<


GALILEO GALILEI
(1564-1642)


CONTENTS

Galileo: An Overview

His Life and Works

His Major Ideas

His Legacy

Galileo's Writings

GALILEO:  AN OVERVIEW

It was when the cause of explaining the movement of the heavens came into the hands of Galileo Galilei that the heliocentric theory of the universe finally became the revolutionary bombshell that rocked the medieval worldview.

It was in the early 1600s that the Italian astronomer Galileo Galilei made his dramatic announcement.  He claimed that from his direct observations of the stars,  it was clear to him that Copernicus' theory was not just a matter of intellectual convenience, but was in fact also the Truth.  Indeed, the sun – not the earth – was the center of things.

His impact did not stop there.  Galileo had been armed with a new-fangled instrument we know as a telescope (even claiming its invention – though it seems he fudged a bit on this truth).  With this telescope he was able to make many unprecedented observations of the heavens beyond even the all-important fact of the earth's loss of central position in the scheme of things.  He observed the pock-marked surface of the moon and the solar flares of the sun – discounting the ancient Greek religious doctrine that these heavenly bodies were the epitome of perfection (actual Platonic Ideals or Forms).

He also observed the moons of Jupiter in their regular orbit as together they all moved about the sun – giving rise to an explanation of how our moon could be similarly held in orbit around the earth as it makes its way around the sun.

Also his telescope revealed considerable mass on the part of some of the heavenly bodies (the planets) which had appeared to the naked eye only as points of light in the sky, demonstrating their existence as substantial material entities: neighbors of the earth. But oddly, even under the powerful scrutiny of the telescope, other lights in the heavens (the stars) still remained as only points of light – giving indication that their distance from our earth must be vastly greater than had been previously imagined!

At first his announcements were met with much interest from the Italian authorities--who seemed initially to be quite supportive of his studies.  But Galileo was a bit of a publicity hound--who found that his celebrity status could be greatly enhanced by clobbering the church with the metaphysical implications of his discoveries.  In case people had not understood the metaphysical implications of his findings he was glad to make them clear.  Thus we was loud in his announcement that both tradition and Scripture – hitherto considered the bedrock of all truth – seemed to be very wrong on their placement of the earth at the center of the universal scheme of things.  Indeed, he seemed to be eager to demonstrate every point he could find where his studies challenged traditional authority.

Being the early 1600s when he made his announcements (in the midst of the Protestant-Catholic religious wars), the church was very sensitive to criticisms of its traditional authority.  A show-down between Galileo and the church was inevitable--given Galileo's personality and the church's highly defensive position.

The world remembers vividly the scene in which Galileo was forced to choose between his theories and his position in Catholic Italy.  It's famed as an example of the blindness of religious ignorance, even bigotry – and the heroism of those who suffered in their efforts to raise the Truth against such ignorance.

In the end, serving as the spokesman for science, he became such a hero.  And science found that as a result of Galileo's boldness it began to move out beyond traditional Christian authority.  His life thus marks the begining the long decline of Christendom and the emergence of the truly secular age of Western culture.

HIS LIFE AND WORKS

Galileo was born in Pisa, Italy, in early 1564, eldest of seven.  His family moved to Florence when he was six and he began attending elementary school, then a monastary, and finally in 1582 the University of Pisa.  By parental choice he was supposed to study medicine.  But he had a keen mind for mathematics and physics, was fond of Euclid and Archimedes' works, and gained an early reputation at the University of Pisa for his philosophical probings.

Though he never completed his degree at Pisa, he nonetheless was called upon to teach at the universities of Pisa and Padua, to serve as mathematician and philosopher in Florence, and embark on a lecture trail that involved teaching and research in mathematics, physics, astronomy, and mechanics.

Galileo was a flambouyant figure, not averse to publicity, the kind of person that stories easily get built around.  One of the more famous ones is his experiment from atop the leaning tower of Pisa from which he dropped weights of a different size to prove that weight made no difference in the speed of their fall – in dramatic refutation of what every person since Aristotle had assumed to be the case.

It was this same flambouyancy, or sense of the dramatic, that got him in trouble with the Catholic authorities.  In his work in astronomy he was tampering with the long-standing world view of Christian civilization – and he was quite aware of the fact. Working with a description of a Dutch telescope, he built a model (claiming  for himself the invention of the concept!) which he used ably in exploring the heavens.

In a short book published in 1610, Messenger of the Stars, he declared that contrary to the teachings of Aristotle, neither the sun nor the moon were perfect spheres.  He detected the solar flares on the surface of the sun, and noted that the surface of the moon was pocked by craters and showed mountains and valleys – much like the earth's.  That is to say, the heavenly realm was not some place of perfection in divine distinction to the imperfection of the earth – as Aristotle had taught.  The realm of the heavens and the realm of the earth were much alike.  He also noticed moons around Jupiter, suggesting that the earth with its moon functioned much like other planetary objects in orbit around the sun.

Evidence of the sun rather than the earth being the center of our heavenly system was further confirmed by Galileo's discovery several years later that Venus evidenced changing light-shadow phases similar to the moon's – and that the cause of these phases or changes was undisputedly the movement of Venus around the sun.

