SettingsFundamental physics concepts
Action (physics)
In physics, action is an attribute of the dynamics of a physical system.
In physics, action is an attribute of the dynamics of a physical system.
Adiabatic invariant
An adiabatic invariant is a property of a physical system that stays constant when changes occur slowly.
An adiabatic invariant is a property of a physical system that stays constant when changes occur slowly.
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system.
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system.
Ampère's circuital law
In classical electromagnetism, Ampère's circuital law, discovered by André-Marie Ampère in 1826, relates the integrated magnetic field around a closed loop to the electric current passing throug...
In classical electromagnetism, Ampère's circuital law, discovered by André-Marie Ampère in 1826, relates the integrated magnetic field around a closed loop to the electric current passing throug...
Ampère's force law
In magnetostatics, the force of attraction or repulsion between two current-carrying wires (see Figure 1) is often called Ampère's force law.
In magnetostatics, the force of attraction or repulsion between two current-carrying wires (see Figure 1) is often called Ampère's force law.
Angular momentum
In physics, angular momentum, moment of momentum, or rotational momentum is a vector quantity that can be used to describe the overall state of a physical system.
In physics, angular momentum, moment of momentum, or rotational momentum is a vector quantity that can be used to describe the overall state of a physical system.
Angular momentum coupling
In quantum mechanics, the procedure of constructing eigenstates of total angular momentum out of eigenstates of separate angular momenta is called angular momentum coupling.
In quantum mechanics, the procedure of constructing eigenstates of total angular momentum out of eigenstates of separate angular momenta is called angular momentum coupling.
Ansatz
Ansatz is a German noun with several meanings in the English language.
Ansatz is a German noun with several meanings in the English language.
Arrow of time
The arrow of time, or time’s arrow, is a term coined in 1927 by the British astronomer Arthur Eddington to describe the "one-way direction" or "asymmetry" of time.
The arrow of time, or time’s arrow, is a term coined in 1927 by the British astronomer Arthur Eddington to describe the "one-way direction" or "asymmetry" of time.
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.
Autocatalytic reaction
Autocatalytic reactions are chemical reactions in which at least one of the reactant is also a product.
Autocatalytic reactions are chemical reactions in which at least one of the reactant is also a product.
BKS theory
The Bohr-Kramers-Slater (BKS) theory was perhaps the final attempt at understanding the interaction of matter and electromagnetic radiation on the basis of the so-called Old quantum theory, in ...
The Bohr-Kramers-Slater (BKS) theory was perhaps the final attempt at understanding the interaction of matter and electromagnetic radiation on the basis of the so-called Old quantum theory, in ...
Bloch oscillations
Bloch oscillation is a phenomenon from solid state physics.
Bloch oscillation is a phenomenon from solid state physics.
Bloch wave
A Bloch wave or Bloch state, named after Swiss physicist Felix Bloch, is the wavefunction of a particle placed in a periodic potential.
A Bloch wave or Bloch state, named after Swiss physicist Felix Bloch, is the wavefunction of a particle placed in a periodic potential.
Bohr magneton
In atomic physics, the Bohr-Procopiu magneton (symbol μB) is a physical constant and the natural unit for expressing an electron magnetic dipole moment.
In atomic physics, the Bohr-Procopiu magneton (symbol μB) is a physical constant and the natural unit for expressing an electron magnetic dipole moment.
Boiling point
The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.
The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.
Boltzmann equation
The Boltzmann equation, also often known as the Boltzmann transport equation, devised by Ludwig Boltzmann, describes the statistical distribution of one particle in rarefied gas.
The Boltzmann equation, also often known as the Boltzmann transport equation, devised by Ludwig Boltzmann, describes the statistical distribution of one particle in rarefied gas.
Bose-Einstein statistics
In statistical mechanics, Bose–Einstein statistics (or more colloquially B–E statistics) determines the statistical distribution of identical indistinguishable bosons over the energy state...
In statistical mechanics, Bose–Einstein statistics (or more colloquially B–E statistics) determines the statistical distribution of identical indistinguishable bosons over the energy state...
Bose–Einstein statistics
In statistical mechanics, Bose–Einstein statistics (or more colloquially B–E statistics) determines the statistical distribution of identical indistinguishable bosons over the energy state...
In statistical mechanics, Bose–Einstein statistics (or more colloquially B–E statistics) determines the statistical distribution of identical indistinguishable bosons over the energy state...
Brownian ratchet
In the philosophy of thermal and statistical physics, the Brownian ratchet or Feynman-Smoluchowski ratchet is a thought experiment about an apparent perpetual motion machine first analyse...
In the philosophy of thermal and statistical physics, the Brownian ratchet or Feynman-Smoluchowski ratchet is a thought experiment about an apparent perpetual motion machine first analyse...
Buoyancy
In physics, buoyancy is an upward force exerted by a liquid, gas or other fluid, that opposes the weight of an immersed object.
In physics, buoyancy is an upward force exerted by a liquid, gas or other fluid, that opposes the weight of an immersed object.
Calculus of variations
Calculus of variations is a field of mathematics, or more specifically calculus, that deals with maximizing or minimizing functionals, which are mappings from a set of functions to the real numbers.
Calculus of variations is a field of mathematics, or more specifically calculus, that deals with maximizing or minimizing functionals, which are mappings from a set of functions to the real numbers.
Canonical transformation
In Hamiltonian mechanics, a canonical transformation is a change of canonical coordinates → that preserves the form of Hamilton's equations, although it might not preserve the Hamilto...
In Hamiltonian mechanics, a canonical transformation is a change of canonical coordinates → that preserves the form of Hamilton's equations, although it might not preserve the Hamilto...
Capacitance
Capacitance is the ability of a body to store an electrical charge.
Capacitance is the ability of a body to store an electrical charge.
Capstan equation
The capstan equation or belt friction equation, also known as Eytelwein's formula, relates the hold-force to the load-force if a flexible line is wound around a cylinder (a bollard, ...
The capstan equation or belt friction equation, also known as Eytelwein's formula, relates the hold-force to the load-force if a flexible line is wound around a cylinder (a bollard, ...
Carnot cycle
The Carnot cycle is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded by Benoit Paul Émile Clapeyron in the 1830s and 40s.
The Carnot cycle is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded by Benoit Paul Émile Clapeyron in the 1830s and 40s.
Causality
Causality is the relationship between an event and a second event, where the second event is understood as a consequence of the first.
Causality is the relationship between an event and a second event, where the second event is understood as a consequence of the first.
Causality (physics)
Causality is the relationship between causes and effects.
Causality is the relationship between causes and effects.
Center of mass
In physics, the center of mass or barycenter is the weighted average location of all the mass in a body or group of bodies.
In physics, the center of mass or barycenter is the weighted average location of all the mass in a body or group of bodies.
Chaos theory
Chaos theory is a field of study in mathematics, with applications in several disciplines including physics, economics, biology, and philosophy.
Chaos theory is a field of study in mathematics, with applications in several disciplines including physics, economics, biology, and philosophy.
Characteristic time
The characteristic time is an estimate of the order of magnitude of the reaction time scale.
The characteristic time is an estimate of the order of magnitude of the reaction time scale.
Charge (physics)
Charge is a quantity which is present in every body (due to mass and mass contains atoms having electrons and protons) and which shows some electrical characteristics.
Charge is a quantity which is present in every body (due to mass and mass contains atoms having electrons and protons) and which shows some electrical characteristics.
Charge density
The linear, surface, or volume charge density is the amount of electric charge in a line, surface, or volume, respectively.
The linear, surface, or volume charge density is the amount of electric charge in a line, surface, or volume, respectively.
Cherenkov radiation
Cherenkov radiation is electromagnetic radiation emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium.
Cherenkov radiation is electromagnetic radiation emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium.
Classical limit
The classical limit or correspondence limit is the ability of a physical theory to approximate or "recover" classical mechanics when considered over special values of its parameters.
The classical limit or correspondence limit is the ability of a physical theory to approximate or "recover" classical mechanics when considered over special values of its parameters.
Classical mechanics
In physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of ...
In physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of ...
Clausius-Mossotti relation
The Clausius–Mossotti relation is named after the Italian physicist Ottaviano-Fabrizio Mossotti, whose 1850 book analyzed the relationship between the dielectric constants of two different media...
The Clausius–Mossotti relation is named after the Italian physicist Ottaviano-Fabrizio Mossotti, whose 1850 book analyzed the relationship between the dielectric constants of two different media...
Clausius–Mossotti relation
The Clausius–Mossotti relation is named after the Italian physicist Ottaviano-Fabrizio Mossotti, whose 1850 book analyzed the relationship between the dielectric constants of two different media...
The Clausius–Mossotti relation is named after the Italian physicist Ottaviano-Fabrizio Mossotti, whose 1850 book analyzed the relationship between the dielectric constants of two different media...
Clockwise
A clockwise motion is one that proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back to the top.
A clockwise motion is one that proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back to the top.
Closed system
The term closed system has different meanings in different contexts.
The term closed system has different meanings in different contexts.
Coherence (physics)
In physics, coherence is an ideal property of waves that enables stationary interference.
In physics, coherence is an ideal property of waves that enables stationary interference.
Commutative property
In mathematics, a binary operation is commutative if changing the order of the operands does not change the end result.
In mathematics, a binary operation is commutative if changing the order of the operands does not change the end result.
Commutativity
In mathematics an operation is commutative if changing the order of the operands does not change the end result.
In mathematics an operation is commutative if changing the order of the operands does not change the end result.
Condensed matter physics
Condensed matter physics is a branch of physics that deals with the physical properties of condensed phases of matter.
Condensed matter physics is a branch of physics that deals with the physical properties of condensed phases of matter.
Conduction (heat)
In heat transfer, conduction (or heat conduction) is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient.
