This is due to the fact the mild coming from items inhabiting those far off areas of Spacetime has no longer had sufficient time to make its lengthy journey to us for the reason that Big Bang--due to the growth of the Universe. In astronomy lengthy Gravity Theory Cream in the past is the same as a ways away. The greater distant an item is in Space, the older it's miles in Time (Spacetime). It is not possible to find an item in Space, without additionally knowing when it existed in Time.