What are the 6 major areas of physics?

  • Helena Kudiabor
  • Jul 12 2023

If you’re interested in pursuing physics for higher education or as a career, it’s a good idea to know the fundamentals of the field, such as which are the biggest areas of physics. Physics research can be divided into two categories, classical and modern.


Classical physics

This category refers to physics research conducted before 1900, and focuses primarily on the laws of motion and attraction. 


Optics is the area of physics concerned with light’s behaviour and properties. When we think of light we typically think of visible light, but physicists also conduct research into other light sources, such as ultraviolet and infrared light. Those working in optic research study how light works, and how it interacts with matter. Our understanding of optical science has led to the development of mirrors, telescopes and even lasers.


Mechanics refers to the relationship between concepts of movement, like motion, force, and matter. A question a mechanical physicist might consider is the impact force has on an object’s velocity. Mechanics is also further categorised into quantum and classical. Quantum mechanics deals with the behaviour of the smallest particles (protons) while classical mechanics focuses on the laws of motion as they apply to physical objects.


Like the name suggests, acoustic physics deals with sound waves. Acoustic physicists study how sound waves are made, what they consist of, and how they move through different states of matter. Concepts that acoustic physicists work with include vibration, ultrasound and transmission.

Modern Physics

This refers to physics research from the early 1900s onwards, and builds on the concepts explored in classical physics. While classical physics focuses on how the laws of physics apply to everyday conditions, modern physics takes a look at physics in extreme conditions (high energies and velocities). Key aspects of modern physics include quantum physics and the theory of relativity. 


You probably know that the universe is made up of atoms. However, quantum physics explains how the universe works at a scale smaller than atoms, so how the particles that make up atoms work. Quantum physics is named due to the fact that a quantum of energy is the least amount of energy possible, so quantum physics explains how this energy moves and interacts. Also, quantum physics research has been used to better understand how electromagnetic waves (like light) work.

Quantum physics is fascinating because of how differently physics works when things are so microscopic. For example, particles may behave as waves and waves may behave as particles, a concept known as wave-particle duality. 


While quantum physics focuses on what makes up atoms, nuclear physics focuses on the structure of the atom’s nuclei. Nuclear physicists work to understand how the nucleus is structured, how it remains stable, and how it decays. This understanding of an atom’s nucleus has been an asset to a range of industries. For instance, the application of nuclear techniques has enabled archeological discoveries, and helped design PET scans. 


Nuclear and atomic physics are two sides of the same coin: atomic physics focuses on atoms while nuclear physics focuses on nuclei. Atomic physics considers how electrons are arranged around the nucleus, and what makes this arrangement change. This branch of physics focuses primarily on understanding atoms in isolation (each holding a single nucleus), instead of how they interact with other atoms. 

If there’s an area of physics we discussed that you’re interested in, why not look into attending a public lecture or museum exhibit about it? This is a great way for you to learn more about physics careers, and understand the real-world applications of physics.