In heat transfer, conduction (or heat conduction) is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient.
Configuration entropy
In statistical mechanics, configuration entropy is the portion of a system's entropy that is related to the position of its constituent particles rather than to their velocity or momentum.
In statistical mechanics, configuration entropy is the portion of a system's entropy that is related to the position of its constituent particles rather than to their velocity or momentum.
Conservation law
In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves.
In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves.
Convection
Convection is the concerted, collective movement of ensembles of molecules within fluids and rheids.
Convection is the concerted, collective movement of ensembles of molecules within fluids and rheids.
Cooper pair
In condensed matter physics, a Cooper pair or BCS pair is two electrons that are bound together at low temperatures in a certain manner first described in 1956 by American physicist Leon C...
In condensed matter physics, a Cooper pair or BCS pair is two electrons that are bound together at low temperatures in a certain manner first described in 1956 by American physicist Leon C...
Copenhagen interpretation
The Copenhagen interpretation is one of the earliest and most commonly taught interpretations of quantum mechanics.
The Copenhagen interpretation is one of the earliest and most commonly taught interpretations of quantum mechanics.
Cosmic catastrophe
The Cosmic catastrophe is a thought experiment in which the sun were to instantaneously disappear.
The Cosmic catastrophe is a thought experiment in which the sun were to instantaneously disappear.
Coulomb gap
First introduced by M. Pollak, the Coulomb gap is a soft gap in the Single-Particle Density of States (DOS) of a system of interacting localized electrons.
First introduced by M. Pollak, the Coulomb gap is a soft gap in the Single-Particle Density of States (DOS) of a system of interacting localized electrons.
Coulomb's law
Coulomb's law or Coulomb's inverse-square law is a law of physics describing the electrostatic interaction between electrically charged particles.
Coulomb's law or Coulomb's inverse-square law is a law of physics describing the electrostatic interaction between electrically charged particles.
Covariance group
In physics, covariance group is a group of coordinate transformations between admissible frames of reference (see for example).
In physics, covariance group is a group of coordinate transformations between admissible frames of reference (see for example).
Covariance principle
In physics, the principle of covariance emphasizes formulation of physical laws using only those physical quantities the measurements of which the observers in different frames of reference coul...
In physics, the principle of covariance emphasizes formulation of physical laws using only those physical quantities the measurements of which the observers in different frames of reference coul...
Covariant formulation of classical electromagnetism
The covariant formulation of classical electromagnetism refers to ways of writing the laws of classical electromagnetism (in particular, Maxwell's equations and the Lorentz force) in a form whic...
The covariant formulation of classical electromagnetism refers to ways of writing the laws of classical electromagnetism (in particular, Maxwell's equations and the Lorentz force) in a form whic...
Cross section (physics)
In nuclear and particle physics, the concept of a cross section is used to express the likelihood of interaction between particles.
In nuclear and particle physics, the concept of a cross section is used to express the likelihood of interaction between particles.
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly, repeating pattern extending in all three spatial dimensions.
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly, repeating pattern extending in all three spatial dimensions.
Current density
In physics, current density in general is a measure of the density of flow of a conserved charge, in other words flux of the charge.
In physics, current density in general is a measure of the density of flow of a conserved charge, in other words flux of the charge.
Deflection (physics)
In physics deflection is the event where an object collides and bounces against a plane surface.
In physics deflection is the event where an object collides and bounces against a plane surface.
Degenerate semiconductor
A degenerate semiconductor is a semiconductor with such a high level of doping that the material starts to act more like a metal than as a semiconductor.
A degenerate semiconductor is a semiconductor with such a high level of doping that the material starts to act more like a metal than as a semiconductor.
Degrees of freedom (physics and chemistry)
A degree of freedom is an independent physical parameter, often called a dimension, in the formal description of the state of a physical system.
A degree of freedom is an independent physical parameter, often called a dimension, in the formal description of the state of a physical system.
Density of states
In solid-state and condensed matter physics, the density of states (DOS) of a system describes the number of states per interval of energy at each energy level that are available to be occ...
In solid-state and condensed matter physics, the density of states (DOS) of a system describes the number of states per interval of energy at each energy level that are available to be occ...
Derivation of the Navier-Stokes equations
The intent of this article is to highlight the important points of the derivation of the Navier–Stokes equations as well as the application and formulation for different families of fluids.
The intent of this article is to highlight the important points of the derivation of the Navier–Stokes equations as well as the application and formulation for different families of fluids.
Derivation of the Navier–Stokes equations
The intent of this article is to highlight the important points of the derivation of the Navier–Stokes equations as well as the application and formulation for different families of fluids.
The intent of this article is to highlight the important points of the derivation of the Navier–Stokes equations as well as the application and formulation for different families of fluids.
Dielectric
A dielectric is an electrical insulator that can be polarized by an applied electric field.
A dielectric is an electrical insulator that can be polarized by an applied electric field.
Dimension
In physics and mathematics, the dimension of a space or object is informally defined as the minimum number of coordinates needed to specify any point within it.
In physics and mathematics, the dimension of a space or object is informally defined as the minimum number of coordinates needed to specify any point within it.
Dirac equation
In physics, more specifically relativistic quantum mechanics, the Dirac equation is a wave equation, formulated by British physicist Paul Dirac in 1928.
In physics, more specifically relativistic quantum mechanics, the Dirac equation is a wave equation, formulated by British physicist Paul Dirac in 1928.
Dispersion relation
In physics and electrical engineering, dispersion most often refers to frequency-dependent effects in wave propagation.
In physics and electrical engineering, dispersion most often refers to frequency-dependent effects in wave propagation.
Eigenvalues and eigenvectors
The eigenvectors of a square matrix are the non-zero vectors that, after being multiplied by the matrix, remain parallel to the original vector.
The eigenvectors of a square matrix are the non-zero vectors that, after being multiplied by the matrix, remain parallel to the original vector.
Electric charge
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter.
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter.
Electric field
In physics, an electric field is the region of space surrounding electrically charged particles and time-varying magnetic fields.
In physics, an electric field is the region of space surrounding electrically charged particles and time-varying magnetic fields.
Electric torque
In simplest case, electric torque is the force heating water in the microwave oven.
In simplest case, electric torque is the force heating water in the microwave oven.
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges.
In physics and electrical engineering, a conductor is a material which contains movable electric charges.
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current.
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current.
Electromagnetic field
An electromagnetic field (also EMF or EM field) is a physical field produced by moving electrically charged objects.
An electromagnetic field (also EMF or EM field) is a physical field produced by moving electrically charged objects.
Electromagnetic wave equation
The electromagnetic wave equation is a second-order partial differential equation that describes the propagation of electromagnetic waves through a medium or in a vacuum.
The electromagnetic wave equation is a second-order partial differential equation that describes the propagation of electromagnetic waves through a medium or in a vacuum.
Electromagnetism
Electromagnetism is the branch of science concerned with the forces that occur between electrically charged particles.
Electromagnetism is the branch of science concerned with the forces that occur between electrically charged particles.
Electron equivalent
Electron Equivalent is a concept commonly used in redox chemistry, reactions involving electron transfer, to define a quantity (e.g.
Electron Equivalent is a concept commonly used in redox chemistry, reactions involving electron transfer, to define a quantity (e.g.
Electrostatics
Electrostatics is the branch of physics that deals with the phenomena and properties of stationary or slow-moving electric charges.
Electrostatics is the branch of physics that deals with the phenomena and properties of stationary or slow-moving electric charges.
Elementary particle
In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not known to be made up of smaller particles.
In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not known to be made up of smaller particles.
Emission spectrum
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted by the element's atoms or the compound's molecules when they...
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted by the element's atoms or the compound's molecules when they...
Empty Lattice Approximation
The Empty Lattice Approximation is a theoretical electronic band structure model in which the potential is defined not more precisely than periodic and weak.
The Empty Lattice Approximation is a theoretical electronic band structure model in which the potential is defined not more precisely than periodic and weak.
Empty lattice approximation
The empty lattice approximation is a theoretical electronic band structure model in which the potential is defined not more precisely than periodic and weak.
The empty lattice approximation is a theoretical electronic band structure model in which the potential is defined not more precisely than periodic and weak.
Energy density
Energy density is a term used for the amount of energy stored in a given system or region of space per unit volume.
Energy density is a term used for the amount of energy stored in a given system or region of space per unit volume.
Energy operator
In quantum mechanics, energy is defined in terms of the energy operator, acting on the wavefunction of the system.
In quantum mechanics, energy is defined in terms of the energy operator, acting on the wavefunction of the system.
Entropy
Entropy is a thermodynamic property that can be used to determine the energy not available for work in a thermodynamic process, such as in energy conversion devices, engines, or machines.
Entropy is a thermodynamic property that can be used to determine the energy not available for work in a thermodynamic process, such as in energy conversion devices, engines, or machines.
Equation of state
In physics and thermodynamics, an equation of state is a relation between state variables.
In physics and thermodynamics, an equation of state is a relation between state variables.
Equipartition theorem
In classical statistical mechanics, the equipartition theorem is a general formula that relates the temperature of a system with its average energies.
In classical statistical mechanics, the equipartition theorem is a general formula that relates the temperature of a system with its average energies.
Equivalence principle
In the physics of general relativity, the equivalence principle is any of several related concepts dealing with the equivalence of gravitational and inertial mass, and to Albert Einstein's asse...
In the physics of general relativity, the equivalence principle is any of several related concepts dealing with the equivalence of gravitational and inertial mass, and to Albert Einstein's asse...
Ergodic hypothesis
In physics and thermodynamics, the ergodic hypothesis says that, over long periods of time, the time spent by a particle in some region of the phase space of microstates with the same energy is ...
In physics and thermodynamics, the ergodic hypothesis says that, over long periods of time, the time spent by a particle in some region of the phase space of microstates with the same energy is ...
