Static field
A field is a physical quantity that has a value for each point in space and time. For example, in a weather forecast, the wind velocity is described by assigning a vector to each point on a map. Each ...
Static field - Wikipedia
What Do You Mean, The Universe Is Flat?
The universe is three-dimensional. The universe is four-dimensional—three for space, one for time. The universe has nine, or ten or eleven dimensions.Matter curves spacetime. The universe is flat.The ...
Quantum scientists create light from vacuum
Scientists at Chalmers have succeeded in creating light from vacuum – observing an effect first predicted over 40 years ago. The results have been published in the journal Nature. In an innovative exp...
Classical field theory
A classical field theory is a physical theory that describes the study of how one or more physical fields interact with matter. The word 'classical' is used in contrast to those field theories that in...
Spacetime symmetries
Spacetime symmetries are features of spacetime that can be described as exhibiting some form of symmetry. The role of symmetry in physics is important in simplifying solutions to many problems, spacet...
Gauge symmetry
In physics, a gauge theory is a type of field theory in which the Lagrangian is invariant under a continuous group of local transformations.The term gauge refers to redundant degrees of freedom in the...
Gauge symmetry - Wikipedia
Speed of gravity
In classical theories of gravitation, the speed of gravity is the speed at which changes in a gravitational field propagate. This is the speed at which a change in the distribution of energy and momen...
Aberration of light
The aberration of light (also referred to as astronomical aberration or stellar aberration) is an astronomical phenomenon which produces an apparent motion of celestial objects about their locations d...
Aberration of light - Wikipedia
Liénard-Wiechert potential
Liénard–Wiechert potentials describe the classical electromagnetic effect of a moving electric point charge in terms of a vector potential and a scalar potential in the Lorenz gauge. Built directly fr...
Near and far field
The near field (or near-field) and far field (or far-field) are regions of the electromagnetic field around an object, such as a transmitting antenna, or the result of radiation scattering off an obje...
Near and far field - Wikipedia
Virtual particle
In physics, a virtual particle is an explanatory conceptual entity that is found in mathematical calculations about quantum field theory. It refers to mathematical terms that have some appearance of r...
Conformal vector field
A conformal vector field (often conformal Killing vector field and occasionally conformal or conformal collineation) of a Riemannian manifold is a vector field that satisfies:for some smooth real-va...
What Do You Mean, The Universe Is Flat?
The universe is three-dimensional. The universe is four-dimensional—three for space, one for time. The universe has nine, or ten or eleven dimensions.Matter curves spacetime. The universe is flat.The ...
Quantum scientists create light from vacuum
Scientists at Chalmers have succeeded in creating light from vacuum – observing an effect first predicted over 40 years ago. The results have been published in the journal Nature. In an innovative exp...
Vacuum genesis
Vacuum genesis (zero-energy universe) is a scientific theory about the Big Bang that states that the universe began as a single particle arising from an absolute vacuum, similar to how virtual particl...
Electrostatics
Electrostatics is a branch of physics that deals with the phenomena and properties of stationary or slow-moving electric charges with no acceleration.Since classical physics, it has been known that so...
Electrostatics - Wikipedia
Quantum tunnelling
Quantum tunnelling or tunneling (see spelling differences) refers to the quantum mechanical phenomenon where a particle tunnels through a barrier that it classically could not surmount. This plays an ...
Quantum tunnelling - Wikipedia
Force carrier
In particle physics, force carriers are particles that give rise to forces between other particles. These particles are bundles of energy (quanta) of a particular kind of field. There is one kind of f...
Killing vector field
In mathematics, a Killing vector field (often just Killing field), named after Wilhelm Killing, is a vector field on a Riemannian manifold (or pseudo-Riemannian manifold) that preserves the metric. K...
Killing vector field - Wikipedia
Unruh effect
The hypothetical Unruh effect (or sometimes Fulling–Davies–Unruh effect) is the prediction that an accelerating observer will observe black-body radiation where an inertial observer would observe none...
Affine vector field
An affine vector field (sometimes affine collineation or affine) is a projective vector field preserving geodesics and preserving the affine parameter. Mathematically, this is expressed by the followi...
Homothetic vector field
A homothetic vector field (sometimes homothetic collineation or homothety) is a projective vector field which satisfies the condition:where c is a real constant. Homothetic vector fields find applicat...
Matter collineation
A matter collineation (sometimes matter symmetry and abbreviated to MC) is a vector field that satisfies the condition,where are the energy-momentum tensor components. The intimate relation between g...
Lagrangian
The Lagrangian, L, of a dynamical system is a mathematical function that summarizes the dynamics of the system. For a simple mechanical system, it is the value given by the kinetic energy of the parti...
Pair production
Pair production is the creation of an elementary particle and its antiparticle, for example an electron and its antiparticle, the positron, a muon and antimuon, or a tau and antitau. Usually it occurs...
Gravitation
Hammer and feather drop: Apollo 15 astronaut David Scott on the Moon enacting the legend of Galileo's gravity experiment. (1.38 MB, ogg/Theora format).Gravity (also called gravitation) is a natural ...
Gravitation - Wikipedia
Quantum fluctuation
The video of an experiment showing vacuum fluctuations (in the red ring) amplified by spontaneous parametric down-conversion.In quantum physics, a quantum fluctuation (or quantum vacuum fluctuation ...
Curvature collineation
A curvature collineation (often abbreviated to CC) is vector field which preserves the Riemann tensor in the sense that,where are the components of the Riemann tensor. The set of all smooth curvature...
Perturbation theory (quantum mechanics)
In quantum mechanics, perturbation theory is a set of approximation schemes directly related to mathematical perturbation for describing a complicated quantum system in terms of a simpler one. The id...
Hydrodynamics
In physics, fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow—the natural science of fluids (liquids and gases) in motion. It has several subdisciplines itself, includi...