Virtual particles are theoretical particles that cannot be
detected directly, but nonetheless are a fundamental part of a theory called quantum
electrodynamics. The particles are fleeting, existing for very short periods of time,
and can seemingly violate the laws of Conservation of Energy. A stationary electron can
emit a virtual photon and remain itself unchanged - energy is not conserved. How can this be?
It's a result of the
Heisenberg Uncertainty Principle, restated as
So if you were to measure the energy of a virtual photon in a small enough time, it would be possible for the uncertainty in energy to be extremely large. The virtual photon in a sense overdraws some energy, then returns it within the time interval specified by
For more information on these elusive particles, and how they are believed to be responsible for the electromagnetic force, check out the following links.
- Uncertainty and Virtual Particles: A brief introduction to the Heisenberg Uncertainty Principle and how it relates to virtual particles.
- The Quantum Picture of Forces: This page describes how virtual photons are responsible for the electromagnetic force.
- Frequently Asked Questions about Virtual Particles: The definitive internet reference for all your virtual particle questions.
- Virtual Particles: This page goes into more detail, and discusses how pairs of virtual particles form.