# Complex Networks in Qunatum Gravity and Cosmology

**When:**Thursday, February 06, 2014 at 1:30 pm

**Where:**DA 5th fl

**Speaker**: Associate Professor Dmitri Krioukov

**Organization**: Northeastern University

**Sponsor**: Joint Network and CCNR Seminar

Causal sets are perhaps the most simplistic approach to quantum gravity. Regardless of what theory of quantum gravity turns out to be correct, if Lorentz invariance is preserved at the Planck scale, then causal sets represent the causal structure of spacetime at this fundamental scale. Causal sets are networks whose nodes are Planck-scale atoms of spacetime (elementary “quantum events”), and two nodes are linked if the two atoms are causally related (if the two events lie within each other’s light cone).

Here we show that these networks in any asymptotically de Sitter space-time, such as the global spacetime of our accelerating universe, is a power-law graph with strong clustering, similar to many complex networks such as the Internet, social, or biological networks. We prove that this structural similarity is a consequence of the asymptotic equivalence between the large-scale growth dynamics of complex networks and de Sitter causal sets. This equivalence suggests that unexpectedly similar laws govern the dynamics of complex networks and spacetime in the universe.