Force A Grand Unified Theory that allows for the combination of the electroweak interaction with the strong force is held out as a possibility with candidate theories such as supersymmetry proposed to accommodate some of the outstanding unsolved problems in physics. Physicists are still attempting to develop self-consistent unification models that would combine all four fundamental interactions into a theory of everything. Einstein tried and failed at this endeavor, but currently the most popular approach to answering this question is string theory. What we now call gravity was not identified as a universal force until the work of Isaac Newton. Before
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