It is claimed by many that the half-time of the technical knowledge we learned in school is about 15 years. In other words, half of them will be obsolete in 15 years. Either we will have gone in other directions or they will have been replaced with new material.
With the aforementioned phenomenon, knowledge has doubled almost every 17 years, we can estimate that the technical knowledge involved in our life will quadruple in about 34 years. Therefore, thirty years later when some of us may be near the high point of the career, we may be faced with quadruple involved knowledge with much of our learned knowledge obsolete.