Bizarre Traveling Flame Discovery
Steve Mould’s videos are always entertaining and informative but this one is also a little bit mind-blowing. If you build a circular trough with just the right dimensions and fill it with lighter fluid, a flame will travel around it. And other shapes will do other things — the effect created by the star/octopus shape is especially cool. The effect is an example of an excitable medium:
An excitable medium is a nonlinear dynamical system which has the capacity to propagate a wave of some description, and which cannot support the passing of another wave until a certain amount of time has passed (known as the refractory time).
A forest is an example of an excitable medium: if a wildfire burns through the forest, no fire can return to a burnt spot until the vegetation has gone through its refractory period and regrown.
Other examples:
Normal and pathological activities in the heart and brain can be modelled as excitable media. A group of spectators at a sporting event are an excitable medium, as can be observed in a Mexican wave (so-called from its initial appearance in the 1986 World Cup in Mexico).
(via waxy)
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