Galileo Galilei

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Galileo Galilei
Presented By Katerina Dimitrova
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Overview

• Born in February 15th 1564 - January 8 1642
• An Italian Physicist, astronomer, astrologer, and
  philosopher associated with the scientific
  revolution.
• His achievements include the first systematic
  studies of uniformly accelerated motion,
  improvements to the telescope, a variety of
  astronomical observations, and support for
  Copernicanism.
• Galileo's experiment-based work is a significant
  break from the abstract approach of Aristotle.
• Galileo is often referred to as the "father of
  modern astronomy," as the "father of modern
  physics", and as the "father of science".

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Biographical Sketch

• Galileo was born in Pisa, in the Tuscany region
  of Italy on Feb. 15th, 1564.
• As a young man he seriously considered the
  priesthood, at his fathers urging he enrolled
  for a medical degree, but instead studied
  mathematics. In 1589 was being appointed to the
  chair of mathematcs.
• In 1592 he moved to the university of Padua,
  teaching Geometry, Mehanics, and Astronomy until
  1610.
• During this period Galileo made significant
  discoveries in both pure science (kinematics of
  motion, and astronomy) and applied science
  (strength of materials, improvement of the
  telescope).

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Biographical Sketch

• In 1610, Galileo published an account of his
  telescopic observations of the moons of Jupiter,
  using this observation to argue in favor of the
  sun-centered, Copernican theory of the universe
  against the dominant earth-centered Ptolemaic and
  Aristotelian theories. The next year Galileo
  visited Rome in order to demonstrate his
  telescope to the influential philosophers and
  mathematicians of the Jesuit Collegio Romano, and
  to let them see with their own eyes the reality
  of the four moons of Jupiter.
• In 1612, opposition arose to the Sun-centered
  solar system which Galileo supported. In 1614,
  from the pulpit of Santa Maria Novella, Father
  Tommaso Caccini (15741648) denounced Galileo's
  opinions on the motion of the Earth, judging them
  dangerous and close to heresy. Galileo went to
  Rome to defend himself against these accusations,
  but, in 1616, Cardinal Roberto Bellarmino
  personally handed Galileo an admonition enjoining
  him neither to advocate nor teach Copernican
  astronomy.
• In 1622, Galileo wrote his first book, The
  Assayer (Saggiatore), which was approved and
  published in 1623.

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Scientific Methods

• Although he tried to remain loyal to the Catholic
  Church, Galileo's adherence to experimental
  results, and their most honest interpretation,
  led to his rejection of blind allegiance to
  authority, both philosophical and religious, in
  matters of science. In broader terms, this helped
  separate science from both philosophy and
  religion, a major development in human thought.
• Galileo was often willing to change his views in
  accordance with observation. Philosopher of
  science Paul Feyerabend also noted the supposedly
  improper aspects of Galileo's methodology, but he
  argued that Galileo's methods could be justified
  retroactively by their results.
• In order to perform his experiments, Galileo had
  to set up standards of length and time, so that
  measurements made on different days and in
  different laboratories could be compared in a
  reproducible fashion. For measurements of
  particularly short intervals of time, Galileo
  sang songs with whose timing he was familiar.

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Astronomy
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Astronomy

• Based only on sketchy descriptions of the
  telescope, invented in the Netherlands in 1608,
  during that same year Galileo made one with about
  3x magnification, and later made others with up
  to about 32x magnification. With this improved
  device he could see magnified, upright images on
  the earth - it was what is now known as a
  terrestrial telescope, or spyglass. He could also
  could use it to observe the sky for a time he
  was one of very few who could construct
  telescopes good enough for that purpose.
• In the week of January 7, 1610 Galileo discovered
  three of Jupiter's four largest satellites
  (moons). He noted that the moons would appear and
  disappear periodically, an observation which he
  attributed to their movement behind Jupiter, and
  concluded that they were orbiting the planet. He
  made additional observations of them in 1620.
  Later astronomers overruled Galileo's naming of
  these objects, changing his originally named
  Medicean stars to Galilean satellites. The
  demonstration that a planet had smaller planets
  orbiting it was problematic for the orderly,
  comprehensive picture of the geocentric model of
  the universe, in which everything circled around
  the Earth.

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Astronomy

• Galileo was one of the first Europeans to observe
  sunspots.
• The very existence of sunspots showed another
  difficulty with the unchanging perfection of the
  heavens as assumed in the older philosophy. And
  the annual variations in their motions, presented
  great difficulties for both the geocentric system
  and that of Tycho Brahe.
• Galileo was also the first to report lunar
  mountains and craters, whose existence he deduced
  from the patterns of light and shadow on the
  Moon's surface. He even estimated the mountains'
  heights from these observations. This led him to
  the conclusion that the Moon was "rough and
  uneven, and just like the surface of the Earth
  itself," rather than a perfect sphere as
  Aristotle had claimed.
• Galileo also observed the planet Neptune in 1612,
  but did not realize that it was a planet and took
  no particular notice of it. It appears in his
  notebooks as one of many unremarkable dim stars.
• Galileo made at least one major scientific error,
  in addition to opposing Kepler's hypothesis that
  the gravity of the moon is the origin of the
  tides. This was his view on the origin of the
  comets of 1618. He argued vehemently in The
  Assayer that they were an optical illusion, in
  opposition to the interpretation of the Jesuit
  Orazio Grassi that they were real, and quite
  distant from the Moon. His alienation of both
  Scheiner and Grazzi likely contributed to the
  hostile response of the Jesuit order to his
  publication of "Dialogue Concerning the Two Chief
  World Systems" in 1632, and the inquisition that
  followed.

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Church Controversy

• By 1616 the attacks on Galileo had reached a
  head, and he went to Rome to try to persuade the
  Church authorities not to ban his ideas. In the
  end, Cardinal Bellarmine, acting on directives
  from the Inquisition, delivered him an order not
  to "hold or defend" the idea that the Earth moves
  and the Sun stands still at the centre. The
  decree did not prevent Galileo from discussing
  heliocentrism hypothetically. For the next
  several years Galileo stayed well away from the
  controversy.
• He was ordered imprisoned the sentence was later
  commuted to house arrest.
• His offending Dialogue was banned and in an
  action not announced at the trial and not
  enforced, publication of any of his works was
  forbidden, including any he might write in the
  future.

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THANK YOU

• Katerina Dimitrova