What is Physics? What are the Subjects of Physics?

Physics is the branch of science that studies the basic principles of the universe and natural phenomena. It covers a wide range of topics such as the motion of matter, energy, force, light and subatomic particles. Physics helps us understand how the universe works by exploring the fundamental laws of nature. This branch of science forms the basis of the technologies we use in our daily lives and is closely related to other branches of science such as engineering, medicine, chemistry and biology. Understanding physical principles plays a key role in shaping the modern world and developing future technological innovations.

What is Physics?

Definition of Physics

General Definition of Physics

Physics is a branch of science that examines the events occurring in nature and tries to explain these events with mathematical models. Physics, one of the cornerstones of natural sciences , investigates the structure, movement, energy of matter and the interaction of this energy with matter.

Purpose and Importance of Physics

The purpose of physics is to understand and explain phenomena in nature . The research conducted and the information obtained during this process contribute greatly to the advancement of technology. Physical principles are applied in many different fields such as engineering, medicine and chemistry and form the basis of innovations that facilitate and improve human life.

Physics Word Meaning and Origin

Etymology of the Word Physics

The word physics derives its origin from the Greek word “physika” . This word refers to nature and natural events.

Greek Word “Physika”

“Physika” means related to nature in Greek and refers to the study of natural phenomena . This term helps to understand the concepts that form the basis of natural sciences.

Historical Development and Evolution

The term physics was first used in Ancient Greece and evolved as a scientific discipline over time. Ancient Greek philosophers made physical observations to understand nature and developed various theories as a result of these observations.

First Use of the Term Physics

The term physics was first used in B.C. It was used by Aristotle in the 4th century . Aristotle collected his works examining and explaining natural phenomena under the name “Physika”. These studies laid the foundations of modern physics and made significant contributions to the development of physical science.

History of Physics

Physics in Ancient Times

Aristotle and Natural Philosophy

Aristotle is one of the first great thinkers to make physical observations to understand and explain natural phenomena. His natural philosophy includes theoretical approaches to understanding the structure and functioning of the universe. Aristotle’s works contain many of the concepts that form the basis of modern physics and are considered the starting point of physical science.

Hellenistic Period and Scientific Developments

The Hellenistic period was a period in which scientific developments accelerated and significant advances were made in the field of physics. During this period , scientists tried to understand natural events by making observations and developed various theories. In particular , scientists such as Archimedes made important contributions to the fields of mechanics and hydrostatics.

Physics in the Middle Ages and Modern Ages

Physics in the Islamic World

In the Middle Ages, the Islamic world made significant contributions to physical science . Islamic scholars compiled and developed the knowledge from the ancient period and carried out important studies in fields such as optics, astronomy and mechanics . Scientists such as Ibn al-Haytham (Alhazen) laid the foundations of modern physics with their studies in the field of optics.

Renaissance and Physical Science in Europe

The Renaissance period was a period in which scientific knowledge was revived in Europe and physical science advanced rapidly. During this period , scientists increased their knowledge by observing natural events and conducting experiments. Scientists such as Galileo Galilei , Johannes Kepler and Isaac Newton made significant contributions to modern science by laying the foundations of classical physics.

Modern Physics and Developments

Newton ve Classical Mechanics

Isaac Newton laid the foundations of modern physics with his work in classical mechanics. Newton’s laws of motion and the law of universal gravitation have become fundamental principles used to explain natural phenomena. Newton’s work formed the main paradigm of physics for many years.

Einstein and the Theory of Relativity

Albert Einstein brought a new perspective to physics with his theory of relativity. Einstein’s theories of special and general relativity redefined the concepts of time and space and provided important information about the structure of the universe. Einstein’s works made great contributions to the development of modern physics and led to the birth of new fields such as quantum mechanics.

Basic Topics of Physics

Classic Mechanic

Motion and Force

Motion and force are the basic subjects of classical mechanics. Newton’s laws of motion describe how objects move and how forces affect these movements. These laws are used in a wide range of areas, from daily life to engineering applications.

