Science / For the first time, scientists have succeeded in creating antimatter atoms whose properties can be measured
Uriel Brizon
About two weeks ago, scientists at the European Institute for Nuclear Research CERN announced that they had for the first time succeeded in examining the properties of antimatter atoms. In the experiment, conducted by a multinational group of leading scientists known as ATRAP, antiproton particles were combined with positron (antielectron) particles to create exotic "antihydrogen" atoms.
In 1928, the British physicist Paul Dirac formulated a theory that describes the movement of electrons in electric and magnetic fields. Dirac succeeded in developing equations that combine quantum mechanics with Einstein's special theory of relativity, and in doing so paved the way for many studies in the theory of the atom. In 1933 he was awarded the Nobel Prize in Physics for this.
One of the unexpected consequences of Dirac's equations was that they predicted, and even required, the existence of a new type of particle. According to Dirac, these particles must be similar to electrons in their properties but opposite to them in their electrical charge. These particles, which were nicknamed "positrons" due to their positive charge, were a side effect of a mathematical equation, but were the first hint of the existence of a new type of matter.
Following Dirac's theory, the community of experimental physicists was harnessed to search for the strange particle. In 1932, the American physicist Carl Anderson managed to photograph the traces of a positron with a special measuring device, known as a "fog chamber". The existence of the new particle was proven and Anderson was awarded the Nobel Prize in 1936 for the discovery.
It soon became clear that Dirac's predictions regarding the electron were also true for the other elementary particles, and that each of them had an antiparticle. According to the theory, antiparticles can join together and create matter that will be very similar to normal matter, except for the fact that it is the opposite of it in its electrical properties. Until the discoveries of Dirac and Anderson, the concept of matter (Matter) was used as a concept that encompasses everything that exists (except for energy, which is also, according to Einstein, an alternative state to matter). When it became clear that something else existed, something similar to matter but not matter in the usual sense, the concept was narrowed down and the combination "antimatter" - the mirror image of matter - was claimed.
When antimatter comes into contact with normal matter the two annihilate each other and release a huge amount of energy. One kilogram of antimatter can produce enough energy to drive a car continuously for 100 years. The idea of harnessing the enormous power of antimatter for human use is extremely tempting, especially as a means of propelling space vehicles. Different groups of researchers, including in the American space agency, NASA, have been working for some time on the design of a space engine based on antimatter. Uses in more mundane settings are considered very carefully, as it is clear that the uncontrolled release of antimatter in an environment composed of ordinary matter could cause accidents.
After the discovery of the antimatter it became clear that it has an important place in cosmological theories about the formation of the universe. In the initial stages of the formation of the universe, near the time of the big bang, matter and antimatter existed in large quantities. Due to the special conditions that prevailed in the ancient universe, the existence of the two was possible without mutual annihilation. Today we find around us only ordinary matter. To test antimatter, it must be produced under special laboratory conditions.
Due to its unique nature, antimatter is known as a problematic object for research. "Hot" antimatter atoms moving at high speeds have been produced in laboratories for a long time, but due to their speed it was not possible to examine their properties before they hit ordinary atoms and their immediate disappearance in a collision. Last year, the ATRAP group reported that it had succeeded in developing a new method for producing anti-hydrogen atoms. The method is based on slowing down antiproton particles and combining them with slow positrons. This enables the production of anti-hydrogen atoms that do not move at high speed and can be investigated. About two weeks ago, the group reported the first success in implementing the method.
After the creation of the anti-hydrogen atoms, it was possible to perform a preliminary test on them by placing them in a magnetic field. Due to the electric charge of the atomic components, it is possible to cause their disintegration in the field, and in this way measure their properties. Prof. Gerald Gabrielse from Harvard University, head of the group, explained that "it's like placing the anti-hydrogen atom next to a battery. The antiproton in the nucleus will be attracted to one side and the positron to the other side." The strength of the field required to disintegrate the antihydrogen nucleus indicates the strength of its internal bonds and may indicate differences between it and a normal hydrogen atom. In the initial examination, no differences were found, but the researchers emphasize that to find out if there are indeed differences, additional tests must be performed.
The next step is to bring the atoms to a state defined as more "normal". Although the experiment succeeded in "cooling" the anti-hydrogen atoms and bringing them to low speeds, the anti-proton particles in their nuclei are still in an excited state and must be brought to a less excited state, more similar to the natural state of ordinary hydrogen atoms. Only after this action will it be possible to perform an experiment and make qualitative comparisons between hydrogen and anti-hydrogen. The general opinion among scientists is that the results of the comparison will make it clear that their properties (except for the charge) are completely equal. If it turns out that there is any difference between them, it will be, according to Gabriels, "the biggest discovery in physics for many decades".
The hypothesis that antimatter existed in the early universe made physicists wonder if the universe could have formed from antimatter in exactly the same way as it did from normal matter. Differences between matter and antimatter, if found in the future, may contradict theories dealing with this question. Research progress on the antimatter's properties will also lead, researchers hope, to future experiments that will test the possibilities of using it for commercial purposes and as a means of future propulsion.
Although the purpose of the current research is purely scientific and no practical uses were foreseen, it turned out that the technology of the experiment, as often happens in experiments of this type, can also be used in different fields. So, for example, the special superconducting magnets, registered as a patent by the team, could be used in the future in advanced medical imaging systems.
Antimatter - the mirror of the universe - on the Cern website
