January 8, 1642
Arcetri (15 February 1564 – 8 January 1642) was an Italian physicist,
astronomer, and philosopher who is closely associated with the scientific
revolution. His achievements include improvements to the telescope,
a variety of astronomical observations, and effective support for Copernicanism.
According to Stephen Hawking, Galileo has probably contributed more
to the creation of the modern natural sciences than anybody else. He
has been referred to as the "father of modern astronomy,"
as the "father of modern physics", and as the "father
of science". The work of Galileo is considered to be a significant
break from that of Aristotle.
Galileo was born
in Pisa, in the Tuscany region of Italy, on February 15, 1564, the son
of Vincenzo Galilei. Galileo was their first child out of seven (some
people believe six). Most authorities say he was the most talented of
Galileo was tutored
from a very young age. Later, he attended the University of Pisa but
was forced to halt his studies there for financial reasons. However,
he was offered a position on its faculty in 1589 and taught mathematics.
Soon after, he moved to the University of Padua and served on its faculty,
teaching geometry, mechanics, and astronomy until 1610. During this
period he concentrated on science, and made many significant discoveries.
Although he was
a devout Roman Catholic, Galileo fathered three children out of wedlock
with Marina Gamba. They had two daughters (Virginia and Livia) and one
son (Vincenzio). Because of their illegitimate birth, both girls were
sent to the convent of San Matteo in Arcetri at early ages and remained
there for the rest of their lives. Virginia took the name Maria Celeste
upon entering the convent. She was Galileo's eldest child, the most
beloved, and inherited her father's sharp mind. She died on April 2,
1634, and is currently buried with Galileo at the Basilica di Santa
Croce di Firenze. Livia (b. 1601) took the name Suor Arcangela, made
no great impact on the world, and was ill for most of her life. Vincenzio
(b. 1606) was later legitimized and married Sestilia Bocchineri.
In 1612, Galileo
went to Rome, where he joined the Accademia dei Lincei and observed
sunspots. In 1612, opposition arose to the Copernican theories, which
Galileo supported. In 1614, from the pulpit of Santa Maria Novella,
Father Tommaso Caccini (1574-1648) 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 to neither advocate nor teach Copernican astronomy as
religious doctrine. In 1622, Galileo wrote the The Assayer (Saggiatore),
which was approved and published in 1623. In 1624, he developed the
first known example of the microscope. In 1630, he returned to Rome
to apply for a license to print the Dialogue Concerning the Two Chief
World Systems, published in Florence in 1632. In October of that year,
however, he was ordered to appear before the Holy Office in Rome. The
court issued a sentence of condemnation and forced Galileo to abjure.
As a result, he was confined in Siena and eventually, in December 1633,
he was allowed to retire to his villa in Arcetri. In 1634, he was deprived
of the support of his beloved daughter, Sister Maria Celeste (1600-1634),
who died prematurely. In 1638, almost totally blind, Galileo published
his final book, Two New Sciences, in Leiden. He died in Arcetri on the
January 8, 1642, in the company of his student Vincenzo Viviani.
In the pantheon of the scientific revolution, Galileo Galilei takes
a high position because of his pioneering use of quantitative experiments
with results analyzed mathematically. There was no tradition of such
methods in European thought at that time; the great experimentalist
who immediately preceded Galileo, William Gilbert, did not use a quantitative
approach. However, Galileo's father, Vincenzo Galilei, a lutenist and
music theorist, had performed experiments in which he discovered what
may be the oldest known non-linear relation in physics, between the
tension and the pitch of a stretched string. These observations were
in the Pythagorean tradition of music, well-known to instrument makers,
that whole-number mathematical relationships define harmonious (pleasing)
scales. Thus, a limited form of mathematics had long made its way into
physical science at the point of music, and young Galileo was in a position
to see his own father's observations generalize that relationship still
further. Galileo himself would find credit as the first to plainly state
that the laws of nature are mathematical, and (as he said) the idea
that "the language of God is mathematics." This was a sharp
break with earlier traditions of science: up until this point, following
Aristotle, logic, not mathematics had been seen to be the basic intellectual
tool of science.
Galileo also contributed
to the rejection of blind allegiance to authority (like the Church)
or other thinkers (such as Aristotle) in matters of science and to the
separation of science from philosophy or religion. These are the primary
justifications for his description as the "father of science".
