Virtual Particles

In the quantum field virtual particles are formed and anhiliated at the speed of light. Quantum fields underlie all particles in quantum field theory (QFT), which is the framework combining quantum mechanics and special relativity. In this framework, virtual particles are a mathematical tool used in perturbation theory to describe interactions between real particles. These virtual particles are not directly observable and don't satisfy the usual energy / momentum relation. In calculations, they appear as intermediate states in particle interactions - like a photon "exchanged" between two electrons in electromagnetic repulsion.