In this blog post, we will follow the history of the study of matter, starting with ancient atomic theory, and examine how string theory attempts to explain the four fundamental forces of nature.
The ancient Greeks believed that all matter was composed of indivisible particles called “atoms.” They believed that the vast and diverse material world was formed by various combinations of a few types of atoms. They reached this conclusion through various philosophical reasoning and observations of nature, which was a very innovative way of thinking at the time. Ancient Greek philosophers, especially Democritus and Leucippus, developed the concept of atoms in their pursuit of a deeper understanding of the nature of matter. This atomic theory remains an important concept that forms the basis of modern science. Over time, the concept of the smallest unit has undergone many changes, but the ancient Greek view of matter is still accepted as truth. In the 19th century, scientists discovered tiny elements that they believed to be the smallest units of matter and named them “atoms,” a term inherited from the Greeks. They believed that atoms were immutable and the basic units of all matter.
However, this was not the smallest unit of matter. In the 1930s, it was discovered that atoms are complex structures consisting of an atomic nucleus composed of protons and neutrons, surrounded by electrons. For some time after that, physicists believed that protons, neutrons, and electrons were the smallest units, or atoms, as the ancient Greeks had thought. However, in 1968, experiments at the Stanford Linear Accelerator Center revealed the shocking fact that even protons and neutrons are not the smallest units of matter. Protons and neutrons are composed of two particles called “down quarks” and “up quarks.” Since then, physicists have invented even more powerful instruments and discovered many new particles.
Why are there so many different types of particles in nature? Why is there no apparent regularity in the values (masses) of each particle? These questions remained a great mystery to physicists for a long time. When we consider the forces acting between particles, the questions become even bigger. There are four forces acting between particles: gravity, electromagnetism, strong force, and weak force, and they all differ in magnitude and nature. Why do these four types of forces exist? These questions have been continuously explored through scientists’ efforts to understand the fundamental principles of nature.
One candidate theory that may answer these questions is superstring theory. The basic concept of superstring theory is that all matter is made up of vibrating strings. According to superstring theory, the appearance of matter depends on how these strings, which are the smallest units of everything, vibrate. Therefore, all particles discovered by physicists are “different faces of vibrating strings.” This idea also applies to the four fundamental forces of nature. For example, heavy particles are made up of strings that vibrate violently, while light particles are made up of strings that vibrate relatively gently.
Previous physicists believed that various particles, considered to be the smallest units of matter, had their own unique forms and characteristics. However, string theory completely overturned this idea. This is because the strings, which are the smallest units of matter, are all the same entity. According to the theory, strings are one-dimensional objects that vibrate at a very small size, and their characteristics are determined by their vibration modes.
If this is true, then the universe, with its countless strings vibrating in different ways, is like a giant stage on which a magnificent “cosmic symphony” is being played. The performers of this cosmic symphony are the fundamental laws of nature, and we are constantly striving to understand the music. The discovery of string theory has opened up new possibilities for physicists and provided important clues for understanding the fundamental principles of the universe.
This theory also has the potential to provide an integrated explanation for various unsolved problems. For example, string theory could be a powerful tool for integrating general relativity and quantum mechanics, and for explaining the initial conditions of the universe. Although this theory has not yet been fully verified, its potential is enormous. Scientists continue to study string theory, and new discoveries and innovations are expected to emerge in the process.
Therefore, through this research, we will gain a deeper understanding of the fundamental principles of nature, which will greatly contribute to the advancement of human knowledge and technology. Ultimately, the search for the smallest unit of matter, which ancient Greek philosophers dreamed of, remains an unsolved mystery at the forefront of modern science. We will continue to strive to solve this mystery and uncover the secrets of the universe one by one through new discoveries.