Euclidean vector
In mathematics, physics, and engineering, a Euclidean vector is a geometric object that has a magnitude and direction and can be added according to the parallelogram law of addition.
In mathematics, physics, and engineering, a Euclidean vector is a geometric object that has a magnitude and direction and can be added according to the parallelogram law of addition.
Euler equations (fluid dynamics)
In fluid dynamics, the Euler equations are a set of equations governing inviscid flow.
In fluid dynamics, the Euler equations are a set of equations governing inviscid flow.
Euler's laws of motion
Euler's laws of motion, formulated by Leonhard Euler about 50 years after Isaac Newton formulated his laws about the motion of particles, extends them to rigid body motion.
Euler's laws of motion, formulated by Leonhard Euler about 50 years after Isaac Newton formulated his laws about the motion of particles, extends them to rigid body motion.
Faraday's law of induction
Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and ...
Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and ...
Fermi's golden rule
In quantum physics, Fermi's golden rule is a way to calculate the transition rate from one energy eigenstate of a quantum system into a continuum of energy eigenstates, due to a perturbation.
In quantum physics, Fermi's golden rule is a way to calculate the transition rate from one energy eigenstate of a quantum system into a continuum of energy eigenstates, due to a perturbation.
Fermi-Dirac statistics
Fermi–Dirac statistics (F–D statistics) is a part of the science of physics that describes the energies of single particles in a system comprising many identical particles that obey the Pauli Ex...
Fermi–Dirac statistics (F–D statistics) is a part of the science of physics that describes the energies of single particles in a system comprising many identical particles that obey the Pauli Ex...
Fermion
In particle physics, a fermion (named after Enrico Fermi) is any particle which obeys the Fermi–Dirac statistics and follows the Pauli exclusion principle, which would include all quarks and lep...
In particle physics, a fermion (named after Enrico Fermi) is any particle which obeys the Fermi–Dirac statistics and follows the Pauli exclusion principle, which would include all quarks and lep...
Fermi–Dirac statistics
Fermi–Dirac statistics (F–D statistics) is a part of the science of physics that describes the energies of single particles in a system comprising many identical particles that obey the Pauli Ex...
Fermi–Dirac statistics (F–D statistics) is a part of the science of physics that describes the energies of single particles in a system comprising many identical particles that obey the Pauli Ex...
Ferromagnetic superconductor
Ferromagnetic superconductors are materials that display intrinsic coexistence of ferromagnetism and superconductivity.
Ferromagnetic superconductors are materials that display intrinsic coexistence of ferromagnetism and superconductivity.
Ferromagnetism
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets.
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets.
Feynman checkerboard
The Feynman Checkerboard or Relativistic Chessboard model was Richard Feynman’s sum-over-paths formulation of the kernel for a free spin ½ particle moving in one spatial dimension.
The Feynman Checkerboard or Relativistic Chessboard model was Richard Feynman’s sum-over-paths formulation of the kernel for a free spin ½ particle moving in one spatial dimension.
Feynman diagram
Feynman diagrams are pictorial representations of the mathematical expressions governing the behavior of subatomic particles.
Feynman diagrams are pictorial representations of the mathematical expressions governing the behavior of subatomic particles.
Field effect (semiconductor)
In physics, the field effect refers to the modulation of the electrical conductivity of a material by the application of an external electric field.
In physics, the field effect refers to the modulation of the electrical conductivity of a material by the application of an external electric field.
File dynamics
In chemistry, physics, mathematics and related fields, file dynamics is the diffusion of N identical Brownian hard spheres in a quasi-one-dimensional channel of length L, such that the s...
In chemistry, physics, mathematics and related fields, file dynamics is the diffusion of N identical Brownian hard spheres in a quasi-one-dimensional channel of length L, such that the s...
Fine-structure constant
In physics, the fine-structure constant is a fundamental physical constant, namely the coupling constant characterizing the strength of the electromagnetic interaction.
In physics, the fine-structure constant is a fundamental physical constant, namely the coupling constant characterizing the strength of the electromagnetic interaction.
First law of thermodynamics
The first law of thermodynamics was expressed in two ways by Clausius.
The first law of thermodynamics was expressed in two ways by Clausius.
Flavour (particle physics)
In particle physics, flavour or flavor is a quantum number of elementary particles.
In particle physics, flavour or flavor is a quantum number of elementary particles.
Flux pumping
Flux pumping is a method for magnetising bulk superconductors to fields in excess of 15 teslas.
Flux pumping is a method for magnetising bulk superconductors to fields in excess of 15 teslas.
Focal cloud
A focal cloud is the collection of focal points of any imperfect lens, whether optical, electrostatic or electromagnetic.
A focal cloud is the collection of focal points of any imperfect lens, whether optical, electrostatic or electromagnetic.
Focus (optics)
In geometrical optics, a focus, also called a focal point is a point located at half the distance of the radius of curvature of a spherical surface.
In geometrical optics, a focus, also called a focal point is a point located at half the distance of the radius of curvature of a spherical surface.
Force
In physics, a force is any influence that causes an object to undergo a certain change, either concerning its movement, direction, or geometrical construction.
In physics, a force is any influence that causes an object to undergo a certain change, either concerning its movement, direction, or geometrical construction.
Forging temperature
Forging temperature is a temperature at which a metal becomes soft like clay or its shape can be changed by applying a relatively small force without creating cracks in metal.
Forging temperature is a temperature at which a metal becomes soft like clay or its shape can be changed by applying a relatively small force without creating cracks in metal.
Four-vector
In the theory of relativity, a four-vector or 4-vector is a vector in a four-dimensional real vector space, called Minkowski space.
In the theory of relativity, a four-vector or 4-vector is a vector in a four-dimensional real vector space, called Minkowski space.
Fourier transform
The Fourier transform, named for Joseph Fourier, is a mathematical transform with many applications in physics and engineering.
The Fourier transform, named for Joseph Fourier, is a mathematical transform with many applications in physics and engineering.
Fractional quantum mechanics
In physics, fractional quantum mechanics is a generalization of standard quantum mechanics.
In physics, fractional quantum mechanics is a generalization of standard quantum mechanics.
Fractional Schrödinger equation
The fractional Schrödinger equation is a fundamental equation of fractional quantum mechanics.
The fractional Schrödinger equation is a fundamental equation of fractional quantum mechanics.
Frame-dragging
Einstein's general theory of relativity predicts that non-static, stationary mass-energy distributions affect spacetime in a peculiar way giving rise to a phenomenon usually known as frame-dragging.
Einstein's general theory of relativity predicts that non-static, stationary mass-energy distributions affect spacetime in a peculiar way giving rise to a phenomenon usually known as frame-dragging.
Free electron model
In solid-state physics, the free electron model is a simple model for the behaviour of valence electrons in a crystal structure of a metallic solid.
In solid-state physics, the free electron model is a simple model for the behaviour of valence electrons in a crystal structure of a metallic solid.
Free particle
In physics, a free particle is a particle that, in some sense, is not bound by an external force, or equivalently not in a region where its potential energy varies.
In physics, a free particle is a particle that, in some sense, is not bound by an external force, or equivalently not in a region where its potential energy varies.
Fuel temperature coefficient of reactivity
Fuel temperature coefficient of reactivity is the change in reactivity of the nuclear fuel per degree change in the fuel temperature.
Fuel temperature coefficient of reactivity is the change in reactivity of the nuclear fuel per degree change in the fuel temperature.
Fundamentals of Physics
Fundamentals of Physics is a calculus-based physics textbook by David Halliday, Robert Resnick, and Jearl Walker.
Fundamentals of Physics is a calculus-based physics textbook by David Halliday, Robert Resnick, and Jearl Walker.
Fusion ignition
Fusion ignition is the point at which a nuclear fusion reaction becomes self-sustaining.
Fusion ignition is the point at which a nuclear fusion reaction becomes self-sustaining.
General relativity
General relativity, or the general theory of relativity, is the geometric theory of gravitation published by Albert Einstein in 1916 and the current description of gravitation in modern ph...
General relativity, or the general theory of relativity, is the geometric theory of gravitation published by Albert Einstein in 1916 and the current description of gravitation in modern ph...
Geodesic
In mathematics, particularly differential geometry, a geodesic ( or ) is a generalization of the notion of a "straight line" to "curved spaces".
In mathematics, particularly differential geometry, a geodesic ( or ) is a generalization of the notion of a "straight line" to "curved spaces".
Gibbs free energy
In thermodynamics, the Gibbs free energy is a thermodynamic potential that measures the "useful" or process-initiating work obtainable from a thermodynamic system at a constant temperature and p...
In thermodynamics, the Gibbs free energy is a thermodynamic potential that measures the "useful" or process-initiating work obtainable from a thermodynamic system at a constant temperature and p...
Gravitation
Gravitation, or gravity, is a natural phenomenon by which physical bodies attract with a force proportional to their masses.
Gravitation, or gravity, is a natural phenomenon by which physical bodies attract with a force proportional to their masses.
Gravitational singularity
A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on th...
A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on th...
Gravitational two-body problem
The gravitational two-body problem concerns the motion of two point particles that interact only with each other, due to gravity.
The gravitational two-body problem concerns the motion of two point particles that interact only with each other, due to gravity.
Green's function
In mathematics, a Green's function is a type of function used to solve inhomogeneous differential equations subject to specific initial conditions or boundary conditions.
In mathematics, a Green's function is a type of function used to solve inhomogeneous differential equations subject to specific initial conditions or boundary conditions.
Guang-Jiong Ni
Prof. Guang-Jiong Ni was born in 1934.
Prof. Guang-Jiong Ni was born in 1934.
H-theorem
In Classical Statistical Mechanics, the H-theorem, introduced by Ludwig Boltzmann in 1872, describes the increase in the entropy of an ideal gas in an irreversible process.
