“The interaction of highly charged heavy ions with electrons is one of the most important atomic processes in high-temperature plasmas,” explains University of Electro-Communications researcher Nobuyuki Nakamura in his recent J Phys B topical review. These high-temperature plasmas occur in a surprisingly large range of scenarios from astrophysical plasmas and solar corona, to fusion reactors and even laser-induced plasmas for short wavelength nanoscale photolithography, raising the stakes for understanding their behaviour. Nakamura’s review summarises how the relativistic effects resulting in the “Breit interaction” can play a significant role in these processes.