We used to think that if we knew one, we knew two, because one and one are two. We are finding out that we must learn a great deal more about 'and'."         
- Sir Arthur Eddington (1882-1944)

Despite the universe's tendency towards disarray (like the socks in your drawer), there is a surprising amount of spontaneous order in the universe: stars clump into galaxies, atoms combine to form organized crystals, ants work together in a colony, species interact with each other and the physical environment to form ecosystems, cells build the different parts of a person, and neurons coordinate their firing to produce thought. When thousands of components get together in just the right way, something remarkable happens—they fall into recognizable, persistent patterns in space or in time. We live in a universe in which interactions among the basic building blocks of matter, or among individuals in our societies, give rise to unpredicted and unexpected emergent behavior. This occurs for many different types of things, large and small, living and inanimate.

Emergence is the study of how order arises from chaos, of how the interactions of simple objects with each other and their environment give rise to highly complex and often surprising behaviors.

Synchrony pervades the living world: some types of fireflies will flash in unison, the cacophony of crickets converges to a unified chirping, and populations of locusts swarm every 17 years. More sophisticated synchrony is found in the life cycle of an ant colony. Individual ants react robotically to chemical signals left by their neighbors during their short life span, while the colony as a whole lives, matures, and dies as a single organism that outlives any of its constituent, crawling parts.