# Galileo Galilei and the Birth of Modern Science

June 27, 2021Galileo Galilei (1564-1642) followed the path opened by Copernicus and Kepler in terms of the establishment of modern science, and laid the foundations of both modern astronomical dynamics and mechanical physics. The establishment of modern natural science took place in Galileo’s system, as it clearly and clearly reveals the general laws of dynamic and mechanical physics, and the last step on this path came from Newton.

Galileo, as a scientist who adopted the heliocentric view of Copernicus, defended this theory practically and theoretically. In his work titled Conversation on the Two Major System of Universes, he compared the geocentric universe understanding of Aristotle and the church with the heliocentric system of Copernicus and took a stand in favor of the Copernican system. That’s why he was persecuted by the church and lived on probation. Galileo was also famous for the discoveries he made with the telescope, and with his telescope he detected the spots of the Sun, the phases of the planet Venus, some unevenness on the moon surface such as mountains and valleys, and the four moons of Jupiter. All these discoveries were not something the church could tolerate. Because the number seven was sacred in Christianity and the existence of seven celestial bodies in the sky, including the earth, the four planets, the moon and the sun, was considered sacred. However, when Galileo included all four satellites, eleven celestial bodies were in question. Traditionalists claimed that the telescope produced images. Of these, Cremonini preferred Aristotle’s evidence to his own senses, instead of looking at the sky with a telescope, and saw Galileo’s findings as sense delusions (Gjertsen, 2000: 166). But time proved Galileo right in many ways.

Galilei’s main contributions were in the field of physics, and his discoveries in this field ensured the establishment of modern physics. Galileo formulated valid laws for all kinds of motion in nature. For this reason, he is considered the father of mechanical physics. He found the laws of free fall and free oscillation of objects, pendulum laws. He was the first to discover acceleration, a very important fact in the motion of falling objects. Acceleration means that the velocity changes in magnitude and direction. Thus, an object moving uniformly in a circle has an acceleration towards the center of the circle at all time points (Russell, 1997: 280). In light of this concept, Galileo formulated the law of falling bodies: if an object is falling freely in vacuum, its speed increases at a constant rate with each passing second; acceleration, that is, the rate of increase of speed per second is 30.48 cm on average. According to this, all objects, whether lead or feather, fall at the same speed and in the same time in an air evacuated environment. Galileo also found the so-called law of inertia within the laws of motion. According to this, an object in motion will continue its motion forever if there is no obstacle in front of it. But if there is any change in velocity or direction of motion, it must be explained by the action of any force. This law would become the first law of action in Newton’s hands. Therefore, this law is also called the law of inertia. However, since there are always factors such as gravity and air pressure in the environment, an object that is initially thrown parallel to the ground, for example, an arrow, will move horizontally for a while and then approach the ground with a speed proportional to the time elapsed since the beginning of the motion. Meanwhile, the line of the path it takes takes the form of a parabola. It does not suddenly decline sharply as it is thought. With all the laws he found in this field, Galileo proved his greatness in terms of being the founder of dynamics.

It is clear that the method Galileo Galilei followed in his technical studies had an important role in achieving successful results: This method is the method of observation and experiment. Natural events are meticulously observed and the results have been confirmed by experiments. Again, in this method, the language of facts is a mathematical-geometric language: all the laws that Galileo found in the field of physics were expressed in a mathematical formulaic language, just like Kepler did, and there is no alternative to it. Because the relationships between phenomena in nature show a structure that can only be expressed through measurement as mathematical ratios and proportions. For this reason, the science of physics has now become a full science of quantity with Galileo. Whereas, according to Aristotle, physical phenomena were nothing but changes in quality in objects in general. Attributes, on the other hand, are not suitable for measurement, in other words to be expressed in a mathematical language. For this reason, Aristotle’s physics of quality inevitably fell short in relational explanations of phenomena in nature. Whereas, according to Galileo, “Nature is a book written in mathematical language.” For this reason, it is necessary to analyze the codes of nature only with a methodical approach using the language of mathematics.

Prepared by: Sociologist Ömer YILDIRIM

Source: Omer YILDIRIM’s Personal Lecture Notes. Atatürk University Sociology Department 1st Year “Introduction to Philosophy” and 2nd, 3rd Year