Actual 4D chess move https://en.wikipedia.org/wiki/Four-dimensional_space >>Higher dimensional spaces (i.e., greater than three) have since become one of the foundations for formally expressing modern mathematics and physics. Large parts of these topics could not exist in their current forms without the use of such spaces. Einstein's concept of **spacetime** uses such a 4D space, though it has a Minkowski structure that is a bit more complicated than Euclidean 4D space. https://en.wikipedia.org/wiki/Minkowski_space >>In mathematical physics, Minkowski space (or Minkowski spacetime) (/mɪŋˈkɔːfski, -ˈkɒf-/[1]) is a combination of three-dimensional Euclidean space and **time**