The Speed Force is a dimension in and of itself. The dimension is composed entirely of the Speed Force energy, and the SF connects with other dimensions, such as the one to which Earth belongs. The Speed Force has enough agency that it can choose people to channel its energies, which manifests in those connected to the Speed Force receiving their characteristic superhuman speed and related abilities. Accessing too much SF energy (which often happens by attempting to move “too quickly”) can lead a speedster to transcend their home dimension and enter the Speed Force as a form of Valhalla/afterlife. It’s supposed to be blissful, but naturally, many speedsters avoid entering the Speed Force because it’s not especially easy to leave.