In the 20th century
some authorities, in particular the distinguished French historian of
science Alexandre Koyré, challenged the validity of Galileo's
experiments. The experiments reported in Two New Sciences to determine
the law of acceleration of falling bodies, for instance, required accurate
measurements of time, which appeared to be impossible with the technology
of the 1600s. According to Koyré, the law was arrived at deductively,
and the experiments were merely illustrative thought experiments.
however, has validated the experiments. The experiments on falling bodies
(actually rolling balls) were replicated using the methods described
by Galileo (Settle, 1961), and the precision of the results were consistent
with Galileo's report. Later research into Galileo's unpublished working
papers from as early as 1604 clearly showed the validity of the experiments
and even indicated the particular results that led to the time-squared
law (Drake, 1973).
He had even attempted
to measure the speed of light. He did it in an ingenious way.
He climbed up a
hill and told someone else to climb up another hill. They both had lanterns
He then opened the shutter of his lantern and counted to see how long
it took for the other person to open theirs.
Using mathematics, he tried to work out how fast the light was travelling.
But when he tried to repeat the experiment with hills further apart,
he still got the same time lapse. This was because he was measuring
the reaction time of the person.
Galileo showed a
remarkably modern appreciation for the proper relationship between mathematics,
theoretical physics, and experimental physics. For example:
He understood the
mathematical parabola, both in terms of conic sections and in terms
of the square-law.
He asserted that the parabola was the theoretically-ideal trajectory,
in the absence of friction and other disturbances. More remarkably,
he stated limits to the validity of this theory, saying that it was
appropriate for laboratory-scale and battlefield-scale trajectories.
He went on to point out, on theoretical physics grounds, that the parabola
could not possibly be correct if the trajectory were so large as to
be comparable to the size of the planet. (Two New Sciences, page 274
of the National Edition)
He recognized that his experimental data would never agree exactly with
any theoretical or mathematical form, because of the imprecision of
measurement, irreducible friction, and other factors.
Due to the merit of his works, Einstein called Galileo the "father
of modern science".
The belief that Galileo invented the telescope is a common misconception.
However, he improved the device, was one of the first to use it to observe
the sky, and for a time was one of very few people able to construct
one good enough for that purpose. Based only on sketchy descriptions
of the telescope, invented in the Netherlands in 1608, Galileo made
one with about 3x magnification, and then made improved models up to
about 32x. On August 25, 1609, he demonstrated his first telescope to
Venetian lawmakers. His work on the device also made for a profitable
sideline with merchants who found it useful for their shipping businesses.
He published his initial telescopic astronomical observations in March
1610 in a short treatise entitled Sidereus Nuncius (Starry Messenger).
It was on this
page that Galileo first noted an observation of the moons of Jupiter.
This observation upset the notion that all celestial bodies must revolve
around the Earth. Galileo published a full description in Sidereus Nuncius
in March 1610.In the week of January 7, 1610 Galileo discovered three
of Jupiter's four largest satellites (moons): Io, Europa, and Callisto.
He discovered Ganymede four nights later. 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 (after his patrons, the Medici) 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.
From September 1610
Galileo observed that Venus exhibited a full set of phases similar to
that of the Moon. The heliocentric model of the solar system developed
by Copernicus predicted that all phases would be visible since the orbit
of Venus around the Sun would cause its illuminated hemisphere to face
the Earth when it was on the opposite side of the Sun and to face away
from the Earth when it was on the Earth-side of the Sun. In contrast,
the geocentric model of Ptolemy predicted that only crescent and new
phases would be seen, since Venus was thought to remain between the
Sun and Earth during its orbit around the Earth. Galileo's observations
of the phases of Venus proved that it orbited the Sun and lent support
to (but did not prove) the heliocentric model.
Galileo was one
of the first Europeans to observe sunspots. He also reinterpreted a
sunspot observation from the time of Charlemagne, which formerly had
been attributed (impossibly) to a transit of Mercury. 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, first noticed by Francesco Sizi, presented great difficulties
for both the geocentric system and that of Tycho Brahe. A dispute over
priority in the discovery of sunspots led Galileo to a long and bitter
feud with Christoph Scheiner; in fact, there is little doubt that both
of them were beaten by David Fabricius and his son Johannes.
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.
the Milky Way, previously believed to be nebulous, and found it to be
a multitude of stars packed so densely that they appeared to be clouds
from Earth. He also located many other stars too distant to be visible
with the naked eye.
