In Conway's Game of Life
The first known puffer, in Conway's Game of Life, was discovered by Bill Gosper; it is a dirty puffer, but eventually stabilizes to leave a pattern of debris that repeats every 140 generations. Since then, many puffers have been discovered for this cellular automaton, with many different speeds and periods. Puffers are significant for Life and related rules for three reasons: First, if they can be stabilized in such a way that they produce only gliders (that is, turned into rakes) they can be used as part of many more complex patterns such as breeders. Second, stabilizations of puffers that eliminate all of their output debris can be used to produce spaceships with arbitrarily large periods. And third, puffers can sometimes be tamed or combined to form spaceships with speeds that do not seem to be achievable in other ways; for instance, in Life, the switch engine is a puffer train discovered by Charles Corderman that moves diagonally at speed c/12, and in 1991 Dean Hickerson showed how to combine several switch engines to form a c/12 spaceship that he called the Cordership.
Read more about this topic: Puffer Train
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