Theoretical physics

Main thing

Theoretical physics is a branch of physics that uses mathematical models and abstractions to explain and predict natural phenomena.
It employs mathematical equations and formulas to represent physical systems and processes, contrasting with experimental physics, which relies on direct observations and measurements.
The goal of theoretical physics is to understand the fundamental laws and principles that govern the behavior of matter and energy, from the smallest subatomic particles to the largest structures in the universe.
Example: Albert Einstein's theory of general relativity explains gravity as a curvature of spacetime caused by the presence of mass and energy, which has been confirmed by observations of gravitational lensing and black holes.

Terms

• Physics - The science that studies matter, energy, and the interactions between them. It is the fundamental scientific discipline that seeks to understand the laws of nature. Example: Studying the motion of planets in the solar system using the laws of physics.

• Experimental physics - The branch of physics that involves conducting experiments to discover properties of physical systems. Example: Using particle accelerators to explore the properties of subatomic particles.

• Mathematical model - A set of equations or formulas that represents a physical system or process. Example: The Schrödinger equation in quantum mechanics describes the behavior of particles at the subatomic scale.

• Abstraction - A simplified or idealized representation of a complex physical system that captures its essential features. Example: Modeling a gas as a collection of identical, non-interacting particles.

• Fundamental law - A basic principle that cannot be derived from other laws and is assumed to be true based on empirical evidence. Example: The conservation of energy, which states that energy cannot be created or destroyed, only converted from one form to another.

• Subatomic particle - A particle smaller than an atom, such as an electron, proton, or quark. Example: The Higgs boson, a particle that gives other particles their mass, was predicted by theoretical physicists and discovered experimentally in 2012.

An analogy

Theoretical physics is like studying a subject in a classroom using textbooks and lectures to understand concepts and solve problems, rather than conducting experiments in a laboratory or field.
Just as students use theoretical knowledge to understand complex subjects and predict outcomes on exams, theoretical physicists use mathematical models to understand complex physical phenomena and predict experimental results.
Example: A student uses the laws of motion learned in class to solve a problem on an exam about predicting the trajectory of a projectile.

A main misconception

Many people believe that theoretical physics is purely abstract and has no practical applications.
However, theoretical physics has led to many technological breakthroughs that we rely on every day, from the development of the laser and the transistor to the GPS system and magnetic resonance imaging (MRI).
Example: The equations of electromagnetism developed by James Clerk Maxwell in the 19th century laid the foundation for the development of radio, television, and wireless communication.

The history

1. In the 17th century, Isaac Newton developed the laws of motion and universal gravitation, which provided a mathematical framework for understanding the behavior of objects on Earth and in the heavens.

2. In the 19th century, physicists such as Michael Faraday and James Clerk Maxwell developed the theory of electromagnetism, which unified the concepts of electricity, magnetism, and light.

3. In the early 20th century, Albert Einstein developed the theories of special and general relativity, which revolutionized our understanding of space, time, and gravity.

4. In the 1920s and 1930s, physicists such as Werner Heisenberg and Erwin Schrödinger developed quantum mechanics, which describes the behavior of matter and energy at the subatomic scale.

5. In the latter half of the 20th century, theoretical physicists developed the Standard Model of particle physics, which describes the fundamental particles and forces that make up the universe.

Three cases how to use it right now

1. A student uses Newton's laws of motion to calculate the trajectory of a basketball thrown at a certain angle and speed, in order to predict where the ball will land and how to aim their shot.

2. An engineer uses Maxwell's equations to design an antenna for a new wireless communication system.

3. A medical physicist uses the principles of nuclear physics to develop a new radiation therapy treatment for cancer patients.

Interesting facts

• The GPS system relies on Einstein's theory of relativity to accurately calculate the position of satellites and the timing of their signals, which are affected by the curvature of spacetime due to the Earth's mass.

• The discovery of the Higgs boson in 2012 confirmed a key prediction of the Standard Model of particle physics, which theorized that a field permeating all of space gives particles their mass.

• Quantum entanglement, a phenomenon predicted by quantum mechanics, allows two particles to be connected across vast distances, such that measuring the properties of one particle instantly affects the other, even if they are light-years apart.

• The concept of antimatter, which consists of particles with the same mass but opposite charge as ordinary matter, was first predicted by theoretical physicist Paul Dirac in 1928, and has since been observed experimentally in particle accelerators.

• The study of black holes, which are regions of space where gravity is so strong that nothing can escape, has led to the development of new branches of theoretical physics, such as quantum gravity and string theory, which attempt to unify quantum mechanics and general relativity.