Cosmological Special Relativity (CSR) is a theory on cosmology that was developed in the early 1990s by theoretical physicist Moshe Carmeli. It describes the large structure of space, time and velocity in the Universe. The CSR theory unites space and velocity analogically as Einstein's special relativity theory does with space and time,[1] however it is associated with cosmos or galaxies in the Universe, respectively, rather than with very fast moving particles. The substance of Carmeli's Universe is called spacevelocity instead of spacetime. Carmeli postulated that the Hubble Law that relates the velocity of the expansion of the universe to the distance of the source is fundamental to all observers in the universe although rewritten into the new form. He replaced the Hubble constant which value varies widely depending on the method used and on the distances to the sources that were used to determine its value with new truly universal constant which is the same for all observers regardless of epoch (i.e. regardless of when the measurement is made) and named it Carmeli-Hubble constant. The CSR theory predicts unusual effects in the cosmos, like length contraction and velocity dilation for large-scale structures in the Universe. By including matter into his theory, Carmeli developed also his theory on Cosmological General Relativity.[2][3]