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 combatant command command (COCOM), a specific type of nontransferable command authority over assigned forces, regardless of branch of service, that is vested only in the CCDRs by federal law in . The chain of command for operational purposes (per the Goldwater–Nichols Act) goes from the President through the Secretary of Defense to the combatant commanders. The current system of unified commands in the US military emerged during World War II with the establishment of geographic theaters of operation composed of forces from multiple service branches that reported to a single commander who was supported by a joint staff. A unified command structure