quantumaniac:

Generating matter and antimatter from the vacuum

Under just the right conditions — which involve an ultra-high-intensity laser beam and a two-mile-long particle accelerator — it could be possible to create something out of nothing, according to University of Michigan researchers.

The scientists and engineers have developed new equations that show how a high-energy electron beam combined with an intense laser pulse could rip apart a vacuum into its fundamental matter and antimatter components, and set off a cascade of events that generates additional pairs of particles and antiparticles.

At the heart of this work is the idea that a vacuum is not exactly nothing.

A vacuum is actually the combination of matter and antimatter - particles and antiparticles. The density of this system is tremendous, and we cannot perceive the particles because the effects cancel each other out. Matter and antimatter destroy each other when they come into contact under normal conditions.

However, in a strong electromagnetic field, this annihilation can be the source of new particles - gamma photons appear, which can produce electrons and positrons. 

A gamma photon is a high-energy particle of light. A positron is an anti-electron, a mirror-image particle with the same properties as an electron, but an opposite, positive charge.

An experiment in the late ’90s managed to generate from a vacuum gamma photons and an occasional electron-positron pair. These new equations take this work a step farther to model how a strong laser field could promote the creation of more particles than were initially injected into an experiment through a particle accelerator.