Loop Quantum Gravity: A Themed Issue in Honor of Prof. Abhay Ashtekar

Dear Colleagues,

Unification of gravity and quantum theory remains one of the most important outstanding problems of theoretical physics. In 1986, Ashtekar’s discovery of new variables led to a novel formulation of general relativity which overcame challenging problems in the canonical quantum gravity approach, leading to the birth of loop quantum gravity program. The reformulation of general relativity not only allowed gravity to be viewed on the lines of Yang-Mills theory, but it also had various applications in classical and quantum aspects of physics of black holes, numerical relativity, and cosmology. In the last three decades, both the canonical and covariant versions of loop quantum gravity have systematically addressed long-standing questions in quantum gravity. While research in the 1990s and the first half of the 2000s established a mathematically rigorous non-perturbative background independent treatment of quantum gravity, showing the way classical differential geometry of Einstein’s theory of general relativity is replaced by quantum geometry,  the last 15 years have seen many developments to understand the detailed structure of quantum Riemannian geometry, quantum dynamics, and the physical implications of quantum geometry for cosmology and black holes.

35 years have passed since Prof. Abhay Ashtekar's detailed paper on the "New Hamiltonian formulation of general relativity." This Special Issue is designed in honor of Prof. Abhay Ashtekar, to highlight developments in various sub-fields of loop quantum gravity and its covariant version of spinfoams. Articles from leading experts in the field, from different regions around the world, showcase the current state of the art.

Prof. Dr. Parampreet Singh
Guest Editor

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