what is 5d dimension

In physics and mathematics, a five-dimensional space is a space with five dimensions. The fifth dimension is considered a spatial dimension, like the three dimensions of length, height, and depth that we are familiar with. In theory, it is a plane of spacetime that is curved in on itself so tightly that the entire dimension is a loop smaller than an atom. The fifth dimension is too small to be noticed by humans, and its existence can only be indirectly observed through its theoretical effects on the fundamental forces of the universe, mainly gravity. The fifth dimension was proposed independently by physicists Oskar Klein and Theodor Kaluza in the 1920s, inspired by Einsteins theory of gravity, which showed that mass warped four-dimensional space-time. The fifth dimension is not directly observable, but it is believed to exist in some theories of physics and mathematics.