Zeldovich played a key role in developing the theory of black hole evaporation due to Hawking radiation. Zeldovich and Charles W. Misner concomitantly predicted the possibility of particle generation by rotating Kerr black holes in 1971, 1972. Previously, In 1965, Zeldovich had predicted that Kerr black holes would split the emission lines of photons as in a Zeeman effect. During Stephen Hawking 's visit to Moscow in 1973, Soviet scientists Zeldovich and Alexei Starobinsky showed Hawking that, according to the quantum mechanical uncertainty principle, rotating black holes should create and emit particles.