Download How a small scientific spark grew during the Renaissance

4/29/2011
HAARLEMMERMEER
LYCEUM
HOW A SMALL SCIENTIFIC SPARK GREW
DURING THE RENAISSANCE
Changes by Ptolemaeus, Copernicus, Kepler, Brahe, and Galileo
| Melanie de Gier 2L
How physics changed during the
renaissance
middle Ages
In the middle ages people were authorized by the Church. The Church adopted the motion of the
Greeks, which meant that they thought the Earth was the centre of the Universe. If anyone would
not accept this, they would be killed by Supervisors, who were spies. And gaining knowledge was
considered to be a passive process of merely having faith in the alleged wisdom of others.
From Ptolemaeus life we don’t know much. But he was more common as Ptolomy. However, he is
known for three scholar works, they all have to do with Geography, Astronomy and Geometry.
Ptolomy made the first steps in understanding our Universe. The model of the solar system
developed by Ptolemy (87 - 150 A.D.) was a refinement of Aristotle's (384 - 322 B.C.) universe. This
model consisted of a series of concentric spheres, with the Earth at the center (geocentric). The
motions of the Sun, Moon, and stars were based on perfect circles. To account for the observed
retrograde motion of the planets, it was necessary to resort to a system of epicycles, whereby the
planets moved around small circular paths that in turn moved around larger circular orbits around
the Earth. This accounts for retrograde motion.
By this and when the end of the middle Ages came, kings get wealthier and the Church is in their
way.
Copernicus was a Polish astronomer and mathematician who was a proponent of the view of an
Earth in daily motion about its axis and in yearly motion around a stationary sun. This theory
profoundly altered later workers' view of the universe, but was rejected by the Catholic Church. He
was born in 1550, and on his deathbed he wrote a book: “On the revolution of heavenly bodies.”
He found out the Earth was rotating around the Sun. This is called the heliocentric system. But
when he stated this, he still had several questions he couldn't answer.
Hundred years later everything changed, people were scared of the church because there was an
inquisition: The military police of the Church who were torturing mankind.
And there was an Index: It was a list with forbidden books, which were in fact the good books
because the Church hated them. It was like a blacklist.
Johannes Kepler was a German mathematician and astronomer who discovered that the Earth and
planets travel about the sun in elliptical orbits. He gave three fundamental laws of planetary
motion. He also did important work in optics and geometry. Kepler was in the lowest side of
society, but even though, he was a master mathematical genius.
Tycho Brahe was a Danish astronomer who is best known for the astronomical observations which
led Kepler to his theories of the Solar system. He was a noble man and lost his nose, which was
replaced by a golden nose. He found Nova Stella, and the Danish king built an observatory for him
in Uranium burg, to break the power of the Church.
And he had a model: The Earth rotates around the Sun, the rest of the planets rotate around the
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earth.
They had huge differences in character, and Johannes Kepler and Ticho Brahe did not work
together. Ticho Brahe feared Kepler would steal his ideas so he only showed him half of his
voluminous data. Later, Ticho Brahe died first and Kepler got his data, with which he worked for 29
years until he died too. But during this period of time he formulated his three laws of Planetary
Motion:
Kepler’s first law:
The orbits of the planets are ellipses, with the Sun at one focus of the ellipse.
Kepler’s second law:
The line joining the planet to the Sun sweeps out equal
areas in equal times as the planet travels around the
ellipse.
Kepler’s third law:
The ratio of the squares of the revolutionary periods for
two planets is equal to the ratio of the cubes of their semi major axes:
In this equation P represents the period of revolution for a planet and R
represents the length of its semi major axis. The subscripts "1" and "2"
distinguish quantities for planet 1 and 2 respectively. The periods for the
two planets are assumed to be in the same time units and the lengths of the semi major axes for
the two planets are assumed to be in the same distance units.
