Scientists of the Scientific Revolution

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Scientists of the Scientific Revolution
Clockwise from top Kepler, Copernicus, Newton,
Galileo, Descartes, and Ptolemy
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Astronomy
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Historical figures in the Copernican Revolution
Ptolemy the geocentric model, that the Earth is
at rest at the center of the Universe.
Copernicus published the heliocentric model.
Galileo his observations by telescope verified
the heliocentric model.
Kepler deduced empirical laws of planetary
motion from Tychos observations of planetary
positions.
Newton developed the full theory of planetary
orbits.
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The Copernican Revolution
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The Geocentric Theory vs. The Heliocentric Theory
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The Geocentric Theory

• The earth is located at the center of the
  universe and all the planets revolve around the
  earth.

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Geocentric Cont..

• The Geocentric theory was believed by the
  Catholic church especially because the church
  taught that God put earth as the center of the
  universe which made earth special and powerful.
• The idea of the Earth actually moving was widely
  felt as a foolish suggestion because, as they saw
  it, if the Earth was moving they would be able to
  feel it.

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Aristotle (384-322 B.C.)

• Developed an early model based on the concept of
  uniform circular motion. He placed the earth at
  the center of the universe and all of the
  planets, sun and stars around it.
• When Aristotle lived, if a person could reason
  out why something happened, then you didnt need
  to do any experiments to see what would happen.

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Scientific Revolution Helio-Centric Theory of
the Universe

• Sun at the center of the universe,
• with the planets orbiting the sun
• Created by Nicholas
• Copernicus (1473-1543),
• a Polish astronomer

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• In the realm of change, the natural motion of
  earthy materials was to seek the center of the
  universe.
• This is why Aristotle placed the earth at the
  center of the cosmos.
• This is also his explanation for why objects fall
  when dropped.
• A dropped object is just following its natural
  tendency to seek the center of the universe.

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• Aristotle reasoned that if the earth rotated
  about its axis, we should fly off into space.
  Since we don't, the earth must be stationary.
• It would be almost 1900 years before Galileo
  introduced the concepts of gravity and inertia
  that explain why these effects are not observed
  even though the earth does move.

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Ptolemy (140 A.D.)

• Ptolemy advanced the geocentric theory in a form
  that prevailed for 1400 years.
• He added mathematics to support the theory

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How did Ptolemy Explain this Problem?

• Ptolemy used geometric models to predict the
  positions of the sun, moon, and planets, using
  combinations of circular motion known as
  epicycles.
• An epicycle is an orbit within an orbit
• Having set up this model, Ptolemy then went on to
  describe the mathematics which he needed in the
  rest of the work.

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Ptolemys Model Epicycles Included
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The Heliocentric Theory

• The Sun is the center of our solar system

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Copernicus (1473-1543)

• Polish astronomer who advanced the theory that
  the Earth and other planets revolve around the
  Sun. This was highly controversial at the time.
  
• The Ptolemaic model had been widely accepted in
  Europe for 1000 years when Copernicus proposed
  his model.

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Discoveries in Astronomy, Physics, and Math

• Early scientists
• Made significant contributions in astronomy,
  physics and math
• Began to explain complexities of solar system,
  limits of physical world
• Nicolaus Copernicus, Polish astronomer, among
  first

• Copernicus
• Found geocentric theory of movement of sun, moon,
  planets not accurate
• Concluded sun, not earth, near center of solar
  system
• Heliocentric theory, earth revolves around sun

• Copernicus theory
• Idea of earth orbiting sun was not completely new
• Copernicus developed detailed mathematical
  explanation of process
• Was first scientist to create complete model of
  solar system

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• On the Revolutions of the Heavenly Spheres
• Copernicus famous book not published until last
  year of his life
• Knew church would oppose work
• Work contradicted teachings of church

• Weaknesses of theory
• Mathematical formulas did not predict positions
  of planets well
• Copernicus did not want to be ridiculed for
  weaknesses
• Died 1543 after work published, other scientists
  expanded on ideas

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• Copernicus was told by many scholars that he
  should make his new findings accessible to others
  by publishing it.
• In 1543 the book called "On the revolutions of
  the heavenly bodies" was released.
• Copernicus's book had a great impact that
  angered the Catholic and Protestant Church.
• The Church became so angry the Geocentric
  theory made human beings seem closer to God and
  since earth was in the center that meant humans
  were more special.
• The heliocentric theory changed that perspective
  completely, making humans lose that position in
  the universe.

