Physicists at CERN have constructed an anti-hydrogen atom made of a positron and antiproton. These antimatter atoms are being used to test a principal called Charge-parity-time, which says that antimatter should behave exactly like regular matter. This means that if our universe were made of majority antimatter, all the physics would work exactly the same.

Working with antimatter isn’t easy – given any opportunity to interact with regular electrons and protons in regular atoms, these antimatter atoms cease to exist as the convert into other particles through a burst of energy. The folks at CERN are getting good at containment, however, and have recently determined that the energy levels of an excited anti-hydrogen atom are the same as those in a regular hydrogen atom, including having tiny differences in energy that come from different spin states as electrons transition between energy levels. This slight difference, called the Lamb shift after it’s discoverer, is small, and is the kind of subtle physics that folks at CERN are checking out one by one as they look for antimatter to behave oddly. So far – antimatter is proving totally normal, if a bit hard to work with.

More Information

• Antimatter hydrogen has the same quantum quirk as normal hydrogen (Science News)