How can the unification of quantum mechanics and general relativity be achieved within a theoretical framework, considering the principles of symmetry, field theory, and mathematical elegance? Additionally, how might emerging theories like string theory, loop quantum gravity, and supersymmetry contribute to this unification, and what experimental evidence could validate or falsify these theoretical constructs? Moreover, what implications would a successful unification have for our understanding of fundamental forces, spacetime geometry, and the nature of the universe at both microscopic and cosmological scales? Finally, how can these theoretical frameworks inform practical applications such as quantum computing, gravitational wave detection, and the quest for a unified theory of physics?