According to Wikipedia Hawking started his work after another physicist pointed out that rotating black holes should emit radiation. Maybe that stuck somehow.

According to Wikipedia Hawking started his work after another physicist pointed out that rotating black holes should emit radiation. Maybe that stuck somehow. Hawking's work followed his visit to Moscow in 1973 where the Soviet scientists Yakov Zeldovich and Alexei Starobinsky showed him that, according to the quantum mechanical uncertainty principle, rotating black holes should create and emit particles.