Physics

Physics is the natural science that studies matter, its motion, and behavior through space and time, and that studies the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.

Physics is divided into two main branches: classical physics, which studies the behavior of matter and energy in the macroscopic world; and quantum physics, which studies the behavior of matter and energy in the microscopic world. Classical physics includes mechanics, heat, electricity and magnetism, light, and sound. Quantum physics includes atomic and subatomic physics, condensed matter physics, nuclear physics, and particle physics.

Physics is essential to the understanding of how the universe works. It has been integral to the development of essential technologies like the telephone, television, computer, and the Internet. Physics is also involved in important medical applications like MRI and CAT scans, and in the development of new materials and energy sources.

Physics is a problem-solving subject, and the biggest mistake is treating it as facts to memorize. The goal is to understand a small number of powerful principles deeply enough to apply them to new situations. Start with mechanics (motion, forces, energy) because everything else builds on it.

Math is the language of physics, so keep your algebra and (for advanced work) trigonometry and calculus sharp — struggling with the math makes the physics feel harder than it is. Work lots of problems, and for each one draw a diagram, identify the principle, and reason before plugging in numbers. Pair the math with physical intuition through demonstrations and experiments; seeing a concept in action makes the equations meaningful. Understand each idea before moving on — physics is relentlessly cumulative.