# Quantum Physics

Julian Voss-Andreae's "Quantum Objects"

Physicist/sculptor Julian Voss-Andreae has created a series of "Quantum Objects" - sculptures that attempt to capture the meaning of fundamental quantum physics concept, such as particle spin, wave/particle duality, and uncertainty.

Quantum Physics: An Overview

This overview of the different aspects of quantum physics is intended to provide some perspective to those new to the subject, so that they can further explore the wonders inherent in this miraculous realm.

What is Quantum Entanglement?

One of the key principles in quantum physics is the idea of quantum entanglement, where multiple objects exist in states that are linked together

Quantum Physics Books

Quantum physics is one of the most complex concepts in modern physics and a number of books have come out in an effort to explain these quantum concepts to the general public. Here are some of them.

What is the Casimir Effect?

The Casimir Effect is one of those curious behaviors predicted by quantum mechanics and experimentally verified. In this strange situation, the energy of "empty space" actually performs work on physical objects!

What are the Fundamental Forces of Physics?

An overview of the four fundamental forces of physics and why they are so fundamental.

EPR Paradox

Definition of the EPR Paradox

What is Quantum Levitation (and How Does It Work)?

It has long been a dream of science (or, at least, science fiction) to create machines that could fly and levitate. This can be done with magnets, of course, but takes a great deal of energy. In recent years, the new phenomenon of quantum levitation has given some possible hope that levitation may be more practical than previously believed.

Wave Particle Duality

We explore wave particle duality: the particle properties of waves and the wave properties of particles. What do these strange properties mean? How can we use them to understand physics?

What is the Heisenberg Uncertainty Principle?

What is the Heisenberg Uncertainty Principle? This amazing principle is at the heart of one of the most unusual aspects of quantum physics, the idea that it's not possible to acquire an infinite degree of precision when measuring certain physical quantities. How and why does it work this way?

Schroedinger's Cat

In 1935, Erwin Schroedinger developed a thought experiment which illuminated some of the problems with extending the microscopic concepts of quantum physics into the macroscopic realm. The thought experiment has been used in the years since to highlight the key concepts of quantum physics, ranging from the role of the observer to the meaning of the wave function.

What Is a Quantum Computer?

Quantum physics allows for many wondrous things, but perhaps none will have more impact than quantum computing ... if anyone ever builds a quantum computer that works (for more than a few nanoseconds).

What is Quantum Optics?

Learn about quantum optics, the field of physics where the study of individual photons is crucial to understanding the nature of the behavior of electromagnetic waves as a whole.

Quantum Enigma: Physics Encounters Consciousness

In * Quantum Enigma: Physics Encounters Consciousness*, two physics professors explore the "skeleton in the closet" of quantum physics. What is the role of the observer, a conscious observer, in quantum theory? In lucid terms, the authors outline the issues and debates surrounding the quantum enigma.

De Broglie Hypothesis

We discuss the De Broglie hypothesis, which proposes that all matter exhibits wave-like properties and relates the observed wavelength of matter to its momentum.

Decoherence and the Measurement Problem

Quantum wavefunction collapse is one of the thorniest conceptual problems in physics, and trying to understand its meaning is known as the "measurement problem." Decoherence is an explanation that allows physicists to work with this concept without really fully resolving the measurement problem itself.

Blackbody Radiation

Research in blackbody radiation created a major dilemma for classical physics. The problem was resolved by Max Planck in 1900 by introducing the concepts which laid the foundation for all of quantum mechanics.

Young's Double Slit Experiment

Learn about Young's Double Slit experiment, where interference patterns seem to prove the wave theory of light. But there's way more to this simple experiment than meets the eye. We'll explain the original experiment and its quantum mechanical permutations.

The Photoelectric Effect

A description of the photoelectric effect and its significance, which includes crushing the classical wave theory of light, Einstein's first publication, Einstein's only Nobel Prize, and one of the major steps in developing quantum mechanics.

The Compton Effect

The Compton effect, where the energy of a photon decreased upon interaction with matter, is another experiment that demonstrated the particle properties of electromagnetic radiation.

What is Unified Field Theory?

Unified field theory, or grand unified theory, or "the theory of everything," is an attempt to consolidate the laws of physics into a single framework. It's actually a collection of assorted theories such as quantum gravity and string theory, all of which have the same ultimate goal of unification.

New Scientist: Quantum World

New Scientist provides this useful resource on the "Quantum World," which includes a number of news reports relating to quantum physics.

Visual Quantum Mechanics

This website of the Kansas State University Physics Education Research Group provides information on quantum physics, including simulations, geared toward the non-science student. It requires Macromedia Shockwave to fully view the site.

Renormalization Made Easy

John Baez has written this article to provide a "gut-level understanding" on the topic of renormalization in quantum field theory. It assumes knowledge of quantum physics which is, at least, advanced undergraduate level.

Journal: Classical & Quantum Gravity

This online journal provides current research in both classical and quantum gravity free to the public.

What is the Higgs Field?

What is the Higgs field? It's the theoretical field that supposedly gives fundamental particles their mass. On July 4, 2012, CERN physicists indicated that they may have found experimental evidence of it.

Bra-Ket Notation

Quantum physics uses an unusual mathematical system called bra-ket notation, which mathematically describes a wavefunction evolving over time.