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Nicholas Copernicus (1473-1543)

• Polish priest studied in Italy
• returns to Poland and works on Astronomy
• writes De Revolutionibus Orbitum Coelestitum (On
  the Revolutions of Heavenly Spheres)
• Earth is just another planet with a 24 hour
  rotation
• retains circular planetary motion (perfection of
  the sphere).

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Copernicus

• On the Revolutions of the Heavenly Spheres.
• Proposed a sun-centered view. (helio-centric)
• Universe consisted of 8 spheres.
• Planets including earth rotated around the sun
  but the moon revolved around the earth.
• Apparent revolution of the sun and stars around
  the earth was due to the rotation of the earth.
• Did not reject the Ptolemaic vision of the fixed
  spheres.
• His views did not make a big splash either pro or
  con, but there was growing dissatisfaction with
  the Ptolemaic view.

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Nicolaus Copernicus(1473-1543)

• Polish astronomer and mathematician
• Introduced to scientific world when he attended
  the University of Krakow in Poland in 1492
• Appointed as a canon in the cathedral of
  Frauenburg where he remained for the rest of his
  life
• Rheticus, a student Copernicus took on in 1539,
  convinced Copernicus to allow him to publish his
  works before death

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Copernicuss Scientific Theories

• Considered the founder of modern science
• Believed that the earth was round and the earth
  revolved around the sun (contrary to popular
  belief)
• The heliocentric theory was not new, but
  Copernicus established the mathematical basis
• To avoid the risk of persecution,
  excommunication, or imprisonment because his were
  revolutionary and contrary to church beliefs,
  Copernicus worked in privacy for more than 30
  years just before his death, friends helped to
  published his work
• Copernicuss theory was first taught in several
  universities in the 1500s and permeated the
  scientific world by 1600

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Copernicus Cont

• Finally we shall place the Sun himself at the
  center of the Universe. All this is suggested by
  the systematic procession of events and the
  harmony of the whole Universe, if only we face
  the facts, as they say, 'with both eyes open.-
  Copernicus

The earth also is spherical, since it presses
upon its center from every direction.-Copernicus

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Nicolaus Copernicus

• The Earth moves, in two ways.
• It rotates on an axis (period 1 day).
• It revolves around the sun (period 1 year).

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The Copernican Universe
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The heliocentric model
The reasons for seasons the Earth travels
around the sun, and its axis of rotation is
tilted by 23.5 degrees to the plane of the orbit.
In July, the northern hemisphere is getting more
sunlight than in January.
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The Copernican Model
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Giordano Bruno 1548 1600 AD

• Italian monk
• Believed Copernicus was right and that the earth
  revolved around the sun
• Believed the earth was alive because it moves
  through space
• Believed the universe is huge and everything is
  made up of atoms

• He did not do original research just used reason
  and speculation.
• Bruno wandered around Europe teaching and writing
  for a living.
• He returned to Italy and found trouble

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Bruno vs the Inquisition

• Bruno had been offered a teaching job in Venice
  and thought his employer would protect him.
• Instead, Bruno was arrested by the Inquisition
  for not supporting the Geo-Centric Theory

• After seven years in prison, Bruno was tried as a
  heretic.
• On February 6, 1600, he was burned at the stake
  for his scientific ideas.

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The Baroque Setting

• In the 1600s church through counter-reformation
  much stricter
• G. BRUNO (Italian 1548) proposes that the Sun is
  just one star out of an infinite number ? burned
  at the stake for heresy 1600
• 30 Years War (1618-1648) between religions
• New inventions telescope, air pump, etc.

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Tycho Brahe
Believed geocentric uni-verse is Scriptural Built
equipment to prove Copernican model
wrong Greatest naked-eye astronomer of all
time Proposed a geocentric model that saved all
appearances
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Tycho Brahe(1546-1601)

• Danish astronomer
• Established an observatory to study heavenly
  bodies
• Accumulated a lot of data on planetary movements
• His tables of astronomical observation was used
  by Kepler to prove Copernicuss
• helio-centric hypothesis

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Brahe Cont

• Believed that the development of astronomy relied
  on accurate observation
• Made lots of astronomical observation with the
  naked eye
• Built and calibrated numerous new instruments
  including
• Created a domicile and observatory which he
  called Uraniborg

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Tycho Brahes original model
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Modified Tychonic Model
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Brahe Cont.

