“Because for Everettians, the explanation of the quantum arrow of time is the same as that of the entropic arrow of time: the initial conditions of the universe. Branching happens when systems become entangled with the environment and decohere, which unfolds as time moves toward the future, not the past. The number of branches of the wave function, just like the entropy, only increases with time. That means that the number of branches was relatively small to begin with. In other words, that there was a relatively low amount of entanglement between various systems and the environment in the far past. As with entropy, this is an initial condition we impose on the state of the universe, and at the present”