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Nuclear fusion is a reaction in which two or more atomic nuclei combine to form a larger nucleus. The difference in mass between the reactants and products...

A neutrino (/njuːˈtriːnoʊ/ new-TREE-noh; denoted by the Greek letter ν) is an elementary particle that interacts via the weak interaction and gravity....

Hawking radiation is black-body radiation released outside a black hole's event horizon due to quantum effects according to a model developed by Stephen...

In physics, Lagrangian mechanics is an alternate formulation of classical mechanics founded on the d'Alembert principle of virtual work. It was introduced...

The following is a list of notable unsolved problems grouped into broad areas of physics. Some of the major unsolved problems in physics are theoretical...

Sir William Lawrence Bragg (31 March 1890 – 1 July 1971) was an Australian-born British X-ray crystallographer who uniquely shared a Nobel Prize with his...

Classical physics consists of scientific theories in the field of physics that are non-quantum or both non-quantum and non-relativistic, depending on the...

The Schwarzschild radius is a parameter in the Schwarzschild solution to Einstein's field equations that corresponds to the radius of a sphere in flat...

The Penrose–Hawking singularity theorems (after Roger Penrose and Stephen Hawking) are a set of results in general relativity that attempt to answer the...

Physics beyond the Standard Model (BSM) refers to the theoretical developments needed to explain the deficiencies of the Standard Model, such as the inability...

Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light is a collection of three books by Isaac Newton that was published...

Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure...

In common usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities. Nevertheless, one...

In classical statistical mechanics, the H-theorem, introduced by Ludwig Boltzmann in 1872, describes the tendency of the quantity H (defined below) to...

Schlieren (/ˈʃlɪərən/ SHLEER-ən; German: [ˈʃliːʁn̩] , German for 'streaks') are optical inhomogeneities in transparent media that are not necessarily visible...

Sir Frederick Charles Frank, FRS (6 March 1911 – 5 April 1998) was a British theoretical physicist. He is best known for his work on crystal dislocations...

In physics, helicity is the projection of the spin onto the direction of momentum. Mathematically, helicity is the sign of the projection of the spin vector...

In astrophysics and physical cosmology, the mass-to-light ratio, normally designated with the Greek letter upsilon, ϒ, is the quotient between the total...

Electron cyclotron resonance (ECR) is a phenomenon observed in plasma physics, condensed matter physics, and accelerator physics. It happens when the frequency...

The Wigner D-matrix is a unitary matrix in an irreducible representation of the groups SU(2) and SO(3). It was introduced in 1927 by Eugene Wigner, and...