In Classical Statistical Mechanics, the H-theorem, introduced by Ludwig Boltzmann in 1872, describes the increase in the entropy of an ideal gas in an irreversible process.
Hamiltonian mechanics
Hamiltonian mechanics is a reformulation of classical mechanics that was introduced in 1833 by Irish mathematician William Rowan Hamilton.
Hamiltonian mechanics is a reformulation of classical mechanics that was introduced in 1833 by Irish mathematician William Rowan Hamilton.
Heat as a transfer of energy
In physics, chemistry, engineering, and thermodynamics, a quantity of heat is an amount of energy produced or transferred from one body, region of space, set of components, or thermodynamic syst...
In physics, chemistry, engineering, and thermodynamics, a quantity of heat is an amount of energy produced or transferred from one body, region of space, set of components, or thermodynamic syst...
Heat capacity
Heat capacity, or thermal capacity, is the measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount.
Heat capacity, or thermal capacity, is the measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount.
Heat engine
In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work.
In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work.
Helmholtz free energy
In thermodynamics, the Helmholtz free energy is a thermodynamic potential which measures the “useful” work obtainable from a closed thermodynamic system at a constant temperature and volume.
In thermodynamics, the Helmholtz free energy is a thermodynamic potential which measures the “useful” work obtainable from a closed thermodynamic system at a constant temperature and volume.
Hysteresis
Hysteresis is the dependence of a system not just on its current environment but also on its past.
Hysteresis is the dependence of a system not just on its current environment but also on its past.
Ideal gas
An ideal gas is a theoretical gas composed of a set of randomly-moving, non-interacting point particles.
An ideal gas is a theoretical gas composed of a set of randomly-moving, non-interacting point particles.
Impulse (physics)
In classical mechanics, an impulse (abbreviated I or J) is defined as the integral of a force with respect to time.
In classical mechanics, an impulse (abbreviated I or J) is defined as the integral of a force with respect to time.
Instability
In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds.
In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds.
Insulator (electrical)
An insulator, also called a dielectric, is a material that resists the flow of electric charge.
An insulator, also called a dielectric, is a material that resists the flow of electric charge.
Insulator (electricity)
A true insulator is a material that does not respond to an electric field and completely resists the flow of electric charge.
A true insulator is a material that does not respond to an electric field and completely resists the flow of electric charge.
Internal energy
In thermodynamics, the internal energy is the total energy contained by a thermodynamic system.
In thermodynamics, the internal energy is the total energy contained by a thermodynamic system.
Intrinsic parity
In quantum mechanics, the intrinsic parity is a phase factor that arises as an eigenvalue of the parity operation (a reflection about the origin).
In quantum mechanics, the intrinsic parity is a phase factor that arises as an eigenvalue of the parity operation (a reflection about the origin).
Introduction to gauge theory
In physics, gauge invariance is the property of a field theory in which different configurations of the underlying fundamental but unobservable fields result in identical observable quantities.
In physics, gauge invariance is the property of a field theory in which different configurations of the underlying fundamental but unobservable fields result in identical observable quantities.
Introduction to mathematics of general relativity
The mathematics of general relativity are very complex.
The mathematics of general relativity are very complex.
Invariant (physics)
In mathematics and theoretical physics, an invariant is a property of a system which remains unchanged under some transformation.
In mathematics and theoretical physics, an invariant is a property of a system which remains unchanged under some transformation.
Invariant mass
The invariant mass, rest mass, intrinsic mass, proper mass or just mass is a characteristic of the total energy and momentum of an object or a system of objects that is ...
The invariant mass, rest mass, intrinsic mass, proper mass or just mass is a characteristic of the total energy and momentum of an object or a system of objects that is ...
Ionic conductivity
Ionic conduction is the transit of ion from one site to another through defects in the crystal lattice of a solid.
Ionic conduction is the transit of ion from one site to another through defects in the crystal lattice of a solid.
Ising model
The Ising model, named after the physicist Ernst Ising, is a mathematical model of ferromagnetism in statistical mechanics.
The Ising model, named after the physicist Ernst Ising, is a mathematical model of ferromagnetism in statistical mechanics.
Johari-Goldstein relaxation
Johari-Goldstein relaxation, also known as the JG β-relaxation, is a process involved in the phase change of amorphous and glass-like substances.
Johari-Goldstein relaxation, also known as the JG β-relaxation, is a process involved in the phase change of amorphous and glass-like substances.
Kinetic scheme
In physics and chemistry and related fields, a kinetic scheme is a network of states and connections among the states representing the scheme of a dynamical process.
In physics and chemistry and related fields, a kinetic scheme is a network of states and connections among the states representing the scheme of a dynamical process.
Kinetic theory
The kinetic theory of gases describes a gas as a large number of small particles, all of which are in constant, random motion.
The kinetic theory of gases describes a gas as a large number of small particles, all of which are in constant, random motion.
Klein-Gordon equation
The Klein–Gordon equation (Klein–Fock–Gordon equation or sometimes Klein–Gordon–Fock equation) is a relativistic version of the Schrödinger equation.
The Klein–Gordon equation (Klein–Fock–Gordon equation or sometimes Klein–Gordon–Fock equation) is a relativistic version of the Schrödinger equation.
Klein–Gordon equation
The Klein–Gordon equation (Klein–Fock–Gordon equation or sometimes Klein–Gordon–Fock equation) is a relativistic version of the Schrödinger equation.
The Klein–Gordon equation (Klein–Fock–Gordon equation or sometimes Klein–Gordon–Fock equation) is a relativistic version of the Schrödinger equation.
Lagrangian
The Lagrangian, L, of a dynamical system is a function that summarizes the dynamics of the system.
The Lagrangian, L, of a dynamical system is a function that summarizes the dynamics of the system.
Legendre transformation
In mathematics, the Legendre transformation or Legendre transform, named after Adrien-Marie Legendre, is an operation that transforms one real-valued function of a real variable into another.
In mathematics, the Legendre transformation or Legendre transform, named after Adrien-Marie Legendre, is an operation that transforms one real-valued function of a real variable into another.
Leggett inequality
The Leggett inequalities, named for Anthony James Leggett, are a related pair of mathematical expressions concerning the correlations of properties of entangled particles.
The Leggett inequalities, named for Anthony James Leggett, are a related pair of mathematical expressions concerning the correlations of properties of entangled particles.
Leggett–Garg inequality
The Leggett–Garg inequality, named for Anthony James Leggett and Anupam Garg, is a mathematical inequality fulfilled by all macrorealistic physical theories.
The Leggett–Garg inequality, named for Anthony James Leggett and Anupam Garg, is a mathematical inequality fulfilled by all macrorealistic physical theories.
Length measurement
Length measurement is implemented in practice in an amazing variety of ways.
Length measurement is implemented in practice in an amazing variety of ways.
Length scale
In physics, length scale is a particular length or distance determined with the precision of one order (or a few orders) of magnitude.
In physics, length scale is a particular length or distance determined with the precision of one order (or a few orders) of magnitude.
Linear
The word linear comes from the Latin word linearis, which means created by lines.
The word linear comes from the Latin word linearis, which means created by lines.
Linear response
A linear response function describes the input-output relationship of a signal transducer such as a radio turning electromagnetic waves into music or a neuron turning synaptic input into a response.
A linear response function describes the input-output relationship of a signal transducer such as a radio turning electromagnetic waves into music or a neuron turning synaptic input into a response.
Linearity
The word linear comes from the Latin word linearis, which means pertaining to or resembling a line.
The word linear comes from the Latin word linearis, which means pertaining to or resembling a line.
Liouville's theorem (Hamiltonian)
In physics, Liouville's theorem, named after the French mathematician Joseph Liouville, is a key theorem in classical statistical and Hamiltonian mechanics.
In physics, Liouville's theorem, named after the French mathematician Joseph Liouville, is a key theorem in classical statistical and Hamiltonian mechanics.
Logarithmic Schrödinger equation
In theoretical physics, the Logarithmic Schrödinger equation (sometimes abbreviated as LNSE or LogSE) is one of the nonlinear modifications of Schrödinger's equation.
In theoretical physics, the Logarithmic Schrödinger equation (sometimes abbreviated as LNSE or LogSE) is one of the nonlinear modifications of Schrödinger's equation.
Long-slit spectroscopy
In astronomy, Long-slit spectroscopy involves observing an elongated celestial object (such as a nebula or along the major axis of a disc galaxy at high inclination) through an elongated slit ap...
In astronomy, Long-slit spectroscopy involves observing an elongated celestial object (such as a nebula or along the major axis of a disc galaxy at high inclination) through an elongated slit ap...
Lorentz force
In physics, particularly electromagnetism, the Lorentz force is the force on a point charge due to electromagnetic fields.
In physics, particularly electromagnetism, the Lorentz force is the force on a point charge due to electromagnetic fields.
Lorentz force velocimetry
Lorentz force velocimetry is a noncontact electromagnetic flow measurement technique.
Lorentz force velocimetry is a noncontact electromagnetic flow measurement technique.
Lorentz interval
The Lorentz interval is a quantity that is used instead of distance when dealing with space-time geometry, because it is the only quantity that is the same to all observers regardless of how fas...
The Lorentz interval is a quantity that is used instead of distance when dealing with space-time geometry, because it is the only quantity that is the same to all observers regardless of how fas...
Lorentz transformation
In physics, the Lorentz transformation or Lorentz-Fitzgerald transformation describes how, according to the theory of special relativity, different measurements of space and time by two ob...
In physics, the Lorentz transformation or Lorentz-Fitzgerald transformation describes how, according to the theory of special relativity, different measurements of space and time by two ob...
Lorenz gauge condition
In electromagnetism, the Lorenz gauge or Lorenz gauge condition is a partial gauge fixing of the electromagnetic vector potential.