Energy and Business

The concepts of energy and work are one of the cornerstones of physics. Energy is the capacity of a system to do work, and work is a measure of energy transfer. Kinetic energy, potential energy and mechanical work are important elements of classical mechanics.


Electricity and Magnetism

Electricity and magnetism are the two main components of electromagnetism. Electric charges and electric fields , electrical events; Magnetic fields and magnetic forces explain magnetic phenomena. Coulomb’s law and Ampere’s law are fundamental principles in these fields.

Electromagnetic Waves

Electromagnetic waves are created by the combination of electric and magnetic fields and include various types of waves, including light. Maxwell’s equations describe the formation and propagation of these waves. Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays are components of the electromagnetic spectrum.


Heat and temperature

Heat and temperature are fundamental topics in thermodynamics. Heat is a form of energy transfer, and temperature determines the thermal state of a substance. Thermometers are used to measure temperature, while calorimeters measure the amount of heat.

Laws of Thermodynamics

The laws of thermodynamics explain the processes of energy transfer and transformation. The first law expresses the principle of conservation of energy, while the second law describes entropy and energy quality. The third law describes the behavior of matter at absolute zero.


Nature of Light

The nature of light is the fundamental subject of optics. Light is an electromagnetic wave with wave and particle properties. Understanding the speed of light and the refractive index is critical to explaining optical phenomena.

Lenses and Mirrors

Lenses and mirrors are optical devices that change the direction and focus of light. Spherical mirrors and lenses provide image formation and direction of light beams. Snell’s law and lens equations describe the operation of these instruments.

Quantum Mechanics

Atomic and Molecular Physics

Atomic and molecular physics is one of the application areas of quantum mechanics. Atomic models and molecular bonds explain atom and molecule behavior. Spectroscopy is a technique used to study these behaviors.

Quantum Theory and Principles

Quantum theory is the theory of physics that explains the microscopic world. Wave-particle duality , Heisenberg’s uncertainty principle and the Schrödinger equation are fundamental principles of quantum mechanics. These principles describe the behavior of subatomic particles.

Nuclear physics

Atomic Nucleus and Radioactivity

Atomic nuclei and radioactivity are the fundamental subjects of nuclear physics. The structure of the atomic nucleus consists of protons and neutrons, and radioactivity is the energy emission resulting from the instability of the nucleus. These processes are explained by the laws of radioactive decay.

Nuclear Reactions and Energy

Nuclear reactions and energy studies the changes in atomic nuclei. Fission and fusion are the two main sources of nuclear energy. These reactions are used in energy production and nuclear technologies.

Application Areas of Physics

Engineering and Technology

Electronics and Communications

Electronics and communications are one of the application areas of physics. Technologies such as electrical circuits, semiconductors, transistors and microchips are based on the principles of physics. Electromagnetism and quantum mechanics provide the basic theoretical background of these fields and enable the development of modern electronic devices and communication systems.

Mechanical and Civil Engineering

Mechanical and civil engineering are application areas of classical mechanics and materials science. Statics, dynamics, thermodynamics and fluid mechanics are the basic physical concepts used in these branches of engineering. These areas play critical roles in the design and construction of buildings, bridges, machinery and other structures.

Health and Medicine

Medical Imaging Techniques

Medical imaging techniques are methods based on physics principles. Techniques such as x-ray, magnetic resonance imaging (MRI), ultrasonography, and positron emission tomography (PET) are used to image the internal structure of the human body. These methods have an important place in the diagnosis and treatment processes.

Radiation Therapy and Oncology

Radiation therapy and oncology involve applications of physics in cancer treatment. Radiotherapy aims to kill cancer cells using high-energy radiation. Physical principles are used to calculate treatment doses and create treatment plans.

Astronomy and Space Sciences

Planetary Science and Cosmology

Planetary science and cosmology involve the study of the universe and planets. Cosmology studies the large-scale structure and evolution of the universe, while planetary science investigates the structure and dynamics of planets, moons, and other celestial bodies. These fields are concerned with applications of astrophysics and gravity theories.

