Quantum physics, also referred to as quantum mechanics, is "A theory of matter that is based on the concept of the possession of wave properties by elementary particles," according to Merriam-Webster. Quantum physics deals with the behavior of light and matter at a subatomic and atomic level.
Quantum physics deals with very small particles such as protons, neutrons, electrons, gluons and quarks. A person who studies quantum mechanics may look at how these particles behave and how they interact with electromagnetic radiation. Quantum physicists developed the quantum theory, which looks at how these particles interact in the large-scale world.
Quantum physicists determined that tiny objects such as photons or electrons are both particles and waves. Since quantum physics was discovered, it became a way to describe the subatomic world. Although scientists such as Albert Einstein argued that the vagueness of quantum physics was unacceptable, today, most scientists agree with its principles.
Quantum physicists have been studying small particles since the 19th century. The theories began when German theoretical physicist Max Planck realized that radiation energy is not continuously emitted. He is responsible for Planck's constant. It was from this study that other quantum theories were born. Other scientists who studied quantum mechanics include Niels Bohr, Hans Geiger, Ernest Marsden and Ernest Rutherford.