Overlapping generations is a spectral issue

If the generations over lap sufficiently then balance is maintained, income and outgoes remain neutral. It s bth a mathematical requirement for their models to converge, but it is a social requirements for the generations to survival.  Survival matches the math. The two almost never match, the theory behind This Time is Different,that famous book on sovereign debt. Often they are not that far apart. Overlappng generations, a valid and testable theory. Proper overlappers survive.

It is a spectral issue because the the optimum overlap minimizes timing mismatches, and that is bell shaped. So we can look at the shape of the population and get a good idea about the health of families in teir day to day lives. Tha is a spectral transform,  and we can usually this with bell shaped curves. Humans do this, they estimate survival then initiate activity on a schedule to survive. We can do this when we over lapped well, otherwise our world gets shocked with pension stampedes, market crashes, bankrupt governments. The bad happens because when not bell shaped, we are aliased, we cycle and pay a cost around the loop. California vs federal government, lousy overlappers and decades of unnecessary cycling a result.

In math we can go from a distribution of events by frequency to a distribution of wealth. The proper overlapping means we are precise enough  let us to aggregate sums over actions. Both distributions are bell shaped.  We don't have that, we cycle big time. Our loop costs large and increasing.