Although both Hans Bethe and Edward Teller advocated for a world without fission bombs, we could not talk about two more different people. Teller’s harsh and aggressive character contrasted with the conciliatory personality of Bethe. The former is remembered because of his unstoppable and unconditional aim to success; the latter for his lead of one of the most select teams of the Manhattan Project, in which also Bethe was involved. Stellar nucleosynthesis, the most intimate process that occurs in the core of the stars, awarded Bethe with the Nobel Prize in 1967. Teller is well known for being the father of the Hydrogen bomb, despite his complaints about the bombing of Hiroshima and Nagasaki. We owe them both much of what we know about nuclear fission, the reaction that generates energy in nuclear plants. This is also the same reaction that unleashes the terrible destruction of an atomic bomb. Both scientists were forced to leave their homes and to take part, from a lab, in a war that they rejected.