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.
and theories of tides
Galileo never accepted Kepler's elliptical orbits of the planets,
despite Kepler's tremendous amount of data collected by Tycho Brahe,
considering the circle a "perfect" shape. While the Copernican
theory used epicycles to account for the variations, which added a great
deal of complexity, Kepler's model did not.
tides to momentum, as opposed to Kepler's theories which used the moon
as a cause. (Neither of these great scientists, however, had a workable
physical theory of tides; this had to wait for the
work of Newton.) Galileo stated in his Dialogue that, if the Earth spins
on its axis and is travelling at a certain speed around the Sun, parts
of the Earth must travel "faster" at night and "slower"
during the day.
If this theory were
correct, there would be only one high tide per day at noon. Galileo
and his contemporaries were aware of this inadequacy because there are
two daily high tides at Venice instead of one, and they travel around
the clock. But Galileo dismissed this anomaly as the result of several
secondary causes, including the shape of the sea, its depth, and other
things. Against the assertion that Galileo was deceptive
in making these arguments, Albert Einstein developed the opinion that
Galileo developed his "fascinating arguments" and accepted
them uncritically out of a desire for physical proof of the motion of
the Earth (Einstein, 1952).
The noted author
Arthur Koestler, in his book 'The Sleepwalkers', argued that Galileo
was grossly unscientific and dishonest in his methods, and rarely gave
credit where due. Others argue that it is unfair to hold him to modern
"scientific standards" (mathematical theory supported by evidential
trial) with which he himself was only beginning to experiment. By the
standards of his own time, Galileo was often willing to change his views
in accordance with observation. It may also be argued that all modern
scientists (not to mention other professionals) filter their observations
and beliefs through pre-conceived notions. Although this may appear
"dishonest", some of it is actually required for the scientific
process to function (see Bayes theorem). Galileo's perceived dishonesty,
then, is not abnormal.
Galileo's theoretical and experimental work on the motions of bodies,
along with the largely independent work of Kepler and René Descartes,
was a precursor of the Classical mechanics developed by Sir Isaac Newton.
He was a pioneer, at least in the European tradition, in performing
rigorous experiments and insisting on a mathematical description of
the laws of nature.
One of the most
famous stories about Galileo is that he dropped balls of different masses
from the Leaning Tower of Pisa to demonstrate that their time of descent
was independent of their mass (excluding the limited effect of air resistance).
This was contrary to what Aristotle had taught: that heavy objects fall
faster than lighter ones, in direct proportion to weight. Though the
story of the tower first appeared in a biography by Galileo's pupil
Vincenzo Viviani, it is not now generally accepted as true. Moreover,
Giambattista Benedetti had reached the same scientific conclusion years
before, in 1553. However, Galileo did perform experiments involving
rolling balls down inclined planes, one of which is in Florence, called
the bell and ball experiment, which proved the same thing: falling or
rolling objects (rolling is a slower version of falling, as long as
the distribution of mass in the objects is the same) are accelerated
independently of their mass. (Although Galileo was the first person
to demonstrate this via experiment, he was not — contrary to popular
belief — the first to argue that it was true. John Philoponus
had argued this centuries earlier: see also the Oxford Calculators).
He determined the
correct mathematical law for acceleration: the total distance covered,
starting from rest, is proportional to the square of the time (). He
expressed this law using geometrical constructions and mathematically-precise
words, adhering to the standards of the day. (It remained for others
to re-express the law in algebraic terms.) He also concluded that objects
retain their velocity unless a force — often friction —
acts upon them, refuting the generally accepted Aristotelian hypothesis
that objects "naturally" slow down and stop unless a force
acts upon them (again this was not a new idea: Ibn al-Haitham had proposed
it centuries earlier, as had Jean Buridan, and according to Joseph Needham,
Mo Tzu had proposed it centuries before either of them, but this was
the first time that it had been mathematically expressed). Galileo's
Principle of Inertia stated: "A body moving on a level surface
will continue in the same direction at constant speed unless disturbed."
