Quantum gravity is a field of theoretical physics that seeks to unify quantum mechanics and general relativity into a single, consistent framework. While quantum mechanics describes the behavior of particles and forces at the smallest scales, and general relativity explains gravity and the structure of spacetime at large scales, the two theories are currently incompatible in extreme environments—such as black holes and the Big Bang.
The goal of quantum gravity is to understand:
- How gravity behaves at the Planck scale, where both quantum and gravitational effects are equally strong
- The quantum nature of spacetime itself, possibly treating it as discrete or fluctuating
- How to resolve paradoxes, such as the black hole information loss problem
Leading approaches to quantum gravity include:
- String theory: Proposes that particles are tiny vibrating strings, and gravity emerges naturally from one of these vibrations
- Loop quantum gravity: Describes space as a network of quantized loops, predicting a granular structure of spacetime
- Causal dynamical triangulations, asymptotic safety, and other models exploring the fabric of space and time using different tools
Although a full theory of quantum gravity has not yet been confirmed by experiment, it remains a major goal in fundamental physics, promising to reveal the true nature of reality, space, time, and gravity.