Sunday, September 20, 2009

The Galileo Myth

Here is they myth about the Galileo case that is still popular with people who should know better. 

Galileo discovered that the earth goes around the sun, using a telescope, which he invented.  The Church, hostile to science, opposed him because of biblical passages that seemed to support geocentrism.  Hauled before the dreaded Inquisition, Galileo would not deny his findings.  He was imprisoned in a dungeon, tortured, humiliated, and at length gave in.  He signed the abject declaration they put before him and was sentenced to prison.  As he tottered out of the court, a broken old man, he muttered, "E pur, se muove!" ("And yet, it does move!") This was a sinister triumph of obscurantism over science. 

Every one of the above statements if false, an actually this legend was concocted over a hundred years after the death of Galileo, when it began to be used to stigmatize the Church as anti-science.  Here is the real story.  Most ancient Greek scientists accepted the geocentric theory, elaborated by Ptolemy.  It is apparently so accurate in accounting for the position of the stars that it is still useful for navigation; in was in short, a theory that worked.  Aristarchus proposed and alternative theory, the heliocentric, but it lacked the symmetry demanded by Greek thought (perfectly circular orbits, for example) and his calculations did not work very well.  Hence, Ptolemy's remained the mainstream astronomical theory for many centuries.  Dissatisfaction with it surfaced in the Middle Ages; inklings of gravity can be found in the work of some medieval physicists, and even Saint Thomas wrote that "the hypotheses of the astrologers (astronomers) are not necessarily true; in employing them they seem to explain the facts, but one is not forced to believe that they are right; perhaps some scheme which is still unknown to man can serve to explain all the appearances of the stellar universe."

Thomas would have had no problem with someone proposing an alternative to the reigning Ptolemaic orthodoxy, and in the early sixteenth century the Catholic cleric Copernicus did so.  The Catholic Church allowed the publication of his work, but Calvin and Luther (who called Copernicsu and ass) condemned it on scriptural grounds.  Some of the technical difficulties with Copernicus' theory were dealt with by Kepler; they made the geocentric theory more plausible, but Kepler was persecuted by the Protestants in Tubingen and had to flee to the Jesuits for protection in 1596.

Enter Galileo.  Obviously, he did no invent the heliocentric theory, but he championed it strongly as not merely a theory but a fact.  He was a better physicist than he was an astronomer, and astronomically he was often on shaky ground.  He did not invent the telescope, though he did improve it.  He did not discover sunspots either.  He wildly wrong about the "moons of Jupiter" and the movement of the tides (as at least on pope tried to explain to him) and though comets were and optical illusion.  Catholic scholars of the time may be forgiven for refusing to admit Galileo's version of heliocentrism as a fact, especially since differently formulated theories had not yet been disproved.  Galileo, however, with his oversized ego and fiery temperament, become more and more intransigent as his theory met with increasing skepticism.  Pope Urban VIII, once so much of a Galileo fan that he wrote an ode in his honor and showed him other signs of favor, suggested that his friend suppor the Copernican system without insisting on its absolute truth because it had not been proved.  Galileo's response was to write his Dialogue Concerning the Two Chief World Systems - Ptolemaic and Copernican, in which he places the Pope's words in the mouth of a dunce.  This amounted to public mockery of a man who was not only Pope, but also a fellow Florentine almost as fiery and hot-tempered as himself. 

In publicly trumpeting his theory as fact despite its apparent contradiction of Scripture, Galileo took it upon himself to interpret Scripture his own way, in spite of his lack of training as an exegete.  "I commenced to play the theologian," he said, commenting on an after-dinner conversation with royalty and scholars.  He was ordered to pipe down, but continued to stir up trouble until at length he found he had gone to far.  Galileo was summoned to Rome to answer to a committee of cardinals.  (In case you've seen pictures of a trembling old man in the midst of a mob of bloodthirsty Inquisitors, those present were exactly four: Galileo, two officials, and a secretary.)  The grounds for complaint against the astronomer were, that if stated as a a fact, his theory could be seen as contradicting passages in Scripture and upsetting the faith of simple people; the public insults to the Pope; the fact that his assertions were not proven; and his apparent claim to the right to decide what Scripture meant in the light of unproven theory. 

During the investigation, Galileo lived in a Vatican palace with a servant, his food and wine provided by the Tuscan ambassador.  He was never in prison, and was neither tortured nor in fear of torture.  The tribunal of cardinals read and voted on the report of the two officials who dealt with the accused; three refused to vote and the Pope never confirmed the verdict.  As Descartes remarked, the action taken against Galileo was merely the disciplinary action of a committee.  Galileo was ordered to remain in his home in Tuscany, where he lived for ten peaceful years, during which he did his best work -on motion and gravity- which would later be built upon by Newton.  This whole sordid episode, the basis for the supposed opposition between science and religion, need never have happened at all if the Galileo had been reasonable as his opponents.  Here is Saint Robert Bellarmine's position: "I say that if there were a true demonstration that the sun is at the center of the world and the earth in the third heaven, and that the sun does not circle the earth but the earth circles the sun, then one would have to proceed with great care in explaining the Scriptures that appear contrary, and say that that we do not understand them than that what is demonstrated is false.  But I will not belief that there is such a demonstration, until it is shown to me."  As Arthur Koestler remarks in The Sleepwalkers, "Galileo did not want to bear the burden of proof; for the crux of the matter is...that he had no proof."

-Catholic Thought and Culture in the Seventeeth Centry. The Scientific Revolution, Diane Mozcar, The Latin Mass, Fall 2006, pages 50-51.

3 comments:

Hans-Georg Lundahl said...

Does he have it since?

Stu said...

Positive, direct proof only came in the 19th century with the demonstration of stellar parallax.

Hans-Georg Lundahl said...

That is what I thought when I was a teenager.

The stallar parallax would have been proof of heliocentrism if all fix stars had been equidistant from sun, and if it had been the real centre of all universe. Then stellar parallax would have been the approximate same size all over.

In fact, stelllar parallax, as it is called, has widely differing sizes and most stars do not have any parallax visible at all. The greatest parallax is less than one second of one degree of a whole circle. 0.76 seconds to be precise. It is the one of proxima Centauri. Proxima Centauri is thought of as closest (need I translate the Latin word?) because it shows greatest parallax. The reasoning behind that is that the "fixed stars" could not do that movement on their own, and the reasoning behind that is that mechanic causes, forces and vectors is all there is to heavenly movements. Which a Christian need not concede.

Here are messages on my blog, two of which are about this question. Study diagrams.

Note that every observation made from earth is necessarily geocentric, so it is not a question of directly heliocentric observations correcting the geocentric ones.