What Branch of Physics Should I Study

One press picks a branch of physics to study, with what it explains.

What Branch of Physics Should I Study

Show all 60
  1. Chaos theorySystems that follow fixed laws yet are highly sensitive to their starting conditions.

Next step Pick a science majorPick a field of math to go with it

How it works

Choosing a course, a research group or a first book? Press the button for one branch of physics, from optics to quantum gravity, each with a line on what it explains.

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Which branch of physics should I study

Go by the scale that pulls you in. Classical mechanics covers the motion of everyday objects, thermodynamics covers heat, work and temperature, and quantum mechanics covers matter and light at the scale of atoms and below. Astrophysics and physical cosmology look outward, to the stars and to the universe as a whole.

Theory, experiment or computing

Theoretical physics builds mathematical models to explain and predict what happens. Experimental physics observes and measures, from simple set-ups to the Large Hadron Collider. Computational physics solves problems numerically, and some regard it as a branch between the other two.

Questions and answers

What are the main branches of physics?

Wikipedia’s article Branches of physics lists classical mechanics, thermodynamics and statistical mechanics, electromagnetism, relativity, quantum mechanics with atomic and molecular physics, optics and acoustics, condensed matter physics, particle and nuclear physics, chaos theory, cosmology and the interdisciplinary fields.

What is the difference between classical and modern physics?

In historical use, classical physics is the physics of before 1900 and modern physics what came after, with quantum mechanics and the theory of relativity. Classical physics deals with everyday conditions, modern physics with speeds near that of light and sizes near that of atoms.

What is the difference between astrophysics and cosmology?

Astrophysics applies physics and chemistry to astronomical objects such as stars, to find out what they are. Physical cosmology models the universe as a whole and asks about its origin, structure, evolution and ultimate fate.

What is the difference between atomic and nuclear physics?

Atomic physics studies the atom as a whole, including its electrons and how they are arranged round the nucleus. Nuclear physics studies the nucleus itself, its constituents and their interactions.

Which branch of physics studies light?

Optics, which studies how light behaves and how it interacts with matter. Quantum optics deals with single photons, and photonics applies the generation, detection and manipulation of light.

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All 60 branches of physics

Motion, heat, light and sound 16

  • Acoustics Mechanical waves in gases, liquids and solids: vibration, sound, ultrasound and infrasound.
  • Aerodynamics How air moves, above all round a solid object such as an airplane wing.
  • Chaos theory Systems that follow fixed laws yet are highly sensitive to their starting conditions.
  • Classical mechanics How forces move everyday objects, from a projectile to a planet.
  • Continuum mechanics How materials deform and pass on forces, treated as continuous and not as particles.
  • Dynamics Forces and their effect on motion. Newton’s second law is its base.
  • Electromagnetism Electric charge and its fields, which tie together electricity, magnetism and optics.
  • Electrostatics Electric charges that stand still or move slowly.
  • Fluid mechanics How liquids, gases and plasmas behave and the forces on them.
  • Kinematics How objects move, described apart from the forces that set them moving.
  • Magnetism Magnetic fields, through which objects attract or repel each other.
  • Optics How light behaves, how it interacts with matter and the instruments that use or detect it.
  • Rheology How matter flows and deforms, in fluids and in soft solids.
  • Statics Forces and torques on a system that is in balance and does not accelerate.
  • Statistical mechanics The properties of matter in bulk, worked out from the laws that govern the motion of atoms.
  • Thermodynamics Heat, work and temperature, and how they relate to energy and entropy.

Relativity and the quantum world 11

  • Atomic physics The atom as electrons and a nucleus, and how the electrons are arranged round it.
  • General relativity Einstein’s geometric theory of gravitation.
  • Nuclear physics Atomic nuclei, what they are made of and how they interact.
  • Particle physics The fundamental particles and forces that make up matter and radiation.
  • Quantum computing Computers that represent and process information using quantum states.
  • Quantum field theory Joins field theory, special relativity and quantum mechanics. The Standard Model is based on it.
  • Quantum gravity The search to unite the theory of gravity with the principles of quantum mechanics.
  • Quantum mechanics How matter and light behave at the scale of atoms and below.
  • Quantum optics Single photons, the quanta of light, and how they interact with atoms and molecules.
  • Special relativity The relationship between space and time, from Einstein’s paper of 1905.
  • String theory A framework in which the point-like particles of particle physics are one-dimensional strings.

Atoms, molecules and materials 8

  • Chemical physics Chemical processes studied from a physical point of view.
  • Condensed matter physics The physical properties of matter, above all in its solid and liquid phases.
  • Cryogenics How very low temperatures are produced and how materials behave at them.
  • Molecular physics The physical properties of molecules and the way they move.
  • Plasma physics Plasma, a state of matter with a large share of charged particles. Stars are almost pure plasma.
  • Polymer physics Polymers: their fluctuations, their mechanical properties and how they form and break down.
  • Soft matter physics Matter that is easily deformed, such as liquids, colloids, polymers, foams and gels.
  • Solid-state physics How the large-scale properties of solids result from their atomic-scale properties.

Space and the Earth 9

  • Astrophysics The physics and chemistry of stars and other astronomical objects: what they are, not where.
  • Atmospheric physics Physics applied to the atmosphere of Earth and of the other planets.
  • Celestial mechanics The motions of objects in outer space and the gravity between them.
  • Geophysics Earth’s shape, its gravitational and magnetic fields and its internal structure.
  • Heliophysics The physics of the Sun and its connection with the Solar System.
  • Physical cosmology The universe as a whole: its origin, structure, evolution and ultimate fate.
  • Physical oceanography Physical conditions in the ocean, above all the motions of its waters.
  • Planetary science Planets, moons, asteroids and comets, and how planetary systems form.
  • Space physics Natural plasmas in Earth’s upper atmosphere and the Solar System, such as aurorae and the solar wind.

Physics meets another field 9

  • Agrophysics Where physics borders on agronomy: the materials and processes of growing and processing crops.
  • Biomechanics The structure, function and motion of living things, studied with the methods of mechanics.
  • Biophysics The methods of physics used to study biological phenomena.
  • Econophysics Theories and methods developed by physicists, applied to problems in economics.
  • Engineering physics Physics, mathematics and chemistry combined with the engineering disciplines.
  • Medical physics The concepts and methods of physics applied to preventing, diagnosing and treating disease.
  • Neurophysics Physical methods used to gain information about the nervous system.
  • Psychophysics The relationship between a physical stimulus and the sensation it produces.
  • Social physics Mathematical tools inspired by physics, used to understand the behavior of human crowds.

Theory, experiment and tools 7

  • Accelerator physics Designing, building and operating particle accelerators.
  • Computational physics Numerical analysis put to work on problems in physics.
  • Experimental physics Observation and experiment, from simple set-ups to the Large Hadron Collider.
  • Mathematical physics The development of mathematical methods for use in physics.
  • Photonics A branch of optics: generating, detecting and manipulating light as photons, put to use.
  • Physics education The methods used to teach physics, and the research that seeks to improve them.
  • Theoretical physics Mathematical models used to explain and predict natural phenomena.