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GALILEI, GALILEO (b. Pisa, Italy, 15 February
1564; d. Arcetri, Italy, 8 January 1642), physics,
astronomy.
against terrestrial motion, Galileo added two
arguments in its favor. One concerned the annual
variations in the paths of sunspots, which could not
be dynamically reconciled with an absolutely stationary
earth. Geometrically, all rotations and revolutions
could be assigned to the sun, but their conservation
would require very complicated forces. The Copernican
distribution of one rotation to the sun and one
rotation and one revolution to the earth fitted a very
simple dynamics. The second new argument concerned
the existence of ocean tides, which Galileo
declared, quite correctly, to be incapable of any
physical explanation without a motion of the earth.
His own explanation happened to be incorrect; he
argued that the earth's double motion of rotation and
revolution caused a daily maximum and minimum
velocity, and a continual change of speed, at every
point on the earth. The continual variation of speed
of sea basins imparted different speeds to their contained
waters. The water, free to move within the
basins, underwent periodic disturbances of level,
greatest at their coasts; the period depended on sizes
of basins, their east-west orientations, depths, and
extraneous factors such as prevailing winds. In order
to account for monthly and annual variations in the
tides, Galileo invoked an uneven speed of the earth-moon
system through the ecliptic during each month,
caused by the moon's motion with respect to the
earth-sun vector; for annual seasonal effects, he noted
changes of the composition of rotational and revolutional
components in the basic disturbing cause.
The Dialogue was completed early in 1630. Galileo
took it to Rome, where it was intended to be published
by the Lincean Academy. There he sought to
secure a license for its printing. This was not immediately
granted, and he returned to Florence without
it. While the matter was still pending, Federico Cesi
died, depriving the Academy of both effective leadership
and funds. Castelli wrote to Galileo, intimating
that for other reasons he would never get the Roman
imprimatur and advising him to print the book at
Florence without delay. Negotiations ensued for permission
to print the book at Florence. Ultimately
these were successful, and the Dialogue appeared at
Florence in March 1632. A few copies were sent to
Rome, and for a time no disturbance ensued. Then,
quite suddenly, the printer was ordered to halt further
sales, and Galileo was instructed to come to Rome
and present himself to the Inquisition during the
month of October.
The Trial of Galileo.
The background of the action
is fairly clear. Several ecclesiastical factions were
hostile to the book but at first produced only shallow
pretexts to suppress it. More serious charges were
lodged against Galileo when Urban was persuaded
that his own decisive argument against the literal
truth of the earth's motion—that God could produce
any effect desired by any means—had been put in
the mouth of the simpleminded Aristotelian in the
dialogue as a deliberate personal taunt by Galileo.
Next, a search of the Inquisition files of 1616 disclosed
the questionable document previously mentioned,
which contained a specific threat of imprisonment for
Galileo if he ever again discussed the Copernican
doctrine in any way. Urban, having known nothing
of any personal injunction at the time Galileo sought
his permission to write the book, assumed that Galileo
had deceitfully concealed it from him. The case was
thereafter prosecuted with vindictive hostility. Galileo,
who had either never received a personal injunction
or had been told that it was without force, was
unaware of any wrongdoing in this respect.
Confined to bed by serious illness, he at first refused
to go to Rome. The grand duke and his Roman
ambassador intervened stoutly in his behalf, but the
pope was adamant. Despite medical certificates that
travel in the winter might be fatal, Galileo was
threatened with forcible removal in chains unless he
capitulated. The grand duke, feeling that no more
could be done, provided a litter for the journey, and
Galileo was taken to Rome in February 1633.
The outcome of the trial, which began in April,
was inevitable. Although Galileo was able to produce
an affidavit of Cardinal Bellarmine to the effect that
he had been instructed only according to the general
edict that governed all Catholics, he was persuaded
in an extrajudicial procedure to acknowledge that in
the Dialogue he had gone too far in his arguments
for Copernicus. On the basis of that admission, his
Dialogue was put on the Index, and Galileo was
sentenced to life imprisonment after abjuring the
Copernican “heresy.” The terms of imprisonment
were immediately commuted to permanent house
arrest under surveillance. He was at first sent to Siena,
under the charge of its archbishop, Ascanio Piccolomini.
Piccolomini, who is said to have been Galileo's
former pupil, was very friendly to him. Within a few
weeks he had revived Galileo's spirits—so crushed
by the sentence that his life had been feared for—and
induced him to take up once more his old work in
mechanics and bring it to a conclusion. While at Siena,
Galileo began the task of putting his lifelong
achievements in physics into dialogue form, using the
same interlocutors as in the Dialogue.
Piccolomini's treatment of Galileo as an honored
guest, rather than as a prisoner of the Inquisition,
was duly reported to Rome. To avoid further scandal,
Galileo was transferred early in 1634 to his villa at