pulse to keep time, he
was surprised to find that the period of an oscillation of the lamp was independent
of the size of the arc of oscillation.
Later, by experiments he showed that
the period of a swinging pendulum is also independent of the weight of the
pendulum's bob and thus depends solely on the length of the pendulum.
reported that Galileo's interest in science and mathematics was roused by this
problem and then further stimulated by the chance attendance at a lecture on
geometry at the university. The result was that he asked for and secured,
parental permission to abandon medicine and to devote himself to science and
mathematics instead, fields in which he possessed strong natural talent.
When twenty-five,Galilieo was appointed professor of mathematics at the
University of Pisa, and while holding this appointment is said to have performed
public experiments with falling bodies. According to the story, before a
crowd of students, faculty, and priests he dropped two pieces of metal, one ten
times the weight of the other from the top of the leaning tower of Pisa. The two
pieces of metal struck the ground at practically the same moment, thus contradicting
Aristotle, who said that a heavier body falls faster than a ligher one.
Galileo arrived at the law that the distance a body a falls is proportional to the
square of the time of falling, in accordance with the familiar formula s = gt2/2.
Even the visual evidence of Galileo's experiments however did not shake the
faith of the other professors at the university in the teaching of Aristotle. The
authorities at the university were so shocked at Galileo's sacrilegious insolence
in contradicting Aristotle that they made life unpleasant for him there with the
result that he resigned his professorship in 1591. The following year he accepted a professorship
at the University of Padua, where there was an at
mosphere more friendly to scientific pursuits. Here, for nearly eighteen years,
Galileo continued his experiments and his teaching and won widespread fame.
By 1609, the news of the invention of the spyglass reached Galileo, who
soon made a spyglass greatly superior to the one made by Lippershey.
Galileo went on and made four more telescopes, as his instruments were
named(from the Greek tele, "far," skopos, "watching"), each more powerful
than the last.
He had discovered Jupiter's four bright satellites and observed a striking confirmation of the Copernican
theory of smaller bodies revolving about larger ones. With his telescope,
Galileo observed sunspots, the mountains on the moon, the phases of Venus,
and Saturn's rings. But these discoveries only aroused once more the bigoted
opposition of many churchmen, who accepted the authority of Aristotle; Aristotle
had asserted that the sun is without blemish and that the earth, and hence
man, is the center of the universe. One churchman even accused Galileo of
placing the four satellites of Jupiter inside his telescope.
Finally, in 1633, one year after his publication of a book that supported the
Copernican theory, Galileo was summoned to appear bofore the Inquisition,
and there an ill and an old man forced under the threat of torture, to recant
his scientific findings. His book was placed on the Index of prohibited works
and remained there for two hundred years. Having perjured his conscience, the
old scholar's life was broken. He was permitted to continue innocuous scientific work,
but became blind and died in January, 1642, still under the supervision of the Inquisition and a virtual
prisoner in his own home.
There is a legend that, as Galileo rose to his feet after his forced recantation
and denial of the earth's motion, he muttered softly under his breath to
himself, "The earth does move all the same." Whatever the basis of this story
it has come to be a sort of proverb to the effect that truth shall prevail despite all
attempts at suppression. And so it come to pass, for the year 1642, which saw
the death of Galileo in captivity, also saw the birth of Isaac Newton.
To Galileo, we owe the modern spirit of science as a harmony between
experiment and theory. He founded the mechanics of freely falling bodies and
laid the foundation of dynamics in general, a foundation upon which Isaac
Newotn was able later to build the science. He was the first to realize the
parabolic nature of the path of a projectile in a vacuum and speculated on laws
involving momentum. He invented the first modern-type microscope and the
once very popular sector compasses. Historically
interesting are statements made by Galileo showing that he grasped the idea of
equivalence of infinite classes, a fundamental point in
Cantor's nineteenth-century theory of sets, which has been so influential in the
development of modern analysis.
It would seem that Galileo was jealous of his famous contemporary. Johann
Kepler, for although Kepler had announced all three of his important laws
of planetary motion by 1619, these laws were completely ignored by Galileo.
All his life. Galileo was a religious man and a devout Catholic. Accordingly,
it distressed him to find the views to which he was irresistibly led by his
observations and reasonings as a scientist condemned as contradicting the
scriptures of the Church, of which he considered himself a loyal member. He
therefore felt compellen to reason for himself the relation between science and
scripture. Many scientists have, from time to time, found themselves in this
position. It occurred, for example, in the middle of the nineteenth century,
when difficulties were felt in reconciling Darwin's theory of evolution with the
Biblical account of the creation of living things.