Transcript Lecture 1

2014-Space, Time & Cosmos
Lecture 1
Prof. Ken Tsang
SCIT 4020: Space, Time and Cosmos
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Instructor: Prof. Ken Tsang
Office: E-409-R9
Phone: 3620606
Email: [email protected]
TA: ??
Assessment
• Continuous Assessment (60%)
– Quizzes (10%)
– Assignments (10%)
– Mid-term test (10%)
– Project (30%)
• Final Examination (40%)
Web-page for this class
• http://www.uic.edu.hk/~kentsang/cosmos14/
SCIT4020cosmos2014.htm
• Link from Ispace as well
Cosmos
• originates from a Greek term κόσμος (kosmos)
meaning "orderly or harmonious arrangement“,
opposite to chaos.
• In many Slavic languages such as Russian,
Bulgarian, and Serbian, the word Космос (cosmos)
also means "outer space".
• In Mandarin Chinese, cosmos and universe (from
Latin universum) are both translated as 宇宙
(yǔzhòu), which literally translated means spacetime.
Cosmology
• Pythagoras ( ~570 - 495 BC) is said to have been
the first philosopher to apply the term cosmos to
the Universe, reflecting his belief that the
universe is an orderly arrangement that can be
understood.
• “Cosmology” is a recent word (first used in 1730
in Christian Wolff's Cosmologia Generalis). But
the study of Universe has a long history involving
science, philosophy, esotericism, and religion.
Creation according to Christian & Jewish Bible
The size of the Moon
• By comparing the size of the Earth’s shadow
cast upon the Moon during a lunar eclipse, it
was possible to estimate the size of the Moon
compared with the Earth. Diameter of Moon
~3200 km
• Eratosthenes estimated the distance to the
Moon as well, ~100 times of its diameter,
320,000 km.
How did the Greek philosophers know
the size of the Sun?
In third century BC, Aristarchus argued that moonshine was
reflected sunshine, and the half moon must occur when the Moon,
Sun & Earth formed a right-angled triangle. He measured the other
angle (~87°, the correct value is 89.85°) in this right-angled triangle
and used trigonometry to work out the ratio between the EarthMoon & Sun-Moon distances.
This means the Sun is 400 times further away than the
Moon.
Finally, the size of the Sun is determined during a solar eclipse, by
comparing the relative size of the Sun and the Moon to an observer
on Earth.
Modern measurements
Moon orbital radius: 363,295 - 405,503 km
Radius: 1,737.10 km
Earth’s orbital radius: 147,098,290 152,098,232 km
Radius: 6,371.0 km
Sun diameter: 1.392684×106 km
Geocentric cosmology
Aristotle postulated a
geocentric cosmology which
was widely accepted up until
the 1500s.
This view was perfected by
Ptolemy (~AD 90 – 168).
From the 3rd century to the
1500s, the dominant view
held that the Earth was the
center of the universe.
Apparent retrograde motion of Mars in 2003 as seen from Earth
The Universe of Aristotle and Ptolemy
The Ptolemaic order of
spheres from Earth outward
is:
Moon
Mercury
Venus
Sun
Mars
Jupiter
Saturn
Fixed Stars
Sphere of Prime Mover
Figure of the heavenly bodies — An illustration of the Ptolemaic
geocentric system by Portuguese cosmographer and cartographer
Bartolomeu Velho, 1568 (Bibliothèque Nationale, Paris)
A brief history of ancient
Western Civilization
800 BC (Greek epic poem) Iliad & Odyssey
Socrates 470? ~ 399 BC; Plato 424? ~ 348 BC
Aristotle 384? ~ 322 BC
Greek
First Roman Emperor: Augustus 63 BC-14 AD
Roman Empire
Constantine I legalized Christianity in Roman Empire,
330 AD moved the capital to Constantinople
395 AD Christianity became official state religion
Byzantine Empire 330-1453 AD
476 AD End of the western Roman Empire
Germanic Roman general Odoacer deposed
Emperor Romulus Augustulus
Homer's Iliad and the Odyssey:
Trojan War
The Trojan War was waged
against the city of Troy by
the Achaeans (Greeks)
after Paris of Troy took
Helen from her husband
Menelaus, king of Sparta.
