The properties of matter are typically the result of complex interactions between electrons. These electrically charged particles are one of the fundamental building blocks of nature. They are well researched, and theoretical physics has determined the electronic structure of the majority of matter. However, the behavior of matter under extreme conditions is still largely unexplained. Such conditions can be found in places where very high pressure and high temperatures prevail, such as in the interior of stars and planets. Here, matter exists in an exotic state on the border between solid, liquid and gas. A research group at Kiel University and the Helmholtz-Zentrum Dresden-Rossendorf has now developed a new method to describe the dynamic properties of this so-called “warm dense matter” for the first time. They have published their computer simulations in Physical Review Letters.