Carl Friedrich Freiherr von Weizsäcker (German: [kaʁl ˈfʁiːdʁɪç fɔn ˈvaɪtsɛkɐ]; 28 June 1912 – 28 April 2007) was a German physicist and philosopher. He was the longest-living member of the team which performed nuclear research in Germany during the Second World War, under Werner Heisenberg's leadership. There is ongoing debate as to whether or not he and the other members of the team actively and willingly pursued the development of a nuclear bomb for Germany during this time.