CAPSTONE Astronomylecture 1, 07.06.2010

Course introduction, models of the sky

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Lect. 1: Large and ancient questions

• Our view of the Universe has undergone extensive change and quantification since the beginnings of recorded science, in the days of the Greeks. Obviously, the Universe is made of stars.

• Are they all painted, as it were, on the vault of heaven or are they dispersed through a boundless Universe?

• Is the Universe made of irreducible atoms, separated by a vacuum, or is matter a plenum, a continuous string of connected material?

•Where is the center of the Universe?

•Are astronomical objects perfect, or physically like Earth, full of asymmetries?

•Is the Universe described by equations, such that knowledge is obtained by quantitative study?

•Or can the nature of things be qualitatively discovered?

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Size and age of UniverseI like to think of the growth in the perceived size of the

Universe in terms of money.

Aristotle’s Universe: 0.003 astronomical units, $0.03.Copernican Universe: 20 AU, $200. Kant’s Universe: 100 Mpc (2x1013 AU), $20,000,000.Einstein’s Universe: 3000 Mpc, or $600,000,000.

The volume of Kant’s Universe was 1036 times larger than that of Copernicus. It is easy to understand that the possibilities of strange things is much greater in the former case. Science fiction writers could, and did, expand their horizons, as well.

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Age of the Universe• With the realization that the Universe was so big, and

that light travels at a finite speed, the age of the Universe had to be much greater than what was previously thought. As shown by the quote at the end of the lecture*, our modern idea of time is world’s apart from the mainstream view up to 1800.

• Bishop Ussher: 1825, ~6000 years.• Darwin:1859, 600,000,000 years (withdrawn after first

edition of OS).• Kelvin, 1850: 30,000,000 years (based on erroneous

model of Earth.)

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• The discovery of radioactivity in 1896 provided a source of heat for the Earth, so a longer time was thought possible.

• By 1926, the estimated age of the Earth was 5,000,000,000 years (and the Universe had to be older).

• We now think the Universe as a whole is about 14,000,000,000 years old.

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The world systems

• Aristotle 300 B.C.• Ptolemy 150 AD• http://www.youtube.com/watch?v=FHSWVLwbb

Nw&feature=related• Copernican (posthumous)• Tychonian (to save appearances, data, and Bible)• Kepler (geometric) (first real cosmology)• http://www.youtube.com/watch?

v=wGjlT3XHb9A&feature=related

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Lipperhey

• Story of Liepperhey—1608.• Murano glass (still sold), Midleberg• VERY first could have been 1585 to 1608• Patent denied. Main interest was in

implements of war (Holland and Spain)

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Stopped down Galilean telescope

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Galileo’s discoveries

• Craters on moon• Sunspots• Many more stars in Milky Way than seen by eye• Moons of Jupiter• Dog ears on Saturn• Phases of Venus• Needed parallax to prove his system over Tychonian.• Stars get smaller as one uses larger telescopes (stars were

far away, contrary to Tycho’s opinion that he could resolve stars and they were nearby, hence should show parallax)

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Tycho’s system

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• An illustration in Yuanjing shuo (1626) explaining the phases of Venus. Venus is shown as circling the Sun while the Sun moves around the earth. (Sun Xiaochun, IHST, CAS, Beijing).

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Riccioli 1650 Tychonian and Copernican system in the balance

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Caption for Riccioli drawing

• Detail from the frontispiece of Giovanni Battista Riccioli’s Almagestum novum (Bologna, 1651). The slogan by the discarded Ptolemy proclaims, “I am raised up by being corrected.” As a Jesuit, Riccioli gave precedence to his own Tychonic-type system, which is more weighty in Urania’s balance than the Copernican system. Note the telescope in the hand of the observer, hundred-eyed Argus. (Collection of Owen Gingerich)

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Result in 1650

• Phases of Venus wiped out Ptolemaic universe• Galileo knew Copernicus was right and Kepler

agreed, but they could not criticize the Tychonic system

• Jesuits demanded Tychonic as not being unscriptural, as opposed to Copernicus.• Accidental discovery of aberration of starlight in

1738 affirmed motion of Earth around the Sun.

3/31/10 PS38000.Telescopes.

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• Galileo’s discoveries dissolved the perfect Universe of Aristotle.

• Accidental discovery of aberration of starlight in 1738 affirmed motion of Earth around the Sun.

RESOLUTION

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• Successful recovery of Comet Halley affirmed that Newton’s physics was useful and had meaning.(circa 1756)

• Parallax found in 1838 removed all doubt.

• Absence of parallax and thought that he could resolve stars with his eye (stars were very close) kept Tychonian system alive

FURTHER RESOLUTION

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Literature (books you may know and when written) aligned with science discoveries.

• The Tao Te Ching (a timeless work of Chinese spiritual philosophy, by Lao Tse, born ca. 570 B. C.) was written in the time of Pythagoras. (Xian, Da Qin, Forest of Stone Steles, arrival of Chrisitanity in China, 638AD, “Light” ).

• Aristophanes' comedy, Clouds (423 B. C.) was written in the time of Democritus, as was Oedipus Rex (after 431 B. C.) by Sophocles.

• The apocryphal book of Judith was written near the time of the poem of Lucretius that records the ideas of Democritus. Machiavelli's The Prince was written in 1513, just before the work of Copernicus.

• Shakespeare wrote Hamlet around 1600-1601, before Kepler developed the laws of planetary motion and at the time that Bruno was killed for advocating the atomist views.

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Literature• John Milton wrote Paradise Lost in 1667, 25 years after the

nearly coincident death of Galileo and birth of Newton. • Milton traveled to Italy and met Galileo in 1638. • Robinson Crusoe was written by Daniel Defoe (1659?-1731) in

1719, near the time of Newton's death. • Candide was written in 1759 by Voltaire (1694-1778), a

champion of science. • Gulliver's Travels was published in 1729, just after Newton

died and Kant was born (by Jonathan Swift, 1667-1745). • Oliver Twist by Charles Dickens (1812-1870) was written in

1838, the year Bessel succeeded in measuring the first parallax, of the star 61 Cygni.

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