Hi, I am struggling to understand Stephen Hawking's view of the universe as a 4D closed manifold. In a recent interview, I believe he had this to say: What I don't understand is how this theory is compatible with the scientific observation that the universe is expanding? I have 2 questions: 1) what is it expanding into? - the word expanding contains an implicit reference to some reference point external to the thing that is expanding? 2) the word 'expanding' contains an implicit reference to time, how does this fit into his theory?