Yakov Borisovich Zel'dovich, Belarusian physicist, astronomer, and cosmologist (b. 1914)
Yakov Borisovich Zeldovich (Belarusian: Я́каў Бары́савіч Зяльдо́віч, Russian: Я́ков Бори́сович Зельдо́вич; 8 March 1914 – 2 December 1987), also known as YaB, was a leading Soviet theoretical physicist, who is known for his prolific contributions in cosmology and the physics of thermonuclear and hydrodynamical phenomena.From 1943, Zeldovich played a crucial role in the development of the Soviet Union's nuclear bomb project. In 1963, he returned to academia to embark on pioneering contributions on the fundamental understanding of the thermodynamics of black holes and expanding the scope of cosmology.