Related Experiment Video

Updated: Jun 18, 2026

Generation and Coherent Control of Pulsed Quantum Frequency Combs
06:42

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Published on: June 8, 2018

Feynman propagator for a free scalar field on a causal set

Steven Johnston1

  • 1Theoretical Physics, Blackett Laboratory, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom. steven.johnston02@imperial.ac.uk

Physical Review Letters
|November 13, 2009
PubMed

More Related Videos

Finite Element Modelling of a Cellular Electric Microenvironment08:23

Finite Element Modelling of a Cellular Electric Microenvironment

Published on: May 18, 2021

Setting Limits on Supersymmetry Using Simplified Models07:46

Setting Limits on Supersymmetry Using Simplified Models

Published on: November 15, 2013

Related Concept Videos

Conservative Vector Fields01:29

Conservative Vector Fields

A conservative vector field describes a force or field in which the work done between two points depends only on the initial and final positions. For a ball moving in Earth’s gravitational field, gravity performs work determined by the difference in height, regardless of whether the ball moves vertically or follows a curved trajectory.A vector field is conservative if it can be expressed as the gradient of a scalar potential function, f. In two dimensions, this is written...
Gauss's Law01:07

Gauss's Law

If a closed surface does not have any charge inside where an electric field line can terminate, then the electric field line entering the surface at one point must necessarily exit at some other point of the surface. Therefore, if a closed surface does not have any charges inside the enclosed volume, then the electric flux through the surface is zero. What happens to the electric flux if there are some charges inside the enclosed volume? Gauss's law gives a quantitative answer to this question.
Plane Electromagnetic Waves I01:30

Plane Electromagnetic Waves I

The existence of combined electric and magnetic fields that propagate through space as electromagnetic (EM) waves is the most significant prediction of Maxwell's equations. As Maxwell's equations hold in free space, the predicted electromagnetic waves do not require a medium for their propagation. An EM wave comprises an electric field, defined as the force per charge on a stationary charge, and a magnetic field, which is the force per charge on a moving charge.
The EM field is assumed to be a...
Poisson's And Laplace's Equation01:25

Poisson's And Laplace's Equation

The electric potential of the system can be calculated by relating it to the electric charge densities that give rise to the electric potential. The differential form of Gauss's law expresses the electric field's divergence in terms of the electric charge density.
Surface Integrals of Vector Fields: Flux01:22

Surface Integrals of Vector Fields: Flux

Understanding the movement of air masses is fundamental to meteorological analysis and atmospheric modeling. A key component in this process is quantifying the total mass of air that flows into or out of a defined region over a specified period of time. This is achieved by evaluating the mass flux across a boundary surface, a conceptual tool that simplifies the complex dynamics of atmospheric systems.To begin, an imaginary boundary surface S is introduced, enclosing the region of interest. The...
The Fundamental Theorem for Line Integrals01:26

The Fundamental Theorem for Line Integrals

A line integral describes the accumulated contribution of a vector field along a curve connecting two points. It is used to evaluate how the direction and magnitude of a vector field interact with the direction of motion along a path. In certain cases, this calculation can be greatly simplified by identifying whether the vector field is associated with a potential function.Let F be a vector field in two or three dimensions. If there exists a scalar function g such...