“How did time begin, and how will it end? Most things have a beginning and an end, including time itself. What was the spark that made it begin, and what will one day bring it to an end?”—”In reality, the beginning and end of the Universe continue to challenge our understanding. In particular, there is still uncertainty about how time began and what it was like in the early Universe. As for the distant future and whether time will end, that’s even harder to say – and it depends partly on what we mean by ‘time’.” “One possible explanation is to again suppose that there are other universes besides our own. ‘There’s a whole bunch of universes and they all just had different initial states,’ says [philosopher Emily] Adlam. However, conscious beings like ourselves could probably only exist in universes that have increasing entropy – as the Twelfth Doctor explains to a lecture hall full of bemused students in The Pilot.” “If this view of time is correct, ‘there’s no special virtue in explaining things by earlier things,’ says Adlam. Instead, the present, future and past all depend on each other in ways we don’t understand. Our language lets us down here, because it is so reliant on the assumption of the one-way flow of time. The above explanation refers to the Universe doing a gigantic calculation, as if there was a time when it hadn’t done it and a later time when it had. But if this interpretation is correct, then concepts like ‘before’ and ‘after’ don’t really apply. You may need to sit with this for a minute.”