Perhaps “multiverse” would have been a better word.
Imagine an electron in an eigenstate. It’s moving around the atom, but the entire waveform is stationary. Similarly, if the entire universe is in an eigenstate, the universe would still be moving, but the probability for a given universe would stay constant. Put another way, as time passes in this universe, a parallel universe just like this one was moments ago moves into its place. We have no way of proving that this doesn’t happen. In fact, to some extent, it must. The immediate past is almost exactly like the present, so a universe that looks just like it must have similar amplitude to this one now.
Perhaps “multiverse” would have been a better word.
Imagine an electron in an eigenstate. It’s moving around the atom, but the entire waveform is stationary. Similarly, if the entire universe is in an eigenstate, the universe would still be moving, but the probability for a given universe would stay constant. Put another way, as time passes in this universe, a parallel universe just like this one was moments ago moves into its place. We have no way of proving that this doesn’t happen. In fact, to some extent, it must. The immediate past is almost exactly like the present, so a universe that looks just like it must have similar amplitude to this one now.