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Lecture

Chapter 6 astronomy.docx

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Department
Natural Science
Course
NATS 1745
Professor
Robin Metcalfe
Semester
Fall

Description
Chapter 6 - At the museum for the history of science by the River Arno in Florence lies Galileo’s finger - He realized that these new sky’s would change the way we understand the universe - There’s a dispute on who invented the telescope - 250 years earlier, craftsmen in Venice begun making small discs of curved glass that people could support in a frame in from of their eyes to improve their vision. Because the glass discs looked like flattened lentils they were called lenses - The first lenses were convex - Then they made concave lenses - In the summer of 1608 a Dutch spectacle maker called Hans Lipperhey found a unique combination of two lenses one convex and one concave could make objects appear much nearer - On September 25 1608, Lipperhey presented a letter to the states general in the Hague applying for a patent for a certain device by means of which all things at a great distance can be seen as if they were nearby - Then two other opticians claimed to have invented the telescope before Lipperhey - Galileo first heard about this in the summer of 1609, when a vendor arrived from Paris to sell a telescope to the Republic of Venice - He realized that it could be a military secret weapon that would let them see enemy ships far out at sea - Venice was a major Mediterranean power - Galileo was at the university of Padua - It was the second most important university in Italy, after Bologna - And he was the professor of math - He also made more money by teaching visiting noblemen the math’s of warfare- surveying, architecture and mechanics - His Geometric and Military compass comprised of a pair of metal rulers linked by third curved ruler with engraved scales that allowed the user to solve every math problem of the day, including changing currencies and setting up cannon - He was ambitious and wanted fame - He was 45 when he discovered the telescope - He soon made a telescope better than any on the market - From the city’s bell tower he showed the Venetian senators approaching ships so far out at sea that it would be 2 hours before the regular lookouts could spot them - He offered his telescope free - The doge of Venice accepted and doubled Galileo’s salary - But he would have to remain in Venice but he missed his hometown of Florence - He was born in 1564 - He wanted to enter the church but his father wanted him to study medicine - His father was a musician Vincenzio - “They who in proof...” said by father when experimenting with instrument - At Pisa he realized he wasn’t good at medicine so he became more and more intrigued by the behaviour of objects in the real world (physics) - One day he was in a service and watched the chandelier swinging - It was the first hint of the pendulum clock; the worlds first accurate time- keeper - He left Pisa without a medical degree - He soon made a name for himself and he was invited back as a lecturer in mathematics - He was very blunt - He saw no point in seeing a gown and he wrote a 301 line poem complaining about it - He was busy discovering the laws of physics - He dropped two balls of different weights from the top of the Leaning Tower of Pisa and they hit the ground at the same time - This might have been a myth - Simon Stevinus did this before him - He was not the first but he was the most thorough - He decided to investigate falling bodies by a very clever trick; by letting balls of various weights roll down a wooden slope - He was trying to disprove Aristotle who said that heavier bodies fall faster than light weight bodies; and once dropped fall at a constant speed - In 1592 he was offered the plum job in Padua where he stayed for 18 years and it was the happiest of his life - This is because he had a mistress Marina Gamba who bore him 3 children - Around this time he became interested in astronomy but only to back up his ideas on physics - He thought the tides go up and down because the earth is rotating under a fixed bulge of water - According to Aristotle and Ptolemy this couldn’t happen because the earth was stationary at the centre of the universe - He read Copernicus’s book that said that the earth both spins around and travels round the sun once a year this idea fitted Galileo’s theory of the tides - He was also sent a book from Kepler - They never met but these twin luminaries were to propel astronomy forward over the next 50 years - Kepler wanted him to speak out “while the assertion that the earth…” - BRUNO o In 1600 in Rome a heretic was publicly burnt at the stake (Giordano Bruno) o Bruno believed in the theories of Copernicus but this was not true; Bruno was a priest but then he proclaimed his own religious ideas. He believed in natural magic. God wasn’t a special divine being; but something you found in every tree. The universe is infinitely big, and every world out there was populated. The devil could be pardoned. Jesus wasn’t divine, but a clever magician. o When things got too hot in Italy he headed north o He converted to the protestant church; but they ended up incensed with his ideas and excommunicated him o Refusing to take back his ideas; he was condemned as a heretic - In 1609 Galileo turned his telescope to the sky - He looked at the moon - Aristotle had said that everything in the heavens was perfect and spherical - Now Galileo could clearly see the moon is not endowed with a smooth and polished surface, but is rough and uneven and like the earth, crowded everywhere with vast prominences, deep chasms and convolutions - He took a carnival toy and turned it into an astronomical instrument - Thomas Harriot had looked at the sky through the telescope shortly before Galileo, while his patron, sir William Lower described the moon “in the full she appears like a tart that my cooke made me last weeke; here a vaine of bright…” - Galileo wasn’t just enthralled with the view, he knew that he was making fundamental new scientific discoveries - He looked at the milky way and concluded that the galaxy is nothing but congeries of innumerable stars - On January 7 1609, he looked at Jupiter and he saw 3 little ‘stars’ close to the planet - A few nights later there were 4 - He kept looking every night and noticed that there were 4 erratic sidereal bodies performing revolutions around Jupiter - They had to be moons - Many critics of Copernicus said that the earth cant be moving because it would leave the moon behind - Clearly Jupiter had some power that made 4 moons move with it; the earth could have been the same power to hold on to our moon as the world orbits the sun - He rushed into print his new findings in ‘starry Messenger’ before anyone else - He had an ulterior motive; he dedicated the short volume to Cosimo de Mdeici; the Grand Duke of Florence - He named the moons of Jupiter the Medicean stars though this never stuck and astronomers now used the classical names proposed by Galileos rival, Simon Marius - He also added “it was Jupiter I say who at your highness’s birth… looked down upon your most fortunate birth from that sublime throne…” - Galileo never believed in astrology but he had no problem in casting a horoscope when occasion demanded - His ploy worked and he became the mathematician and philosopher to the Grand Duke of Tuscany and word spread and
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