Unified field theory classical field theory and, two years later, that of Theodor Kaluza, who extended General Relativity to five dimensions. Continuing in this latter direction, Oscar Klein proposed in 1926 that the fourth spatial dimension be curled up into a small, unobserved circle. In Kaluza–Klein theory, the gravitational curvature of the extra spatial direction behaves as an additional force similar to electromagnetism. These and other models of electromagnetism and gravity were pursued by Albert Einstein in his attempts at a classical unified field theory. By 1930 Einstein had already considered the Einstein–Maxwell–Dirac System [Dongen]. This system is (heuristically) the super-classical [Varadarajan] limit
Unified interoperability Unified interoperability Unified interoperability is the property of a system that allows for the integration of real-time and non-real time communications, activities, data, and information services (i.e., unified) and the display and coordination of those services across systems and devices (i.e., interoperability). Unified interoperability provides the capability to communicate and exchange processing across different applications, data, and infrastructure. Unified communications has been led by the business world, which has a need for efficiency, simplicity, and speed. Rather than a single tool or product, unified communications is a set of products that deliver a nearly identically user experience across multiple devices