When you think about it, a package’s arrival on your front porch is no simple matter.

Your click on the World Wide Web (a network) passed through the physical internet (a network) that is powered by the power grid (a network), which itself relies on its own private communications network. Finally, your package traveled through the postal network to come to your door.

Had any of these networks broken down, your delivery could never have happened.

“We depend on interacting networks every day, and we’re hugely susceptible if they fail,” says SFI External Professor Raissa D’Souza, who organized a conference on the topic in June at SFI.

Despite our dependence on interacting networks, their emergent properties are hardly understood, even though the science of networks has come of age over the last decade or so, she says.

The gathering brought together network theorists and practitioners to develop new tools to identify and understand the unforeseen consequences of these interactions.

“We are developing theoretical techniques to model interdependent networks,” she says. “Bringing theorists and practitioners together will help ensure the models are realistic.”