How will interest rates and growth rates re-equalise?

In the United States and the euro zone at present, interest rates are considerably lower than growth rates. Yet, in the long term, they will inevitably re - equalise . So what mechanisms could potentially lead interest rates and growth rates to converge towards a common value? Under the mechanism expected by central banks, the very low interest rates will eventually lift inflation (and possibly also real potential growth), which will allow interest rates to rise to the level of growth; A nother possibility is that growth may fall to the level of interest rates instead . T his could result from the neo-Fisherian mechanism (low nominal interest rates depress expected inflation and therefore inflation in the long term) or from a fall in savings and therefore in investment, suppressing real growth. In Japan, where interest rates have been very low for 20 years, we note that: First, the interest rate is still lower than the growth rate, and inflation is still very low; The neo-Fisherian mechanism (a lower nominal interest rate leads to lower inflation) may be at work; Potential growth has declined, as has the savings rate. The convergence between interest rates and growth rates is therefore slow, and will tend to take place via a fall in growth.