Space Research and Technology

Space exploration and technology covers technologies used for the exploration and study of space. Satellite technologies, rockets, space probes and space telescopes have been developed thanks to physical principles and engineering applications. These researches allow us to learn more about the universe and make new discoveries.

The Relationship of Physics with Other Sciences

Chemistry and Physics

Physical Chemistry and Quantum Chemistry

Physical chemistry and quantum chemistry are at the intersection of physical and chemical sciences. Physical chemistry attempts to understand the physical principles of chemical reactions by studying the thermodynamic and kinetic properties of chemical systems. Quantum chemistry explains the electronic structure and chemical bonds of atoms and molecules using the principles of quantum mechanics.

Chemical Reactions and Energy

Chemical reactions and energy is an area where physics and chemistry work together. Chemical thermodynamics studies the energy changes and balances of reactions. Reaction kinetics aims to understand the rates and mechanisms of chemical reactions. This information plays an important role in applications such as energy production and storage.

Biology and Physics

Biophysics and Molecular Physics

Biophysics and molecular physics involve the application of physical principles to biological systems. Biophysics studies the physical properties of biological molecules and cellular structure. Molecular physics uses physical laws to understand the structure, dynamics and interactions of molecules. These fields contribute to the understanding of biological processes and the development of biotechnological applications.

Physical Biochemistry

Physical biochemistry studies the physical and chemical principles of biochemical phenomena. Protein folding, enzyme kinetics and biomolecular interactions are the fundamental topics of this field. Physical biochemistry uses techniques such as spectroscopy, calorimetry , and crystallography to understand the structures and functions of biomolecules . This information is important in medical applications such as drug development and treatment of diseases.

Physics Education and Career Opportunities

Physics Education and Academic Career

Physics Departments at Universities

Physics departments at universities teach students physical principles and theories. Universities that offer physics education at undergraduate, master’s and doctoral levels help students develop academic and research skills. These sections cover basic topics such as classical physics, modern physics, quantum mechanics, thermodynamics and electromagnetism.

Physics Research and Development

Physics research and development is an important part of an academic career. Physicists contribute to the discovery of new knowledge by working on various projects at universities and research institutes. These studies promote progress in the world of science and form the basis of technological innovations.

Career Opportunities for Physicists in Industry

R&D and Technology Companies

R&D and technology companies offer a wide range of career opportunities for physicists. Physicists working in these fields contribute to the development of new products and technologies. In sectors such as semiconductors, nanotechnology, energy systems and telecommunications , knowledge of physics plays an important role.

Defense and Space Industry

The defense and space industry is another important area where the talents of physicists are utilized. In these sectors , new defense systems and space research vehicles are developed using physical principles. Physicists undertake critical roles in fields such as rocket science, satellite technology and radar systems .

Frequently Asked Questions in Physics

What is Physics used for?

Physics is a fundamental branch of science that helps us understand nature and the universe. This knowledge forms the basis of technological innovations and engineering applications. Physics helps explain and understand many phenomena we encounter in our daily lives.

What is the Difference Between Physics and Other Sciences?

The difference between physics and other sciences lies in the explanation of physical phenomena with mathematical models and theoretical frameworks. Other branches of science, such as chemistry, biology, and geology , apply physical principles to their fields. Physics provides the general principles that form the basic building blocks of these sciences .

What are the Applications of Physics in Daily Life?

The applications of physics in daily life are quite wide. The electronic devices we use thanks to electricity and magnetism , carrying systems thanks to mechanics , and glasses and cameras thanks to optics are reflections of physical principles in daily life. It facilitates and improves our lives in many areas such as physics, health, communication and energy .


Physics is of central importance in the scientific world and continues to expand humanity’s knowledge. Its role in understanding and explaining natural phenomena provides a critical foundation for technological and engineering applications. Physical science has a wide potential for new discoveries and innovations in the future as well. Therefore , physics education and research will continue to be of great importance in both academic and industrial fields.

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