Understanding antimatter

Antimatter has defied scientific comprehension ever since its existence was predicted by the British physicist Paul Dirac back in 1928.

But in a paper published today in the journal Physical Review Letters, Yasunori Yamazaki, a CERN antimatter researcher, said his experiment had succeeded in creating a significant number of antihydrogen atoms in flight, a development which will ultimately help him and his team understand the enigmas of antimatter.

At the time of the Big Bang, approximately 15 billion years ago, equal amounts of matter and antimatter should have been created, but the latter appears to have disappeared, and to look into the universe is to see nothing but former.

The theoretical explanation for that imbalance is that in the first seconds of the universe the number of matter particles very fractionally outnumbered that of antimatter, and that when the two made contact and rapidly began to annihilate each other, the only thing that survived was the excess matter.

That being the case, scientists have never been able to get a handle on antimatter. But they are working hard to fill that gap.

One way of doing so is to take a hydrogen atom, which consists of one proton and one electron, and see whether its antimatter counterpart, antihydrogen, which is made up of an antiproton and a positron, shares its behavioral properties. If they were able to detect differences between the two, researchers would have some insight into what happened at the very beginning of life as we have come to know it.

"By solving this question," Yamazaki said in an interview with Deutsche Welle, "we would have a basis of our existence."

In for the long haul

This new discovery comes approximately two weeks after the same CERN team announced that they had trapped 38 antihydrogen atoms. The CERN scientists have spent the past five years working on ways of creating antihydrogen atoms to be kept away from ordinary matter in order to study its behavioral properties.

They produced the antihydrogen atoms by using what is known as a CUSP trap to bring a combination of magnetic fields and antiprotons together and subsequently channeled the atoms along a vacuum pipe where they can be studied in flight.

Although the technique is still a long way from providing the world with an insight into the whereabouts of antimatter, Yamazaki said the method of producing and eventually studying antihydrogen means it is only a question of time before the secrets of antimatter are unlocked.

Symmetry versus non-symmetry

To get there, he and his team are trying to understand the charge, parity and time (CPT) symmetry between matter and antimatter. At the moment the symmetry is believed to exist, but the physicists are planning to do high precision spectroscopy of antihydrogen to gain greater knowledge.

"If our experiment reveals non-conservation of the CPT symmetry in some way, it would be a really revolutionary discovery," Yamazaki said. "I am very much looking forward to getting some information on the CPR symmetry and the mystery of the non-existence of antimatter in our universe."

He says the first simple spectroscopy could take place as early as next year, but that the more earnest spectroscopy which could reveal deviation of antihydrogen from hydrogen would take several years to get prepare.

A long way from practical use

Thomas Lohse, particle physics at Berlin's Humboldt University, welcomed the progress, which he said he hoped would answer some very specific questions.

"If the antihydrogen atom is the same as the hydrogen one, does the light have the same frequency?" he mused. "Another interesting issue is whether antihydrogen would fall to the floor or float upwards."

He believes it could take decades before scientists truly understand the properties of antimatter, and even longer before their findings are put to practical use. But that is par for the course in the world of physics. And to highlight the point, Lohse cited Gustav Herz's discovery that electromagnetism could produce electromagnetic waves.

"At the time people asked what it was good for, but without electromagnetic waves we would not have satellites, radios, televisions, modern communication," Lohse told Deutsche Welle. "It is possible that there will be an application for antimatter, but it is hard to predict."

Reporter: Tamsin Walker
Editor: Cyrus Farivar