It may be that the great technology slow-down noted here (and also in Charles

Murray’s book Human Accomplishment) is linked to demographic decline.

I have just written a book that contains the following paragraph:

When you assemble materials for a broad intellectual history like this, you
find … that the achievements of the 19th century tend to dominate your
narrative. Whether you take that century in the strictly calendrical sense
of 1800-1899, or in the more subtle Lukacsian sense of 1815-1914, it was a
period of simply stunning intellectual achievement. Mathematics in
particular, and algebra in very particular, went through a period of
sensational growth — “explosive development,” say Bashmakova and Smirnova —
through that century. The 20th century, while not a complete waste of time,
was disappointing by comparison. I have mentioned (§ 4.3) James J. Walsh’s
book The Thirteenth, Greatest of Centuries. It’s an interesting book, but
Walsh was fundamentally mistaken. For the enlargement of human
understanding and for sheer boiling intellectual creativity, the Nineteenth
was the greatest of centuries. There is simply no competitor.