Puzzles in the QG landscape

The second edition of “Puzzles in the QG Landscape” took place in Graz, Austria, from 14 to 18 September 2026. Following the inaugural meeting held at the Perimeter Institute in 2023, the conference again brought together researchers from across the quantum gravity community to share results and — perhaps more ambitiously — to build a common language between the many different theoretical approaches to the subject. The conference was organized by Alessia Platania (U of Graz), Benjamin Knorr (Heidelberg U), and Marc Schiffer (Nijmegen U).

The scientific program covered a broad spectrum of approaches to quantum gravity, ranging from effective field theory, amplitudes, and the S-matrix bootstrap, through string theory and the swampland program, to loop quantum gravity and spin foams, asymptotic safety, dynamical triangulations, causal sets, group field theory, non-commutative geometry, and quantum gravity phenomenology.

Twenty invited speakers presented their respective approaches to quantum gravity, as well as their work, representing institutions across Europe, North America, and beyond. Among them were Markus Aspelmeyer (U Vienna), Emil Bjerrum-Bohr (NBI Copenhagen), Bianca Dittrich (Perimeter Institute), Fay Dowker (Imperial College), Astrid Eichhorn (Heidelberg U), Roberto Emparan (U of Barcelona), Laurent Freidel (Perimeter Institute), Renate Loll (U of Nijmegen), and Roberto Percacci (SISSA), to name just a few. The schedule also featured longer discussion sessions after the morning talks and panel discussions in the afternoon. The days closed with time for informal discussions over coffee and cake.

The long panel discussions in the afternoon were a highlight. With their broad perspective and sometimes provocative questions, such as “Key open problems in QG: can we agree?”, “What would falsify your QG approach?” and “What should the next decade of QG research look like?”, they challenged panel members and audience to think beyond their daily work. Interesting discussions among the participants ensued and common ground was often found despite the wide variety of opinions and viewpoints that were expressed.

The program was complemented by a gong show and poster session for contributed work, with the best posters awarded a closing talk slot. The poster session was impressive, with many excellent entries. The Poster Prize winners were Gabriel Assant (University of Sussex) and Lidia Marino (Heidelberg U), honorable mentions went to Daniele Berruti (Heidelberg U), Francesco Ferrarin (NBI), Francesco Del Porro (NBI) and Paul P. Sprenge (Heidelberg U).

The city of Graz, surrounded by picturesque mountains, with its splendidly preserved historic center, its castle hill, and many inviting restaurants and cafés added to the good time of the participants.

Overall, the meeting was intense and rewarding for me, and to my mind it demonstrated once again that the quantum gravity community benefits from regular occasions to step back from individual research programs, learn about progress in adjacent approaches, discuss overarching questions, and be challenged by different viewpoints. The next edition of Puzzles is eagerly anticipated.