Atoms from the mirror world of antimatter were captured and analysed for the first time this year. Two teams at CERN, the European Laboratory for Particle Physics near Geneva, have created large numbers of long-lived antihydrogen atoms, which can be used to test fundamental theories about the Universe.
In total, the teams produced thousands of antihydrogen atoms by using magnetic fields to bring together antiprotons and anti-electrons. This was a considerable technical achievement in itself, but the real interest lies in studying the properties of antihydrogen. Theory suggests that it should mirror the properties of hydrogen, but no one knows for sure, says Rolf Landua, spokesman for the ATHENA collaboration, which announced its results in September1.
The standard model of fundamental particles and forces holds that hydrogen and antihydrogen should have the same properties and obey the same rules, but it can't predict why the Universe is almost devoid of antimatter. Finding a difference between matter and antimatter could lead to an explanation, and perhaps force physicists to reformulate the standard model.
A second CERN team, called ATRAP, has also captured antihydrogen atoms2, and has subsequently made preliminary measurements of their most excited energy states3. “There's still a lot of work to do,” says Gerald Gabrielse of Harvard University, spokesman for ATRAP.
“This is just the start,” agrees Landua. “Everything is fresh; we haven't exploited all of our potential.”
References
Amoretti, M. et al. Nature 419, 456–459 (2002).
Gabrielse, G. et al. Phys. Rev. Lett. 89, 213401 (2002).
Gabrielse, G. et al. Phys. Rev. Lett. 89, 233401 (2002).
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Brumfiel, G. Holding up a mirror to physics' world view. Nature 420, 731 (2002). https://doi.org/10.1038/420731b
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DOI: https://doi.org/10.1038/420731b
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