In what physicists have called a “technical tour-de-force”, scientists have for the first time made measurements of how antimatter atoms absorb light.1
Researchers from the ALPHA collaboration team at CERN, the European particle physics laboratory outside Geneva, collected cold antihydrogen atoms in a magnetic “bottle” and irradiated them with an ultraviolet laser to test what frequency of light is needed to excite the antimatter atoms into an excited state. This was done to test to see if antimatter atoms behave the same way as their normal matter counterparts. No discrepancy (a null result) was found with standard theory, which predicts that antihydrogen should have the same energy levels as normal hydrogen.
The null result is still a thrill for researchers who have been working for decades towards antimatter spectroscopy, the study of how light is absorbed and emitted by antimatter. The hope is that this field could provide a new test of a fundamental symmetry of the known laws of physics, called CPT (charge-parity-time) symmetry.
CPT symmetry predicts that energy levels in antimatter and matter should be the same. Even the tiniest violation of this rule would require a serious rethink of the standard model of particle physics.
So what? you might ask!