366 | Galileo Galilei

Galileo was born on February 15 in Pisa. His youth was marked by intellectual curiosity. He initially began studying medicine at the University of Pisa, but soon shifted his focus to mathematics and natural philosophy. This decision marked the beginning of a career that would fundamentally change the way humanity understands nature.

After completing his studies, Galileo became a lecturer in mathematics in Pisa. He became known for his critical attitude toward traditional Aristotelian natural philosophy, which dominated the academic world at the time. His experiments with falling bodies—including the famous, though historically debated, experiment from the Leaning Tower of Pisa—demonstrated that objects do not fall faster simply because they are heavier. This insight contradicted centuries-old beliefs and laid the foundation for modern mechanics.

In 1592, Galileo moved to Padua, where he taught at the university for eighteen years. This period is often regarded as his most productive phase. He investigated motion, acceleration, and projectile trajectories, and developed instruments such as the geometric compass. His work was characterized by a systematic combination of experiment, mathematics, and observation—an approach that would later become the core of the scientific method.

In 1609, Galileo reached a turning point in his career when he learned of a new optical instrument developed in the Netherlands: the telescope. He built his own improved version and turned it toward the heavens. He discovered that the Moon was not a perfectly smooth celestial body but had mountains and craters. He observed four moons orbiting Jupiter, directly challenging the idea that everything in the universe revolves around the Earth. The phases of Venus further confirmed that this planet orbits the Sun. These observations provided powerful evidence for the heliocentric model of Nicolaus Copernicus, which until then had been largely theoretical.

Galileo published his findings in Sidereus Nuncius (1610), a work that brought him international fame. He was appointed court astronomer to the Grand Duke of Tuscany and became a member of the prestigious Accademia dei Lincei.

His growing conviction that heliocentrism was the correct description of the universe brought Galileo into conflict with the Catholic Church. Although the Church was initially cautious rather than hostile, this changed when Galileo defended his ideas too openly. In 1632, he published Dialogo sopra i due massimi sistemi del mondo, a dialogue comparing the geocentric and heliocentric worldviews. Although formally neutral, the work clearly favored heliocentrism. The Inquisition regarded this as a violation of earlier warnings.

In 1633, Galileo was forced to recant his position. He was convicted and sentenced to lifelong house arrest, which he spent at his home in Arcetri, near Florence. Despite his advanced age and declining health, he continued to work. He wrote Discorsi e dimostrazioni matematiche, in which he laid out the foundations of modern mechanics.

Galileo died in 1642, but his influence extended far beyond his own lifetime. His work formed a crucial link between classical natural philosophy and modern science. By combining experimentation with mathematical analysis, he introduced a way of thinking that became the foundation of physics as we know it today.

His astronomical discoveries transformed humanity’s view of the universe, and his methodological approach inspired generations of scientists. It is no coincidence that he is often called the “father of modern science.”

His work marks the transition from medieval natural philosophy to a systematic, observation- and experiment-based approach to science.