The ancient Greeks
thought that the Trojan
War was a historical event
that had taken place in the
13th or 12th century BC,
and believed that Troy was
located in modern-day
Turkey.
Alexander the Great (356 –323 BC)
Shakespearean tragedy: Antony and
Cleopatra
The last pharaoh of Ancient Egypt, Cleopatra, consummated
a liaison with Julius Caesar that solidified her power.
After Caesar's assassination in
44 BC, she aligned with Mark
Antony (Roman general and
important supporter of Julius
Caesar) in opposition to
Caesar's legal heir, Gaius
Julius Caesar Octavianus
(Augustus). After losing the
Battle of Actium to Octavian's
forces, Antony & Cleopatra
committed suicide.
The Printing Press
• The world's first movable type
printing technology was invented
and developed in China by Bi Sheng
(毕升 ？-1051) between the years
1041 and 1048. [沈括《梦溪笔谈》]
• Re-invented and improved by a
goldsmith from Mainz, Germany,
Johannes Gutenberg, ~1450.
Wine Press Screw
Carolingian Script
Paper
Moveable type
The Printing Press
• First book ever
printed on a printing
press using
moveable type:
• The Gutenberg Bible
~1450
Why Printing Press is so important to the
Scientific Revolution
• Books became more affordable to ordinary
people (cost producing a book becomes 300
times cheaper).
• No more transcription errors, making
knowledge accumulation much easier.
– “nothing new under the sun”, ancient discoveries
soon became forgotten.
Books produced per Year
Economic Impact of the Printing Press
The Historical Revolt
• Consequence of the invention of movable type
printing press
– In 1517, Martin Luther started the Protestant
Reformation (宗教改革)
– In science, the spread of Heliocentric cosmology and
the inductive method of reasoning with
experimental data
Pre-Copernicus heliocentric models
Early traces of a heliocentric model are found in several
anonymous Vedic Sanskrit texts composed in ancient
India before the 7th century BCE.
In the sixth century the Indian astronomer and
mathematician Aryabhata anticipated elements of
Copernicus's work.
Aristarchus of Samos in the 3rd century BCE proposed
what was the first scientific model of a heliocentric
solar system: the Earth and all other planets revolving
around the Sun, the Earth rotating around its axis daily,
the Moon in turn revolving around the Earth once a
month. His heliocentric work has not survived.
History of Copernicanism
In 1514 Copernicus made available to friends a short handwritten manuscript describing his ideas about the
heliocentric hypothesis. Thereafter he continued gathering
data for a more detailed work.
In 1533, Johann Albrecht Widmannstetter, secretary of the
pope, delivered in Rome a series of lectures outlining
Copernicus' theory. The lectures were heard with interest
by Pope Clement VII and several Catholic cardinals.
Copernicus' work was in its final form in 1536, and rumors
about his theory had reached educated people all over
Europe. Despite urgings from many, Copernicus delayed the
publication of his book, perhaps from fear of criticism.
Roman Catholic Church's decree
Copernicus died in Frombork on 24 May 1543.
Legend has it that the first printed copy of De
Revolutionibus was placed in his hands on the very
day that he died.
It has been much debated why it was not until six
decades later that the Catholic Church took any
official action against Copernicus's work.
In March 1616, the Roman Catholic Church's
Congregation of the Index issued a decree
suspending De Revolutionibus until it could be
"corrected“.
Main points of Copernicus' theory
•There is no one center of all the celestial circles or
spheres.
•The center of the earth is not the center of the
universe, but only of gravity and of the lunar
sphere.
•All the spheres revolve about the sun as their
midpoint, and therefore the sun is the center of the
universe.
Kepler's laws of planetary motion
Kepler studied the data from Tycho Brahe’s observation.
Around 1605, Kepler found that Brahe's observations of
the planets' positions followed three relatively simple
mathematical laws.
Kepler's laws challenged Aristotelean and Ptolemaic
geocentric view. His asserted that the Earth moved in
ellipses, and his proved that the planets' speeds varied.
Almost a century later Isaac Newton was able to deduce
Kepler's laws from Newton's own laws of motion and his
law of universal gravitation.
Contribution of Galileo Galilei
The key to all of Galileo's discoveries was the
accurate measurement of time.
Galileo used the uniform motion of the
pendulum to measure time
Galileo experimented with various sorts of
motions and falling bodies.