This principle was incorporated into Newton's laws of motion (first
Dome of the cathedral
of Pisa with the "lamp of Galileo"Galileo also noted that
a pendulum's swings always take the same amount of time, independently
of the amplitude. The story goes that he came to this conclusion by
watching the swings of the bronze chandelier in the cathedral of Pisa,
using his pulse to time it. While Galileo believed this equality of
period to be exact, it is only an approximation appropriate to small
amplitudes. It is good enough to regulate a clock, however, as Galileo
may have been the first to realize. (See Technology below)
In the early 1600s,
Galileo and an assistant tried to measure the speed of light. They stood
on different hilltops, each holding a shuttered lantern. Galileo would
open his shutter, and, as soon as his assistant saw the flash, he would
open his shutter. At a distance of less than a mile, Galileo could detect
no delay in the round-trip time greater than when he and the assistant
were only a few yards apart. While he could reach no conclusion on whether
light propagated instantaneously, he recognized that the distance between
the hilltops was perhaps too small for a good measurement.
Galileo is lesser
known for, yet still credited with being one of the first to understand
sound frequency. After scraping a chisel at different speeds, he linked
the pitch of sound to the spacing of the chisel's skips (frequency).
In his 1632 Dialogue
Galileo presented a physical theory to account for tides, based on the
motion of the Earth. If correct, this would have been a strong argument
for the reality of the Earth's motion. (The original title for the book,
in fact, described it as a dialogue on the tides; the reference to tides
was removed by order of the Inquisition.) His theory gave the first
insight into the importance of the shapes of ocean basins in the size
and timing of tides; he correctly accounted, for instance, for the negligible
tides halfway along the Adriatic Sea compared to those at the ends.
As a general account of the cause of tides, however, his theory was
a failure. Kepler and others correctly associated the Moon with an influence
over the tides, based on empirical data; a proper physical theory of
the tides, however, was not available until Newton.
Galileo also put
forward the basic principle of relativity, that the laws of physics
are the same in any system that is moving at a constant speed in a straight
line, regardless of its particular speed or direction. Hence, there
is no absolute motion or absolute rest. This principle provided the
basic framework for Newton's laws of motion and is the infinite speed
of light approximation to Einstein's special theory of relativity.
While Galileo's application of mathematics to experimental physics was
innovative, his mathematical methods were the standard ones of the day.
The analysis and proofs relied heavily on the Eudoxian theory of proportion,
as set forth in the fifth book of Euclid's Elements. This theory had
become available only a century before, thanks to accurate translations
by Tartaglia and others; but by the end of Galileo's life it was being
superseded by the algebraic methods of Descartes.
one piece of original and even prophetic work in mathematics: Galileo's
paradox, which shows that there are as many perfect squares as there
are whole numbers, even though most numbers are not perfect squares.
Such seeming contradictions were brought under control 250 years later
in the work of Georg Cantor.
A replica of the earlest surviving telescope attributed to Galileo Galilei,
on display at the Griffith ObservatoryGalileo made a few contributions
to what we now call technology as distinct from pure physics, and suggested
others. This is not the same distinction as made by Aristotle, who would
have considered all Galileo's physics as techne or useful knowledge,
as opposed to episteme, or philosophical investigation into the causes
Galileo devised and improved a "Geometric and Military Compass"
suitable for use by gunners and surveyors. This expanded on earlier
instruments designed by Niccolo Tartaglia and Guidobaldo del Monte.
For gunners, it offered, in addition to a new and safer way of elevating
cannons accurately, a way of quickly computing the charge of gunpowder
for cannonballs of different sizes and materials. As a geometric instrument,
it enabled the construction of any regular polygon, computation of the
area of any polygon or circular sector, and a variety of other calculations.
(or possibly earlier), Galileo made a thermometer, using the expansion
and contraction of air in a bulb to move water in an attached tube.
In 1609, Galileo
was among the first to use a refracting telescope as an instrument to
observe stars, planets or moons.
In 1610, he used
a telescope as a compound microscope, and he made improved microscopes
in 1623 and after. This appears to be the first clearly documented use
of the compound microscope.
In 1612, having
determined the orbital periods of Jupiter's satellites, Galileo proposed
that with sufficiently accurate knowledge of their orbits one could
use their positions as a universal clock, and this would make possible
the determination of longitude. He worked on this problem from time
to time during the remainder of his life; but the practical problems
were severe. The method was first successfully applied by Giovanni Domenico
Cassini in 1681 and was later used extensively for large land surveys;
this method, for example, was used by Lewis and Clark. (For sea navigation,
where delicate telescopic observations were more difficult, the longitude
problem eventually required development of a practical portable chronometer,
such as that of John Harrison).
