Physicists at the ALPHA facility at CERN report that they have managed to contain antimatter for several minutes, a huge improvement over their previous attempt at antimatter containment last year, which lasted only two tenths of a second.
Antimatter is comprised of particles that have the same mass as “normal” particles, like protons or electrons, but have opposite charge: for example, anti-protons have negative charge, while anti-electrons (aka positrons) have positive charge. The antimatter in the ALPHA experiment is in the form of neutral anti-hydrogen — an anti-proton and a positron — created in a high energy state. Anti-hydrogen is the antimatter counterpart to hydrogen, the simplest and by far the most abundant element in the universe.
Physicists at particle accelerates have been able to produce positrons and anti-protons for a long time. Getting them to stick together to form a neutral anti-hydrogen atom and keep it contained has been the real trick. The ALPHA physicists used electric fields to clear out stray charged particles, and used superconducting magnets to hold the remaining anti-hydrogen particles in place. The purpose for containing antimatter for a long periods of time is to allow study of its properties and see how it differs from normal matter. Why is this important? Out of laziness, I’ll just quote myself from a previous article:
… big bang theory requires that equal amounts of matter and antimatter existed in the very early history of the universe. The matter and antimatter would collide and annihilate, producing a burst of energy. The great mystery is why our galaxy and everything we observe appears to be made of matter. Actually, the great mystery is why there is any matter at all, for if there was an equal amount of antimatter, all of it should have been annihilated. Some theories propose a tiny asymmetry, with slightly more matter than antimatter, but these theories raise problems of their own.
What physicists hope to understand is why matter came to dominate the universe instead of antimatter (or no matter at all). Some sort of asymmetry has to exist, and studying anti-hydrogen may reveal what that is.