A stadium wave, also referred to as "The Wave," refers to a planned, rolling movement of spectators inside a sporting venue or stadium. The wave usually starts with a small group of spectators standing up and raising their arms in unison, then grows as more spectators join in. The end product is a rolling motion that seems to circle the stadium, giving the illusion of a wave.
The physics underlying The Wave is fairly straightforward: the movement is brought about by the sequential contraction and relaxation of groups of muscles in the fans' upper arms and bodies. A rolling motion moves through the audience as one section of fans raises their arms and stands up, then another section does the same, and so on.
The Wave has been investigated by scientists and mathematicians as an example of self-organizing behavior in crowds, despite being mainly a form of sports fan cheer. The Wave is a well-known tradition at sporting events all over the world because it is an amazing illustration of how a straightforward, well-coordinated action can spread through a big crowd and foster a feeling of unity and enthusiasm.