Finding the real world in a foam bath

A new approach to simulating quantum geometry suggests that starting with a random froth, one might expect a world of three dimensions of space and one of time to appear naturally at large scales. J Ambjørn of the Niels Bohr Institute in Copenhagen, J Jurkiewicz of Jagellonian University in Krakow, and R Loll of Utrecht University have added one crucial ingredient to the randomness – causality, or a speed limit of the speed of light – and this turns out to be enough to yield a world much like the one we live in. The authors comment that to their knowledge this is the “first example of a theory of quantum gravity that generates a quantum space-time with such properties dynamically.”