• Uraniborg

Azimuth Quadrant made in 1577.
Instrument for measuring altitude
Instrument to measure angles
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Tycho Brahe The Data Taker

• Key question Where are
  things?
• Catalogued positions of planets in Uraniborg and
  Prague
• Working without telescope
• Data ten times as accurate as before
• Died at banquet binge drinking

Tycho Brahe (15461601)
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Tycho Brahe - An Observer

• Tycho Brahe was a prominent scholar and
  aristocrat in Denmark in the mid-late 1500's
• He made a huge number of observations of the
  stars and planets, all with the naked eye
• Even without a telescope, he was very accurate in
  his measurements
• Also recorded the appearance of comets and
  supernovae
• The Tycho supernova remnant is still visible today

Tycho (1546-1601)
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Tycho Brahe

• collects detailed and accurate (1-2 accuracy)
  observations of stellar and planetary positions
  over a period of 20 years
• His research costed 5-10 of Danish GNP
• shows that comets and novas are extralunar
  contrary to Aristotle
• Shows that stars can change
• (Supernova of 1572)

Tycho Brahe observing
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Brahe and Kepler

• Brahe, Danish Astronomer
• Wrote book proving bright object over Denmark sky
  was newly visible star
• Called it supernova, distant exploding star
  suddenly visible on earth
• Book impressed Denmarks King Frederick II
• Gave Brahe money to build two observatories

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Johannes Kepler - A Theorist

• Shortly before his death, Tycho began working
  with another scientist named Kepler
• Kepler was put to the task of creating a model to
  fit all of Tycho's planetary data
• Kepler spent the remainder of his life
  formulating a set of laws that explained the
  motion of the planets

Kepler (1571 - 1630)
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Keplers Beginnings

• Astrologer and Mystic
• Tried to find music in the skies
• Tried to explain distances of the 5 known
  planets by
• spheres resting on the
• 5 mathematical bodies
• ? pre-scientific

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Johannes Kepler (1571-1630)

• Student of mathematics and astronomy
• studied with Tycho Brahe
• tested hypothesis after hypothesis until he
  determined that planets move in ellipses
• Three Laws of Planetary Motion
• planets move in ellipses with sun as one focus
• velocity of a planet is not uniform
• equal area of the plane is covered in equal time
  by the planets.

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Johannes Kepler(1571-1630)

• Built on the detailed observations of Tycho
  Brahe.
• Confirmed Copernicuss heliocentric theory
• Worked out the laws that governed planetary
  motion.
• Discovered that orbits were elliptical, not
  circular.
• Killed off the Ptolemaic theory of crystalline
  spheres and a perfect heaven.
• Opens the door to the question of what the
  planets and stars are made of and what governs
  their motion.

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Johannes Kepler(1571-1630)

• Used Brahes work to successfully prove
  Copernicuss helio-centric model mathematically
• However, he disproved Brahes claim that planets
  move in circular motion found that they move in
  ellipses
• Discovered that the speed of planets increase as
  they near the sun and decrease as they go away
  from it
• Discovered three laws of planetary motion
• the planets orbit the sun in elliptical orbits
  the sun is at one focus of the ellipse
• An imaginary line drawn from the center of the
  sun to the center of a planet will sweep out
  equal areas in equal intervals of time
• The ratio of the squares of the periods of any
  two planets is equal to he ratio of the cubes of
  their average distance from the sun
• Worked in optics, discovered two new regular
  polyhedra, created the first proof of logarithms,
  and created a way to find the volume of solids of
  revolution (which influenced calculus)
• Proof of logs based off of the work of Napier and
  Euclid

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Kepler Cont.

• Very religious (protestant) believed in
  Intelligent Design, and that God made the
  Universe according to a mathematical plan
• Math was considered a way to find truth, so
  Kepler thought that this gave man a way to find
  and understand the truth of the Universe
• Worked as an aide to Tycho Brahe and continued
  Brahes work and used it in his own work
• Established the idea of observational error

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Johannes Kepler (1571 1630)
discovered three empirical laws of planetary
motion in the heliocentric solar system

1. Each planet moves on an elliptical orbit.
2. The radial vector sweeps out equal areas in equal
   times.
3. The square of the period is proportional to the
   cube of the radius.

