Collective Motion: Intro

Herds, flocks, schools, and even crowds can behave in fluid-like ways. On Science Friday, Stanford professor Nicholas Ouellette explains some of the physics behind these similarities. Fluids are, after all, made up of a many, many individual particles – typically molecules – just the way a crowd of people or a school of fish contains many individuals. What makes the collective behaviors of groups harder to model than a fluid, however, is a lack of randomness. In something like water, all the molecules move randomly, which allows scientists to make certain simplifications in how we describe that motion.

In animal group behaviors, on the other hand, the motion of an individual is not completely random. It instead seems to be governed by relatively simple rules based on the observations that an individual can make. Combine those rules across a large number of individuals and you can get what’s called emergent behavior – exactly the sort of large-scale patterns we see in swarms of insects, flocks of birds, and schools of fish. (Image credits: fish – N. Sharp; starlings – N. Fielding, source; battle – New Line Cinema; podcast credit: Science Friday; submitted by Michelle D.)

This week on FYFD, we’ll explore the world of collective motion and how it overlaps with fluid dynamics.

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