In electromagnetism, the Lorenz gauge or Lorenz gauge condition is a partial gauge fixing of the electromagnetic vector potential.
Macroscopic scale
The macroscopic scale is the length scale on which objects or processes are of a size which is measurable and observable by the naked eye.
The macroscopic scale is the length scale on which objects or processes are of a size which is measurable and observable by the naked eye.
Magnetic braking
Magnetic braking is a theory explaining the loss of solar angular momentum due to material getting captured by the solar magnetic field and thrown out at great distance from the surface of the Sun.
Magnetic braking is a theory explaining the loss of solar angular momentum due to material getting captured by the solar magnetic field and thrown out at great distance from the surface of the Sun.
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials.
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials.
Magnetization reversal by circularly polarized light
Discovered only recently (2006) by C.D. Stanciu and F. Hansteen and published in Physical Review Letters this effect is generally called all-optical magnetization reversal.
Discovered only recently (2006) by C.D. Stanciu and F. Hansteen and published in Physical Review Letters this effect is generally called all-optical magnetization reversal.
Magnetohydrodynamics
Magnetohydrodynamics is an academic discipline which studies the dynamics of electrically conducting fluids.
Magnetohydrodynamics is an academic discipline which studies the dynamics of electrically conducting fluids.
Majorana fermion
A Majorana fermion is a fermion that is its own anti-particle.
A Majorana fermion is a fermion that is its own anti-particle.
Mass
In physics, mass, more specifically inertial mass, can be defined as a quantitative measure of an object's resistance to the change of its speed.
In physics, mass, more specifically inertial mass, can be defined as a quantitative measure of an object's resistance to the change of its speed.
Mass versus weight
In everyday usage, the mass of an object is often referred to as its weight though these are in fact different concepts and quantities.
In everyday usage, the mass of an object is often referred to as its weight though these are in fact different concepts and quantities.
Mass-to-charge ratio
The mass-to-charge ratio ratio is a physical quantity that is widely used in the electrodynamics of charged particles, e.g. in electron optics and ion optics.
The mass-to-charge ratio ratio is a physical quantity that is widely used in the electrodynamics of charged particles, e.g. in electron optics and ion optics.
Master equation
In physics and chemistry and related fields, a master equation is a phenomenological set of first-order differential equations describing the time evolution of the probability of a system to occ...
In physics and chemistry and related fields, a master equation is a phenomenological set of first-order differential equations describing the time evolution of the probability of a system to occ...
Matrix mechanics
Matrix mechanics is a formulation of quantum mechanics created by Werner Heisenberg, Max Born, and Pascual Jordan in 1925.
Matrix mechanics is a formulation of quantum mechanics created by Werner Heisenberg, Max Born, and Pascual Jordan in 1925.
Maxwell relations
Maxwell's relations are a set of equations in thermodynamics which are derivable from the definitions of the thermodynamic potentials.
Maxwell's relations are a set of equations in thermodynamics which are derivable from the definitions of the thermodynamic potentials.
Maxwell's demon
In the philosophy of thermal and statistical physics, Maxwell's demon is a thought experiment created by the Scottish physicist James Clerk Maxwell to "show that the Second Law of Thermodynamics...
In the philosophy of thermal and statistical physics, Maxwell's demon is a thought experiment created by the Scottish physicist James Clerk Maxwell to "show that the Second Law of Thermodynamics...
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits.
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits.
Maxwell's equations in curved spacetime
In physics, Maxwell's equations in curved spacetime govern the dynamics of the electromagnetic field in curved spacetime (where the metric may not be the Minkowski metric) or where one uses an a...
In physics, Maxwell's equations in curved spacetime govern the dynamics of the electromagnetic field in curved spacetime (where the metric may not be the Minkowski metric) or where one uses an a...
Maxwell-Boltzmann statistics
In statistical mechanics, Maxwell–Boltzmann statistics describes the statistical distribution of material particles over various energy states in thermal equilibrium, when the temperature is hig...
In statistical mechanics, Maxwell–Boltzmann statistics describes the statistical distribution of material particles over various energy states in thermal equilibrium, when the temperature is hig...
Maxwell–Boltzmann statistics
In statistical mechanics, Maxwell–Boltzmann statistics describes the statistical distribution of material particles over various energy states in thermal equilibrium, when the temperature is hig...
In statistical mechanics, Maxwell–Boltzmann statistics describes the statistical distribution of material particles over various energy states in thermal equilibrium, when the temperature is hig...
Mean field theory
Mean field theory (MFT, also known as self-consistent field theory) is a method to analyse physical systems with multiple bodies.
Mean field theory (MFT, also known as self-consistent field theory) is a method to analyse physical systems with multiple bodies.
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid.
The melting point of a solid is the temperature at which it changes state from solid to liquid.
Metric tensor
In the mathematical field of differential geometry, a metric tensor is a type of function defined on a manifold which takes as input a pair of tangent vectors v and w and produces a real...
In the mathematical field of differential geometry, a metric tensor is a type of function defined on a manifold which takes as input a pair of tangent vectors v and w and produces a real...
MHV Amplitudes
In theoretical particle physics, maximally helicity violating amplitudes are amplitudes with n external gauge bosons, where n-2 gauge bosons have a particular helicity and the other two have the...
In theoretical particle physics, maximally helicity violating amplitudes are amplitudes with n external gauge bosons, where n-2 gauge bosons have a particular helicity and the other two have the...
Microscopic scale
The microscopic scale is the scale of size or length used to describe objects smaller than those that can easily be seen by the naked eye and which require a lens or microscope to see them clearly.
The microscopic scale is the scale of size or length used to describe objects smaller than those that can easily be seen by the naked eye and which require a lens or microscope to see them clearly.
Minkowski space
In mathematical physics, Minkowski space or Minkowski spacetime (named after the mathematician Hermann Minkowski) is the mathematical setting in which Einstein's theory of special relativi...
In mathematical physics, Minkowski space or Minkowski spacetime (named after the mathematician Hermann Minkowski) is the mathematical setting in which Einstein's theory of special relativi...
Moment of inertia
In classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an obje...
In classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an obje...
Moving magnet and conductor problem
The moving magnet and conductor problem is a famous thought experiment, originating in the 19th century, concerning the intersection of classical electromagnetism and special relativity.
The moving magnet and conductor problem is a famous thought experiment, originating in the 19th century, concerning the intersection of classical electromagnetism and special relativity.
Moyal bracket
In physics, the Moyal bracket is the suitably normalized antisymmetrization of the phase-space star product.
In physics, the Moyal bracket is the suitably normalized antisymmetrization of the phase-space star product.
Navier-Stokes equations
In physics, the Navier–Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, describe the motion of fluid substances.
In physics, the Navier–Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, describe the motion of fluid substances.
Navier–Stokes equations
In physics, the Navier–Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, describe the motion of fluid substances.
In physics, the Navier–Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, describe the motion of fluid substances.
Negative frequency
The concept of negative and positive frequency can be as simple as a wheel rotating one way or the other way.
The concept of negative and positive frequency can be as simple as a wheel rotating one way or the other way.
Negative refraction
Negative refraction is the name for an electromagnetic phenomenon where light rays are refracted at an interface in the reverse sense to that normally expected.
Negative refraction is the name for an electromagnetic phenomenon where light rays are refracted at an interface in the reverse sense to that normally expected.
Neutron
The neutron is a subatomic hadron particle which has the symbol or, no net electric charge and a mass slightly larger than that of a proton.
The neutron is a subatomic hadron particle which has the symbol or, no net electric charge and a mass slightly larger than that of a proton.
Newton's law of universal gravitation
Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and i...
Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and i...
Newton's laws of motion
Newton's laws of motion are three physical laws that he was stupid form the basis for classical mechanics.
Newton's laws of motion are three physical laws that he was stupid form the basis for classical mechanics.
Newton's theorem of revolving orbits
In classical mechanics, Newton's theorem of revolving orbits identifies the type of central force needed to multiply the angular speed of a particle by a factor k without affecting its radia...
In classical mechanics, Newton's theorem of revolving orbits identifies the type of central force needed to multiply the angular speed of a particle by a factor k without affecting its radia...
Newtonian dynamics
In physics, the Newtonian dynamics is understood as the dynamics of a particle or a small body according to Newton's laws of motion.
In physics, the Newtonian dynamics is understood as the dynamics of a particle or a small body according to Newton's laws of motion.
Noether's theorem
Noether's (first) theorem states that any differentiable symmetry of the action of a physical system has a corresponding conservation law.
Noether's (first) theorem states that any differentiable symmetry of the action of a physical system has a corresponding conservation law.
Non-contact force
A non-contact force is a force applied to an object by another body that is not in direct contact with it.
A non-contact force is a force applied to an object by another body that is not in direct contact with it.
Non-equilibrium thermodynamics
Non-equilibrium thermodynamics is a branch of thermodynamics that deals with systems that are not in thermodynamic equilibrium.
Non-equilibrium thermodynamics is a branch of thermodynamics that deals with systems that are not in thermodynamic equilibrium.
Nonlinear system
In mathematics, a nonlinear system is one that does not satisfy the superposition principle, or one whose output is not directly proportional to its input; a linear system fulfills these conditions.
In mathematics, a nonlinear system is one that does not satisfy the superposition principle, or one whose output is not directly proportional to its input; a linear system fulfills these conditions.
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission refers to either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts, often prod...
In nuclear physics and nuclear chemistry, nuclear fission refers to either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts, often prod...
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus.
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus.
Nuclear physics
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei.
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei.
Observer (physics)
The term observer has a number of non-equivalent uses in science.
The term observer has a number of non-equivalent uses in science.
Octave (electronics)
In electronics, an octave is a doubling or halving of a frequency.
In electronics, an octave is a doubling or halving of a frequency.
