2018, Paper: "This paper shows that aging has positive effect on output growth per capital at positive interest rates, due to capital deepening. This is consistent with cross country data. This correlation, however, reverses itself if the process goes to far (as in post 2008) and a negative real interest rate is needed to clear the market. In that case, the data shows that aging has negative effect on output growth per capita. This new cross-country correlation is predicted by the secular stagnation hypothesis suggested by Summers (2014). We review the cross-country correlation in the data and highlight the mechanisms in a stripped down two generation OLG model with capital and nominal frictions."