A null reaction is a reaction between two or more objects that has no net effect, as if the objects did not react at all. The most common usage is for a reaction with a catalyst or sparker that is equivalent to if the catalyst or sparker had not been there. The term was popularized and possibly created by David Raucci, although he incorrectly believed it was already in common use at the time.[citation needed]
This is a period-18 sparker. The first interaction with the two period-6 sparkers is required for the oscillator to function, but the second is a null reaction—some of the sparks evolve differently, but it doesn't affect the overall evolution. (click above to open LifeViewer)