It is called Eternalism. It’s the philosophy adopted from the quantum theory that the past, present, and future all exist at the same time. In other words, the past, present, and future are not linear. One does not take place right after the other, rather they all exist equally.
In the past (Ha!), time was regarded as a force that acted upon the other three dimensions. With quantum mechanics and the space time continuum, time is considered the fourth dimension, referred to as a “block,” unchanging, like the other three.