(needed for the CAPA)
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Keplers First Law

• The orbits of the planets are ellipses, with the
  Sun at one focus

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Kepler's First Law

• Kepler first noted that the orbital path of a
  planet around the Sun is an ellipse, not a
  perfect circle
• The Sun lies at one of the foci of the ellipse
• The eccentricity of an ellipse is a measure of
  how 'squished' from a circle the shape is
• Most planets in the Solar System are very close
  to a perfect circle
• Eccentricity, e 0 for a circle

Focus
Focus
Kepler's 1st Law The orbital paths of the
planets are elliptical with the Sun at one focus.
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Kepler's First Law
closest to the Sun
farthest from the Sun
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Keplers Second Law
An imaginary line connecting the Sun to any
planet sweeps out equal areas of the ellipse in
equal times
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Keplers Third Law

• The square of a planets orbital period is
  proportional to the cube of its orbital
  semi-major axis
• P 2 ? a3
• a
  P
• Planet Orbital Semi-Major Axis Orbital Period
  Eccentricity P2/a3
• Mercury 0.387 0.241 0.206 1.002
• Venus 0.723 0.615 0.007 1.001
• Earth 1.000 1.000 0.017 1.000
• Mars 1.524 1.881 0.093 1.000
• Jupiter 5.203 11.86 0.048 0.999
• Saturn 9.539 29.46 0.056 1.000
• Uranus 19.19 84.01 0.046 0.999
• Neptune 30.06 164.8 0.010 1.000
• Pluto 39.53 248.6 0.248 1.001
• (A.U.) (Earth years)

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Kepler's Second Law

• Kepler also noticed that the planets sweep out
  equal areas in their orbit over equal times
• Notice that this means the planet must speed up
  and slow down at different points
• If it takes the same amount of time to go through
  A as it does C, at what point is it moving
  faster?
• C, when it is closest to the Sun

Kepler's 2nd Law An imaginary line connecting
the Sun to any planet sweeps out equal areas of
the ellipse over equal intervals of time.
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Kepler's Third Law

• Finally, Kepler noticed that the period of
  planet's orbit squared is proportional to the
  cube of its semi major axis
• This law allowed the orbits of all the planets to
  be calculated
• It also allowed for the prediction of the
  location of other possible planets

Kepler's 3rd Law Simplified
NOTE In order to use the equation as shown, you
must be talking about a planet in the Solar
System, P must be in years, and a must be in A.U.
!!!
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Kepler's Third Law - Examples

• Suppose you found a new planet in the Solar
  System with a semi major axis of 3.8 A.U.
• A planet with a semi major axis of 3.8 A.U. would
  have an orbital period of 7.41 years

years
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Kepler's Third Law - Examples

• Suppose you want to know the semi major axis of a
  comet with a period of 25 years
• A planet with an orbital period of 25 years would
  have a semi major axis of 8.55 A.U.

A.U.
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How did Kepler determine the planetary orbits?
Compare the heliocentric model to naked-eye
astronomy
Mars
The inner planet is Earth the outer one is Mars.
Plot their positions every month. Mars lags
behind the Earth so its appearance with respect
to the Zodiac is shifting.
Earth
The most complete data had been collected over a
period of many years by Keplers predecessor,
Tycho Brahe of Denmark.
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KEPLER
Instrument to show relative distances of planets
according to Copernican System

• And to us Jupiter, like Mars, and in the morning
  Mercury and Sirius, appeared four-cornered. And
  one of the diameters running between the corners
  was blue, the other red, in the middle the body
  was yellow, and amazingly bright.Account of
  personal observations...

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Keplers Solution

• Kepler solved main problem of Copernican theory
• Copernicus assumed planets orbited in circle
• Kepler found assumption untrue
• Proved planets orbited in oval pattern, ellipse
• Wanted to prove Copernicus wrong, instead proved
  heliocentric theory correct
• Keplers mathematical solar system model also
  correct

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Galileo on ScriptureThe Scriptures teach us
how to go to heaven, not how the heavens go.
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Galileo (1564-1642)

• An Italian scientist, Galileo was renowned for
  his contributions to physics, astronomy, and
  scientific philosophy.
• He is regarded as the chief founder of modern
  science.
• Galileo was condemned by the Catholic Church for
  his view of the cosmos based on the theory of
  Copernicus.

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Galileo Galilei The Experimentalist

• Did experiments (falling bodies) rather
• than studying Aristotle
• Major Works
• Siderius Nuntius (1610)
• Dialogue concerning the Two Chief World Systems
  (1632)
• The latter discusses Copernicus vs Ptolemy ?ban
  by Church (1633)
• revoked by pope 1992

• (15641642)

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Galileos Places

• Born at Pisa, Tuscany
• Childhood in Florence, Tuscany
• Studies at University of Pisa
• Begins teaching at Pisa
• Gets a position at Padua, Province of Venice
• Stays for 18 years

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Galileos Places (contd)

• Returns to Florence, Tuscany in 1610 under Grand
  duke Cosimo II.
• 1633 Trial in Rome
• From 1633 house arrest in Acetri, near Florence
• 1637 loses eyesight
• 1992 ban on Galileo lifted by Pope John Paul II.

