Anti-de Sitter space bell. It might be described as being the "opposite" of the surface of a sphere, which has a positive curvature. General relativity is a theory of the nature of time, space and gravity in which gravity is a curvature of space and time that results from the presence of matter or energy. Energy and mass are equivalent (as expressed in the equation "E" = "mc"), and space and time can be translated into equivalent units based on the speed of light ("c" in the "E" = "mc" equation). A common analogy involves the way that a dip in a flat
Southern Pacific class MC-6 Southern Pacific class MC-6 Southern Pacific Company's MC-6 class of steam locomotives is made up of two batches: the first consisting of 15 locomotives weighing built in 1912, the second consisting of 5 locomotives weighing built in 1913. All of the locomotives were built by Baldwin Locomotive Works. This was the last class of 2-8-8-2 locomotives that Southern Pacific (SP) ordered as cab forward locomotives. Locomotive number 4043, the newest of the early class of MC-6 locomotives, was displayed at the Panama–Pacific International Exposition along with SP's first locomotive, "C. P. Huntington". All but three of the locomotives in this