In 1970 they published a proof that if the universe obeys the general theory of relativity and fits any of the models of physical cosmology developed by Alexander Friedmann, then it must have begun as a singularity.
Tahun 1970, mereka mengumumkan bukti bahwa apabila alam semesta mematuhi teori relativitas umum dan pas dengan semua model kosmologi fisik Alexander Friedmann, alam semesta pasti berawal dari singularitas (ketunggalan).