Classical unified field theories Classical unified field theories Since the 19th century, some physicists, notably Albert Einstein, have attempted to develop a single theoretical framework that can account for all the fundamental forces of nature – a unified field theory. Classical unified field theories are attempts to create a unified field theory based on classical physics. In particular, unification of gravitation and electromagnetism was actively pursued by several physicists and mathematicians in the years between the two World Wars. This work spurred the purely mathematical development of differential geometry. This article describes various attempts at formulating a classical (non-quantum), relativistic unified field theory. For
Unified growth theory take-off from an epoch of stagnation to the modern era of sustained growth. The testable predictions of this evolutionary theory and its underlying mechanisms have been confirmed empirically and quantitatively. Unified growth theory contributes to Macrohistory. It sheds light on the divergence in income per capita across the globe during the past two centuries. It identifies the factors that have governed the transition from stagnation to growth and have thus contributed to the observed worldwide differences in economic development. It highlights the persistent effects that variations in historical and prehistorical conditions have had on the composition of human capital and