A team in the PRISMA+ cluster of excellence at the Johannes Gutenberg University in Mainz succeeded in computing how atomic nuclei of the Calcium element behave in collisions with electrons. Results agree very well with available experimental data. For the first time, a calculation based on a fundamental theory is capable of correctly describing experiments for a nucleus as heavy as Calcium. Of particular relevance is the potential that such calculations could have in the future to interpret neutrino experiments. The renowned journal Physical Review Letters reports on the achieved milestone in its current volume.