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Galileos discoveries in Astronomy
Galileo did not invent the telescope, but when he
heard about the invention he figured out how to
build telescopes. He had the best telescopes of
his time. He was the first person to use
telescopes to look at the heavenly bodies. He was
first, so he made the discoveries.

• ? Craters and mountains on the moon
• ? Moons of Jupiter
• ? Phases of Venus
• ? The Milky Way consists of innumerable stars.
• ? Sunspots move across the suns face.
• All of these favored the Copernican
  (heliocentric) model.

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Galileo Galilei (15641642)

• Astronomical observations that contradict
  Aristotle
• Observed mountains on the Moon, suggesting that
  the Earth is not unique
• Sunspots suggests that celestial bodies are not
  perfect and can change
• Observed four moons of Jupiter showed that not
  all bodies orbit Earth

• Observed phases of Venus (and correlation of
  apparent size and phase) evidence that Venus
  orbits the Sun
• Also observed
• the rings of Saturn
• that the Milky Way is made of stars

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Galileos sketch of the moon as seen from his
telescope
A photograph of the moon
What do you think of the foremost philosophers
of this university? In spite of my oft repeated
efforts and invitations, they have refused, with
the obstinacy of a glutted adder, to look at the
planets or Moon or my telescope. (letter to
Kepler)
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Galileo made many specific discoveries in
astronomy, through observations by telescope.

• The general implications
• ? The planets are objects like the Earth masses
  rather than some kind of special heavenly
  objects. Or, to put it another way, the Earth is
  just another planet.
• ? The planets, including Earth, travel around the
  sun.
• ? The Universe is a lot bigger than we can see by
  the naked eye.

These ideas could be dangerous.
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Galileo Galilei (1564-1642)

• Astronomy
• used a telescope, proved the heavens are not
  perfect (craters on moon)
• supported Heliocentric system
• Laws of Motion
• dropping weights from the Tower of Pisa
• imagined motion without constraint!!!!
• Thought of inertia
• Problems with the church
• argues for separation of science and theology
  because we are endowed with reason
• 1633 banned by Church and house arrest
• must recant heliocentric system to save neck.

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Galileos Books

• Galileo published his discoveries and support for
  the Copernican model in two books published in
  1616 and 1632.
• Galileo was unusual for the time because he wrote
  in Italian rather than Latin like most scholars.
• Galileo also took great pains to make his books
  interesting often writing them in the form of
  dialogues rather than dry, boring dissertations.
• After his first book, "Starry Messenger", was
  published he was warned by the Church not to
  publicly support Copernicism again.

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Reactions to Galileo

• Italy and Spain
• More freedom in France, England and Holland
• University of Padua was under Venice, the most
  anti-clerical state in Europe Copernicus,
  Galileo and Harvey studied there
• Protestants as hostile as Catholics on Biblical
  grounds, less state control in Protestant nations
  and in the end Protestant nations become more
  liberal than at first.

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Galileo Galilei 1564 1642AD

• Italian
• Was a Professor of Mathematics at Pisa University
• Became interested in science after reading the
  works of Copernicus and Bruno
• These books convinced him that the earth revolved
  around the sun.

• He also made huge discoveries in physics.
• He proved that a pendulum swings the same time no
  matter the size.
• He used mathematical rules to explain this it
  was the first time math had been used to describe
  an object in motion.

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Galileo

• These discoveries proved once again that
  Aristotles theories were wrong.
• The moon wasnt a perfect round ball as the
  ancient Greeks believed, but had bumps and
  craters.

• In 1609, he switched from being a physicist to
  being an astronomer.
• He heard about the newly-invented telescope and
  built his own.
• He used it to discover 4 moons of Jupiter and the
  mountains on the moons.

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Galileo Continued

• Watched as the planets Venus and Saturn travel
  around the sun
• This proved that the Earth was not the center of
  the solar system.

• Galileo wrote a book in 1610 about his
  discoveries
• This is where his trouble with the Catholic
  Church begins.