Onsager reciprocal relations
In thermodynamics, the Onsager reciprocal relations express the equality of certain ratios between flows and forces in thermodynamic systems out of equilibrium, but where a notion of local equil...
In thermodynamics, the Onsager reciprocal relations express the equality of certain ratios between flows and forces in thermodynamic systems out of equilibrium, but where a notion of local equil...
Outline of physics
Physics – natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force.
Physics – natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force.
Paramagnetism
Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field.
Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field.
Parity (physics)
In physics, a parity transformation (also called parity inversion) is the flip in the sign of one spatial coordinate.
In physics, a parity transformation (also called parity inversion) is the flip in the sign of one spatial coordinate.
Partition function (statistical mechanics)
In statistical mechanics, the partition function, Z, encodes the statistical properties of a system in thermodynamic equilibrium.
In statistical mechanics, the partition function, Z, encodes the statistical properties of a system in thermodynamic equilibrium.
Path integral formulation
The path integral formulation of quantum mechanics is a description of quantum theory which generalizes the action principle of classical mechanics.
The path integral formulation of quantum mechanics is a description of quantum theory which generalizes the action principle of classical mechanics.
Pauli exclusion principle
The Pauli exclusion principle is a quantum mechanical principle formulated by the Austrian physicist Wolfgang Pauli in 1925.
The Pauli exclusion principle is a quantum mechanical principle formulated by the Austrian physicist Wolfgang Pauli in 1925.
Permeability (electromagnetism)
In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself.
In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself.
Permittivity
In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium.
In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium.
Perturbation theory
Perturbation theory comprises mathematical methods that are used to find an approximate solution to a problem which cannot be solved exactly, by starting from the exact solution of a related problem.
Perturbation theory comprises mathematical methods that are used to find an approximate solution to a problem which cannot be solved exactly, by starting from the exact solution of a related problem.
Phase (matter)
In the physical sciences, a phase is a region of space, throughout which all physical properties of a material are essentially uniform.
In the physical sciences, a phase is a region of space, throughout which all physical properties of a material are essentially uniform.
Phase space
In mathematics and physics, a phase space, introduced by Willard Gibbs in 1901, is a space in which all possible states of a system are represented, with each possible state of the system corres...
In mathematics and physics, a phase space, introduced by Willard Gibbs in 1901, is a space in which all possible states of a system are represented, with each possible state of the system corres...
Phase transition
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.
Photon
In physics, a photon is an elementary particle, the quantum of light and all other forms of electromagnetic radiation, and the force carrier for the electromagnetic force.
In physics, a photon is an elementary particle, the quantum of light and all other forms of electromagnetic radiation, and the force carrier for the electromagnetic force.
Photon dynamics in the double-slit experiment
The dynamics of photons in the double-slit experiment describes the relationship between classical electromagnetic waves and photons, the quantum counterpart of classical electromagnetic waves, ...
The dynamics of photons in the double-slit experiment describes the relationship between classical electromagnetic waves and photons, the quantum counterpart of classical electromagnetic waves, ...
Photon polarization
Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave.
Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave.
Physical body
In physics, a physical body or physical object is a collection of masses, taken to be one.
In physics, a physical body or physical object is a collection of masses, taken to be one.
Physical theories modified by general relativity
These physical theories modified by general relativity are described below.
These physical theories modified by general relativity are described below.
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force.
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force.
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized.
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized.
Poisson bracket
In mathematics and classical mechanics, the Poisson bracket is an important binary operation in Hamiltonian mechanics, playing a central role in Hamilton's equations of motion, which govern the ...
In mathematics and classical mechanics, the Poisson bracket is an important binary operation in Hamiltonian mechanics, playing a central role in Hamilton's equations of motion, which govern the ...
Polarization (waves)
Polarization is a property of certain types of waves that describes the orientation of their oscillations.
Polarization is a property of certain types of waves that describes the orientation of their oscillations.
Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron.
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron.
Potential gradient
A potential gradient is the local space rate of change of the potential with respect to displacement.
A potential gradient is the local space rate of change of the potential with respect to displacement.
Potentiometric surface
A potentiometric surface is based on hydraulic principles.
A potentiometric surface is based on hydraulic principles.
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed.
In physics, power is the rate at which energy is transferred, used, or transformed.
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object.
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object.
Principle of covariance
In physics, the principle of covariance emphasizes formulation of physical laws using only those physical quantities the measurements of which the observers in different frames of reference coul...
In physics, the principle of covariance emphasizes formulation of physical laws using only those physical quantities the measurements of which the observers in different frames of reference coul...
Principle of least action
In physics, the principle of least action – or, more accurately, the principle of stationary action – is a variational principle that, when applied to the action of a mechanica...
In physics, the principle of least action – or, more accurately, the principle of stationary action – is a variational principle that, when applied to the action of a mechanica...
Probability density function
In probability theory, a probability density function, or density of a continuous random variable, is a function that describes the relative likelihood for this random variable to take on ...
In probability theory, a probability density function, or density of a continuous random variable, is a function that describes the relative likelihood for this random variable to take on ...
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge.
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge.
QED vacuum
The quantum electrodynamic vacuum or QED vacuum is the field-theoretic vacuum of quantum electrodynamics.
The quantum electrodynamic vacuum or QED vacuum is the field-theoretic vacuum of quantum electrodynamics.
Quantization (physics)
In physics, quantization is the process of explaining a classical understanding of physical phenomena in terms of a newer understanding known as "quantum mechanics".
In physics, quantization is the process of explaining a classical understanding of physical phenomena in terms of a newer understanding known as "quantum mechanics".
Quantum chromodynamics
In theoretical physics, quantum chromodynamics (QCD) is a theory of the strong interaction (color force), a fundamental force describing the interactions between quarks and gluons which ma...
In theoretical physics, quantum chromodynamics (QCD) is a theory of the strong interaction (color force), a fundamental force describing the interactions between quarks and gluons which ma...
Quantum electrodynamics
Quantum electrodynamics is the relativistic quantum field theory of electrodynamics.
Quantum electrodynamics is the relativistic quantum field theory of electrodynamics.
Quantum field theory
Quantum field theory (QFT) provides a theoretical framework for constructing quantum mechanical models of systems classically parametrized (represented) by an infinite number of degrees of...
Quantum field theory (QFT) provides a theoretical framework for constructing quantum mechanical models of systems classically parametrized (represented) by an infinite number of degrees of...
Quantum mechanics
Quantum mechanics (QM - also known as quantum physics, or quantum theory) is a branch of physics dealing with physical phenomena where the action is on the order of the Planck constant.
Quantum mechanics (QM - also known as quantum physics, or quantum theory) is a branch of physics dealing with physical phenomena where the action is on the order of the Planck constant.
Quantum non-equilibrium
Quantum non-equilibrium is a concept within stochastic formulations of the De Broglie–Bohm theory of quantum physics.
Quantum non-equilibrium is a concept within stochastic formulations of the De Broglie–Bohm theory of quantum physics.
Quantum number
Quantum numbers describe values of conserved quantities in the dynamics of the quantum system.
Quantum numbers describe values of conserved quantities in the dynamics of the quantum system.
Quantum potential
The de Broglie–Bohm theory, also called the pilot-wave theory, Bohmian mechanics, and the causal interpretation, is an interpretation of quantum theory.
The de Broglie–Bohm theory, also called the pilot-wave theory, Bohmian mechanics, and the causal interpretation, is an interpretation of quantum theory.
Quantum pseudo-telepathy
Quantum pseudo-telepathy is a phenomenon in quantum game theory resulting in anomalously high success rates in coordination games between separated players.
Quantum pseudo-telepathy is a phenomenon in quantum game theory resulting in anomalously high success rates in coordination games between separated players.
Quantum triviality
This phenomenon is referred to as quantum triviality.
This phenomenon is referred to as quantum triviality.
Quark
A quark is an elementary particle and a fundamental constituent of matter.
A quark is an elementary particle and a fundamental constituent of matter.
Quasiparticle
In physics, quasiparticles and collective excitations are emergent phenomena that occur when a microscopically complicated system such as a solid behaves as if it contained different w...
In physics, quasiparticles and collective excitations are emergent phenomena that occur when a microscopically complicated system such as a solid behaves as if it contained different w...
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space.
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space.
Random walk
A random walk is a mathematical formalisation of a trajectory that consists of taking successive random steps.
A random walk is a mathematical formalisation of a trajectory that consists of taking successive random steps.
Redlich-Kwong equation of state
In physics and thermodynamics, the Redlich–Kwong equation of state is an equation that is derived from the van der Waals equation.
In physics and thermodynamics, the Redlich–Kwong equation of state is an equation that is derived from the van der Waals equation.
Redlich–Kwong equation of state
In physics and thermodynamics, the Redlich–Kwong equation of state is an equation that is derived from the van der Waals equation.
In physics and thermodynamics, the Redlich–Kwong equation of state is an equation that is derived from the van der Waals equation.
Reduced dimensions form
In biophysics and related fields, reduced dimension forms are unique on-off mechanisms for random walks that generate two-state trajectories.
In biophysics and related fields, reduced dimension forms are unique on-off mechanisms for random walks that generate two-state trajectories.
Reduced Dimensions Forms
Reduced Dimensions Forms are unique on-off mechanisms for random walks that generate two state trajectories.
Reduced Dimensions Forms are unique on-off mechanisms for random walks that generate two state trajectories.
Reflection (physics)
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.
Refractive index
In optics the refractive index n of a substance is a number that describes how light, or any other radiation, propagates through that medium.
In optics the refractive index n of a substance is a number that describes how light, or any other radiation, propagates through that medium.
Relational approach to quantum physics
The relational approach to quantum physics is an alternative approach to and interpretation of quantum mechanics.
The relational approach to quantum physics is an alternative approach to and interpretation of quantum mechanics.
