Compact dimension

In string theory, a model used in theoretical physics, a compact dimension is curled up in itself and very small (usually Planck length). Anything moving along this dimension's direction would return to its starting point almost instantaneously, and the fact that the dimension is smaller than the smallest particle means that it cannot be observed by conventional means. Extra dimensions in a theory which are made compact are said to have undergone compactification. In string theory, a model used in theoretical physics, a compact dimension is curled up in itself and very small (usually Planck length). Anything moving along this dimension's direction would return to its starting point almost instantaneously, and the fact that the dimension is smaller than the smallest particle means that it cannot be observed by conventional means. Extra dimensions in a theory which are made compact are said to have undergone compactification.