Quantum gravity research has continued to be an active and vibrant field of study following Stephen Hawking's work and the ongoing development of string theory. While Stephen Hawking made significant contributions to our understanding of black holes, his work did not provide a complete theory of quantum gravity.
String theory, which emerged as a prominent framework in the late 20th century, remains an active area of research. It is a theoretical framework that attempts to reconcile quantum mechanics with general relativity by describing fundamental particles as tiny vibrating strings. However, string theory is still a work in progress and has not yet been experimentally confirmed. Researchers are actively exploring various aspects of string theory, such as its mathematical structure, different string compactifications, and its relationship to other areas of physics.
In addition to string theory, there are other approaches and ideas being pursued in the quest for quantum gravity. Some notable areas of research include loop quantum gravity, causal dynamical triangulation, asymptotic safety, and holography (such as the AdS/CFT correspondence). These approaches aim to address the challenges of quantum gravity by proposing alternative frameworks, exploring different mathematical structures, and examining the relationship between gravity and other fundamental forces.
It's important to note that quantum gravity research is a highly complex and challenging field. The unification of quantum mechanics and general relativity remains one of the most significant open problems in theoretical physics. Progress in this area requires deep mathematical insights, experimental validation, and the exploration of new theoretical frameworks. While there has been ongoing research, a complete and definitive theory of quantum gravity is yet to be realized.