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Galileo Galilei

• In 1609 Galileo built his own telescope to
  observe the night skies
• Galileo worked with Kepler who discovered by
  using convex lens it would increase the
  magnification
• Galileos telescope developed in 1609, modeled
  based off other telescopes
• Could magnify three times more than other
  telescopes his later telescope magnified twenty
  times
• He could see the moon, four satellites, a
  supernova,
• the phases of Venus, and sunspots

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Galileo Galilei (1564-1642)

• First European to make systematic observations of
  the heavens using a telescope.
• Established that the planets were made of
  material stuff quite similar to the earth.
• The Starry Messenger.
• Publicized the shift in scientific thinking away
  from the Ptolemaic view.

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Galileo Galileo (1564-1642)

• The Starry Messenger
• Published in 1610
• Stunned contemporaries and did more to make
  Europe aware of the new picture of the universe
  than the mathematical theories of Copernicus and
  Kepler
• Galileo, the Church and Inquisition
• Dialogue on the Two Chief World Systems
  Ptolemaic Copernican
• Placed under house arrest and during his final
  eight years Galileo studied mechanics discovering
  the principles of inertia force

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Science and the Church

• Galileos Theories
• Brought him into direct conflict with the church
• Church leaders pressured him not to support ideas
  of Copernicus
• Dialogue concerning Two Chief World Systems,
  1632, showed support

• Trial
• Pope Urban VII ordered Galileo to Rome to stand
  trial before Inquisition
• Church wanted to stamp out heresy, or dissenting
  views
• Trial held, April 1633

• House Arrest
• Galileo stated would not use Copernican theory in
  work
• Received lenient sentence in return
• Pope ordered Galileo under house arrest, where he
  spent rest of life

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Trial Before the Inquisition

• Galileo abided by this edict until 1632 when he
  published "A Dialogue on the Two Chief World
  Systems". This book's outright support for the
  Copernican model and its ridiculing of the
  Ptolemaic model earned Galileo a trial before the
  Inquisition.
• Galileo was accused of heresy and sentenced to
  house arrest for life. However, he got off easily
  compared to fellow Italian Giordano Bruno who was
  burned at the stake in 1600 for teaching
  Copernican ideas.

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Galileo and the Church

• In 1616, Galileo promised to give up his ideas.
• But he then published a book making fun of the
  Catholics teaching of the Geo-Centric Theory.
• In his book, he uses a fictional dialogue or
  conversation to make fun of the Church.

• The character who backed the Churchs views was
  called Simplicius, which means stupid.
• In 1633 after a series of warnings against his
  teaching, Galileo was put on trial before the
  Inquisition
• The charge was heresy with the likely punishment
  of death
• He was 70 years old at the time

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Galileos Letter to Castelli

• I am inclined to think that the authority of
  Holy Scripture is intended to convince men of
  those truths which are necessary for their
  salvation, and which being far above man's
  understanding cannot be made credible by any
  learning, or any other means than revelation by
  the Holy Spirit.  But that the same God has
  endowed us with senses, reason, and
  understanding, does not permit us to use them,
  and desires to acquaint us in any other way with
  such knowledge as we are in a position to acquire
  for ourselves by means of those faculties, that
  it seems to me I am not bound to believe,
  especially concerning those sciences about which
  the Holy Scriptures contain only small fragments
  and varying conclusions and this is precisely
  the case with astronomy, of which there is so
  little that the planet are not even all
  enumerated....

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Galileo and the Church

• To save his life, Galileo confessed that the
  Earth did not go around the sun.
• According to legend, he muttered under his
  breath But it still moves.
• He was sentenced to life imprisonment and ended
  up locked in his own home where he went blind
  and had to give up his scientific work.

• Some historians believe Galileo was tortured,
  because he suffered from weakened muscles in his
  gut from the stretching rack.
• Others say he was just shown the torture chamber
  to scare him.

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Galileo the Heretic

• Church found his findings dangerous. Why?
• Removed Humans from the center of the earth,
• Did away with the perfection of circular orbits
  and
• No longer had God in a fixed place.
• Inquisition condemns this view he recants under
  pressure.
• Is placed under house arrest for the last 8 years
  of he life.
• Attitude of the church crimped further scientific
  inquiry into the heavens in Italy

