It's for me very hard to think of parts of the world that are taking part, acting, go to a place where they can't be seen or show anymore. The physical world is one would be my way to put it. But it's reconciled me a little to that to realize that what we're talking about, in the formation of a black hole, is in some ways the reverse of what we talk about when we talk of the Big Bang in which the universe was born. A lot of physical activity coming out of a region where there is no physical activity to begin with. Well, we're very far from being able to deal with these ultimate questions in a truly satisfactory way now. I would put the question in its largest form this way: how come existence? How come that there is anything at all? And the black hole is a standing invitation to consider that issue, because you get something going to nothing, well, then, how do you get out of nothing, something? How do you turn it around? Here we're skating at the frontier between physics and philosophy. I always say that philosophy is too important to be left to the philosophers, but it's one thing to say that, it's another thing to see what philosophical idea will carry us through this new frontier of mystery that faces us now with renewed force. Renewed force because we study the evidence for the big bang ever more fully in astrophysics, and we study the evidence of crunch to a black hole ever more in the cores of Milky Ways like ours.