Antimatter Atom Created for First Time
Physicists for the first time have created atoms of antimatter, offering hope of finding clues to one of the most perplexing of mysteries: Why is our universe made of matter and not antimatter? And why does matter exist at all?
According to news reports Thursday, the first anti-atoms were created at the European Laboratory for Particle Physics (CERN) in Geneva. Some U.S. physicists were not aware of the result, but when informed they weren’t surprised, because the finding was expected. Several U.S. groups are working on similar experiments.
“It’s confirming,” said Nobel laureate Leon Lederman of the Fermi National Accelerator Laboratory in Batavia, Ill. “It emphasizes how much we know. If they could prove that you could not make anti-hydrogen, that would be a Nobel Prize-winning achievement.”
But physicist Robert Forward, who for many years published an antimatter newsletter, said the result was “wonderful.”
Particles of matter and antimatter are mirror images of each other; on contact, they are annihilated in a burst of pure energy. Conversely, matter and antimatter are created out of pure energy--but always in pairs.
Presumably, all the matter formed at the creation of the universe was matched with an equal amount of antimatter. The question is: Where did the antimatter go? And why didn’t all the matter and antimatter simply annihilate each other? Why is there any matter left at all?
Clearly, physicists think there’s something important they don’t know about matter. Science fiction writers and even scientists have long speculated about the possible existence of antimatter people living in antimatter universes.
“There is this huge mystery,” Forward said. Matter and antimatter should exist in precisely the same amounts. “And yet, the universe isn’t that way,” he said. “That means we really don’t know fundamentally how matter is made.”
Antimatter was discovered by physicist P.A.M. Dirac as an unexpected minus sign that popped up in an equation. It suggested that another “negative” kind of matter must exist. Three years later, in 1932, physicist Carl Anderson saw a track in a particle detector that looked like an electron curving in the wrong direction. At first, colleagues thought his film was upside-down; others thought the idea of antimatter was pure nonsense. But it was soon confirmed as the first detected antielectron, or positron.
Today, antimatter is almost mundane--not only in physics, but in medicine. Doctors use PET scans (positron emission tomography) to see inside the human body. Physicists use positrons and antiprotons in accelerator experiments that re-create a flash of energy similar to the conditions at the origins of the universe, the beginning of time.
But putting two or more antiparticles together into an anti-atom had thus far eluded physicists. The researchers at CERN succeeded at least in part because they got the antiprotons quieted down enough so that the newly formed atom wouldn’t immediately fall apart. Even so, the nine anti-hydrogen atoms created only hung around for 40 billionths of a second before running into a matter particle and mutually annihilating.
Essentially, the CERN researchers were able to get an antielectron and an antiproton traveling at the same velocity long enough to cozy up to each other and create an atom.
“They go off on the same train and they get friendly,” Forward said.
