In the 1960s, economists began to investigate the origins of the technological level, but in the 1970s, when immense macroeconomic problems began to crop up in almost every corner of the world, we economists turned our attention to problems other than growth.
Since the 1980s, economic research has made a focused and intensive attempt to include the factors that affect the increase in productivity, within the framework of economic models, in what is known as “the new theory of economic growth.” The results of this new theory of economic growth are spelled out at length in an excellent book that my friend, Professor Elhanan Helpman, published in 2004 under the title The Mystery of Economic Growth.