Relative density
Relative density, or specific gravity, is the ratio of the density of a substance to the density of a given reference material.
Relative density, or specific gravity, is the ratio of the density of a substance to the density of a given reference material.
Relativistic heat conduction
The theory of relativistic heat conduction (RHC) claims to be the only model for heat conduction (and similar diffusion processes) that is compatible with the theory of special relativity, the s...
The theory of relativistic heat conduction (RHC) claims to be the only model for heat conduction (and similar diffusion processes) that is compatible with the theory of special relativity, the s...
Renormalization
In quantum field theory, the statistical mechanics of fields, and the theory of self-similar geometric structures, renormalization is any of a collection of techniques used to treat infinities a...
In quantum field theory, the statistical mechanics of fields, and the theory of self-similar geometric structures, renormalization is any of a collection of techniques used to treat infinities a...
Rest (physics)
Rest in physics refers to an object being stationary relative to a particular frame of reference or another object.
Rest in physics refers to an object being stationary relative to a particular frame of reference or another object.
Reversible reference system propagation algorithm
Reversible reference system propagation algorithm (r-RESPA) is a time stepping algorithm used in molecular dynamics.
Reversible reference system propagation algorithm (r-RESPA) is a time stepping algorithm used in molecular dynamics.
Rotational Brownian motion
Rotational Brownian motion is the random change in the orientation of a polar molecule due to collisions with other molecules.
Rotational Brownian motion is the random change in the orientation of a polar molecule due to collisions with other molecules.
Rotational diffusion
Rotational diffusion is a process by which the equilibrium statistical distribution of the overall orientation of particles or molecules is maintained or restored.
Rotational diffusion is a process by which the equilibrium statistical distribution of the overall orientation of particles or molecules is maintained or restored.
Saturation velocity
Saturation velocity is the maximum velocity a charge carrier in a semiconductor, generally an electron, attains in the presence of very high electric fields.
Saturation velocity is the maximum velocity a charge carrier in a semiconductor, generally an electron, attains in the presence of very high electric fields.
Scalar (physics)
In physics, a scalar is a simple physical quantity that is not changed by coordinate system rotations or translations, or by Lorentz transformations or space-time translations.
In physics, a scalar is a simple physical quantity that is not changed by coordinate system rotations or translations, or by Lorentz transformations or space-time translations.
Scale of temperature
Scale of temperature is a way to measure temperature quantitatively.
Scale of temperature is a way to measure temperature quantitatively.
Scattering
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more localized non-u...
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more localized non-u...
Schrödinger equation
In quantum mechanics, the Schrödinger equation is an equation that describes how the quantum state of a physical system changes with time.
In quantum mechanics, the Schrödinger equation is an equation that describes how the quantum state of a physical system changes with time.
Schrödinger's cat
Schrödinger's cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935.
Schrödinger's cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935.
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system.
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system.
Semiconductor
A semiconductor is a material with electrical conductivity intermediate in magnitude between that of a conductor and an insulator.
A semiconductor is a material with electrical conductivity intermediate in magnitude between that of a conductor and an insulator.
Sokolov–Ternov effect
The Sokolov–Ternov effect is the effect of self-polarization of relativistic electrons or positrons moving at high energy in a magnetic field.
The Sokolov–Ternov effect is the effect of self-polarization of relativistic electrons or positrons moving at high energy in a magnetic field.
Sommerfeld expansion
A Sommerfeld expansion is an approximation method developed by Arnold Sommerfeld for a certain class of integrals which are common in condensed matter and statistical physics.
A Sommerfeld expansion is an approximation method developed by Arnold Sommerfeld for a certain class of integrals which are common in condensed matter and statistical physics.
Spacetime
In physics, spacetime is any mathematical model that combines space and time into a single continuum.
In physics, spacetime is any mathematical model that combines space and time into a single continuum.
Special relativity
Special relativity (SR, also known as the special theory of relativity or STR) is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Alber...
Special relativity (SR, also known as the special theory of relativity or STR) is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Alber...
Specific gravity
Specific gravity is the ratio of the density (mass of a unit volume) of a substance to the density (mass of the same unit volume) of a reference substance.
Specific gravity is the ratio of the density (mass of a unit volume) of a substance to the density (mass of the same unit volume) of a reference substance.
Specific properties
Specific properties of a substance are derived from other intrinsic and extrinsic properties (or intensive and extensive properties) of that substance.
Specific properties of a substance are derived from other intrinsic and extrinsic properties (or intensive and extensive properties) of that substance.
Spectrum
defined when a grope of radiation is passed through a dispersion medium, an arrangement of radiation is obtained in order of their wave-length, this arrangement is known as spectrum A ...
defined when a grope of radiation is passed through a dispersion medium, an arrangement of radiation is obtained in order of their wave-length, this arrangement is known as spectrum A ...
Speed of light
The speed of light in vacuum, usually denoted by c, is a universal physical constant important in many areas of physics.
The speed of light in vacuum, usually denoted by c, is a universal physical constant important in many areas of physics.
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles, and atomic nuclei.
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles, and atomic nuclei.
Spontaneous emission
Spontaneous emission is the process by which a light source such as an atom, molecule, nanocrystal or nucleus in an excited state undergoes a transition to a state with a lower energy, e.g., the...
Spontaneous emission is the process by which a light source such as an atom, molecule, nanocrystal or nucleus in an excited state undergoes a transition to a state with a lower energy, e.g., the...
Standard Gibbs function of formation
The standard Gibbs function of formation of a compound is the change of Gibbs function that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements...
The standard Gibbs function of formation of a compound is the change of Gibbs function that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements...
Standard gravity
Standard gravity, or standard acceleration due to free fall, usually denoted by g0 or gn, is the nominal acceleration of an object in a vacuum near the surface of the Earth.
Standard gravity, or standard acceleration due to free fall, usually denoted by g0 or gn, is the nominal acceleration of an object in a vacuum near the surface of the Earth.
Standard Model
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles.
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles.
Statistical ensemble (mathematical physics)
In mathematical physics, especially as introduced into statistical mechanics and thermodynamics by J. Willard Gibbs in 1878, an ensemble (also statistical ensemble or thermodynamic ense...
In mathematical physics, especially as introduced into statistical mechanics and thermodynamics by J. Willard Gibbs in 1878, an ensemble (also statistical ensemble or thermodynamic ense...
Statistical mechanics
Statistical mechanics or statistical thermodynamics is a branch of physics that applies probability theory, which contains mathematical tools for dealing with large populations, to the stu...
Statistical mechanics or statistical thermodynamics is a branch of physics that applies probability theory, which contains mathematical tools for dealing with large populations, to the stu...
Stimulated emission
In optics, stimulated emission is the process by which an atomic electron interacting with an electromagnetic wave of a certain frequency, may drop to a lower energy level transferring its energ...
In optics, stimulated emission is the process by which an atomic electron interacting with an electromagnetic wave of a certain frequency, may drop to a lower energy level transferring its energ...
Strangeness
In particle physics, strangeness S is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic reactions, which occur in a shor...
In particle physics, strangeness S is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic reactions, which occur in a shor...
Stress-energy tensor
The stress–energy tensor (sometimes stress–energy–momentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the...
The stress–energy tensor (sometimes stress–energy–momentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the...
Stress–energy tensor
The stress–energy tensor (sometimes stress–energy–momentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the...
The stress–energy tensor (sometimes stress–energy–momentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the...
String theory
String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity.
String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity.
Strong interaction
In particle physics, the strong interaction (also called the strong force, strong nuclear force, or color force) is one of the four fundamental interactions of nature, the othe...
In particle physics, the strong interaction (also called the strong force, strong nuclear force, or color force) is one of the four fundamental interactions of nature, the othe...
Super Bloch oscillations
In physics, a Super Bloch oscillation describes a certain type of motion of a particle in a lattice potential under external periodic driving.
In physics, a Super Bloch oscillation describes a certain type of motion of a particle in a lattice potential under external periodic driving.
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature.
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature.
Superfluid
Superfluid is a state of matter in which the matter behaves like a fluid with zero viscosity and zero entropy.
Superfluid is a state of matter in which the matter behaves like a fluid with zero viscosity and zero entropy.
Superfluid helium-4
Superfluid is a state of matter in which the matter behaves like a fluid with zero viscosity and zero entropy.
Superfluid is a state of matter in which the matter behaves like a fluid with zero viscosity and zero entropy.
Superinsulator
A superinsulator is a material that at low temperatures under certain conditions has an infinite resistance and no current will pass through it.
A superinsulator is a material that at low temperatures under certain conditions has an infinite resistance and no current will pass through it.
Superionic Water
Superionic water is a theoretical phase of water under extreme heat and pressure which has properties of both a solid and a liquid.
Superionic water is a theoretical phase of water under extreme heat and pressure which has properties of both a solid and a liquid.
Superionic water
Superionic water is a theoretical phase of water under extreme heat and pressure which has properties of both a solid and a liquid.
Superionic water is a theoretical phase of water under extreme heat and pressure which has properties of both a solid and a liquid.
Superposition principle
In physics and systems theory, the superposition principle, also known as superposition property, states that, for all linear systems, the net response at a given place and time caused by ...
In physics and systems theory, the superposition principle, also known as superposition property, states that, for all linear systems, the net response at a given place and time caused by ...
Supersymmetry
In particle physics, supersymmetry is a symmetry that relates elementary particles of one spin to other particles that differ by half a unit of spin and are known as superpartners.
In particle physics, supersymmetry is a symmetry that relates elementary particles of one spin to other particles that differ by half a unit of spin and are known as superpartners.
Surface stress
Surface stress was first defined by Josiah Willard Gibbs as the amount of reversible work per unit area needed to elastically stretch a pre-existing surface.
Surface stress was first defined by Josiah Willard Gibbs as the amount of reversible work per unit area needed to elastically stretch a pre-existing surface.
