In the first half of the 20th century a great deal was written about capital theory, including writers such as Hayek, Böhm-Bawerk, Sraffa, Knight, Robinson and Fisher. Many of these figures debated and often staked out radically different schools of thought with regards to capital and interest. These debates seem to me some of the most interesting and difficult in all of economic theory. My impression as a non-economist is that there has not been much interest in the 21st century in these debates and it is not taught to students. My question is: is this true, and what is currently the "state of the art" in modern capital theory?
EDIT: Let me elaborate a bit. In the writers I mentioned, some favoured a "pure productivity" theory of interest (Knight), others favoured a "pure time preference" theory (Mises and, I would assume, Hayek), others favour a mixed productivity-time preference theory (Fisher), and other said that the interest rate is simply set by power relations and not by any market equilibrium (Sraffa). Robinson, I would assume, as a Keynesian, favoured a liquidity-preference theory. My impression is that modern economists favour some kind of synthesis between the Fisherian theory and the liquidity preference theory (is this impression of mine accurate?).
With regards to the Romer and Solow growth model mentioned by muflon, as far as I understand these are models with a homogeneous capital stock and so is essentially a "Knightian" theory, the same kind of theory that ignited the Cambridge Capital Controversy. I have seen one economist (Nick Rowe of "Worthwhile Canadian Initiative") say that the whole CCC debate was silly because both sides were trying to explain interest rates without any reference to time preference.
What motivated this question is that when I have tried to understand capital and interest I tend to get drawn to these very old works and very old debates. The various neoclassical growth models certainly use the concept of capital, but I wouldn't say they constitute capital theory in that don't seem to tackle the more fundamental questions associated with capital that got raised in the early 20th century debates.