Highly intense laser could generate matter and antimatter from nothing
Ann Arbor, MI--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 (U-M) 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.
"We can now calculate how, from a single electron, several hundred particles can be produced. We believe this happens in nature near pulsars and neutron stars," said Igor Sokolov, an engineering research scientist who conducted this research along with associate research scientist John Nees, emeritus electrical engineering professor Gerard Mourou and their colleagues in France.
At the heart of this work is the idea that a vacuum is not exactly nothing. "It is better to say, following theoretical physicist Paul Dirac, that a vacuum, or nothing, is the combination of matter and antimatter--particles and antiparticles. Their density is tremendous, but we cannot perceive any of them because their observable effects entirely cancel each other out," Sokolov said.
Matter and antimatter destroy each other when they come into contact under normal conditions. "But in a strong electromagnetic field, this annihilation, which is typically a sink mechanism, can be the source of new particles," Nees said, "In the course of the annihilation, gamma photons appear, which can produce additional electrons and positrons." The researchers describe this work as a theoretical breakthrough, and a "qualitative jump in theory."
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.
The researchers have developed a tool to put their equations into practice in the future on a very small scale using the HERCULES laser at U-M. To test their theory's full potential, a HERCULES-type laser would have to be built at a particle accelerator such as the SLAC National Accelerator Laboratory at Stanford University. Such infrastructure is not currently planned. This work could potentially have applications in inertial confinement fusion, which could produce cleaner energy from nuclear fusion reactions, the researchers say.
A paper on this work, "Pair Creation in QED-Strong Pulsed Laser Fields Interacting with Electron Beams" is published in Physical Review Letters.
SOURCE: University of Michigan; http://ns.umich.edu/htdocs/releases/story.php?id=8167
Posted by:Gail Overton
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