Grown from scratch, simulated magnetic fields could explain cosmic mystery

Far beyond the magnet on your refrigerator door, out past the magnetic fields of Earth, the Sun, and the Milky Way, are invisible field lines that permeate the barren voids between galaxies. But the genesis of these expansive fields has remained a mystery. Some have proposed that they arose as a result of the big bang, but a new study adds support to an alternative hypothesis: These fields can be born relatively easily, anywhere and anytime in the universe. The study relies on computer simulations that illustrate how gravity can stir up charged particles in ways that generate tiny magnetic seeds, which become amplified as their field lines twist. The result, to appear on 31 July in Physical Review Letters , links together each of these steps into a complete chain for the first time. Alexander Schekochihin, a plasma physicist at the University of Oxford who was not involved in the work, says the result is a “significant advance.” It’s a sort of milestone in this kind of research,” he says. Most magnetic fields arise when charged particles move in concert, like the spinning electrons in your fridge magnet or the swirling electrical currents in Earth’s liquid iron outer core. But in astrophysical plasma—the hot ionized gas that comprises most of the universe’s matter—electric charge doesn’t flow in harmony. “These are blobs of stuff,” Schekochihin says. “Everything’s very messy.” Moreover, plasma is virtual...
Source: ScienceNOW - Category: Science Source Type: news