Surface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force.
Surface tension is a property of the surface of a liquid that allows it to resist an external force.
Symmetry (physics)
In physics, symmetry includes all features of a physical system that exhibit the property of symmetry—that is, under certain transformations, aspects of these systems are "unchanged", according ...
In physics, symmetry includes all features of a physical system that exhibit the property of symmetry—that is, under certain transformations, aspects of these systems are "unchanged", according ...
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold.
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold.
Tensor
Tensors are geometric objects that describe linear relations between vectors, scalars, and other tensors.
Tensors are geometric objects that describe linear relations between vectors, scalars, and other tensors.
Ternary fission
Ternary fission, discovered in 1946, is a comparatively rare type of nuclear fission in which three charged products are produced, rather than two.
Ternary fission, discovered in 1946, is a comparatively rare type of nuclear fission in which three charged products are produced, rather than two.
Tetron Model
The Tetron Model was developed by Bodo Lampe in an attempt to reduce the 24 observed quark and lepton flavors and their interactions to a simple structure based on the permutation group S4, ...
The Tetron Model was developed by Bodo Lampe in an attempt to reduce the 24 observed quark and lepton flavors and their interactions to a simple structure based on the permutation group S4, ...
Theoretical and experimental justification for the Schrödinger equation
The theoretical and experimental justification for the Schrödinger equation motivates the discovery of the Schrödinger equation, the equation that describes the dynamics of nonrelativistic particles.
The theoretical and experimental justification for the Schrödinger equation motivates the discovery of the Schrödinger equation, the equation that describes the dynamics of nonrelativistic particles.
Theoretical motivation for general relativity
A Theoretical motivation for general relativity, including the motivation for the geodesic equation and the Einstein field equation, can be obtained from special relativity by examining the dyna...
A Theoretical motivation for general relativity, including the motivation for the geodesic equation and the Einstein field equation, can be obtained from special relativity by examining the dyna...
Thermal conduction
In heat transfer, conduction is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient.
In heat transfer, conduction is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient.
Thermal equilibrium
Thermal equilibrium is a theoretical physical concept, used especially in theoretical texts, that means that all temperatures of interest are unchanging in time and uniform in space.
Thermal equilibrium is a theoretical physical concept, used especially in theoretical texts, that means that all temperatures of interest are unchanging in time and uniform in space.
Thermodynamic limit
In thermodynamics, particularly statistical mechanics, the thermodynamic limit is reached as the number of particles (atoms or molecules) in a system, N, approaches infinity.
In thermodynamics, particularly statistical mechanics, the thermodynamic limit is reached as the number of particles (atoms or molecules) in a system, N, approaches infinity.
Thermodynamics
Thermodynamics is the branch of physical science concerned with heat and its relation to other forms of energy and work.
Thermodynamics is the branch of physical science concerned with heat and its relation to other forms of energy and work.
Thermomass Theory
Thermomass is defined as the equivalent mass of the thermal energy in heat transfer, which is determined by the Einstein’s mass-energy equivalence.
Thermomass is defined as the equivalent mass of the thermal energy in heat transfer, which is determined by the Einstein’s mass-energy equivalence.
Thought experiment
A thought experiment or Gedankenexperiment (from German) considers some hypothesis, theory, or principle for the purpose of thinking through its consequences.
A thought experiment or Gedankenexperiment (from German) considers some hypothesis, theory, or principle for the purpose of thinking through its consequences.
Time
Time is the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future.
Time is the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future.
Torque
Torque, moment or moment of force, is the tendency of a force to rotate an object about an axis, fulcrum, or pivot.
Torque, moment or moment of force, is the tendency of a force to rotate an object about an axis, fulcrum, or pivot.
Track (automobile)
The Track of a road vehicle is the distance at which both the front and rear wheels are apart.
The Track of a road vehicle is the distance at which both the front and rear wheels are apart.
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes.
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes.
Twin paradox
In physics, the twin paradox is a thought experiment in special relativity, in which a twin makes a journey into space in a high-speed rocket and returns home to find he has aged less than his i...
In physics, the twin paradox is a thought experiment in special relativity, in which a twin makes a journey into space in a high-speed rocket and returns home to find he has aged less than his i...
Two-body problem
In classical mechanics, the two-body problem is to determine the motion of two point particles that interact only with each other.
In classical mechanics, the two-body problem is to determine the motion of two point particles that interact only with each other.
Uncertainty principle
In quantum mechanics, the uncertainty principle is any of a variety of mathematical inequalities asserting a fundamental limit on the precision with which certain pairs of physical properties of...
In quantum mechanics, the uncertainty principle is any of a variety of mathematical inequalities asserting a fundamental limit on the precision with which certain pairs of physical properties of...
Uniform motion
Uniform motion occurs when an object moves an equal distance in a given direction during any arbitrary amount of time.
Uniform motion occurs when an object moves an equal distance in a given direction during any arbitrary amount of time.
Universal force field
Universal force field (UFF) is an all atom potential containing parameters for every atom.
Universal force field (UFF) is an all atom potential containing parameters for every atom.
Van der Waals equation
The van der Waals equation is an equation of state for a fluid composed of particles that have a non-zero volume and a pairwise attractive inter-particle force (such as the van der Waals force.)...
The van der Waals equation is an equation of state for a fluid composed of particles that have a non-zero volume and a pairwise attractive inter-particle force (such as the van der Waals force.)...
Vector potential
In vector calculus, a vector potential is a vector field whose curl is a given vector field.
In vector calculus, a vector potential is a vector field whose curl is a given vector field.
Virtual particle
In physics, a virtual particle is a particle that exists for a limited time and space.
In physics, a virtual particle is a particle that exists for a limited time and space.
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress.
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress.
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains.
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains.
Volume (thermodynamics)
In thermodynamics, the volume of a system is an important extensive parameter for describing its thermodynamic state.
In thermodynamics, the volume of a system is an important extensive parameter for describing its thermodynamic state.
Wave
In physics, a wave Kateria and summer are a disturbance or oscillation that travels through spacetime, accompanied by a transfer of energy.
In physics, a wave Kateria and summer are a disturbance or oscillation that travels through spacetime, accompanied by a transfer of energy.
Wave equation
The wave equation is an important second-order linear partial differential equation for the description of waves – as they occur in physics – such as sound waves, light waves and water waves.
The wave equation is an important second-order linear partial differential equation for the description of waves – as they occur in physics – such as sound waves, light waves and water waves.
Wave function
A wave function or wavefunction is a probability amplitude in quantum mechanics describing how a particle or a system of particles behaves in a given quantum state.
A wave function or wavefunction is a probability amplitude in quantum mechanics describing how a particle or a system of particles behaves in a given quantum state.
Wave function (quantum mechanics)
A wave function or wavefunction is a probability amplitude in quantum mechanics describing how a particle or a system of particles behaves in a given quantum state.
A wave function or wavefunction is a probability amplitude in quantum mechanics describing how a particle or a system of particles behaves in a given quantum state.
Wave function collapse
In quantum mechanics, wave function collapse is the phenomenon in which a wave function—initially in a superposition of several different possible eigenstates—appears to reduce to a single one o...
In quantum mechanics, wave function collapse is the phenomenon in which a wave function—initially in a superposition of several different possible eigenstates—appears to reduce to a single one o...
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.
Wavenumber
In the physical sciences, the wavenumber is a property of a wave, its spatial frequency, that is proportional to the reciprocal of the wavelength.
In the physical sciences, the wavenumber is a property of a wave, its spatial frequency, that is proportional to the reciprocal of the wavelength.
Weak interaction
Weak interaction, is one of the four fundamental forces of nature, alongside the strong nuclear force, electromagnetism, and gravity.
Weak interaction, is one of the four fundamental forces of nature, alongside the strong nuclear force, electromagnetism, and gravity.
Wetting transition
When contact angle experiences change we observe a wetting transition.
When contact angle experiences change we observe a wetting transition.
Weyl quantization
In mathematics and physics, in the area of quantum mechanics, Weyl quantization is a method for systematically associating a "quantum mechanical" Hermitian operator with a "classical" kernel fun...
In mathematics and physics, in the area of quantum mechanics, Weyl quantization is a method for systematically associating a "quantum mechanical" Hermitian operator with a "classical" kernel fun...
Wheelbase
In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels.
In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels.
Wigner quasi-probability distribution
The Wigner quasi-probability distribution is a quasi-probability distribution.
The Wigner quasi-probability distribution is a quasi-probability distribution.
Work function
In solid-state physics, the work function is the minimum energy (usually measured in electron volts) needed to remove an electron from a solid to a point immediately outside the solid surface (o...
In solid-state physics, the work function is the minimum energy (usually measured in electron volts) needed to remove an electron from a solid to a point immediately outside the solid surface (o...
World tube
In physics, a world tube is the path of an object occupies a nonzero region of space at every moment in time, as it travels through 4-dimensional spacetime.
In physics, a world tube is the path of an object occupies a nonzero region of space at every moment in time, as it travels through 4-dimensional spacetime.
Yang–Mills theory
Yang–Mills theory is a gauge theory based on the SU(N) group.
Yang–Mills theory is a gauge theory based on the SU(N) group.
Zero mode
In physics, a zero mode is an eigenvector with a vanishing eigenvalue.
In physics, a zero mode is an eigenvector with a vanishing eigenvalue.
Zero-point energy
Zero-point energy is the lowest possible energy that a quantum mechanical physical system may have; it is the energy of its ground state.
Zero-point energy is the lowest possible energy that a quantum mechanical physical system may have; it is the energy of its ground state.
ZZ diboson
ZZ dibosons are rare pairs of Z bosons that are extremely difficult to detect.
ZZ dibosons are rare pairs of Z bosons that are extremely difficult to detect.