Causal Dynamical Triangulations (CDT) is a theoretical approach to quantum gravity that models the geometry of spacetime using simple, discrete building blocks. Instead of treating spacetime as a smooth continuum, CDT approximates it with tiny, flat, triangular pieces—like 4D versions of Lego bricks—that are pieced together in a way that respects causality (the distinction between past and future).
Key features of CDT:
- Spacetime is constructed from simplices, the higher-dimensional analogs of triangles and tetrahedra, to form a dynamically evolving geometry.
- Unlike earlier methods that allowed spacetime to branch or behave chaotically, CDT preserves a consistent causal structure, keeping time flowing forward.
- It allows physicists to simulate quantum spacetime numerically, exploring how classical spacetime (like general relativity) might emerge from quantum rules at tiny scales.
Notable results and implications:
- CDT has reproduced four-dimensional spacetime from basic rules, suggesting that large-scale spacetime can emerge from quantum discreteness.
- It provides a path to understanding how quantum fluctuations in geometry behave at the Planck scale.
- CDT avoids many of the pathologies found in earlier “Euclidean” approaches to quantum gravity.
Though still a developing field, Causal Dynamical Triangulations offers a promising and intuitive framework for understanding the quantum origin of space and time, rooted in simplicity, causality, and computability.