Everything around us is made of matter. This is an obvious truth at the same time as being a fact that is one of the great mysteries in the world of physics, because the universe should not consist exclusively of matter if the rules of physics apply. There should also be antimatter – until recently a mystical antimass that closely resembles matter, apart from having the reverse electrical charge. The mystery of the apparently missing antimatter has been haunting physicists for many years, but this can now change.
"After two decades of targeted work to develop methods and equipment, our group now has a unique opportunity to make a start on the ultimate research in antimatter physics. The aim is to investigate whether matter and antimatter obey the same physical laws. All the laws state that the two should behave identically. If it turns out that there's asymmetry in their structures – then you could say that we've found the Holy Grail of antiparticle physics. And then we'll have to rewrite a large part of the modern theory book," explains Jeffrey Hangst, professor with special responsibilities (MSO), Department of Physics and Astronomy, Aarhus University.
Professor Hangst is the head of ALPHA (Antihydrogen Laser PHysics Apparatus) – the international research group that now has an opportunity to open the door to the unknown world. This year, the European Research Council (ERC) has awarded Professor Hangst a prestigious Advanced Grant valued at EUR 2.1 million so that he and the group can develop methods to provide answers to one of the most fundamental questions remaining in physics.
In brief, antimatter is the diametrical opposite of the matter that makes up the universe we know. Where a hydrogen atom is built up of a nucleus of a positively charged proton with a negatively charged electron, antimatter consists of a negatively charged antiproton with a positive positron. This is 'negativity', so to speak.
The European Organization for Nuclear Research – known as CERN – is currently the only place in the world with the capacity to produce antiprotons. Antimatter and matter cannot exist at the same place. It was therefore an extremely major challenge to set up an experiment where it was possible to trap antihydrogen long enough to study its properties.
In 2011, Professor Hangst and the ALPHA group spectacularly succeeded in storing antihydrogen for sixteen minutes in a trap. With the aid of magnets, extreme vacuum and ultracold conditions, they were able to separate it from any form of matter.
And if that was not enough – they also managed to carry out the first measurement ever, because the antimatter reached its natural ground state within the time frame. This means that the world was able for the first time to observe an antihydrogen atom in its 'natural' form.
"The fact is that our research group is the first in the world to develop methods for producing, storing and studying antihydrogen. We'd now like to develop a new branch of physics. Thanks to the ERC grant, we can now try to see if we can find evidence of what's missing in the structure of antihydrogen," says Professor Hangst.
History in the making
The result can unashamedly be called historic because this breakthrough now makes it possible to carry out the first focused precision measurements ever on pure antimatter atoms.
With the ERC Advanced Grant, the group can now develop an apparatus that can actually enable the physicists to observe a matter that, up until a few years ago, primarily existed in Dan Brown novels and space films.
"But whatever the outcome, we'll find out some fundamental new things about the universe. As the first in the history of the world, we'll get to carry out these precise measurements on pure antimatter. It's a fantastic honour to be part of this," explains Professor Hangst.
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