Science, Tech, Math › Science Quantum Physics Overview How Quantum Mechanics Explains the Invisible Universe Share Flipboard Email Print traffic_analyzer / Getty Images Science Physics Quantum Physics Physics Laws, Concepts, and Principles Important Physicists Thermodynamics Cosmology & Astrophysics Chemistry Biology Geology Astronomy Weather & Climate By Andrew Zimmerman Jones Math and Physics Expert M.S., Mathematics Education, Indiana University B.A., Physics, Wabash College Andrew Zimmerman Jones is a science writer, educator, and researcher. He is the co-author of "String Theory for Dummies." our editorial process Andrew Zimmerman Jones Updated August 16, 2019 Quantum physics is the study of the behavior of matter and energy at the molecular, atomic, nuclear, and even smaller microscopic levels. In the early 20th century, scientists discovered that the laws governing macroscopic objects do not function the same in such small realms. What Does Quantum Mean? "Quantum" comes from the Latin meaning "how much." It refers to the discrete units of matter and energy that are predicted by and observed in quantum physics. Even space and time, which appear to be extremely continuous, have the smallest possible values. Who Developed Quantum Mechanics? As scientists gained the technology to measure with greater precision, strange phenomena was observed. The birth of quantum physics is attributed to Max Planck's 1900 paper on blackbody radiation. Development of the field was done by Max Planck, Albert Einstein, Niels Bohr, Richard Feynman, Werner Heisenberg, Erwin Schroedinger, and other luminary figures in the field. Ironically, Albert Einstein had serious theoretical issues with quantum mechanics and tried for many years to disprove or modify it. What's Special About Quantum Physics? In the realm of quantum physics, observing something actually influences the physical processes taking place. Light waves act like particles and particles act like waves (called wave particle duality). Matter can go from one spot to another without moving through the intervening space (called quantum tunnelling). Information moves instantly across vast distances. In fact, in quantum mechanics we discover that the entire universe is actually a series of probabilities. Fortunately, it breaks down when dealing with large objects, as demonstrated by the Schrodinger's Cat thought experiment. What is Quantum Entanglement? One of the key concepts is quantum entanglement, which describes a situation where multiple particles are associated in such a way that measuring the quantum state of one particle also places constraints on the measurements of the other particles. This is best exemplified by the EPR Paradox. Though originally a thought experiment, this has now been confirmed experimentally through tests of something known as Bell's Theorem. Quantum Optics Quantum optics is a branch of quantum physics that focuses primarily on the behavior of light, or photons. At the level of quantum optics, the behavior of individual photons has a bearing on the outcoming light, as opposed to classical optics, which was developed by Sir Isaac Newton. Lasers are one application that has come out of the study of quantum optics. Quantum Electrodynamics (QED) Quantum electrodynamics (QED) is the study of how electrons and photons interact. It was developed in the late 1940s by Richard Feynman, Julian Schwinger, Sinitro Tomonage, and others. The predictions of QED regarding the scattering of photons and electrons are accurate to eleven decimal places. Unified Field Theory Unified field theory is a collection of research paths that are trying to reconcile quantum physics with Einstein's theory of general relativity, often by trying to consolidate the fundamental forces of physics. Some types of unified theories include (with some overlap): Quantum Gravity Loop Quantum Gravity String Theory / Superstring Theory / M-Theory Grand Unified Theory Supersymmetry Theory of Everything Other Names for Quantum Physics Quantum physics is sometimes called quantum mechanics or quantum field theory. It also has various subfields, as discussed above, which are sometimes used interchangeably with quantum physics, though quantum physics is actually the broader term for all of these disciplines. Major Findings, Experiments, and Basic Explanations Earliest Findings Black Body Radiation Photoelectric Effect Wave-Particle Duality Young's Double Slit Experiment De Broglie Hypothesis The Compton Effect Heisenberg Uncertainty Principle Causality in Quantum Physics - Thought Experiments and Interpretations The Copenhagen Interpretation Schrodinger's Cat EPR Paradox The Many Worlds Interpretation Cite this Article Format mla apa chicago Your Citation Jones, Andrew Zimmerman. "Quantum Physics Overview." ThoughtCo, Aug. 28, 2020, thoughtco.com/quantum-physics-overview-2699370. Jones, Andrew Zimmerman. (2020, August 28). Quantum Physics Overview. Retrieved from https://www.thoughtco.com/quantum-physics-overview-2699370 Jones, Andrew Zimmerman. "Quantum Physics Overview." ThoughtCo. https://www.thoughtco.com/quantum-physics-overview-2699370 (accessed October 27, 2021). copy citation Watch Now: Can the Theories of Relativity and Quantum Mechanics Be Merged?