The Nature of Space & Time

Spacetime is quantized. Geometry has a smallest possible area and volume, and the universe is built from a network of these atomic geometric units.

Spacetime is a discrete network of cause-and-effect relationships, not a smooth manifold. Order plus number equals geometry. The Sorkin program is one of the longest-running discrete-spacetime quantum-gravity research lines, with one striking quasi-empirical prediction (the magnitude of the cosmological constant).

Spacetime may not be fundamental. It could emerge from quantum entanglement, thermodynamic relations, or a discrete causal order, different proposals, same starting commitment.

Build spacetime from simple geometric blocks glued along a strict arrow of cause and effect. Run the path integral on a computer. A four-dimensional universe self-organizes from the discrete data. The most computationally productive discrete-spacetime program, with concrete numerical results no other quantum-gravity approach has produced at comparable detail.

A power-counting renormalizable quantum gravity theory that abandons full Lorentz invariance at high energies in favor of anisotropic scaling between space and time.