If the large uranium nucleus split into two smaller nuclei, the smaller nuclei would weigh less in total than their common parent. How much less? That was a calculation she could easily work: about one-fifth the mass of a proton less. Process one-fifth of the mass of a proton through E = mc2. “One fifth of a proton mass,” Frisch exclaims, “was just equivalent to 200 MeV. So here was the source for that energy; it all fitted!”992