In his last year,
when totally blind, he designed an escapement mechanism for a pendulum
clock. The first fully operational pendulum clock was made by Christiaan
Huygens in the 1650s.
He created sketches
of various inventions, such as a candle and mirror combination to reflect
light throughout a building, an automatic tomato picker, a pocket comb
that doubled as an eating utensil, and what appears to be a ballpoint
1857 painting Galileo facing the Roman InquisitionPsalms 93:1; 96:10;
104:5, 1Chronicles 16:30 and Ecclesiastes 1:4,5 speak of the (in some
sense) "firm" and "established" position of the
earth. Galileo defended heliocentrism, and claimed it was not contrary
to those Scripture passages. He took Augustine's position on Scripture:
not to take every passage too literally, particularly when the scripture
in question is a book of poetry and songs, not a book of instructions
or history. The writers of the Scripture wrote from the perspective
of the terrestrial world, and from that vantage point the sun does rise
and set. In fact, it is the earth's rotation which gives the impression
of the sun in motion across the sky.
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 hypothesizing heliocentrism. For the next several years Galileo
stayed well away from the controversy.
He revived his project
of writing a book on the subject, encouraged by the election of Cardinal
Barberini as Pope Urban VIII in 1623. Barberini was a friend and admirer
of Galileo, and had opposed the condemnation of Galileo in 1616. The
book, Dialogue Concerning the Two Chief World Systems, was published
in 1632, with formal authorization from the Inquisition and papal permission.
Pope Urban VIII
personally asked Galileo to give arguments for and against heliocentrism
in the book, and to be careful not to advocate heliocentrism. He made
another request, that his own views on the matter be included in Galileo's
book. Only the latter of those requests was fulfilled by Galileo. Whether
unknowingly or deliberate, Simplicius, the defender of the Aristotelian
Geocentric view in Dialogue Concerning the Two Chief World Systems,
was often caught in his own errors and sometimes came across as a fool.
This fact made Dialogue Concerning the Two Chief World Systems appear
as an advocacy book; an attack on Aristotelian geocentrism and defense
of the Copernican theory. To add insult to injury, Galileo put the words
of Pope Urban VIII into the mouth of Simplicius. Most historians agree
Galileo did not act out of malice and felt blindsided by the reaction
to his book. However, the Pope did not take the public ridicule lightly,
nor the blatant bias. Galileo had alienated one of his biggest and most
powerful supporters, the Pope, and was called to Rome to explain himself.
With the loss of
many of his defenders in Rome because of Dialogue Concerning the Two
Chief World Systems, Galileo was ordered to stand trial on suspicion
of heresy in 1633. The sentence of the Inquisition was in three essential
Galileo was required
to recant his heliocentric ideas; the idea that the Sun is stationary
was condemned as "formally heretical".
He was ordered imprisoned; the sentence was later commuted to house
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.
After a period with the friendly Ascanio Piccolomini (the Archbishop
of Siena), Galileo was allowed to return to his villa at Arcetri near
Florence, where he spent the remainder of his life under house arrest,
dying on January 8, 1642. It was while Galileo was under house arrest
when he dedicated his time to one of his finest works, Two New Sciences.
This book has received high praise from both Sir Isaac Newton and Albert
Einstein. As a result of this work, Galileo is often called, the "father
of modern physics".
Galileo was reburied
on sacred ground at Santa Croce in 1737. He was formally rehabilitated
in 1741, when Pope Benedict XIV authorized the publication of Galileo's
complete scientific works (a censored edition had been published in
1718), and in 1758 the general prohibition against heliocentrism was
removed from the Index Librorum Prohibitorum. On 31 October 1992, Pope
John Paul II expressed regret for how the Galileo affair was handled,
as the result of a study conducted by the Pontifical Council for Culture.
In modern scientific
terms, we consider Galileo's views on heliocentricity to be no fundamental
advance. Most of his discoveries were only further advances of Copernicus'
views. The heliocenticity model that Galileo presented was no more accurate
than the Tychonic system model, the main competing theory at the time.
Stellar parallax, the first evidence from outside the solar system that
the Earth does indeed move, would not be observed until 1838 (Consolmagno
150-152). Today, we know the Sun is no more the centre of the universe
than the Earth is, as it has its own orbit in the Milky Way Galaxy,
just like the Galilean moons of Jupiter have orbits around Jupiter while
Jupiter orbits the Sun. He found this because he realized that the only
orbit the moons could follow is that which orbits behind Jupiter.
