Wh<answer>i</answer>le the B<answer>i</answer>g Bang model <answer>i</answer>s well establ<answer>i</answer>shed <answer>i</answer>n cosmology, <answer>i</answer>t <answer>i</answer>s l<answer>i</answer>kely to be ref<answer>i</answer>ned <answer>i</answer>n the future. L<answer>i</answer>ttle <answer>i</answer>s known about the earl<answer>i</answer>est moments of the un<answer>i</answer>verse's h<answer>i</answer>story. The Penrose–Hawk<answer>i</answer>ng s<answer>i</answer>ngular<answer>i</answer>ty theorems requ<answer>i</answer>re the ex<answer>i</answer>stence of a s<answer>i</answer>ngular<answer>i</answer>ty at the beg<answer>i</answer>nn<answer>i</answer>ng of cosm<answer>i</answer>c t<answer>i</answer>me. However, these theorems assume that general relat<answer>i</answer>v<answer>i</answer>ty <answer>i</answer>s correct, but general relat<answer>i</answer>v<answer>i</answer>ty must break down before the un<answer>i</answer>verse reaches the Planck temperature, and a correct treatment of quantum grav<answer>i</answer>ty may avo<answer>i</answer>d the s<answer>i</answer>ngular<answer>i</answer>ty.
How much is known about the early states of the universe?
i