In branching processes you can find the probability of the system going extinct by finding the roots of the polynomial where the coefficients are the probabilities and the exponents are the number generated.  The smallest root between 0 and 1 will be the answer.  What do the other roots mean?  Basically the root corresponds to when the system is zero (extinct).  We can have all kinds of roots: complex, negative, positive > 1 roots.  So, what do they mean?  Do they mean anything.  Well wikipedia has a page on exotic probability so, I guess they might have some meaning… http://en.wikipedia.org/wiki/Exotic_probability. Can’t find anything on the subject so who knows…