May 1, 2025

The Cathedral (Duomo) and Galileo

The cathedral is the greatest masterpiece of Pisa Romanesque architecture.

In the 11th century, Pisa, having participated in the Crusades, engaged in a naval battle against an Islamic fleet off the coast of Palermo, Sicily, and emerged victorious.

To commemorate this victory, the cathedral was built over 50 years using the gold and silver treasures seized from the Muslims.

The columns used in the construction were brought back as war trophies from Greek temples in Palermo.

Inside the cathedral, there are numerous works of high historical and artistic value.

Among them, the most notable is the pulpit of early 14th century, which is considered one of the finest examples of Italian Gothic sculpture.

However, for us, an even more important item is the lamp hanging in front of this pulpit.

It was in 1583, before Galileo’s discovery of the "law of falling bodies," that he, then a medical student at the University of Pisa, observed this lamp.

Having received a rigorous education from his enthusiastic father, Galileo entered medical school at the age of 17.

He stood in front of the pulpit of the Duomo, watching a bronze chandelier (lamp) swaying in the wind.

He noticed that, even as the amplitude of the pendulum’s swing gradually decreased, the time for one complete oscillation remained constant.

He was a medical student, so he confirmed this observation by timing it with his own pulse.

This was the discovery of the "isochronism of the pendulum."

Since then, the chandelier in Pisa’s cathedral has been called the “Lamp of Galileo.”

Today, it is believed that Galileo had actually discovered the pendulum’s principle six years before observing this lamp.

Later, disillusioned by his medical lectures, Galileo dropped out of medical school and pursued mathematics, physics, and astronomy.

He went on to teach these disciplines for many years at the universities of Pisa and Padua.

One of his most historically significant contributions was in the field of astronomy.

①    The existence of moons orbiting Jupiter.

②    The phases of Venus.

③    The presence of sunspots on the Sun.

These three discoveries led Galileo to firmly believe that they were evidence supporting the heliocentric theory (that the Earth orbits the Sun).

It is well known that Galileo was convicted by the Catholic Church for advocating heliocentrism, which contradicted the geocentric theory (that the Sun orbits the Earth).

He was disliked because he understood the essence of Christianity better than the church priests and explained it using scientific terms.

As a result, he was sentenced in a sham trial.

Galileo was sentenced to life imprisonment, but his sentence was immediately commuted to house arrest.

However, he was not allowed to return to his home in Florence and was forced to live under surveillance in a designated residence, forbidden from going outside, until his death.

Naturally, he was stripped of all his titles.

Even after his death, his honor was not restored, and he was not permitted a Christian burial.

The Grand Duke of Tuscany, Galileo’s patron, could not bear to see him buried as a heretic and postponed his funeral until permission from the Pope was granted.

More than 100 years later, in the 18th century, Galileo was finally given a proper burial in the Basilica of Santa Croce in Florence with the Pope’s approval.

Eventually, in 1965, Pope Paul VI mentioned the Galileo trial, which initiated a reevaluation of the case.

Finally, in 1992, Pope John Paul II officially admitted that the trial had been a mistake and issued an apology to Galileo.

This is an event that remains fresh in our memories.

This happened 350 years after Galileo’s death—how moving!

April 1, 2025

The Leaning Tower of Pisa and Galileo Galilei

Pisa is a port town located 90 kilometers west of Florence, at the mouth of the Arno River where it flows into the Ligurian Sea.

During its peak (11th–13th centuries), Pisa reigned over the Mediterranean as a maritime trading state alongside Venice, Genoa, and Amalfi.

In the 16th century, when Pisa gained fame as a university city, Galileo Galilei was born here.

Galileo taught at the University of Pisa and solidified the institution's reputation in the sciences.

Speaking of Pisa, one cannot overlook the Leaning Tower, Italy’s most famous building.

Construction of this bell tower, an annex to the adjacent cathedral (Duomo), began in the 12th century—during Japan’s Heian period.

Due to the weak foundation on the marshy ground, the tower began to tilt shortly after construction started.

Despite several interruptions in the building process, the tower was completed in the 14th century (Japan’s Muromachi period), about 200 years after its inception, with a tilt of approximately five degrees.

The tilted tower’s height measures 55.2 meters on the northern side and 54.5 meters on the southern side, creating a 70-centimeter difference.

The topmost level is displaced by three meters relative to the base.

Galileo Galilei famously conducted an experiment using this tilted tower.

He challenged Aristotle’s claim that "the speed of a falling object is proportional to its weight"—a widely accepted idea in ancient Greece.

To disprove this, Galileo dropped two lead cannonballs of different sizes from the southern tip of the tower's roof.

Lead cannonballs were used because their high density and small volume minimized air resistance.

The result?

Both cannonballs hit the ground simultaneously.

This confirmed that "in the absence of air resistance, the speed of a falling object is independent of its weight."

Galileo later published this groundbreaking discovery in the 17th century in his work Dialogue Concerning Two New Sciences, which introduced the famous Law of Falling Bodies.

As mentioned in the Florence episode, Galileo Galilei applied the method of "direct observation and verification" to his work in astronomy and physics.

He emphasized observation and believed that experiments were essential to validate his theories.

While this approach is considered fundamental today, it was revolutionary at the time, standing in opposition to deeply rooted traditions and the powerful Catholic Church.

Nevertheless, Galileo remained undeterred, continuing his research with unyielding faith in his own convictions.