Galileo was born
in Pisa, Italy on February 15, 1564. His father, Vincenzo Galilei, was
a musician. Galileo's mother was Giulia degli Ammannati. Galileo was
the first of six (though some people believe seven) children. His family
belonged to the nobility but was not rich. In the early 1570's, he and
his family moved to Florence.
In 1581, Galileo
began studying at the University of Pisa, where his father hoped he
would study medicine. While at the University of Pisa, Galileo began
his study of the pendulum while, according to legend, he watched a suspended
lamp swing back and forth in the cathedral of Pisa. However, it was
not until 1602 that Galileo made his most notable discovery about the
pendulum - the period (the time in which a pendulum swings back and
forth) does not depend on the arc of the swing (the isochronism). Eventually,
this discovery would lead to Galileo's further study of time intervals
and the development of his idea for a pendulum clock.
At the University
of Pisa, Galileo learned the physics of the Ancient Greek scientist,
Aristotle. However, Galileo questioned the Aristotelian approach to
physics. Aristotelians believed that heavier objects fall faster through
a medium than lighter ones. Galileo eventually disproved this idea by
asserting that all objects, regardless of their density, fall at the
same rate in a vacuum. To determine this, Galileo performed various
experiments in which he dropped objects from a certain height. In one
of his early experiments, he rolled balls down gently sloping inclined
plane and then determined their positions after equal time intervals.
He wrote down his discoveries about motion in his book, De Motu, which
means "On Motion."
In 1592, Galileo
was appointed professor of mathematics at the University of Padua. While
teaching there, he frequently visited a place called the Arsenal, where
Venetian ships were docked and loaded. Galileo had always been interested
in mechanical devices. Naturally, during his visits to the Arsenal,
he became fascinated by nautical technologies, such as the sector and
shipbuilding. In 1593, he was presented with the problem involving the
placement of oars in galleys. He treated the oar as a lever and correctly
made the water the fulcrum. A year later, he patented a model for a
pump. His pump was a device that raised water by using only one horse.
Galileo was never
married. However, he did have a brief relationship with Marina Gamba,
a woman he met on one of his many trips to Venice. Marina lived in Galileo's
house in Padua where she bore him three children. His two daughters,
Virginia and Livia, were both put in convents where they became, respectively,
Sister Maria Celeste and Sister Arcangela. In 1610, Galileo moved from
Padua to Florence where he took a position at the Court of the Medici
family. He left his son, Vincenzio, with Marina Gamba in Padua. In 1613,
Marina married Giovanni Bartoluzzi, and Vincenzio joined his father
many mechanical devices other than the pump, such as the hydrostatic
balance. But perhaps his most famous invention was the telescope. Galileo
made his first telescope in 1609, modeled after telescopes produced
in other parts of Europe that could magnify objects three times. He
created a telescope later that same year that could magnify objects
twenty times. With this telescope, he was able to look at the moon,
discover the four satellites of Jupiter, observe a supernova, verify
the phases of Venus, and discover sunspots. His discoveries proved the
Copernican system which states that the earth and other planets revolve
around the sun. Prior to the Copernican system, it was held that the
universe was geocentric, meaning the sun revolved around the earth.
if yer The Inquisition
in the Copernican System eventually got him into trouble with the Catholic
Church. The Inquisition was a permanent institution in the Catholic
Church charged with the eradication of heresies. A committee of consultants
declared to the Inquisition that the Copernican proposition that the
Sun is the center of the universe was a heresy. Because Galileo supported
the Copernican system, he was warned by Cardinal Bellarmine, under order
of Pope Paul V, that he should not discuss or defend Copernican theories.
In 1624, Galileo was assured by Pope Urban VIII that he could write
about Copernican theory as long as he treated it as a mathematical proposition.
However, with the printing of Galileo's book, Dialogue Concerning the
Two Chief World Systems, Galileo was called to Rome in 1633 to face
the Inquisition again. Galileo was found guilty of heresy for his Dialogue,
and was sent to his home near Florence where he was to be under house
arrest for the remainder of his life. In 1638, the Inquisition allowed
Galileo to move to his home in Florence, so that he could be closer
to his doctors. By that time he was totally blind. In 1642, Galileo
died at his home outside Florence.