Seeing the ‘Big Bang’

How can astronomers look in any direction and see the ‘Big Bang’? Look in one direction and look back 13 billion years. Look in the opposite a see the same time. So the Universe is 26 billion light years across, right? WRONG It is so easy to confuse space and time when they are so bound up together. Indeed you have to change your geometry to understand it. In this instance to spherical.