In November 2010, the European Organization for Nuclear Research (CERN) announced yet another breakthrough: the capture of a number of antihydrogen atoms (a form of antimatter) for the first time.
Antimatter is a form of antiparticle theorized to exist by modern particle physics. When matter and antimatter meet, they destroy each other completely. (The energy released is substantial, which is why some science fiction vaguely refers to antimatter power production.) In the very early universe, it is believed that matter and antimatter once both existed in prodigious quantities. However, they annihilated each other. Matter outnumbered antimatter by a small proportion, and that remainder makes up today’s observable universe. Because matter and antimatter cannot coexist for any extensive amount of time in nature, today antimatter must be produced synthetically, and is very short-lived – as well as fantastically expensive. In theory, producing a gram of antimatter would cost billions of dollars.
CERN’s latest achievement is the most recent in a lengthy chain of incremental progress made in the production of antimatter. In fact, antihydrogen was first synthesized in 1995, also by CERN, in its LEAR (Low Energy Antiproton Ring) experiment. CERN first produced antiprotons and positrons, which were mixed, forming antihydrogen. (A positron is another name for an anti-electron, so named because anti-electrons have positive charges.) The problem with producing antimatter atoms, though, is that they are neutral. The standard method for creating and sustaining matter requires a charged container, since if the antimatter comes into contact with the sides of whatever bottle is holding it, it will be destroyed.
CERN solves this problem with a special device known as the ALPHA apparatus, which is able to use extremely weak magnetic interactions with the internal structure of the atom. In the latest experiment, they mixed ten million positrons (anti-electrons) with several hundred million antiprotons, and their device then registered 38 “events” – reactions resulting in the creation of antihydrogen atoms. After very briefly holding the atoms, they were released to collide with the sides of the detector, and the releases of energy caused as they were annihilated were used as confirmation of the (former) existence of the antihydrogen.
Antihydrogen is no bigger than regular hydrogen, of course, so the synthetic production of just over three dozen atoms may seem insignificant. Still, everything must start small. In the meantime, scientists still have to figure out why more matter than antimatter existed in the early universe (which it must have, since we’re still here).