According to Gordon up until about 1750 growth was driven by population growth. Since then we have had three industrial revolutions. The first from 1750 to 1830 and was the age of steam. It brought us railroads and some industrial labor saving machines.
The second revolution which occurred in the early and mid 20th century was built technologies discovered in the late 19th century such as electricity, the internal combustion engine, running water, sewage and communication such as radio and telephone. This was an age that had a huge impact on the living standards of people.
The third was the information age which started about 50 years ago. It consisted of semiconductors, computers and the internet. It gave us access to increasing amounts of information but not much else.
It was during the second industrial revolution that economic growth increased while with a few exceptions the rate begin to decline at the beginning of the information age. There have been few really new technological innovation in the 20th century just building on the old.
Of course the end of cheap resources like oil will only exacerbate the problem. The good old days are not coming back - get used to it!