Then in 1616 he wrote an open Letter to the Grand Duchess Christina in which he cautioned against taking certain biblical passages as being literally true (such as the sun standing still so that Joshua could finish a successful battle against the Canaanites).  In defense of scripture, he suggested that the meaning of such passages was to be found at a level much deeper, more allegorical, than at their face-value testimony.

In the context of the hot theological debates taking during the Catholic-Protestant religious wars, and in the zeal of the Church to stamp out further heresy, Galileo's attempt to move scripture from a literal to an allegorical truth-basis was not well received by the Italian authorities.  His friend, Cardinal Belarmine, warned Galileo to interpret his own astronomical findings more as allegory than as literal truth!

For a while Galileo backed down.  But in 1632 he published his Dialogue Concerning the Two Chief World Systems: Ptolemaic and Copernican.  In this he clearly attacked the old Ptolemaic world-view that Western culture had been built on since ancient times--the comforting idea that the earth was the center of all creation.  He amassed vast data to prove that Copernicus was correct in asserting that the sun, not the earth, was the center of the scheme of things.  No matter how uncomfortable that might make us feel about the earth being dethroned as the center of all things, this was simply the truth.

Immediately the Inquisition banned the book.  However it was not ready to condemn Galileo himself – and thus church authorities undertook efforts to get him to come quietly under compliance with the religious priorities of the day.  Galileo wrote a brief apology for the extremity of his work, but could not bring himself to denounce his work.  This appeared as simple intransigence to the authorities and Galileo was placed under arrest – much to his naive surprise.  In the end his sentence was reduced from imprisonment to house arrest – for the rest of his life.  And thus did he live out his days.

Nonetheless he was able to get a final work of his, Concerning Two New Sciences, published in the Protestant Netherlands in 1638.  Here he laid out clearly the underlying assumptions of his work:  that the universe is a composite of matter operating quite predictably in accordance with certain laws of motion.  There was no real distinction between how those laws worked on the earth or in the starry realm.

Four years later, still under house arrest, Galileo died blind – but not forgotten.  His works, however injudicious politically, had left their permanent mark on Western history.  There would be no going back to the old Ptolemaic world view.
HIS MAJOR IDEAS

Galileo challenged deeply the widely held Aristotelian vision of a divine heavenly realm set on its unchanging or eternal course, standing in stark distinction above the realm of the earth with its somewhat confused play-out of things as they struggle to make their way forward to their particular destinies.  To Aristotle and the Christian world that came after him, the heavens were perfect in their shape and movements – complete or fulfilled in their being.  The earth however was highly imperfect.  It was a strange mix of fire, water, earth and air – constantly changing in their combination and in their behavior as things moved to fulfill their particular uncompleted destinies.

Galileo put everything, in heaven and on earth, under one single set of mechanics.  Galileo demonstrated that the heavens were no different from earth – and earth was no different from the heavens.  They both worked under the same set of principles--ones that could be expressed mathematically.

To be sure, Galileo was unable to demonstrate this assertion--for even his mathematical interpretations of the movements of the heavens were flawed.  He, like the Aristotelians, still supposed that the starry realm moved in circular orbits--when in fact they moved in eliptical orbits.  Therefore his computations were not without their mistakes – which his opponents were quick to point out.

But he believed that such a mathematical expression of the composition and movement of creation was possible – and close at hand.  He was close to a mathematical description of the movement of the heavens and knew it.  In fact it took only the adjustments to his theories by Kepler to bring his work to completion.

Thus in his own time Galileo had to pursue this line of logic partly as an act of faith – the kind of powerful faith that moved him forward even against powerful criticism.

HIS LEGACY

This faith in such mathematical precision was his gift to Western culture.  Even today, when we still stand unable to give such precision to our description of human behavior and social dynamics, we still believe with Galileo that such a possiblity exists.  Thus does modern Western science move forward in its hope to formulate all life in accordance with mathematical laws.

Some say that Galileo was a Pythagorean – who inherited the ancient faith of Pythagoras that underlyhing all life are beautiful mathematical principles, awaiting human discovery (though for Pythagoras such discovery arose more a from proper mystical meditation than from proper laboratory research!).  Or that he was a Platonist (not unrelated to Pythagoras) who believed that there were precise formulations which stood behind the welter of change in our physical world.

In any case he left a very compelling argument for us to look at our world quite differently than we had in the past.  Life was described not as the outworking of inherent urges to completion by vast sets of beings and types of beings, each with their own distinct urges (which is what Aristotle thought gave them their particular identities).  The implications of Galileo's thoughts is not that stars do star things, and trees do tree things, and rocks do rock things, and peasants do peasant things, and kings do king things--but that all things operate in a similar manner in accordance to universal mathematical principles.

This was to have revolutionary implications in a world that was in the process of overthrowing a long-standing feudal-ecclesiastical order.

GALILEO'S WRITINGS

  Galileo's major works or writings:

The Messenger of the Stars (1610)
Letter to the Grand Duchess Christina (1616)
The Assayer (1623)
Dialogue Concerning the Two Chief World Systems:  Ptolemaic and Copernican
       (1632)
Concerning Two New Sciences (1638)

Go to the history section: Europe During the First Half of the 1600s

  Miles H. Hodges