No. of Recommendations: 2
The Big Bang Theory posits an expanding universe, but I don't understand this concept and despite reading multiple books, I'm still clueless. So if anybody can shed some light on this, I would appreciate it. The analogy is usually given of a balloon expanding so that every point on its surface gets further and further away from every other point. That's fine but if the balloon was the universe itself, what is it expanding into? There is nothing outside of the universe. (Forget the 2D vs 3D, I can accept though can't visualize a 3D surface as a boundary of a 4D shape).