94
Galileo Church

• While at the University of Padua, Galileo became
  very much involved with Copernicuss heliocentric
  theory of the universe
• Galileos invention of the telescope enabled him
  to make observations that supported and proved
  the Copernican theory and encouraged him to
  publicly support it
• For this and for other letters, works, etc. that
  criticized the scripture as simply symbolical,
  Galileo was summoned to Rome where he was tried
  by the Inquisition in 1633
• They forced him to recant his belief in the
  Copernican Theories
• In April of 1633 Galileo is interrogated before
  the Inquisition. He agrees to plead guilty to a
  lesser charge in exchange for a more lenient
  sentence.
• Galileo was sentenced to house arrest in Siena
• Only in 1992 did the Church officially admit
  their mistake with the Galileo Trial
• The Trial caused fear among scientists and
  encouraged them to keep their findings from the
  Church and thus from the public
• In February 1632, Galileo published his book,
  Dialogue Concerning the Two Chief Systems of the
  World Ptolemaic and Copernican

95
Galileos Forced Statement

• I, Galileo, son of the late Vincenzo Galilei,
  Florentine, aged seventy years, arraigned
  personally before this tribunal, and kneeling
  before you, Most Eminent and Reverend Lord
  Cardinals, Inquisitors-General against heretical
  depravity throughout the entire Christian
  commonwealth, having before my eyes and touching
  with my hands, the Holy Gospels, swear that I
  have always believed, do believe, and by God's
  help will in  the future believe, all that is
  held, preached, and taught by the Holy Catholic
  and Apostolic Church. But whereas -- after an
  injunction had been judicially intimated to me by
  this Holy Office, to the effect that I must
  altogether abandon the false opinion that the sun
  is the center of the world and immovable, and
  that the earth is not the center of the world,
  and moves, and that I must not hold, defend, or
  teach in any way whatsoever, verbally or in
  writing, the said false doctrine, and after it
  had been notified to me that the said doctrine
  was contrary to Holy Scripture -- I wrote and
  printed a book in which I discuss this new
  doctrine already condemned, and adduce arguments
  of great cogency in its favor, without presenting
  any solution of these, and for this reason I have
  been pronounced by the Holy Office to be
  vehemently suspected of heresy, that is to say,
  of having held and believed that the Sun is the
  center of the world and immovable, and that the
  earth is not the center and moves 

96
Galileos Abjuration before the Inquisition, 1633
because I have been enjoined, by this Holy
Office, altogether to abandon the false opinion
which maintains that the sun is the center and
immovable, and forbidden to hold, defend, or
teach, the said false doctrine in any manner
therefore, with a sincere heart and unfeigned
faith, I abjure, curse, and detest the said
errors and heresies, and generally every other
error and sect contrary to the said Holy Church
and I swear that I will never more in future say,
or assert anything, verbally nor in writing,
which may give rise to a similar suspicion of me
but that if I shall know any heretic, or any one
suspected of heresy, I will denounce him to this
Holy Office, or to the Inquisitor and Ordinary of
the place in which I may be.                      
                             
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Galileos sketch of the moon as seen from his
telescope
A photograph of the moon
What do you think of the foremost philosophers
of this university? In spite of my oft repeated
efforts and invitations, they have refused, with
the obstinacy of a glutted adder, to look at the
planets or Moon or my telescope. (letter to
Kepler)
98
Galileo
Replica of Galileos Telescope

• Scenes from the Trial of Galileo

99
(No Transcript)
100
Galileo made many specific discoveries in
astronomy, through observations by telescope.

• The general implications
• ? The planets are objects like the Earth masses
  rather than some kind of special heavenly
  objects. Or, to put it another way, the Earth is
  just another planet.
• ? The planets, including Earth, travel around the
  sun.
• ? The Universe is a lot bigger than we can see by
  the naked eyeeye.

These ideas could be dangerous.
101
Questions Raised by Galielo

• Galileos conflict with the Church Can questions
  about the natural world be settled by the Bible?
• Or must they be settled by the best empirical and
  mathematical methods of science?
• Are we free to investigate nature, or must we be
  constrained by religious authority?
• The book of God The history of God and his
  creation, written in a language for general human
  comprehension
• The book of Nature The natural world itself,
  revealing its laws in the phenomena--
• --but written in the language of mathematics.

