Based on contributions from the Jerzy Lewandowski Memorial Conference, held from September 15–19, 2025, at the Banach Center in Warsaw, this collection of peer-reviewed articles intends to include review papers as well as original research honoring his memory and continue scientific discussions in the areas that were central to his research passion.

All speakers, as well as selected poster presenters, are invited to submit their papers for peer review to the journal General Relativity and Gravitation. Publication under the subscription model is free of charge, open-access is offered for a fee or under the terms of Springer's institutional agreements.

This collection is based on peer-reviewed contributions from ICERM's Topical Workshop at Brown University, where researchers in mathematical and numerical relativity gathered to discuss extremal black holes and the implications of a recent disproof of the third law of black-hole thermodynamics. The dynamics and criticality of extremal and near-extremal black holes are particularly interesting in light of recently found instabilities.

The rigorous mathematical proof that an extremal Reissner–Nordström black hole can form dynamically raises questions about the regions of parameter space that do so as well as speculations about extremal Kerr dynamics. Numerical and mathematical work of workshop participants address many of these questions.

All speakers are invited to submit their papers for peer review to the journal General Relativity and Gravitation. Publication under the subscription model is free of charge, open-access is offered for a fee or under the terms of Springer's institutional agreements.