Scientists at Europe’s atom-smashing lab say they can produce a steady stream of hydrogen antimatter, a breakthrough that opens the way to testing one of the conceptual cornerstones of physics.
The researchers at the European Organisation for Nuclear Research (CERN) in Geneva say they have been able to manufacture tens of thousands of atoms of antihydrogen, the ”mirror” substance to normal hydrogen.
Antimatter may be a staple of science fiction, although physicists say it exists in reality, even though it is extraordinarily elusive to detect and study.
The theory is that when energy is converted into matter, it also produces a counterpart, called anti-matter, whose particles are of the opposite electrical charge to matter.
In normal hydrogen, for instance, the atom comprises a nucleus, called a proton, which has a positive charge, and it is orbited by an electron, which has a negative charge.
In hydrogen antimatter, the picture is reversed — the nucleus, called the antiproton, is negatively charged, and it is circled by a positively charged electron called a positron.
But there has been little chance to find out what anti-matter is, even though it could hold the key to confirming ? or bulldozing — a century-old conceptual framework about particle physics known as the Standard Model.
Until seven years ago, no-one had even seen any anti-atoms.
They were detected in particle accelerators at CERN, in 1995, and at America’s Fermilab, in 1996, but because they whizzed around at close to the speed of light before ”annihilating” (smashing into) their normal counterpart, very little information could be gleaned about them.
That all may change, according to research reported on Thursday in Nature, the British science weekly.
Working on a project called Athena, the CERN team say they have devised a technique for producing large numbers of anti-atoms of hydrogen and holding them at a very low temperature, which means they move far more slowly and are easier to study.
”You get the ingredients for antihydrogen, which are the antiprotons and the positrons, and capture them in a trap, a sort of electromagnetic bottle in almost perfect vacuum, at very low temperature, 10 degrees (Kelvin) above absolute zero (-263 C, -441 F)”, said researcher Jeffrey Hangst.
”They you mix them together. The particles are trapped because they are charged. But when they form a neutral atom, they are no longer trapped and the atom flies out of the apparatus.
”Since it’s antimatter, when it meets normal matter, it annihilates, with a burst of energy that converts immediately back into matter again,” he said. That burst has ”a characteristic signature” that can be spotted in an imaging particle detector.
The neutral anti-atoms cannot be stored at the moment, but this should not be impossible, using extremely low temperatures and a magnetic trap, he said.
The textbooks say that matter and anti-matter are like mirror images and should behave the same. They are, however, incompatible, and when they meet up they annihilate each other.
If it turns out that there are differences between matter and antimatter, that will raise big questions over the validity of the Standard Model, with its bestiary of particles and forces that determines our perception of the Universe.
Those differences could also explain one of the big unknowns of physics — why matter dominates over antimatter in the visible Universe.
According to the Big Bang theory, the Universe was created in a cataclysmic explosion between 10 and 15-billion years ago.
By all logic, the explosion should have created equal amounts of matter and antimatter. The particles would have all paired up and annihilated, leaving a void.
But somehow, within a fraction of a second — possibly for some asymmetry that remains mysterious — a surplus of matter prevailed, and to this we owe our existence today. – Sapa-AFP