He formulated the basic law of falling bodies,
which he verified by careful measurement.
Galileo’s contribution to Astronomy
Improved telescope (~1608).
Discovered (1610) Jupiter's four largest moons: Io, Europa, Callisto,
and Ganymede and obtained remarkably accurate estimates for their
periods.
Observed that Venus exhibited a full set of phases similar to that of
the Moon.
First European to observe sunspots, the first one to report lunar
mountains and craters, the planet Neptune (1612), and the planet
Saturn (but he was confused by its ring).
Observed the Milky Way, previously believed to be nebulous, and
found it to be a multitude of stars packed so densely that they
appeared to be clouds from Earth.
Located many other stars too distant to be visible with the naked eye.
By 1616 the attacks on the ideas of Copernicus had reached a climax, and Galileo
went to Rome to try to persuade Catholic Church authorities not to ban Copernicus'
ideas. In the end, a decree of the Congregation of the Index was issued, declaring
that the ideas that the Sun stood still and that the Earth moved were "false" and
"altogether contrary to Holy Scripture“.
Galileo was ordered to stand
trial on suspicion of heresy in
1633. and was found guilty of
heresy. He was ordered
imprisoned; the sentence was
later commuted to house
arrest, until his death in 1642.
Cristiano Banti's 1857 painting Galileo
facing the Roman Inquisition
Rehabilitation of Galileo
• Galileo was accused of heresy in 1633 for his
support of Copernicus' heliocentrism and it was
not until 1992 that Pope John Paul II announced
that the Catholic Church's denunciation of
Galileo's work had been a tragic error and
officially conceded that the Earth was not
stationary.
• Pope Benedict XVI later (21 December 2008)
praised Galileo, at events marking the 400th
anniversary of Galileo's earliest observations with
a telescope.
After Galileo’s Death
 The weight of papal authority which had succeeded
in halting the growth of the new science in Italy.
 Following Galileo's death in 1642 that the greatest
advances in science would come from outside Italy in
Protestant countries (with a tradition of protest and
toleration) like England, Holland and Germany.
1642 as a Significant Year
Isaac Newton (1642-1727雍正五年), the man
most responsible for producing modern science
was born.
1620. Francis Bacon published Novum
Organum Scientiarum
1644. René Descartes: (Principles of Philosophy)
“I think, therefore I am”
1644. The Manchu conquer China ending the
Ming Dynasty.
~1760: Beginning of Industrial Revolution
Newton's laws of motion
Newton's First Law (the Law of Inertia) states that an object at rest
tends to stay at rest and that an object in uniform motion tends to
stay in uniform motion unless acted upon by a net external force.
Newton's Second Law states that an applied force
on an object equals the time rate of change of its
momentum, or with constant mass:
F= ma
Newton's Third Law states that for every action there is
an equal and opposite reaction.
Newton's law of gravity
Pierre-Simon Laplace (1749 –1827):
…if we conceive of an intelligence
that at a given instant comprehends
all the relations of the entities of
this universe, it could state the
respective position, motions, and
general affects of all these entities
at any time in the past or future.
The Newtonian Worldview
Reductionism
to understand any complex phenomenon, you
need to take it apart; properties of a system are
explainable by explaining the individual behavior
of its smallest parts.
Materialism
all phenomena, whether physical, biological are
ultimately constituted of matter
The Newtonian Worldview
• Determinism/mechanism
– If you know the initial positions and velocities of
the particles constituting a system together with
the forces acting on those particles (which are
themselves determined by the positions of these
and other particles), then you can in principle
predict the further evolution of the system with
complete certainty and accuracy.
The Newtonian Worldview
Dualism
The Newtonian worldview considers the physical
and spiritual realms to be entirely separate.
while material objects obey mechanical laws, the
mind does not
This way physics can avoid conflicting with
religion.
The Clockwork Universe
• The Universes is like a giant clock that was
assembled and wound up by “God”, but no
longer needs anything else to keep
functioning according to its rule of operation.
Influence of Newtonian
Worldview
Newtonian thinking has had a profound
influence on society: the concept of
natural law inspired democracy
The mechanistic and deterministic view of
nature also inspired communism.
Dualism has had a profound impact on the way
we see ourselves in relation to nature.