Universe
It is worth mediately determining what the Cosmos is all about: Its appearance is the beginning of the expansion of the Universe, before which the Universe was in a singular state, that is, it had infinite density and temperature. In fact, singularity is a very contradictory concept, because having infinite density, a substance cannot have infinite temperature - and vice versa. That is why the phenomenon of cosmic singularity is one of the biggest mysteries of modern astrophysics, because the data allow scientists to guess what was AFTER the Big Bang, but not what was before...