When Galileo Galilei was just 19 years old, he was a medical student, but like all university students of his time, he was required to attend church services regularly. Despite attending mass, Galileo found the sermons dull and uninteresting, and his mind often wandered to the fascinating problems of science that captured his curiosity more. One day, he noticed a lamp hanging from the church ceiling swinging back and forth. It had likely been nudged while being lit, but what intrigued Galileo was that the lamp continued to swing for a long time and with a regular rhythm. He observed that although the swings gradually became smaller, the time it took for each swing remained almost the same. Curious, he used the beat of his own pulse to measure the timing and confirmed his observation.
After the church service, Galileo was so fascinated by the swinging lamp that he could not eat or rest. He collected small objects around him, such as keys, ink bottles, stones, and other items, to create makeshift pendulums. He tested each object repeatedly, swinging them on strings of different lengths. Through careful observation, he discovered that the time for one complete swing of a pendulum does not depend on the weight of the object but only on the length of the string. A longer string caused slower swings, while a shorter string caused faster swings. This simple yet profound discovery laid the foundation for the laws of pendulums. Galileo then applied it practically by inventing a device called a pulsometer, which allowed doctors to measure a patient’s pulse. By adjusting the pendulum to match the heartbeat, the doctor could determine whether the pulse was fast or slow based on the string’s length, providing a reliable and innovative way to assess a patient’s condition.
Galileo also challenged the widely accepted Aristotelian idea that heavier objects fall faster than lighter ones. While teaching mathematics at the University of Pisa, he posed a clever question to his skeptical colleagues: “If a 1-kilogram stone falls slower than a 10-kilogram stone, what happens if you tie them together? Does the lighter stone slow the heavier one down, or does the combined mass fall even faster?” To test this, he conducted an experiment by dropping stones of different weights from a tall tower. Initially, due to air resistance, the heavier stone reached the ground slightly before the lighter one, a difference of only a few centimeters. Observing this, Galileo realized that in a vacuum, without air resistance, all objects fall at the same rate regardless of their mass. This experiment not only disproved Aristotle’s long-held belief but also revealed the impact of air resistance on falling objects, marking a significant breakthrough in the understanding of physics.
Galileo’s scientific curiosity also led him to defend the revolutionary ideas of Copernicus. Copernicus proposed that the Earth is not the center of the universe but revolves around the Sun, along with other planets, and that there are many stars like the Sun in the universe. To support this heliocentric model, Galileo published “Dialogue Concerning the Two Chief World Systems” in 1632. This angered the Catholic Church, which had long taught that the Earth was the center of creation. Galileo, nearly seventy years old, was summoned by the Inquisition, forced to place his hand on the Bible, and made to renounce his support for Earth’s motion under threat of excommunication. Yet, as he left the court, he famously muttered, “And yet it moves,” standing by the truth he had discovered.
Galileo’s relentless pursuit of knowledge, careful experimentation, and fearless defense of scientific truth sparked the scientific revolution of the 17th century, transforming our understanding of the universe and laying the groundwork for modern science. His story remains a powerful example of courage, intelligence, and dedication to evidence-based discovery.