Zhores A. Medvedev

Scientist Zhores Mevedvev was the first scientist in the West to determine that the Soviet Union suffered a nuclear accident in 1957, three decades before Chernobyl. He has a new book called "The Legacy of Chernobyl," about the latter disaster -- which contributed to the Soviet Union's glasnost and perestroika reforms. Medvedev's father was exiled from Russia; Medvedev himself faced persecution for his research and activism.