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
Comparametric equation Comparametric equation A comparametric equation is an equation that describes a parametric relationship between a function and a dilated version of the same function, where the equation does not involve the parameter. For example, "ƒ"(2"t") = 4"ƒ"("t") is a comparametric equation, when we define "g"("t") = "ƒ"(2"t"), so that we have "g" = 4"ƒ" no longer contains the parameter, "t". The comparametric equation "g" = 4"ƒ" has a family of solutions, one of which is "ƒ" = "t". To see that "ƒ" = "t" is a solution, we merely substitute back in: "g" = "ƒ"(2"t") = (2"t") = 4"t" =