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About Galileo Galilei
Biography | Chronology
Biography:
(1564–1642). Modern physics owes its beginning to Galileo,
who was the first astronomer to use a telescope. By discovering
four satellites of the planet Jupiter, he gave visual evidence that
supported the Copernican theory. Galileo thus helped disprove much
of the medieval thinking in science.
Galileo Galilei, who is generally known only by his first name,
was born in Pisa, Italy. His family belonged to the nobility but
was not rich. His father sent him to study medicine at the local
university. Galileo, however, soon turned to a career in science.
In 1583 Galileo discovered the law of the pendulum by watching
a chandelier swing in the cathedral at Pisa. He timed it with his
pulse and found that, whether it swung in a wide or a narrow arc,
it always took the same time to complete an oscillation. He thus
gave society the first reliable means of keeping time.
A lecture on geometry kindled his interest in mathematics, and
he got his father's consent to change his studies. Lack of money
forced him to leave school in 1585, and he became a lecturer at
the Academy of Florence. The next year he attracted attention with
discoveries in hydrostatics. His work in dynamics won him an appointment
as lecturer on mathematics at the University of Pisa in 1589.
He soon made enemies with his arguments against what he considered
mistakes in the science of the day. According to a popular story,
he dropped weights from the leaning tower of Pisa to prove his views
concerning falling bodies. His writings, however, do not mention
such an experiment. In any case, resentment against his views drove
him out of Pisa in 1591.
In 1592 the University of Padua offered Galileo a professorship
in mathematics. About 1609, after word from Holland of Hans Lippershey's
newly invented telescope reached him, he built his own version of
the instrument. He developed magnifying power until on Jan. 7, 1610,
he saw four satellites of Jupiter. He also saw the mountains and
craters on the moon and found the Milky Way to be a dense collection
of stars. Galileo moved to Florence in September 1610 and was a
philosopher and mathematician there for many years. In 1609 Johannes
Kepler published his laws of planetary motion based upon the Copernican
theory. Galileo supported this view strongly. In 1616 he received
a formal warning that the theory was contrary to the teachings of
the church. Nevertheless, he again supported the Copernican view
in a dialogue, ‘The Great Systems of the Universe'.
During his last eight years Galileo lived near Florence under house
arrest for having “held and taught” Copernican doctrine. He became
blind in 1637 but continued to work until his death on Jan. 8, 1642.
Nearly 342 years later, Galileo was pardoned by Pope John Paul II
and the Roman Catholic church finally accepted his teachings.
Galileo's contributions to mechanics include the law of falling
bodies, the fact that the path of a projectile is a parabola, the
demonstration of the laws of equilibrium, and the principle of flotation.
He devised a simple thermometer and inspired a pupil, Evangelista
Torricelli, to invent the barometer. His great contribution to scientific
thinking was the principle of inertia. Before his time everyone
followed Aristotle's theory that when an object moved, something
had to act continuously to keep it moving. Galileo countered this
with the theory that if a body is moving freely, something must
happen to stop it or to make it change direction.
"Galileo" Britannica Student Encyclopedia
http://search.eb.com/ebi/article?eu=296371&query=galileo%20galilei
[Accessed August 13, 2002]
Chronology:
- February 15, 1564
- Galileo born in Pisa (in Tuscany), Italy
- 1564-81
- Educated at Florence and Vallombrosa, Italy
- November 1581
- Enrolls in University of Pisa, intended for medical degree
- Early 1583
- Begins to study math instead of regular studies
- May 1585
- Leaves University without degree
- November 1589-May 1592
- Professor of mathematics at University of Pisa; becomes critical
of Aristotle’s teaching on motion
- December 1592-August 1610
- Professor of mathematics at University of Padua (Venetian Republic)
- 1596-99
- Adapts and improves compass for gunnery calculations
- November 1602
- Letter to Guidobaldo on long pendulums
- October 1604
- Has pendulum law and times-squared law of fall
- 1605-08
- Work culminates in finding speed of fall proportional to time,
and parabolic trajectory of projectiles
- August 1609
- Produces first nine-power telescope
- December 1609
- Determines that lunar surface is rough and mountainous
- January 1610
- Discovers moons of Jupiter
- March 1610
- Starry Messenger published in Venice
- September 1610
- Moves to Florence in employ of Grand Duke of Tuscany
- June 1612
- Bodies in Water published in Florence
- May 1613
- Letters on Sunspots published in Rome
- February 1616
- Cautioned by Roman Inquisition to abandon Copernicanism
- October 1623
- The Assayer published in Rome
- April-June 1624
- Visits old friend in Rome, now Pope Urban VIII; soon begins
to write Dialogue
- February 21, 1632
- Dialogue published in Florence
- June 22, 1633
- Condemned by Inquisition for suspicion of heresy
- December 1633
- Returns to home in Arcetri
- June 1638
- Two New Sciences published in Leyden, Holland
- January 8, 1642
- Galileo dies in Arcetri
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