Physics

Physics is a field of science that is focused on the discovery of the natural laws of the universe through experimentation, measurement, and mathematical analysis. Along with biology, chemistry, environmental science, and astronomy, it is one of the five basic sciences. In one form or another, humans have actively pursued the study of physics since ancient times. Over the years, the field has evolved into a broad, complex science with an array of distinct branches that range from simple mechanics to advanced particle physics.

Historical Background

The history of physics can be traced back to ancient times and early scientific minds such as the Greek philosopher Aristotle and the Hellenistic astronomer Ptolemy. For his part, Aristotle developed a theory of terrestrial physics based on the idea that earth, water, air, and fire are the four elements of which all matter is composed. Ptolemy, on the other hand, turned his attention to the stars and produced a geocentric, or Earth-centered, model of the universe that explained the orbits of celestial bodies.

Unfortunately, much of what early Western scientists established about the realm of physics was lost when Europe began to enter the Dark Ages with the fall of the Roman Empire. Luckily, Islamic academics in the East, such as Al-Battani, picked up where their Western counterparts left off. Eventually, in the late Middle Ages, European society entered the early stages of renewed interest in the sciences, including physics. However, it was not until the start of the Scientific Revolution in the sixteenth century that serious advances were made in the study of physics. During that era, great thinkers such as Nicolaus Copernicus, Johannes Kepler, and Galileo Galilei made significant contributions to humankind’s understanding of the arrangement of the universe and the movement of celestial bodies that were drastically different, but far more accurate, than those of their predecessors. Others also made equally important breakthroughs in explaining the laws governing physical processes such as motion. The Scientific Revolution culminated in the work of Isaac Newton, who essentially redefined physics with the publication of his Principia Mathematica in 1687. Most famously, Newton described the concept of gravity and outlined the laws of motion.

With the advent of Newtonian physics, the modern version of the field was born. Over the course of the eighteenth, nineteenth, and twentieth centuries, physics evolved at a rapid rate thanks to the creative input of innovators such as Leonhard Euler, James Clerk Maxwell, and Albert Einstein. Einstein in particular, through his theory of relativity and other contributions, took physics to theoretical heights never before seen. In the modern era, physics is cutting-edge science that has continued to lead the way to a greater scientific understanding of the universe.

Branches of Physics

The various branches of physics generally fall into one of two broader categories: classical physics and modern physics. The division between these two categories is based on both chronology and approach. Chronologically, classical physics generally refers to branches of physics that emerged prior to about 1900, while modern physics encompasses branches that appeared after that point. In terms of approach, classical physics focuses on the macroscopic aspects of physics, or things that can be observed with the five senses alone. Modern physics, meanwhile, focuses on the submicroscopic study of particles, energy, and anything else that cannot be directly observed even with the most powerful microscopes.

The oldest and most fundamental branch of classical physics is mechanics, which is the study of motion and the physical forces—including gravity, electromagnetism, and atomic attraction—that define how motion works. The contemporary study of mechanics is still largely built around the theories and laws put forth by Newton.

Another major branch of classical physics is thermodynamics, which is the study of heat and the role it plays in relation to work. To some extent, thermodynamics as a field developed because of early-nineteenth-century interest in building an effective steam engine.

Other branches of classical physics include optics, acoustics, magnetism, and electricity. Optics is the study of light and related concepts such as reflection, refraction, and diffraction. Acoustics is the study of sound and sound waves. The study of both magnetism and electricity focuses on the behavior of certain particles when they are at rest and when they are in motion.

The various branches of modern physics are extremely advanced in comparison to those of classical physics and are often theoretical in nature. Particle physics, for example, is concerned with the study of the properties and behavior of the elementary subatomic particles that result from high-energy particle collisions. Similarly, nuclear physics is the study of the subatomic particles that make up the nuclei of atoms—protons and neutrons—and their properties, energy states, radioactivity, and more. Nuclear physics is also closely tied to atomic physics, which is focused on the structure and properties of atoms in relation to the electrons that surround the nucleus. Following atomic physics in this chain of related modern physics branches is molecular physics, which is centered on the grouping of atoms into molecules, intermolecular forces, and more.

Other branches of modern physics include state-based physics, mathematical physics, and theoretical physics. State-based physics refers to the fields of physics that focus on the different states of matter, including solids, liquids, gases, and plasma. Mathematical physics is the study of physical phenomena through mathematics. Theoretical physics, which is closely related to mathematical physics, is an experimental branch of physics in which researchers strive to gain a greater understanding of nature through theory and experimentation.

Lastly, there are some branches of modern physics that serve to connect physics with the other major sciences. Examples of these fields include geophysics and astrophysics, which unite physics with environmental science and astronomy, respectively.

Bibliography

Gliozzi, Mario. A History of Physics over the Last Two Centuries. Cambridge Scholars Publishing, 2022.

Nagel, Rob, editor. "Physics." UXL Encyclopedia of Science. Vol. 8, UXL, 2006, pp. 1513–16.

Pollard, William G. "Physics." McGraw-Hill Encyclopedia of Science & Technology. Vol. 13, McGraw-Hill, 2007, pp. 523–24.

Weisel, G. J. "Physics." New Dictionary of the History of Ideas. Vol. 5, Charles Scribner's Son, 2005, pp. 1809–21.

"What Is Physics in Simple Words?" National Physical Laboratory, www.npl.co.uk/what-is-physics-in-simple-words. Accessed 23 Sept. 2024.