A highschool physics teacher tried to explain it to us, before sighing and saying we'd see if we pursue education in this field otherwise screw it, with the idea that we measure the position of things as if they're in a grid.

One moment the nearby grid is 1 million blocks wide for the x, y and z axis. The following moment, the grid measures the same things but it's a 1 million and 1 blocks for the x, y and z axis. Some moments later, it's now 1 million and 2 blocks, still for the very same things inside. From our perspective on the inside, it gives an impression of getting further away.