I'm imagining our Universe being more or less like a sphere, with its outer edge expanding at light-speed (or close to it). But any sphere has a center, and I would guess the Universe is no exception (if indeed it resembles that form). If we were to go backwards in time, all the matter in the Universe would converge towards this center point. And that's where I thought the Big Bang happened. Then I googled a bit and found this page: "The best, non-mathematical description that any cosmologist can create for describing the Big Bang is that it occurred in every cubic centimeter of space in the universe with no unique starting point." No unique starting point... how could that be? Any thoughts?