Capt. James KirkKirk

Used the H4 chronometeron his 2nd and 3rd voyagesof discovery

Boldly voyaged whereno-one had gone before

Eventual Acceptance: Laplace Eventual Acceptance: Laplace 17961796

Astronomy considered in its entirety is the Astronomy considered in its entirety is the finest monument of the human mind, the finest monument of the human mind, the noblest essay of its intelligence. Seduced by noblest essay of its intelligence. Seduced by the illusions of the senses and of self-pride, the illusions of the senses and of self-pride, for a long time man considered himself as the for a long time man considered himself as the centre of the movement of the stars; his centre of the movement of the stars; his vainglory has been punished by the terrors vainglory has been punished by the terrors which its own ideas have inspired. At last the which its own ideas have inspired. At last the efforts of several centuries brushed aside the efforts of several centuries brushed aside the veil which concealed the system of the veil which concealed the system of the world…world…

continuedcontinued

……We discover ourselves upon a planet, We discover ourselves upon a planet, itself almost imperceptible in the vast itself almost imperceptible in the vast extent of our solar system, which in turn is extent of our solar system, which in turn is only an insensible point in the immensity only an insensible point in the immensity of space. The sublime results to which this of space. The sublime results to which this discovery has led should suffice to console discovery has led should suffice to console us for our extreme littleness, and the rank us for our extreme littleness, and the rank which it assigns to the earth. which it assigns to the earth.

Eventual Acceptance: Eventual Acceptance: Goethe 1810Goethe 1810

““But among all the discoveries and new convictions nothing But among all the discoveries and new convictions nothing may have produced greater effect on the human spirit than may have produced greater effect on the human spirit than the doctrine of Copernicus. The world had scarcely been the doctrine of Copernicus. The world had scarcely been recognized as round and complete in itself when it was recognized as round and complete in itself when it was expected to relinquish the enormous privilege of being the expected to relinquish the enormous privilege of being the center of the universe. A greater demand may never have center of the universe. A greater demand may never have been addressed to mankind. For think of all the things that been addressed to mankind. For think of all the things that went up in smoke as a result of accepting this: a second went up in smoke as a result of accepting this: a second Paradise, a world of innocence, poetry and piety, the Paradise, a world of innocence, poetry and piety, the testimony of the senses, the conviction of a poetic-religious testimony of the senses, the conviction of a poetic-religious faith: it is no wonder that people did not want to give up all of faith: it is no wonder that people did not want to give up all of this, and that they opposed such a doctrine in every way--a this, and that they opposed such a doctrine in every way--a doctrine that justified those who accepted it in, and doctrine that justified those who accepted it in, and summoned them to a previously unknown, indeed unimagined summoned them to a previously unknown, indeed unimagined freedom of thought and largeness of views”freedom of thought and largeness of views”