Score another victory in science’s relentless pursuit to make all things Star Trek a reality. To the list that already includes universal translators, voice-activated computers, and–sort of–replicators, we now get to add antimatter containment pods. Scientists at CERN have rigged a container to trap anti-matter for more than 16 minutes. It may be a while before they’re used to store energy for antimatter fuel cells, but these ingenious containers are expected to allow particle physicists to go where no particle physicists have gone before.
To begin with, in case you were wondering: yes, antimatter is real. As one of the wonderful examples of where a discovery is worked out on paper before it’s actually observed, English physicist and quantum mechanics giant Paul Dirac predicted antimatter while working out a mathematical model of the subatomic world. Four years later the American physicist Carl Anderson observed such a particle: an electron with the same mass as normal electrons, but with a positive charge. And electrons weren’t unique in having evil twin brothers. Physicists soon concluded that every particle of matter has its own antiparticle with the same mass but opposite charge. In 1955 the both the antineutron and antiproton were discovered.
Since those initial discoveries physicists have been trying to create antimatter in the lab to study it. But trapping antimatter is no easy task. Matter and antimatter make for bad company. When they come in contact with one another they annihilate as, in a flash, their masses are converted to energy. The challenge for the CERN scientists then was to find a way to trap the anti-matter without allowing it to come in contact with matter. Instead of regular matter, they used magnetic fields to contain the antihydrogen. But a magnetic field only works if the particle is charged. At extremely low temperatures–near absolute zero–antiparticles becomes charged and the magnetic field becomes an effective barrier.
The scientists collaborating on the so-called ALPHA (Antihydrogen Laser Physics Apparatus) experiment, were able to trap the antihydrogen atoms for as long as 1,000 seconds–or just over 16 minutes–“which is forever,” says CERN spokesman Professor Jeffrey Hangst. Hydrogen, nature’s simplest atom, is made up of a positively-charged proton and a negatively-charged electron. To produce antihydrogen, the ALPHA team brought together negatively-charged antiprotons and positive antielectrons–also known as positrons–in the very cold vacuum chamber where they combined to make antihydrogen. The longevity of their antihydrogen is remarkable given that they’d only trapped it for the first time November 2010, and at the time for just a fleeting sixth of a second. They confirm their antimatter trappings by simply shutting off the magnetic field and, as the antiparticles fly into the sides of the container, they count the annihilation events like counting popping mosquitos as fly into electric traps. The team has trapped some 300 antimatter atoms. And these smart CERN scientists have gotten so good at it that they expect to begin performing experiments on the exotic particles later this year. It’s huge to be able to go from the annihilation event watching that physicists have been until now limited to, to performing actual experiments. CERN physicist, Tom Whyntie, told the Telegraph “It’s the difference between observing an animal’s tracks or droppings, and studying it in captivity.”
What I'm calling a "container" looks more like the innards of a space station. Take a tour of the ALPHA facility in the video below.
Uncovering the properties of antiparticles may help answer some of the questions that have been nagging physicists since their discovery. To understand what’s been keeping them up at night we have to go back–all the way back to the Big Bang.
According to theory, the initial moments following the Big Bang included an stupendous expansion phase known as the ‘inflationary epoch.’ In just a really really small fraction of a second, the size of the universe increased by a factor of at least 10^26. At the start of inflation there were no particles, just energy. But out of this energy soup popped particles. The conversion of energy to matter followed a strict rule: for every particle created its antiparticle was also created. And so the early universe was awash in both matter and antimatter, supposedly, in equal amounts. But if that really was the case, then why didn’t they completely annihilate each other and leave no particulate universe to speak of?
Put another way: why are we and everything around us made of matter? Antimatter’s conspicuous absence is one of the great mysteries in physics today. Matter could only have won out over antimatter if the mirror-like symmetry between them was somehow tipped in matter’s favor. Right now we don’t know what differences might account for such a break with symmetry, but with the ALPHA team’s breakthrough scientists will now be able to poke and prod antimatter and possibly identify those differences. Symmetry is a complex notion that describes mirror-like balances occurring across many realms of physics like different forces and even time, not just matter and antimatter. A fundamental feature of many leading cosmological theories, disproving symmetry would mean it’s back to the drawing board for physicists. “Any hint of symmetry-breaking would require a serious rethink of our understanding of nature,” Hangst told the Telegraph. “But half of the universe has gone missing, so some kind of rethink is on the agenda.”
To answer the question of whether or not matter is different from antimatter, the ALPHA physicists have planned two key experiments to be started later this year. One will determine if antihydrogen reacts to light the same way hydrogen does, the other will compare how they interact with gravity.
In related news, physicists at the Brookhaven National Laboratory have recently discovered helium’s evil twin brother. In a masterful display of technology, the researchers joined together four antiparticles to create antihelium-4, the heaviest antiparticle detected to date. No doubt the team Brookhaven is on the phone right now with team ALPHA making plans for some seriously cool collaboration. Whatever they find is sure to advance particle physics and cosmology. I'm just going to sit back and watch, and wait until they announce the photon torpedoes.