The  paper of  the  month,  chosen  by  the Editor-in-Chief,  is  "Old Questions and New Results – Recent Advances in Superconductivity"  by A. Wittlin;

DOI: 10.12693/APhysPolA.147.370

Superconductivity has been studied for over 100 years and is believed to be well understood. The generally accepted theory, i.e., the BCS theory, is based on electron pairing due to interactions with phonons. Despite its successes, this theory a widespread belief is that it cannot provide the ultimate mechanism of superconductivity. The failure of BCS to explain high-temperature superconductivity contributes to the need for finding a more fundamental mechanism. In the recommended paper, the author describes alternative approaches to superconductivity, concentrating on the hole theory formulated by J. Hirsch. This theory is not confirmed by experiments and is not as popular as the BSC. Nevertheless, it is very interesting to compare the approaches and find arguments for and against them. The paper sheds light on the problems and challenges of superconductivity. It is recommended for everybody interested in superconductivity and modern condensed matter physics.

The Editor-in-Chief