102
Galileo on science and Scripture I think it
would be the part of wisdom not to allow any one
to apply passages of Scripture in such a way as
to force them to support as true any conclusions
concerning nature, the contrary of which may
afterwards be revealed by the evidence of our
senses, or by actual demonstration. Who will set
bounds to man's understanding ? Who can assure us
that every thing that can be known in the world
is known already ?
103
Galileo on science and Scripture (continued) . .
. I am inclined to think that Holy Scripture is
intended to convince men of those truths which
are necessary for their salvation, and which
being far above man's understanding cannot be
made credible by any learning, or by any other
means than revelation. But that the same God who
has endowed us with senses, reason, and
understanding, does not permit us to use them,
and desires to acquaint us in another way with
such knowledge as we are in a position to acquire
for ourselves by means of those faculties that,
it seems to me I am not bound to believe
104
Galileos Genius

• Careful observation of a phenomenon
• Deriving conclusions from data
• Making new predictions
• Publishing results for everyone in Italian
• Anticipates his opponents arguments, and
  nullifies them by using stringent logic

105
Galileos Genius Applied to Sunspots

• Careful observation of a phenomenon
• Observes sunspots (as did others before him)
• Follows them over several weeks
• Deriving conclusions from data
• Concludes that these are things very close to the
  Suns surface
• Making new predictions
• Deduces that the sun rotates around itself in 26
  days
• Makes a prediction as to the Suns rotational
  axis
• Publishing results for everyone in Italian
• Letters on Sunspots (1612)
• Anticipates his opponents arguments, and
  nullifies them by using stringent logic
• Shows that sunspots cant be inner planets

106
Saturn

• Sketch of 1616
• Engraving in The Assayer (1623)

107
Applications

• From the distance r between two bodies and the
  gravitational acceleration a of one of the
  bodies, we can compute the mass M of the other
• F ma G Mm/r2 (m cancels out)
• From the weight of objects (i.e., the force of
  gravity) near the surface of the Earth, and known
  radius of Earth RE 6.4?103 km, we find ME
  6?1024 kg
• Your weight on another planet is F m ? GM/r2
• E.g., on the Moon your weight would be 1/6 of
  what it is on Earth

108
Applications (contd)

• The mass of the Sun can be deduced from the
  orbital velocity of the planets MS
  rOrbitvOrbit2/G 2?1030 kg
• actually, Sun and planets orbit their common
  center of mass
• Orbital mechanics. A body in an elliptical orbit
  cannot escape the mass it's orbiting unless
  something increases its velocity to a certain
  value called the escape velocity
• Escape velocity from Earth's surface is about
  25,000 mph (7 mi/sec)

109
Objections to the Heliocentric Model Answered

• If the Earth is moving, why do dropped objects
  appear to fall straight down?
• Dropped objects start with the velocity of Earth
  (Galileo)
• If the Earth rotates, why don't we get thrown
  off?
• Earth's rotation isn't fast enough!
• If the Earth revolves around the Sun, why don't
  we observe stellar parallax?
• It's there, but very small, because the stars are
  so far away (Aristarchus)
• Why don't we feel the wind of our motion?
• The air moves along with the Earth

110

• In 1992, the Roman Catholic Church finally
  repealed the ruling of the Inquisition against
  Galileo. The Church gave a pardon to Galileo and
  admitted that the heliocentric theory was
  correct. This pardon came 350 years after
  Galileo's death.

111
The observed solar system at the time of Newton
Sun Mercury Venus Earth Mars Jupiter Saturn
(all except Earth are named after Roman gods,
because astrology was practiced in ancient Rome)
Three outer planets discovered later Uranus
(1781, Wm Herschel) Neptune (1846 Adams
LeVerrier) Pluto (1930, Tombaugh)
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Isaac Newton
Newton solved the premier scientific problem of
his time --- to explain the motion of the planets.
To explain the motion of the planets, Newton
developed three ideas

1. The laws of motion
2. The theory of universal gravitation
3. Calculus, a new branch of mathematics

If I have been able to see farther than others
it is because I stood on the shoulders of
giants. --- Newtons letter to Robert
Hooke, perhaps referring to Galileo and Kepler
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Newtons Theory of Universal Gravitation
Newton and the Apple
Newton asked good questions ? the key to his
success.
Observing Earths gravity acting on an apple, and
seeing the moon, Newton asked whether the Earths
gravity extends as far as the moon.
(The apple never fell on his head, but sometimes
a stupid person will say that, trying to be
funny.)
114
William Herschel 1782 and Caroline Herschel
1750 1848AD

• His sister, Caroline, helped her brother make the
  lenses for telescopes and kept his daily records.
• She went on to discover seven comets and to list
  all the main stars. This became a vital source
  of information for astronomers.
• She was awarded many medals by the Royal
  Astronomical Society and the King of Prussia

• Became Britains top astronomer
• Discovered the planet Uranus
• Found many types of new stars and comets
• 1783 Found a new type of light called infrared

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William and Caroline