It is a well-established fact that the universe is expanding. It grows without center, like an inflating raisin cake, but an infinite raisin cake filling all of space in all directions. The raisins are the galaxies. A problem I’ve had with this explanation is that if everything were to double in size — galaxies, houses, you and me, rulers — then we’d never notice. I might be a towering giant, but if the room is equally huge, I wouldn’t know….