It can't be stressed enough that the multiverse is utterly hypothetical—but that doesn't mean it isn't real. - Sean M. Carroll

The “reasons” and “causes” why things happen, in other words, aren’t fundamental; they are emergent. We need to dig in to the actual history of the universe to see why these concepts have emerged.

... I just want to understand the large-scale story that string gas cosmology is trying to sell us. We have nine dimensions of space — they are all very small — and in three dimensions they start unwinding and getting bigger. Is that the basic idea?

The mystery of the arrow of time comes down to this: Why were the conditions in the early universe set up in a particular way, in a configuration of low entropy that enabled all of the interesting and irreversible processes to come?