What about us that thinks that everything goes in cycles, but that a downturn can be prevented?
About science developing in an exponential manner without growth spurts, i think that it's only true if you look at the large picture. If you were to look closer you would find areas where little to none innovation are going on, and others where there are clear growth spurts. For example, i would say that road building were an area where many new innovations were made during the 20'ies and 30'ies. In the later years almost no new major ways to build roads (or even transportation infrastructure) have been found. In almost all areas it will look the same, but as a whole we're advancing faster and faster.