12 years after the death of Kepler, Galileo Galilei was born. Galileo Galilei was an Italian scientist
who formulated the basic law of falling bodies, which he verified by careful measurements. He
constructed a telescope with which he studied lunar craters, and discovered four moons revolving
around Jupiter and espoused the Copernican cause. Galileo’s telescope was made of one smaller
strong lens, and one bigger less strong lens. This type of telescope was first used for seeing
enemies from far away, but it was originally Dutch. With it, Galileo was able to see the four major
moons of Jupiter (now called the Galilean Satellites in his honour, but he called them the “Medician
Sarts”). Besides these, which rank among the most important of his observations, Galileo drew
detailed diagrams of Earth's moon, observing valleys and mountains and craters. He also looked at
the sun and observed dark blemishes on its surface, which are now called sunspots. From the
movement of these, he was able to determine that the sun has a rotation period of about one
month.
He published a book on these observations of celestial bodies, and it was called Sidereus Nuncius
(The Starry Messenger).
Galileo liked the ideas of Copernicus, but he had some critics: Why don’t we notice the fast
movement; how can we walk on the ground etc.
He tested the laws of falling bodies, and motion. And he came to these conclusions:
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Law of falling bodies:
If two objects falling at the same time, they will reach the ground at the same
moment, and the weight difference does not matter. This is defined by:
{This law he got out of the law of Inertia, which he defined earlier.}
Law of Motion:
An object that is in motion will not change its velocity unless an unbalanced force acts upon it.
He also had a principle: All bodies fall with the same acceleration, regardless of its mass and its
composition. The motion of any body depends only on the event and its initial velocity when it was
released. And from that he made the law of Gravitation: Heavy objects fall as fast as light objects.
This law was worked out later by Newton and Einstein, who both used this law as an example. But
Galileo also used ideas of Archimedes, e.g. his law of lever and the balance of torques were both
second nature to him.
The observations of Heavens
When in 1604 a new star(nova) appeared, Galileo took his chance to support the Copernican
theory instead of Aristotle’s after doing observation on the ‘new’ star. This appearance led to
Galileo’s interest in Astronomy. He improved the Telescope in 1609, so he had a powerful tool to
observe heavens. With the telescope, Galileo discovered mountains and valleys on the moon in
1610. He also discovered the Moons of Jupiter, and the sun spots, as well as many stars. In the
same year, Galileo became court philosopher and mathematician of the Medici Family, the dukes
of Toscany- who offered him a good salary. In 1616, he met inquisition officials who forbade him to
support the Copernicus theory, because it was against the Church.
Galileo did publish a book after their visit called the Dialogue. However, it wasn’t so successful, the
Church was very quick and the book was placed on the Index of Prohibited Books and Galileo was
taken to Rome to stand trial before the Inquisition. He was sentenced to home imprisonment,
although it didn’t stop him. He continued his scientific activities and published an important book:
Discourse on Two New Sciences, in which he summarized all his ideas. The book was smuggled out
of Italy and was distributed throughout Europe. In 1638, Galileo became completely blind. A lot of
people think this was because of his observations of the sunspots, but these were always done
during sunset, and weren’t dangerous for his eyes. In fact he was blinded by cataracts and
glaucoma, when he was 72-74 years old. He continued his activities though, and he was helped be
students, whom he dedicated his letters. In 1642 Galileo past away, but he left a big help for our
world.
All the scientific thinkers have contributed to the world of today. Whether they had wrong or right
ideas, these could and should be remembered and improved. After Galileo, Newton and Einstein
helped the world by their wonderful ideas. But to summarize them one by one:
Melanie de Gier
“By this I would like thank these heroes’s in science. They helped us
understand the universe, and they had wonderful ideas. I think there still a lot
to learn for us on the world. This essay helped me to understand some difficult
thinking were people gave their life for”-Melanie de Gier
Resources:
http://www.lasalle.edu/~smithsc/Astronomy/retrograd.html
http://filer.case.edu/~sjr16/advanced/pre20th_europe.html
http://csep10.phys.utk.edu/astr161/lect/history/kepler.html
http://library.thinkquest.org/11924/galileo.html
http://muse.tau.ac.il/museum/galileo/galileo_low_of_fall.html
http://www.mtholyoke.edu/courses/mpeterso/galileo/scaling8.pdf
http://www.phy.syr.edu/courses/modules/LIGHTCONE/newton-gr.html
http://muse.tau.ac.il/museum/galileo/galileo.html
http://www.physics.byu.edu/faculty/rees/202/00general/high.pdf
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Melanie de Gier